5 Wk: MASTER IT 1 ASSIGNMENT: Macronutrients (Protein focus)
25 POINTS
PURPOSE
PART I: YOUR FOOD RECORD
A major component of this class is an in-depth assessment of your own diet using Cronometer, which is
a nutrition tracking application that analyses your dietary intake. Each Diet Analysis assignment is
designed to help you apply the concepts you learn in this course to your own diet and analyze how your
dietary choices affect your health. You’ll set goals to be healthier in each assignment, too. It is a good
“ball park” estimate and not considered a very accurate look at your intake since it is only one day and it
is based on many estimates and the challenge of having accurate records and correct data input when
you are new to this activity.
PURPOSE: The purpose of this part of the assignment is to, first, keep a 1-day food record that will be
used for analysis in the Cronometer application. Studies show that keeping a food journal can help make
people more aware of day-to-day food choices. Being more aware of your food choices and thinking
about your personal eating goals helps give you guidance about how you are doing, and where you
might want to improve.
INSTRUCTIONS
PART A: KEEP A 1-DAY FOOD RECORD (5 points)
•
•
•
To get started, choose 1 day to record your food and beverage intake. Select 1 typical weekday
(Monday, Tuesday, Wednesday, Thursday or Friday) to record your intake.
Record what you eat using the Food Diary form provided in D2L. You may find it helpful to take
pictures of your meal and drinks for the day to have for a double check if your records are
complete. To make the data more useful, try to avoid the natural tendency to change your
eating habits or level of activity while you are recording your food intake.
Be detailed and as accurate as possible when you are recording your food and beverage intake.
Be sure to include amount or portion sizes (cups, ounces, teaspoons, tablespoons, etc.) and the
preparation method (fresh, grilled, fried, baked, etc.) as it applies.
Record each bite or sip through the day. Don’t forget water, beverages, condiments, spreads, snacks You
will complete a 1-day food record and then enter it into Cronometer for nutrition analysis. You’ll use
your 1-day food record and the Nutrient Summary report your saved as a pdf from Cronometer to
complete this Master It Assignment.
The purpose of this assignment is to take an in-depth look at your personal macronutrient intake. You
will analyze the types of protein you personally consume and discuss a vegetarian case study. Then,
you’ll evaluate your overall protein intake and discuss specific ways you might improve.
As a reminder, the purpose of each ‘Master It’ assignment is to show that you have “mastered” the
concepts in each module. The ‘Master It’ assignments are meant to be equivalent to an exam. As so,
your answers should be comprehensive, well-thought and organized to demonstrate you have
mastered the concepts.
Learning Objectives from Ch 6 Reviewed in this Assignment:
•
•
•
Explain the relationship between protein intake and health.
Analyze how your own macronutrient intake compares to your body’s needs
Analyze how your protein choices affect your health.
INSTRUCTIONS
PART B: Macronutrients IN YOUR FOOD RECORD (15 points)
Using your 1-day food journal and the Nutrient Summary report from Cronometer, answer the following
questions. For full credit, you must answer each part of the question.
1. Use your Nutrient Summary report to indicate the total grams of carbohydrate you consumed.
Then, calculate what percent of your total calories came from carbohydrate. (determine calories
from carbohydrate and then divide by total calories) How does this compare to the AMDR for
carbohydrate? What percent of your calories came from sugar? *How does this compare to
recommendations?
A. Total Grams of
B. Percent of Total Calories
C. How does this compare to
D.Total Grams of sugar intake:
Carbohydrate you ate
that Came from
the AMDR for Carbohydrate?
E. Calculate % of total calories
(use table from nutrient
Carbohydrate
that came from sugar.
summary report & not
(show your work for your
Determine calories from sugar &
the chart which gives net calculation)
divide by total calories) (show
carbohydrates instead of
work)
total carbohydrates)
F. *How it Compares to diet
recommendations:
2. Use your Nutrient Summary report to indicate the total grams of protein you consumed. Then,
calculate what percent of your total calories came from protein. (Determine calories from
protein and then divide by total calories) How does this compare to the AMDR for protein?
A. Total Grams of Protein you
ate
B. Percent of Total Calories that
Came from Protein
(show your work for your
calculation)
C. How does this compare to
the AMDR for protein?
D. How does it compare to
your minimal protein
requirements?
3. Use your Nutrient Summary report to indicate the total grams of fat you consumed. Then,
calculate percent of your total calories that came from fat. How does this compare to the AMDR
for fat? (Determine calories from fat then divide by total calories)
4.
Total Grams of fat
Percent of Total
How does this
What % of calories
you ate
Calories from fat
compare to the
came from saturated
(show your work for
AMDR for fat ?
fat?
your calculation)
How does this compare
to recommendations?
5. The Recommended Daily Allowance (RDA) for protein is based on an individual’s body weight.
Most healthy adults need 0.8 grams of protein for every kilogram (kg) of body weight. To
determine a person’s minimum daily protein requirements, first, convert their body weight from
pounds to kilograms. Then, multiplying the weight in kilograms by 0.8. (TIP: There are 2.2 pounds
in 1 kilogram).
6. Using the formula above, calculate your minimum daily protein needs by using the RDA for
protein. Describe how this compares to the total grams of protein you consumed? Show your
work for your calculations and answer in a paragraph.
Kg ___ X .8 gm/kg = _______. Grams you consumed on this day _______
Paragraph:
7. A. What type(s) of protein primarily make up your diet?
B. Are there any plant-based proteins in your 1-day food record?
C. What personal or environmental factors affect your personal protein food choices?
PART B: VEGETARIAN CASE STUDY (5 points)
Use the case scenario below to answer questions 6 and 7. For full credit, you must answer each part of
the question. Each response should be a minimum of 100 words.
Case Scenario: Molly is a 28-year-old college student. She weighs 132 pounds and is moderately active.
She is also a lacto-ovo vegetarian. On a typical day, Molly eats:
Breakfast: 1 cup of oatmeal with 2 Tbs soy milk, ½ cup raspberries and 6 walnut halves, 1 hardboiled
egg; coffee
Lunch: 2 slices of whole grain toast, 2 Tbs peanut butter, 1 small banana, 6 oz Greek yogurt; water
Dinner: 1 cup quinoa, ½ avocado, 1 cup roasted vegetables and ¼ cup hummus; water
Snack: 1 KIND bar, 1 medium apple
8. Molly tells you that she recently learned about the concept of high-quality and complementary
proteins. Since she is vegetarian, Molly is wondering if she should be eating complementary
proteins. To begin answering Molly’s question, start by describing the difference between highquality and complementary proteins. What does being a lacto-ovo vegetarian mean? Then
explain whether Molly needs to be concerned about this based on your assessment of her usual
food intake.
9. Molly also tells you that she has been thinking about becoming vegan. She has heard that a
plant-based diet is “the best diet,” but she has also been told that vegans are at risk for certain
nutrient deficiencies. Describe the benefits to eating a plant-based diet to Molly. Then, give her
advice about planning a nutritious vegan diet if she chose to become vegan. What nutrients may
become deficient in a vegan diet if not properly planned? (Make sure to identify at least one
vitamin, mineral and macronutrient)
CHAPTER 4.
CARBOHYDRATES
Chapter 4. Carbohydrates | 227
Introduction
E ʻai i ka mea i loaʻa
What you have, eat
Two
Breadruit by
Michael
Coghlan /
CC BY-SA 2.0
Learning Objectives
By the end o this chapter, you will be able to
•
Describe the dierent types o simple and complex
carbohydrates
Introduction | 229
•
Describe the process o carbohydrate digestion and
absorption
•
Describe the unctions o carbohydrates in the
body
•
Describe the body’s carbohydrate needs and how
personal choices can lead to health benets or
consequences
Throughout history, carbohydrates have and continue to be a major
source o people’s diets worldwide. In ancient Hawai‘i the Hawaiians
obtained the majority o their calories rom carbohydrate rich plants
like the ‘uala (sweet potato), ulu (breadruit) and kalo (taro). For
example, mashed kalo or poi was a staple to meals or Hawaiians.
Research suggests that almost 78 percent o the diet was made up
1
o these ber rich carbohydrate oods.
Carbohydrates are the perect nutrient to meet your body’s
nutritional needs. They nourish your brain and nervous system,
provide energy to all o your cells when within proper caloric limits,
and help keep your body t and lean. Specically, digestible
carbohydrates provide bulk in oods, vitamins, and minerals, while
indigestible carbohydrates provide a good amount o ber with a
host o other health benets.
Plants synthesize the ast-releasing carbohydrate, glucose, rom
1. Fujita R, Braun KL, Hughes CK. (2004). The traditional
Hawaiian diet a review o the literature. Pacic Health
Dialogue, 11(2). http//pacichealthdialog.org.j/
Volume2011/no2/
PHD1120220p2162022120Yamada20orig.pd. Accessed
October 19, 2017.
230 | Introduction
carbon dioxide in the air and water, and by harnessing the sun’s
energy. Recall that plants convert the energy in sunlight to chemical
energy in the molecule, glucose. Plants use glucose to make other
larger, more slow-releasing carbohydrates. When we eat plants we
harvest the energy o glucose to support lie’s processes.
Figure 4.1
Carbohydrat
e
Classicatio
n Scheme
Carbohydrat
es are broken
down into
the
subgroups
simple and
complex
carbohydrate
s. These
subgroups
are urther
categorized
into mono-,
di-, and
polysacchari
des.
Carbohydrates are a group o organic compounds containing a ratio
o one carbon atom to two hydrogen atoms to one oxygen atom.
Basically, they are hydrated carbons. The word “carbo” means
carbon and “hydrate” means water. Glucose, the most abundant
carbohydrate in the human body, has six carbon atoms, twelve
hydrogen atoms, and six oxygen atoms. The chemical ormula or
glucose is written as C6H12O6. Synonymous with the term
carbohydrate is the Greek word “saccharide,” which means sugar.
The simplest unit o a carbohydrate is a monosaccharide.
Carbohydrates are broadly classied into two subgroups, simple
(“ast-releasing”)
and
complex
(“slow-releasing”).
Simple
Introduction | 231
carbohydrates are urther grouped into the monosaccharides and
disaccharides.
Complex
carbohydrates
are
long
chains
o
monosaccharides.
Simple/Fast-Releasing Carbohydrates
Simple carbohydrates are also known more simply as “sugars” and
are
grouped
as
either
monosaccharides
or
disaccharides.
Monosaccharides include glucose, ructose, and galactose, and the
disaccharides include lactose, maltose, and sucrose.
Simple carbohydrates stimulate the sweetness taste sensation,
which is the most sensitive o all taste sensations. Even extremely
low concentrations o sugars in oods will stimulate the sweetness
taste
sensation.
Sweetness
varies
between
the
dierent
carbohydrate types—some are much sweeter than others. Fructose
is the top naturally-occurring sugar in sweetness value.
Monosaccharides
For all organisms rom bacteria to plants to animals, glucose is the
preerred uel source. The brain is completely dependent on glucose
as its energy source (except during extreme starvation conditions).
The monosaccharide galactose diers rom glucose only in that a
hydroxyl (−OH) group aces in a dierent direction on the number
our carbon (Figure 4.2 “Structures o the Three Most Common
Monosaccharides Glucose, Galactose, and Fructose”). This small
structural alteration causes galactose to be less stable than glucose.
As a result, the liver rapidly converts it to glucose. Most absorbed
galactose is utilized or energy production in cells ater its
conversion to glucose. (Galactose is one o two simple sugars that
232 | Introduction
are bound together to make up the sugar ound in milk. It is later
reed during the digestion process.)
Fructose also has the same chemical ormula as glucose but
diers in its chemical structure. The ructose ring contains 4
carbons while the glucose ring contains 5 carbons. Fructose, in
contrast to glucose, is not an energy source or other cells in the
body. Mostly ound in ruits, honey, and sugarcane, ructose is one
o the most common monosaccharides in nature. It is also ound
in sot drinks, cereals, and other products sweetened with high
ructose corn syrup.
Figure 4.2
Structures o
the Three
Most
Common
Monosacchar
ides: Glucose,
Galactose,
and Fructose
Circles
indicate the
structural
dierences
between the
three.
Pentoses are less common monosaccharides which have only ve
carbons and not six. The pentoses are abundant in the nucleic acids
RNA and DNA, and also as components o ber.
Lastly, there are the sugar alcohols, which are industrially
synthesized derivatives o monosaccharides. Some examples o
sugar alcohols are sorbitol, xylitol, and glycerol. (Xylitol is similar
in sweetness as table sugar). Sugar alcohols are oten used in place
o table sugar to sweeten oods as they are incompletely digested
and absorbed, and thereore less caloric. The bacteria in your mouth
opposes them, hence sugar alcohols do not cause tooth decay.
Introduction | 233
Interestingly, the sensation o “coolness” that occurs when chewing
gum that contains sugar alcohols comes rom them dissolving in the
mouth, a chemical reaction that requires heat rom the inside o the
mouth.
Disaccharides
Disaccharides are composed o pairs o two monosaccharides linked
together. Disaccharides include sucrose, lactose, and maltose. All o
the disaccharides contain at least one glucose molecule.
Sucrose, which contains both glucose and ructose molecules,
is otherwise known as table sugar. Sucrose is also ound in many
ruits and vegetables, and at high concentrations in sugar beets
and sugarcane, which are used to make table sugar. Lactose, which
is commonly known as milk sugar, is composed o one glucose
unit and one galactose unit. Lactose is prevalent in dairy products
such as milk, yogurt, and cheese. Maltose consists o two glucose
molecules bonded together. It is a common breakdown product o
plant starches and is rarely ound in oods as a disaccharide.
Figure 4.3
The Most
Common
Disaccharide
s
Image by
Allison
Calabrese /
CC BY 4.0
234 | Introduction
Complex/Slow-Releasing Carbohydrates
Complex carbohydrates are polysaccharides, long chains o
monosaccharides that may be branched or not branched. There are
two main groups o polysaccharides starches and bers.
Starches
Starch molecules are ound in abundance in grains, legumes, and
root vegetables, such as potatoes. Amylose, a plant starch, is a
linear chain containing hundreds o glucose units. Amylopectin,
another plant starch, is a branched chain containing thousands o
glucose units. These large starch molecules orm crystals and are
the energy-storing molecules o plants. These two starch molecules
(amylose and amylopectin) are contained together in oods, but the
smaller one, amylose, is less abundant. Eating raw oods containing
starches provides very little energy as the digestive system has a
hard time breaking them down. Cooking breaks down the crystal
structure o starches, making them much easier to break down
in the human body. The starches that remain intact throughout
digestion are called resistant starches. Bacteria in the gut can break
some o these down and may benet gastrointestinal health.
Isolated and modied starches are used widely in the ood industry
and during cooking as ood thickeners.
Figure 4.4
Structures o
the Plant
Starches and
Glycogen
Introduction | 235
Humans and animals store glucose energy rom starches in the orm
o the very large molecule, glycogen. It has many branches that
allow it to break down quickly when energy is needed by cells in the
body. It is predominantly ound in liver and muscle tissue in animals.
Dietary Fibers
Dietary bers are polysaccharides that are highly branched and
cross-linked. Some dietary bers are pectin, gums, cellulose,
hemicellulose, and lignin. Lignin, however, is not composed o
carbohydrate units. Humans do not produce the enzymes that can
break down dietary ber; however, bacteria in the large intestine
(colon) do. Dietary bers are very benecial to our health. The
Dietary Guidelines Advisory Committee states that there is enough
scientic evidence to support that diets high in ber reduce the
risk or obesity and diabetes, which are primary risk actors or
2
cardiovascular disease.
Dietary ber is categorized as either water-soluble or insoluble.
Some examples o soluble bers are inulin, pectin, and guar gum
and they are ound in peas, beans, oats, barley, and rye. Cellulose
and lignin are insoluble bers and a ew dietary sources o them
are whole-grain oods, fax, caulifower, and avocados. Cellulose is
the most abundant ber in plants, making up the cell walls and
providing structure. Soluble bers are more easily accessible to
2. US Department o Agriculture. Part D. Section 5:
Carbohydrates. In Report o the DGAC on the Dietary
Guidelines or Americans, 2010.
http//www.cnpp.usda.gov/Publications/
DietaryGuidelines/2010/DGAC/Report/
D-5-Carbohydrates.pd. Accessed September 30, 2011.
236 | Introduction
bacterial enzymes in the large intestine so they can be broken down
to a greater extent than insoluble bers, but even some breakdown
o cellulose and other insoluble bers occurs.
The last class o ber is unctional ber. Functional bers have
been added to oods and have been shown to provide health
benets to humans. Functional bers may be extracted rom plants
and puried or synthetically made. An example o a unctional ber
is psyllium-seed husk. Scientic studies show that consuming
psyllium-seed husk reduces blood-cholesterol levels and this health
claim has been approved by the FDA. Total dietary ber intake is the
sum o dietary ber and unctional ber consumed.
Figure 4.5
Dietary Fiber
Image by
Allison
Calabrese /
CC BY 4.0
Introduction | 237
Learning Activities
Technology Note The second edition o the Human
Nutrition Open Educational Resource (OER) textbook
eatures interactive learning activities. These activities are
available in the web-based textbook and not available in the
downloadable versions (EPUB, Digital PDF, Print_PDF, or
Open Document).
Learning activities may be used across various mobile
devices, however, or the best user experience it is strongly
recommended that users complete these activities using a
desktop or laptop computer.
An interactive H5P element has been excluded
rom this version o the text. You can view it
online here:
humannutrition2e22/?p=165#h5p-42
An interactive H5P element has been excluded
rom this version o the text. You can view it
238 | Introduction
online here:
humannutrition2e22/?p=165#h5p-43
Introduction | 239
Digestion and Absorption of
Carbohydrates
From the Mouth to the Stomach
The mechanical and chemical digestion o carbohydrates begins
in the mouth. Chewing, also known as mastication, crumbles the
carbohydrate oods into smaller and smaller pieces. The salivary
glands in the oral cavity secrete saliva that coats the ood particles.
Saliva contains the enzyme, salivary amylase. This enzyme breaks
the bonds between the monomeric sugar units o disaccharides,
oligosaccharides, and starches. The salivary amylase breaks down
amylose and amylopectin into smaller chains o glucose, called
dextrins and maltose. The increased concentration o maltose in the
mouth that results rom the mechanical and chemical breakdown
o starches in whole grains is what enhances their sweetness. Only
about ve percent o starches are broken down in the mouth. (This
is a good thing as more glucose in the mouth would lead to more
tooth decay.) When carbohydrates reach the stomach no urther
chemical breakdown occurs because the amylase enzyme does not
unction in the acidic conditions o the stomach. But mechanical
breakdown is ongoing—the strong peristaltic contractions o the
stomach mix the carbohydrates into the more uniorm mixture o
chyme.
240 | Digestion and Absorption o
Carbohydrates
Figure 4.6
Salivary
Glands in the
Mouth
Salivary
glands
secrete
salivary
amylase,
which begins
the chemical
breakdown
o
carbohydrate
s by breaking
the bonds
between
monomeric
sugar units.
From the Stomach to the Small Intestine
The chyme is gradually expelled into the upper part o the small
intestine. Upon entry o the chyme into the small intestine, the
pancreas releases pancreatic juice through a duct. This pancreatic
juice contains the enzyme, pancreatic amylase, which starts again
the breakdown o dextrins into shorter and shorter carbohydrate
chains. Additionally, enzymes are secreted by the intestinal cells
that line the villi. These enzymes, known collectively as
disaccharidase, are sucrase, maltase, and lactase. Sucrase breaks
sucrose into glucose and ructose molecules. Maltase breaks the
bond between the two glucose units o maltose, and lactase breaks
the bond between galactose and glucose. Once carbohydrates are
Digestion and Absorption o Carbohydrates | 241
chemically broken down into single sugar units they are then
transported into the inside o intestinal cells.
When people do not have enough o the enzyme lactase, lactose is
not suciently broken down resulting in a condition called lactose
intolerance. The undigested lactose moves to the large intestine
where bacteria are able to digest it. The bacterial digestion o
lactose produces gases leading to symptoms o diarrhea, bloating,
and abdominal cramps. Lactose intolerance usually occurs in adults
and is associated with race. The National Digestive Diseases
Inormation Clearing House states that Arican Americans, Hispanic
Americans, American Indians, and Asian Americans have much
higher incidences o lactose intolerance while those o northern
1
European descent have the least.
Most people with lactose
intolerance can tolerate some amount o dairy products in their
diet. The severity o the symptoms depends on how much lactose is
consumed and the degree o lactase deciency.
Absorption: Going to the Blood Stream
The cells in the small intestine have membranes that contain many
transport proteins in order to get the monosaccharides and other
nutrients into the blood where they can be distributed to the rest o
the body. The rst organ to receive glucose, ructose, and galactose
is the liver. The liver takes them up and converts galactose to
glucose, breaks ructose into even smaller carbon-containing units,
1. Lactose Intolerance. National Digestive Diseases
Inormation Clearing House.
http//digestive.niddk.nih.gov/ddiseases/pubs/
lactoseintolerance/. Updated April 23, 2012. Accessed
September 22, 2017.
242 | Digestion and Absorption o Carbohydrates
and either stores glucose as glycogen or exports it back to the
blood. How much glucose the liver exports to the blood is under
hormonal control and you will soon discover that even the glucose
itsel regulates its concentrations in the blood.
Figure 4.7
Carbohydrat
e Digestion
Carbohydrat
e digestion
begins in the
mouth and is
most
extensive in
the small
intestine.
The resultant
monosacchar
ides are
absorbed
into the
bloodstream
and
transported
to the liver.
Maintaining Blood Glucose Levels: The Pancreas
and Liver
Glucose levels in the blood are tightly controlled, as having either
too much or too little glucose in the blood can have health
consequences. Glucose regulates its levels in the blood via a process
called negative eedback. An everyday example o negative eedback
is in your oven because it contains a thermostat. When you set
the temperature to cook a delicious homemade noodle casserole
at 375°F the thermostat senses the temperature and sends an
electrical signal to turn the elements on and heat up the oven.
When the temperature reaches 375°F the thermostat senses the
Digestion and Absorption o Carbohydrates | 243
temperature and sends a signal to turn the element o. Similarly,
your body senses blood glucose levels and maintains the glucose
“temperature” in the target range. The glucose thermostat is located
within the cells o the pancreas. Ater eating a meal containing
carbohydrates glucose levels rise in the blood.
Insulin-secreting cells in the pancreas sense the increase in
blood glucose and release the hormone, insulin, into the blood.
Insulin sends a signal to the body’s cells to remove glucose rom the
blood by transporting it into dierent organ cells around the body
and using it to make energy. In the case o muscle tissue and the
liver, insulin sends the biological message to store glucose away as
glycogen. The presence o insulin in the blood signies to the body
that glucose is available or uel. As glucose is transported into the
cells around the body, the blood glucose levels decrease. Insulin has
an opposing hormone called glucagon. Glucagon-secreting cells in
the pancreas sense the drop in glucose and, in response, release
glucagon into the blood. Glucagon communicates to the cells in the
body to stop using all the glucose. More specically, it signals the
liver to break down glycogen and release the stored glucose into the
blood, so that glucose levels stay within the target range and all cells
get the needed uel to unction properly.
244 | Digestion and Absorption o Carbohydrates
Figure 4.8
The
Regulation o
Glucose
Image by
Allison
Calabrese /
CC BY 4.0
Leftover Carbohydrates: The Large Intestine
Almost all o the carbohydrates, except or dietary ber and
resistant starches, are eciently digested and absorbed into the
body. Some o the remaining indigestible carbohydrates are broken
down by enzymes released by bacteria in the large intestine. The
products
o
bacterial
digestion
o
these
slow-releasing
carbohydrates are short-chain atty acids and some gases. The
short-chain atty acids are either used by the bacteria to make
energy and grow, are eliminated in the eces, or are absorbed into
cells o the colon, with a small amount being transported to the
liver. Colonic cells use the short-chain atty acids to support some
o their unctions. The liver can also metabolize the short-chain
atty acids into cellular energy. The yield o energy rom dietary
ber is about 2 kilocalories per gram or humans, but is highly
dependent upon the ber type, with soluble bers and resistant
Digestion and Absorption o Carbohydrates | 245
starches yielding more energy than insoluble bers. Since dietary
ber is digested much less in the gastrointestinal tract than other
carbohydrate types (simple sugars, many starches) the rise in blood
glucose ater eating them is less, and slower. These physiological
attributes o high-ber oods (i.e. whole grains) are linked to a
decrease in weight gain and reduced risk o chronic diseases, such
as Type 2 diabetes and cardiovascular disease.
Figure 4.9
Overview o
Carbohydrat
e Digestion
Image by
Allison
Calabrese /
CC BY 4.0
A Carbohydrate Feast
You are at a your grandma’s house or amily dinner and you just
consumed kalua pig, white rice, sweet potatoes, mac salad, chicken
long rice and a hot sweet bread roll dripping with butter. Less
than an hour later you top it o with a slice o haupia pie and
then lie down on the couch to watch TV. The “hormone o plenty,”
insulin, answers the nutrient call. Insulin sends out the physiological
message that glucose is abundant in the blood, so that cells can
absorb it and either use it or store it. The result o this hormone
246 | Digestion and Absorption o Carbohydrates
message is maximization o glycogen stores and all the excess
glucose, protein, and lipids are stored as at.
Image by
Allison
Calabrese /
CC BY 4.0
A typical American Thanksgiving meal contains many oods that are
dense in carbohydrates, with the majority o those being simple
sugars and starches. These types o carbohydrate oods are rapidly
digested and absorbed. Blood glucose levels rise quickly causing a
spike in insulin levels. Contrastingly, oods containing high amounts
o ber are like time-release capsules o sugar. A measurement
o the eects o a carbohydrate-containing ood on blood-glucose
levels is called the glycemic response.
Glycemic Index
The glycemic responses o various oods have been measured and
then ranked in comparison to a reerence ood, usually a slice o
white bread or just straight glucose, to create a numeric value called
the glycemic index (GI). Foods that have a low GI do not raise bloodglucose levels neither as much nor as ast as oods that have a
higher GI. A diet o low-GI oods has been shown in epidemiological
and clinical trial studies to increase weight loss and reduce the risk
2
o obesity, Type 2 diabetes, and cardiovascular disease.
2. Brand-Miller J, et al. (2009). Dietary Glycemic Index
Digestion and Absorption o Carbohydrates | 247
Table 4.1 The Glycemic Index Foods In Comparison To Glucose – Low GI
Foods (< 55)
Foods
GI Value
Apple, raw
36
Orange, raw
43
Banana, raw
51
Mango, raw
51
Carrots, boiled
39
Taro, boiled
53
Corn tortilla
46
Spaghetti (whole wheat)
37
Baked beans
48
Soy milk
34
Skim milk
37
Whole milk
39
Yogurt, ruit
41
Yogurt, plain
14
Ice cream
51
Health Implications. Journal o the American College o
Nutrition, 28(4),
446S–49S.https//www.ncbi.nlm.nih.gov/pubmed/
20234031. Accessed September 27, 2017.
248 | Digestion and Absorption o Carbohydrates
Table 4.2 The Glycemic Index Foods In Comparison To Glucose –
Medium GI Foods (56–69)
Foods
GI Value
Pineapple, raw
59
Cantaloupe
65
Mashed potatoes
70
Whole-wheat bread
69
Brown rice
55
Cheese pizza
60
Sweet potato, boiled
63
Macaroni and cheese
64
Popcorn
65
Digestion and Absorption o Carbohydrates | 249
Table 4.3 The Glycemic Index Foods In Comparison To Glucose – High GI
Foods (70 and higher)
Foods
GI Value
Banana (over-ripe)
82
Corn chips
72
Pretzels
83
White bread
70
White rice
72
Bagel
72
Rice milk
86
Cheerios
74
Raisin Bran
73
Fruit roll-up
99
Gatorade
78
For
the
Glycemic
Index
on
dierent
oods,
visit
http//www.mendosa.com/gilists.htm.
The type o carbohydrate within a ood aects the GI along with
its at and ber content. Increased at and ber in oods increases
the time required or digestion and delays the rate o gastric
emptying into the small intestine which, ultimately reduces the GI.
Processing and cooking also aects a ood’s GI by increasing their
digestibility. Advancements in the technologies o ood processing
and the high consumer demand or convenient, precooked oods in
the United States has created oods that are digested and absorbed
more rapidly, independent o the ber content. Modern breakast
cereals, breads, pastas, and many prepared oods have a high GI.
In contrast, most raw oods have a lower GI. (However, the more
ripened a ruit or vegetable is, the higher its GI.)
The GI can be used as a guide or choosing healthier carbohydrate
choices but has some limitations. The rst is GI does not take into
account the amount o carbohydrates in a portion o ood, only the
type o carbohydrate. Another is that combining low- and high-GI
250 | Digestion and Absorption o Carbohydrates
oods changes the GI or the meal. Also, some nutrient-dense oods
have higher GIs than less nutritious ood. (For instance, oatmeal has
a higher GI than chocolate because the at content o chocolate is
higher.) Lastly, meats and ats do not have a GI since they do not
contain carbohydrates.
More Resources
Visit this online database to discover the glycemic indices
o oods. Foods are listed by category and also by low,
medium, or high glycemic index.
http//www.gilisting.com/
Learning Activities
Technology Note The second edition o the Human
Nutrition Open Educational Resource (OER) textbook
eatures interactive learning activities. These activities are
available in the web-based textbook and not available in the
downloadable versions (EPUB, Digital PDF, Print_PDF, or
Open Document).
Learning activities may be used across various mobile
devices, however, or the best user experience it is strongly
recommended that users complete these activities using a
desktop or laptop computer.
Digestion and Absorption o Carbohydrates | 251
An interactive H5P element has been excluded
rom this version o the text. You can view it
online here:
https://pressbooks.oer.hawaii.edu/
humannutrition2e22/?p=172#h5p-44
An interactive H5P element has been excluded
rom this version o the text. You can view it
online here:
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252 | Digestion and Absorption o Carbohydrates
The Functions of
Carbohydrates in the Body
There are ve primary unctions o carbohydrates in the human
body. They are energy production, energy storage, building
macromolecules, sparing protein, and assisting in lipid metabolism.
Energy Production
The primary role o carbohydrates is to supply energy to all cells
in the body. Many cells preer glucose as a source o energy versus
other compounds like atty acids. Some cells, such as red blood
cells, are only able to produce cellular energy rom glucose. The
brain is also highly sensitive to low blood-glucose levels because
it uses only glucose to produce energy and unction (unless under
extreme starvation conditions). About 70 percent o the glucose
entering the body rom digestion is redistributed (by the liver) back
into the blood or use by other tissues. Cells that require energy
remove the glucose rom the blood with a transport protein in their
membranes. The energy rom glucose comes rom the chemical
bonds between the carbon atoms. Sunlight energy was required to
produce these high-energy bonds in the process o photosynthesis.
Cells in our bodies break these bonds and capture the energy to
perorm cellular respiration. Cellular respiration is basically a
controlled burning o glucose versus an uncontrolled burning. A cell
uses many chemical reactions in multiple enzymatic steps to slow
the release o energy (no explosion) and more eciently capture the
energy held within the chemical bonds in glucose.
The rst stage in the breakdown o glucose is called glycolysis.
Glycolysis, or the splitting o glucose, occurs in an intricate series
The Functions o Carbohydrates in
the Body | 253
o ten enzymatic-reaction steps. The second stage o glucose
breakdown occurs in the energy actory organelles, called
mitochondria. One carbon atom and two oxygen atoms are
removed, yielding more energy. The energy rom these carbon
bonds is carried to another area o the mitochondria, making the
cellular energy available in a orm cells can use.
Figure 4.10
Cellular
Respiration
Image by
Allison
Calabrese /
CC BY 4.0
Cellular respiration is the process by which energy is captured rom
glucose.
Energy Storage
I the body already has enough energy to support its unctions, the
excess glucose is stored as glycogen (the majority o which is stored
in the muscles and liver). A molecule o glycogen may contain in
excess o ty thousand single glucose units and is highly branched,
allowing or the rapid dissemination o glucose when it is needed to
make cellular energy.
254 | The Functions o Carbohydrates in the Body
The amount o glycogen in the body at any one time is equivalent
to about 4,000 kilocalories—3,000 in muscle tissue and 1,000 in the
liver. Prolonged muscle use (such as exercise or longer than a ew
hours) can deplete the glycogen energy reserve. Remember that this
is reerred to as “hitting the wall” or “bonking” and is characterized
by atigue and a decrease in exercise perormance. The weakening
o muscles sets in because it takes longer to transorm the chemical
energy in atty acids and proteins to usable energy than glucose.
Ater prolonged exercise, glycogen is gone and muscles must rely
more on lipids and proteins as an energy source. Athletes can
increase their glycogen reserve modestly by reducing training
intensity and increasing their carbohydrate intake to between 60
and 70 percent o total calories three to ve days prior to an event.
People who are not hardcore training and choose to run a
5-kilometer race or un do not need to consume a big plate o
pasta prior to a race since without long-term intense training the
adaptation o increased muscle glycogen will not happen.
The liver, like muscle, can store glucose energy as a glycogen,
but in contrast to muscle tissue it will sacrice its stored glucose
energy to other tissues in the body when blood glucose is low.
Approximately one-quarter o total body glycogen content is in the
liver (which is equivalent to about a our-hour supply o glucose)
but this is highly dependent on activity level. The liver uses this
glycogen reserve as a way to keep blood-glucose levels within a
narrow range between meal times. When the liver’s glycogen supply
is exhausted, glucose is made rom amino acids obtained rom the
destruction o proteins in order to maintain metabolic homeostasis.
Building Macromolecules
Although most absorbed glucose is used to make energy, some
glucose is converted to ribose and deoxyribose, which are essential
building blocks o important macromolecules, such as RNA, DNA,
The Functions o Carbohydrates in the Body | 255
and ATP. Glucose is additionally utilized to make the molecule
NADPH, which is important or protection against oxidative stress
and is used in many other chemical reactions in the body. I all o the
energy, glycogen-storing capacity, and building needs o the body
are met, excess glucose can be used to make at. This is why a diet
too high in carbohydrates and calories can add on the at pounds—a
topic that will be discussed shortly.
Figure 4.11
Chemical
Structure o
Deoxyribose
The sugar
molecule
deoxyribose
is used to
build the
backbone o
DNA.
Image by
rozeta / CC
BY-SA 3.0
256 | The Functions o Carbohydrates in the Body
Figure 4.12
Double-stran
ded DNA
Image by
Forluvot /
Public
Domain
Sparing Protein
In a situation where there is not enough glucose to meet the body’s
needs, glucose is synthesized rom amino acids. Because there is
no storage molecule o amino acids, this process requires the
destruction o proteins, primarily rom muscle tissue. The presence
o adequate glucose basically spares the breakdown o proteins
rom being used to make glucose needed by the body.
Lipid Metabolism
As blood-glucose levels rise, the use o lipids as an energy source
The Functions o Carbohydrates in the Body | 257
is inhibited. Thus, glucose additionally has a “at-sparing” eect.
This is because an increase in blood glucose stimulates release o
the hormone insulin, which tells cells to use glucose (instead o
lipids) to make energy. Adequate glucose levels in the blood also
prevent the development o ketosis. Ketosis is a metabolic condition
resulting rom an elevation o ketone bodies in the blood. Ketone
bodies are an alternative energy source that cells can use when
glucose supply is insucient, such as during asting. Ketone bodies
are acidic and high elevations in the blood can cause it to become
too acidic. This is rare in healthy adults, but can occur in alcoholics,
people who are malnourished, and in individuals who have Type 1
diabetes. The minimum amount o carbohydrate in the diet required
to inhibit ketosis in adults is 50 grams per day.
Carbohydrates
are
critical
to
support
lie’s
most
basic
unction—the production o energy. Without energy none o the
other lie processes are perormed. Although our bodies can
synthesize glucose it comes at the cost o protein destruction. As
with all nutrients though, carbohydrates are to be consumed in
moderation as having too much or too little in the diet may lead to
health problems.
Learning Activities
Technology Note The second edition o the Human
Nutrition Open Educational Resource (OER) textbook
eatures interactive learning activities. These activities are
available in the web-based textbook and not available in the
downloadable versions (EPUB, Digital PDF, Print_PDF, or
Open Document).
258 | The Functions o Carbohydrates in the Body
Learning activities may be used across various mobile
devices, however, or the best user experience it is strongly
recommended that users complete these activities using a
desktop or laptop computer.
An interactive H5P element has been excluded
rom this version o the text. You can view it
online here:
https://pressbooks.oer.hawaii.edu/
humannutrition2e22/?p=177#h5p-46
An interactive H5P element has been excluded
rom this version o the text. You can view it
online here:
https://pressbooks.oer.hawaii.edu/
humannutrition2e22/?p=177#h5p-47
The Functions o Carbohydrates in the Body | 259
Health Consequences and
Benefits of
High-Carbohydrate Diets
Can America blame its obesity epidemic on the higher consumption
o added sugars and rened grains? This is a hotly debated topic
by both the scientic community and the general public. In this
section, we will give a brie overview o the scientic evidence.
Added Sugars
Figure 4.13
Sugar
Consumptio
n (In
Teaspoons)
From
Various
Sources
Image by
Forluvot /
Public
Domain
The Food and Nutrition Board o the Institute o Medicine (IOM)
denes added sugars as “sugars and syrups that are added to oods
during processing or preparation.” The IOM goes on to state, “Major
sources o added sugars include sot drinks, sports drinks, cakes,
cookies, pies, ruitades, ruit punch, dairy desserts, and candy.”
260 | Health Consequences and
Benets o High-Carbohydrate Diets
Processed oods, even microwaveable dinners, also contain added
sugars. Added sugars do not include sugars that occur naturally
in whole oods (such as an apple), but do include natural sugars
such as brown sugar, corn syrup, dextrose, ructose, ruit juice
concentrates, maple syrup, sucrose, and raw sugar that are then
added to create other oods (such as cookies). Results rom a survey
o orty-two thousand Americans reports that in 2008 the average
intake o added sugars is 15 percent o total calories, a drop rom 18
1
percent o total calories in 2000.
This is still above the recommended intake o less than 10 percent
o total calories. The US Department o Agriculture (USDA) reports
that sugar consumption in the American diet in 2008 was, on
average, 28 teaspoons per day (Figure 4.13 “Sugar Consumption (in
Teaspoons) rom Various Sources”).
Obesity, Diabetes, and Heart Disease and Their
Hypothesized Link to Excessive Sugar and
Refined Carbohydrate Consumption
To understand the magnitude o the health problem in the United
States consider this—in the United States approximately 130 million
adults are overweight, and 30 percent o them are considered
obese. The obesity epidemic has reached young adults and children
and will markedly aect the prevalence o serious health
consequences in adulthood. Health consequences linked to being
1. Welsh JA, Sharma AJ, et al. (2011). Consumption o Added
Sugars Is Decreasing in the United States. American
Journal o Clinical Nutrition, 94(3), 726–34.
http//www.ncbi.nlm.nih.gov/pubmed/21753067.
Accessed September 22, 2017.
Health Consequences and Benets o High-Carbohydrate Diets | 261
overweight or obese include Type 2 diabetes, cardiovascular
disease, arthritis, depression, and some cancers. An inatuation with
sugary oods and rened grains likely contributes to the epidemic
proportion o people who are overweight or obese in this country,
but so do the consumption o high-calorie oods that contain too
much saturated at and the sedentary liestyle o most Americans.
There is much disagreement over whether high-carbohydrate diets
increase weight-gain and disease risk, especially when calories are
not signicantly higher between compared diets. Many scientic
studies demonstrate positive correlations between diets high in
added sugars with weight gain and disease risk, but some others do
not show a signicant relationship. In regard to rened grains, there
are no studies that show consumption o rened grains increases
weight gain or disease risk. What is clear, however, is that getting
more o your carbohydrates rom dietary sources containing whole
grains instead o rened grains stimulates weight loss and reduces
disease risk.
A major source o added sugars in the American diet is sot drinks.
There is consistent scientic evidence that consuming sugary sot
drinks increases weight gain and disease risk. An analysis o over
thirty studies in the American Journal o Clinical Nutrition
concluded that there is much evidence to indicate higher
consumption o sugar-sweetened beverages is linked with weight
2
gain and obesity. A study at the Harvard School o Public Health
linked the consumption o sugary sot drinks to an increased risk or
3
heart disease.
2. Malik VS, Schulze MB, Hu FB. (2006). Intake o SugarSweetened Beverages and Weight Gain A Systematic
Review. American Journal o Clinical Nutrition, 84(2),
274–88. http//www.ajcn.org/content/84/2/274.long.
Accessed September 22, 2017.
3. Public Health Takes Aim at Sugar and Salt. Harvard
262 | Health Consequences and Benets o High-Carbohydrate Diets
While the sugar and rened grains and weight debate rages on,
the results o all o these studies has led some public health
organizations like the American Heart Association (AHA) to
recommend even a lower intake o sugar per day (ewer than 9
teaspoons per day or men and ewer than 6 teaspoons or women)
than what used to be deemed acceptable. Ater its 2010 scientic
conerence on added sugars, the AHA made the ollowing related
4
dietary recommendations
• First, know the number o total calories you should eat each
day.
• Consume an overall healthy diet and get the most nutrients or
the calories, using oods high in added sugars as discretionary
calories (those let over ater getting all recommended
nutrients subtracted rom the calories used).
• Lower sugar intake, especially when the sugars in oods are not
tied to positive nutrients such as in sugary drinks, candies,
cakes, and cookies.
• Focus on calories in certain ood categories such as beverages
and conections, and encourage consumption o positive
nutrients and oods such as cereals and low-at or at-ree
dairy products.
School o Public Health. https//www.hsph.harvard.edu/
news/magazine/sugar-and-salt/. Published 2009.
Accessed September 30, 2017.
4. Van Horn L, Johnson RK, et al.(2010). Translation and
Implementation o Added Sugars Consumption
Recommendations. Circulation, 122,
2470–90.http//circ.ahajournals.org/content/122/23/
2470/tab-supplemental. Accessed September 27, 2017.
Health Consequences and Benets o High-Carbohydrate Diets | 263
The Most Notorious Sugar
Beore high-ructose corn syrup (HFCS) was marketed as the best
ood and beverage sweetener, sucrose (table sugar) was the
number-one sweetener in America. (Recall that sucrose, or table
sugar, is a disaccharide consisting o one glucose unit and one
ructose unit.) HFCS also contains the simple sugars ructose and
glucose, but with ructose at a slightly higher concentration. In
the production o HFCS, corn starch is broken down to glucose,
and some o the glucose is then converted to ructose. Fructose
is sweeter than glucose; hence many ood manuacturers choose
to sweeten oods with HFCS. HFCS is used as a sweetener or
carbonated beverages, condiments, cereals, and a great variety o
other processed oods.
Some scientists, public health personnel, and healthcare
providers believe that ructose is the cause o the obesity epidemic
and its associated health consequences. The majority o their
evidence stems rom the observation that since the early 1970s
the number o overweight or obese Americans has dramatically
increased and so has the consumption o oods containing HFCS.
However, as discussed, so has the consumption o added sugars
in general. Animal studies that uel the ructose opponents show
ructose is not used to produce energy in the body; instead it is
mostly converted to at in the liver—potentially contributing to
insulin resistance and the development o Type 2 diabetes.
Additionally, ructose does not stimulate the release o certain
appetite-suppressing hormones, like insulin, as glucose does. Thus,
a diet high in ructose could potentially stimulate at deposition and
weight gain.
In human studies, excessive ructose intake has sometimes been
associated with weight gain, but results are inconsistent. Moderate
ructose intake is not associated with weight gain at all. Moreover,
264 | Health Consequences and Benets o High-Carbohydrate Diets
other studies show that some ructose in the diet actually improves
5
glucose metabolism especially in people with Type 2 diabetes.
In act, people with diabetes were once advised to use ructose
as an alternative sweetener to table sugar. Overall, there is no good
evidence that moderate ructose consumption contributes to
weight gain and chronic disease. At this time conclusive evidence
is not available on whether ructose is any worse than any other
added sugar in increasing the risk or obesity, Type 2 diabetes, and
cardiovascular disease.
Do Low-Carbohydrate Diets Affect Health?
Since the early 1990s, marketers o low-carbohydrate diets have
bombarded us with the idea that eating ewer carbohydrates
promotes weight loss and that these diets are superior to others in
their eects on weight loss and overall health. The most amous o
these low-carbohydrate diets is the Atkins diet. Others include the
“South Beach” diet, the “Zone” diet, and the “Earth” diet. Despite the
claims these diets make, there is little scientic evidence to support
that low-carbohydrate diets are signicantly better than other diets
in promoting long-term weight loss. A study in The Nutritional
Journal concluded that all diets, (independent o carbohydrate, at,
and protein content) that incorporated an exercise regimen
5. Elliott SS, Keim NL, et al. (2002). Fructose, Weight Gain,
and the Insulin Resistance Syndrome. American Journal
o Clinical Nutrition, 76(5),911–22. http//www.ajcn.org/
content/76/5/911.ull. Accessed September 27, 2017.
Health Consequences and Benets o High-Carbohydrate Diets | 265
signicantly decreased weight and waist circumerence in obese
6
women.
Some studies do provide evidence that in comparison to other
diets, low-carbohydrate diets improve insulin levels and other risk
actors or Type 2 diabetes and cardiovascular disease. The overall
scientic consensus is that consuming ewer calories in a balanced
diet will promote health and stimulate weight loss, with signicantly
better results achieved when combined with regular exercise.
Health Benefits of Whole Grains in the Diet
While excessive consumption o simple carbohydrates is potentially
bad or your health, consuming more complex carbohydrates is
extremely benecial to health. There is a wealth o scientic
evidence supporting that replacing rened grains with whole grains
decreases the risk or obesity, Type 2 diabetes, and cardiovascular
disease. Whole grains are great dietary sources o ber, vitamins,
minerals, healthy ats, and a vast amount o benecial plant
chemicals, all o which contribute to the eects o whole grains
on health. Eating a high-ber meal as compared to a low-ber
meal (see Figure 4.14 “Fibers Role in Carbohydrate Digestion and
Absorption”) can signicantly slow down the absorption process
6. Kerksick CM, Wismann-Bunn J, et al. (2010). Changes in
Weight Loss, Body Composition, and Cardiovascular
Disease Risk ater Altering Macronutrient Distributions
During a Regular Exercise Program in Obese Women.
The Journal o Nutrition, 9(59).
https//www.ncbi.nlm.nih.gov/pmc/articles/
PMC3000832/ . Accessed September 27, 2017.
266 | Health Consequences and Benets o High-Carbohydrate Diets
thereore aecting blood glucose levels. Americans typically do not
consume the recommended amount o whole grains, which is 50
percent or more o grains rom whole grains.
Figure 4.14
Fibers Role
in
Carbohydrat
e Digestion
and
Absorption
Image by
Allison
Calabrese /
CC BY 4.0
Diets high in whole grains have repeatedly been shown to decrease
weight. A large group o studies all support that consuming more
than two servings o whole grains per day reduces one’s chances
7
o getting Type 2 diabetes by 21 percent. The Nurses’ Health Study
ound that women who consumed two to three servings o whole
grain products daily were 30 percent less likely to have a heart
8
attack.
7. de Munter JS, Hu FB, et al. (2007). Whole Grain, Bran,
and Germ Intake and Risk o Type 2 Diabetes A
Prospective Cohort Study and Systematic Review. PLOS
Medicine, 4(8), e261. https//www.ncbi.nlm.nih.gov/
pubmed/17760498. Accessed September 27, 2017.
8. Liu S, Stamper MJ, et al. (1999). Whole-Grain
Consumption and Risk o Coronary Heart Disease
Health Consequences and Benets o High-Carbohydrate Diets | 267
9
The AHA makes the ollowing statements on whole grains
• “Dietary ber rom whole grains, as part o an overall healthy
diet, helps reduce blood cholesterol levels and may lower risk
o heart disease.”
• “Fiber-containing oods, such as whole grains, help provide a
eeling o ullness with ewer calories and may help with
weight management.”
Figure 4.15
Grain
Consumptio
n Statistics
in America
Results rom the Nurses’ Health Study. American Journal
o Clinical Nutrition, 70(3), 412–19. http//www.ajcn.org/
content/70/3/412.long. Accessed September 27, 2017.
9. Whole Grains and Fiber. American Heart Association.
http//www.heart.org/HEARTORG/GettingHealthy/
NutritionCenter/HealthyDietGoals/Whole-Grains-andFiber_UCM_303249_Article.jsp. Updated 2017. Accessed
September 30, 2017.
268 | Health Consequences and Benets o High-Carbohydrate Diets
Source Economic Research Service. http//www.ers.usda.gov/
data-products/commodity-consumption-by-populationcharacteristics/documentation.aspx.
More Resources
Did you know that ber content diers by whole grain?
Visit this site to discover the ber content o various
sources o whole grains in our diet.
https//wholegrainscouncil.org/whole-grains-101/
identiying-whole-grain-products/ber-whole-grains
Learning Activities
Technology Note The second edition o the Human
Nutrition Open Educational Resource (OER) textbook
eatures interactive learning activities. These activities are
available in the web-based textbook and not available in the
downloadable versions (EPUB, Digital PDF, Print_PDF, or
Open Document).
Learning activities may be used across various mobile
devices, however, or the best user experience it is strongly
recommended that users complete these activities using a
desktop or laptop computer.
Health Consequences and Benets o High-Carbohydrate Diets | 269
An interactive H5P element has been excluded
rom this version o the text. You can view it
online here:
https://pressbooks.oer.hawaii.edu/
humannutrition2e22/?p=182#h5p-48
An interactive H5P element has been excluded
rom this version o the text. You can view it
online here:
https://pressbooks.oer.hawaii.edu/
humannutrition2e22/?p=182#h5p-49
270 | Health Consequences and Benets o High-Carbohydrate Diets
Carbohydrates and Personal
Diet Choices
In this chapter, you learned what carbohydrates are, the dierent
types o carbohydrates in your diet, and that excess consumption
o some types o carbohydrates cause disease while others decrease
disease risk. Now that we know the benets o eating the right
carbohydrate, we will examine exactly how much should be eaten to
promote health and prevent disease.
How Many Carbohydrates Does a Person Need?
The Food and Nutrition Board o IOM has set the Recommended
Dietary Allowance (RDA) o carbohydrates or children and adults
at 130 grams per day. This is the average minimum amount the
brain requires to unction properly. The Acceptable Macronutrient
Distribution Range (AMDR) or carbohydrates is between 45 and
65 percent o your total caloric daily intake. This means that on
a 2,000 kilocalorie diet, a person should consume between 225
and 325 grams o carbohydrate each day. According to the IOM
not more than 25 percent o total calories consumed should come
rom added sugars. The World Health Organization and the AHA
recommend much lower intakes o added sugars—10 percent or less
o total calories consumed. The IOM has also set Adequate Intakes
or dietary ber, which are 38 and 25 grams or men and women,
respectively. The recommendations or dietary ber are based upon
the intake levels known to prevent against heart disease.
Carbohydrates and Personal Diet
Choices | 271
Table 4.4 Dietary Reerence Intakes For Carbohydrates And Fiber
Carbohydrate Type
RDA (g/day)
AMDR (%
calories)
Total Carbohydrates
130
45–65
Added Sugars
Fiber
< 25
38 (men),* 25
(women)*
* denotes Adequate Intake
Dietary Sources of Carbohydrates
Carbohydrates are contained in all ve ood groups grains, ruits,
vegetables, meats, beans (only in some processed meats and beans),
and dairy products. Fast-releasing carbohydrates are more
prevalent in ruits, ruit juices, and dairy products, while slowreleasing carbohydrates are more plentiul in starchy vegetables,
beans, and whole grains. Fast-releasing carbohydrates are also
ound in large amounts in processed oods, sot drinks, and sweets.
On average, a serving o ruits, whole grains, or starches contains
15 grams o carbohydrates. A serving o dairy contains about 12
grams o carbohydrates, and a serving o vegetables contains about
5 grams o carbohydrates. Table 4.5 “Carbohydrates in Foods
(grams/serving)” gives the specic amounts o carbohydrates, ber,
and added sugar o various oods.
272 | Carbohydrates and Personal Diet Choices
Table 4.5 Carbohydrates in Foods (grams/serving)
Foods
Total
Carbohydrates
Sugars
Fiber
Added
Sugars
Banana
27 (1 medium)
14.40
3.1
0
Lentils
40 (1 c.)
3.50
16.0
0
Snap beans
8.7 (1 c.)
1.60
4.0
0
Green pepper
5.5 (1 medium)
2.90
2.0
0
Corn tortilla
10.7 (1)
0.20
1.5
0
Bread, wheat
bran
17.2 (1 slice)
3.50
1.4
3.4
Bread, rye
15.5 (1 slice)
1.20
1.9
1.0
Bagel (plain)
53 (1 medium)
5.30
2.3
4.8
Brownie
36 (1 square)
20.50
1.2
20.0
Oatmeal cookie
22.3 (1 oz.)
12.00
2.0
7.7
Cornfakes
23 (1 c.)
1.50
0.3
1.5
Pretzels
47 (10 twists)
1.30
1.7
0
Popcorn
(homemade)
58 (100 g)
0.50
10.0
0
Skim milk
12 (1 c.)
12.00
0
0
Cream (hal and
hal)
0.65 (1 Tbs.)
0.02
0
0
Cream
substitute
1.0 (1 tsp.)
1.00
0
1.0
Cheddar cheese
1.3 (1 slice)
0.50
0
0
Yogurt (with
ruit)
32.3 (6 oz.)
32.30
0
19.4
Caesar dressing
2.8 (1 Tbs.)
2.80
0
2.4
Sources
• National Nutrient Database or Standard Reerence. US
Department o Agriculture. http//www.nal.usda.gov/nic/
oodcomp/search/. Updated December 7, 2011. Accessed
Carbohydrates and Personal Diet Choices | 273
September 17, 2017.
• Database or the Added Sugars Content o Selected Foods. US
Department o Agriculture. http//www.nal.usda.gov/nic/
oodcomp/search/. Published February 2006. Accessed
September 27, 2017.
It’s the Whole Nutrient Package
In choosing dietary sources o carbohydrates the best ones are
those that are nutrient dense, meaning they contain more essential
nutrients per calorie o energy. In general, nutrient-dense
carbohydrates are minimally processed and include whole-grain
breads and cereals, low-at dairy products, ruits, vegetables, and
beans. In contrast, empty-calorie carbohydrate oods are highly
processed and oten contain added sugars and ats. Sot drinks,
cakes, cookies, and candy are examples o empty-calorie
carbohydrates.
They
are
sometimes
reerred
to
as
‘bad
carbohydrates,’ as they are known to cause health problems when
consumed in excess.
Understanding Carbohydrates from Product
Information
While nutrition acts labels aid in determining the amount o
carbohydrates you eat, they do not help in determining whether
a ood is rened or not. The ingredients list provides some help
in this regard. It identies all o the ood’s ingredients in order o
concentration, with the most concentrated ingredient rst. When
choosing between two breads, pick the one that lists whole wheat
(not wheat four) as the rst ingredient, and avoid those with other
four ingredients, such as white four or corn four. (Enriched wheat
274 | Carbohydrates and Personal Diet Choices
four reers to white four with added vitamins.) Eat less o products
that list HFCS and other sugars such as sucrose, honey, dextrose,
and cane sugar in the rst ve ingredients. I you want to eat less
processed oods then, in general, stay away rom products with
long ingredient lists. On the ront o ood and beverages the
manuacturers may include claims such as “sugar-ree,” “reduced
sugar,” “high ber,” etc.. The Nutrition and Labeling Act o 1990
has dened or the ood industry and consumers what these labels
mean (Table 4.6 “Food Labels Pertaining to Carbohydrates”).
Table 4.6 Food Labels Pertaining to Carbohydrates
Label
Meaning
Sugar-ree
Contains less than 0.5 grams o sugar per serving
Reduced
sugar
Contains 25 percent less sugar than similar product
Less sugar
Contains 25 percent less sugar than similar product, and
was not altered by processing to become so
No sugars
added
No sugars added during processing
High ber
Contains at least 20 percent o daily value o ber in each
serving
A good
source o
ber
Contains between 10 and 19 percent o the daily value o
ber per serving
More ber
Contains 10 percent or more o the daily value o ber per
serving
Source Appendix A Denitions o Nutrient Claims. Guidance or
Industry A Food Labeling Guide. US Food and Drug Administration.
http//www.da.gov/Food/
GuidanceComplianceRegulatoryInormation/
GuidanceDocuments/FoodLabelingNutrition/FoodLabelingGuide/
ucm064911.htm. Updated October 2009. Accessed September 22,
2017.
In addition, the FDA permits oods that contain whole oats (which
contain soluble ber) to make the health claim on the package
Carbohydrates and Personal Diet Choices | 275
that the ood reduces the risk o coronary heart disease. The FDA
no longer permits Cheerios to make the claim that by eating their
cereal “you can lower your cholesterol our percent in six weeks.”
Personal Choices
Carbohydrates are in most oods so you have a great variety o
choices with which to meet the carbohydrates recommendations
or a healthy diet. The 2010 Dietary Guidelines recommends eating
more unrened carbohydrates and more ber, and reducing
consumption o oods that are high in added sugars. To accomplish
these recommendations use some or all o the ollowing
suggestions
• Get more daily carbohydrate servings rom whole grains by
eating a whole-grain cereal or breakast, using whole-grain
bread to make a sandwich or lunch, and eating a serving o
beans and/or nuts with dinner.
• Make sure to get at least three servings (or more) o all the
grains you eat as whole grains every day. A serving o whole
grains is equal to one slice o whole-wheat bread, one ounce o
whole-grain cereal, and one-hal cup o cooked cereal, brown
rice, or whole-wheat pasta.
Food products made with cornmeal use the whole grain so
choose tortillas, corn cereals, and corn breads with cornmeal
listed as the rst ingredient.
• When baking, substitute whole-wheat four or other wholegrain four or some o the rened white four.
• I you like bread at dinner, choose a whole-grain mun over a
Kaiser roll or baguette.
Add beans, nuts, or seeds to salad—they add texture and taste.
• Choose whole-grain pastas and brown rice, cook al dente, and
add some beans and vegetables in equal portions.
276 | Carbohydrates and Personal Diet Choices
• Change it up a bit and experience the taste and satisaction o
other whole grains such as barley, quinoa, and bulgur.
• Eat snacks high in ber, such as almonds, pistachios, raisins,
and air-popped popcorn.
Add an artichoke and green peas to your dinner plate more
oten.
• Calm your “sweet tooth” by eating ruits, such as berries or an
apple.
• Replace sugary sot drinks with seltzer water, tea, or a small
amount o 100 percent ruit juice added to water or soda water.
The Food Industry: Functional Attributes of
Carbohydrates and the Use of Sugar Substitutes
In the ood industry, both ast-releasing and slow-releasing
carbohydrates are utilized to give oods a wide spectrum o
unctional attributes, including increased sweetness, viscosity, bulk,
coating ability, solubility, consistency, texture, body, and browning
capacity. The dierences in chemical structure between the
dierent carbohydrates coner their varied unctional uses in oods.
Starches, gums, and pectins are used as thickening agents in making
jam, cakes, cookies, noodles, canned products, imitation cheeses,
and a variety o other oods. Molecular gastronomists use slowreleasing carbohydrates, such as alginate, to give shape and texture
to their ascinating ood creations. Adding ber to oods increases
bulk. Simple sugars are used not only or adding sweetness, but
also to add texture, consistency, and browning. In ice cream, the
combination o sucrose and corn syrup imparts sweetness as well as
a glossy appearance and smooth texture.
Due to the potential health consequences o consuming too many
added sugars, sugar substitutes have replaced them in many oods
and beverages. Sugar substitutes may be rom natural sources or
articially made. Those that are articially made are called articial
Carbohydrates and Personal Diet Choices | 277
sweeteners and must be approved by the FDA or use in oods
and beverages. The articial sweeteners approved by the FDA are
saccharin, aspartame, acesulame potassium, neotame, advantame,
and sucralose. Stevia is an example o a naturally derived sugar
substitute. It comes rom a plant commonly known as sugarlea
and does not require FDA approval. Sugar alcohols, such as xylitol,
sorbitol, erythritol, and mannitol, are sugar alcohols that occur
naturally in some ruits and vegetables. However, they are
industrially synthesized with yeast and other microbes or use as
ood additives. The FDA requires that oods disclose the act that
they contain sugar alcohols, but does not require scientic testing
o it. (Though many o them have undergone studies anyway.) In
comparison to sucrose, articial sweeteners are signicantly
sweeter (in act, by several hundred times), but sugar alcohols are
more oten less sweet than sucrose (see Table 4.7 “Relative
Sweetness o Sugar Substitutes”). Articial sweeteners and Stevia
are not digested or absorbed in signicant amounts and thereore
are not a signicant source o calories in the diet. Sugar alcohols
are somewhat digested and absorbed and, on average, contribute
about hal o the calories as sucrose (4 kilocalories/gram). These
attributes
make
sugar
substitutes
attractive
or
many
people—especially those who want to lose weightand/or better
manage their blood-glucose levels.
278 | Carbohydrates and Personal Diet Choices
Table 4.7 Relative Sweetness O Sugar Substitutes
Sweetener
Trade Names
Sweeter than Sucrose (times)
Saccharine
“Sweet-N-Lo”
300.0
Aspartame
“NutraSweet,” “Equal”
80-200.0
Acesulame-K
“Sunette”
200.0
Neotame
7,000.0–13,000.0
Advantame
20,000
Sucralose
“Splenda”
600.0
Stevia
250.0–300.0
Xylitol
0.8
Mannitol
0.5
Sorbitol
0.6
Erythritol
1.0
Benefits of Sugar Substitutes
Consuming oods and beverages containing sugar substitutes may
benet health by reducing the consumption o simple sugars, which
are higher in calories, cause tooth decay, and are potentially linked
to chronic disease. Articial sweeteners are basically non-nutrients
though not all are completely calorie-ree. However, because they
are so intense in sweetness they are added in very small amounts
to oods and beverages. Articial sweeteners and sugar alcohols are
not “ermentable sugars” and thereore they do not cause tooth
decay. Chewing gum with articial sweeteners is the only proven
way that articial sweeteners promote oral health. The American
Dental Association (ADA) allows manuacturers o chewing gum to
label packages with an ADA seal i they have convincing scientic
evidence demonstrating their product either reduces plaque acids,
cavities, or gum disease, or promotes tooth remineralization.
There is limited scientic evidence that consuming products with
Carbohydrates and Personal Diet Choices | 279
articial sweeteners decreases weight. In act, some studies suggest
the intense sweetness o these products increases appetite or
sweet oods and may lead to increased weight gain. Also, there
is very limited evidence that suggests articial sweeteners lower
blood-glucose levels. Additionally, many oods and beverages
containing articial sweeteners and sugar alcohols are still emptycalorie oods (i.e. chewing sugarless gum or drinking diet soda pop)
are not going to better your blood-glucose levels or your health.
Health Concerns
The most common side eect o consuming products containing
sugar substitutes is gastrointestinal upset, a result o their
incomplete digestion. Since the introduction o sugar substitutes to
the ood and beverage markets, the public has expressed concern
about their saety. The health concerns o sugar substitutes
originally
stemmed
rom
scientic
studies,
which
were
misinterpreted by both scientists and the public.
In the early 1970s scientic studies were published that
demonstrated that high doses o saccharin caused bladder tumors
in rats. This inormation ueled the still-ongoing debate o the
health consequences o all articial sweeteners. In actuality, the
results rom the early studies were completely irrelevant to humans.
The large doses (2.5 percent o diet) o saccharine caused a pellet
to orm in the rat’s bladder. That pellet chronically irritated the
bladder wall, eventually resulting in tumor development. Since this
study, scientic investigation in rats, monkeys, and humans have
not ound any relationship between saccharine consumption and
bladder cancer. In 2000, saccharin was removed rom the US
National Toxicology Program’s list o potential carcinogens.
1. Articial Sweeteners and Cancer. National Cancer
280 | Carbohydrates and Personal Diet Choices
1
There have been health concerns over other articial sweeteners,
most notably aspartame (sold under the trade names o NutraSweet
and Equal). The rst misconception regarding aspartame was that
it was linked with an increase in the incidence o brain tumors in
the United States. It was subsequently discovered that the increase
in brain tumors started eight years prior to the introduction o
aspartame to the market. Today, aspartame is accused o causing
brain damage, autism, emotional disorders, and a myriad o other
disorders and diseases. Some even believe aspartame is part o a
governmental conspiracy to make people dumber. The reality is
there is no good scientic evidence backing any o these
accusations, and that aspartame has been the most scientically
tested ood additive. It is approved or use as an articial sweetener
in over ninety countries.
Aspartame is made by joining aspartic acid and phenylalanine to
a dipeptide (with a methyl ester). When digested, it is broken down
to aspartic acid, phenylalanine, and methanol. People who have the
rare genetic disorder phenylketonuria (PKU) have to avoid products
containing aspartame. Individuals who have PKU do not have a
unctional enzyme that converts phenylalanine to the amino acid
tyrosine. This causes a buildup o phenylalanine and its metabolic
products in the body. I PKU is not treated, the buildup o
phenylalanine causes progressive brain damage and seizures. The
FDA requires products that contain aspartame to state on the
product label, “Phenylketonurics Contains Phenylalanine.” For more
details on sugar substitutes please reer to Table 4.8 “Sweeteners”.
Institute. http//www.cancer.gov/cancertopics/
actsheet/Risk/articial-sweeteners. Updated August 5,
2009. Accessed September 22, 2017.
Carbohydrates and Personal Diet Choices | 281
Table 4.8 Sweeteners
Sweeteners
with Trade
Name
Calories
Aspartame
• NutraSweet 4 kcal/g
• Equal
Source/Origin
Composed o two
amino acids
(phenylalanine +
aspartic acid) +
methanol.Two
hundred times
sweeter than
sucrose.
282 | Carbohydrates and Personal Diet Choices
Consumer
Controversial
Recommendations Issues
FDA set maximum
Acceptable Daily
Intakes (ADI):50
mg/kg body
weight = 16 12 oz.
diet sot drinks or
adults.
*Cannot be used
in products
requiring cooking.
People with PKU
should not
consume
aspartame.
Children have
potential to reach
ADI i consuming
many beverages,
desserts, rozen
desserts, and
gums containing
aspartame
routinely.
Sweeteners
with Trade
Name
Calories
Source/Origin
Consumer
Controversial
Recommendations Issues
1970s, high doses
o saccharin
associated with
bladder cancer in
laboratory
animals. In 1977,
FDA proposed
banning saccharin
rom use in ood
Saccharin
• Sweet ‘n’
Low
0 kcal/g
Acesulame K
• Sunnette
• Sweet One
0 kcal/g
Discovered in 1878.
The basic
substance is
benzoic
sulnide.Three
hundred times
sweeter than
sucrose.
Discovered in 1967.
Composed o an
organic salt,
potassium (K).
Structure is very
similar to
saccharin’s.It
passes through the
body unchanged
which means it
does not provide
energy.
ADI 5 mg/kg body
weight.*Can be
used in cooking.
• protest
launched by
consumer &
interest
groups
• warning label
listed on
products
about
saccharin and
cancer risk in
animals until
2001 when
studies
concluded
that it did no
cause cancer
in humans
ADI 15 mg/kg
body weight.Body
cannot digest it.
*Can be used in
cooking.
Two hundred
times sweeter than
sucrose.
Carbohydrates and Personal Diet Choices | 283
Sweeteners
with Trade
Name
Calories
Cyclamates
• Sugar Twin
0 kcal/g
Source/Origin
Consumer
Controversial
Recommendations Issues
Thirty times
sweeter than
No ADI available.
sucrose.Discovered
in 1937.
284 | Carbohydrates and Personal Diet Choices
1949, cyclamate
approved by FDA
or use. Cyclamat
was classied as
GRAS (Generally
Recognized As
Sae) until 1970
when it was
removed rom
GRAS status and
banned rom use
in all ood and
beverage product
within the United
States on the basi
o one study that
indicated it cause
bladder cancer in
rats. Approval stil
pending or use in
the United States
since the
ban.Canada and
other countries
use this type o
sweetener.
Sweeteners
with Trade
Name
Calories
Sucralose
First discovered in
1976. Approved or
use in 1998 in the
United States and
in 1991 in
1
Canada.Derived
Splenda
rom sucrose in
packet
which three o its
contains
hydroxyl (OH)
3.31
groups are
calories
replaced by
= 1g
chlorine (Cl−).
• Splenda
Source/Origin
Consumer
Controversial
Recommendations Issues
ADI 5 mg/kg body
weight.*Can be
used in cooking.
Six hundred times
sweeter than
sugar.
Stevioside
• Stevia
• Sweet Lea
N/A
Derived rom
stevia plant ound
in South America.
Stevia rebaudiana
leaves.
Classied as
GRAS.Considered
to be a dietary
supplement and
approved not as an
additive, but as a
dietary
supplement.
Used sparingly,
stevia may do littl
harm, but FDA
could not approve
extensive use o
this sweetener du
to concerns
regarding its eec
on reproduction,
cancer
development, and
energy
metabolism.
Carbohydrates and Personal Diet Choices | 285
Sweeteners
with Trade
Name
Calories
Sucrose
• Sugar
~4
kcal/g
Source/Origin
Consumer
Controversial
Recommendations Issues
Extracted rom
either sugar beets
or sugar cane,
which is then
puried and
crystallized.
It is illegal to sell
true raw sugar in
the United States
because when raw
it contains dirt
and insect parts,
as well as other
byproducts. Raw
sugar products
sold in the United
States have
actually gone
through more
than hal o the
same steps in the
rening process as
table sugar.
286 | Carbohydrates and Personal Diet Choices
Over-consumptio
has been linked to
several health
eects such as
tooth decay or
dental caries and
contributes to
increased risk or
chronic diseases.
Sweeteners
with Trade
Name
Honey
HFCS
• high
ructose
corn syrup
Calories
3 kcal/g
Dry
orm 4
kcal/g;
Liquid
orm 3
kcal/g
Source/Origin
Consumer
Controversial
Recommendations Issues
Made rom
sucrose. Contains
nectar o fowering
plants. Made by
bees. Sucrose is
ructose + glucose;
however, honey
contains more
calories than
sucrose because
honey is denser.
*Considered sae
or baking and
cooking.Inants
under twelve
months old should
not be given
honey because
their digestive
tracts cannot
handle the
bacteria ound in
honey. Older
children and
adults are immune
to these eects.
Honey contains
some harmul
bacteria that can
cause atal ood
poisoning in
inants.
Corn is milled to
produce corn
starch, then the
cornstarch is
urther processed
to yield corn syrup.
Controversial
because it is oun
ubiquitously in
processed ood
products, which
could lead to
overconsumption
Study results are
varied regarding
its role in chronic
disease.
Carbohydrates and Personal Diet Choices | 287
Sweeteners
with Trade
Name
Sugar Alcohols
• Sorbitol
• Xylitol
• Mannitol
Calories
Source/Origin
Consumer
Controversial
Recommendations Issues
2–4
kcal/
g.Not
calorie
ree
Sugar
alcohols.Sorbitol is
derived rom
glucose.
Less likely to
cause tooth decay
than
sucrose.Sugar
alcohols have a
laxative eect.
May cause
diarrhea and
gastrointestinal
distress i
consumed in large
amounts.
Regulation
Prior to introducing any new articial sweetener into oods it is
rigorously tested and must be legally approved by the FDA. The
FDA regulates articial sweeteners along with other ood additives,
which number in the thousands. The FDA is responsible or
determining whether a ood additive presents “a reasonable
certainty o no harm” to consumers when used as proposed. The
FDA uses the best scientic evidence available to make the
statement o no harm, but it does declare that science has its limits
and that the “FDA can never be absolutely certain o the absence o
2
any risk rom the use o any substance.”
2. Overview o Food Ingredients, Additives and Colors. US
Food and Drug Administration. https//wayback.archiveit.org/7993/20170722025446/https//www.da.gov/
Food/IngredientsPackagingLabeling/
288 | Carbohydrates and Personal Diet Choices
The
FDA
additionally
has
established
ADIs
or
articial
sweeteners. The ADIs are the maximum amount in milligrams per
kilogram o body weight considered sae to consume daily (mg/kg
bw/day) and incorporates a large saety actor. The ollowing list
contains the articial sweeteners approved or use in oods and
beverages in the United States, and their ADIs
• Acesulame potassium (Sunett, Sweet One). ADI = 15 mg/kg
bw/day
• Aspartame (Equal, NutraSweet). ADI = 50 mg/kg bw/day
• Neotame. ADI = 18 mg/kg bw/day
• Saccharin (SugarTwin, Sweet’N Low). ADI = 5 mg/kg bw/day
• Sucralose (Splenda). ADI = 5 mg/kg bw/day
Learning Activities
Technology Note The second edition o the Human
Nutrition Open Educational Resource (OER) textbook
eatures interactive learning activities. These activities are
available in the web-based textbook and not available in the
downloadable versions (EPUB, Digital PDF, Print_PDF, or
Open Document).
Learning activities may be used across various mobile
devices, however, or the best user experience it is strongly
FoodAdditivesIngredients/ucm094211.htm. Updated
April 2010. Accessed September 22, 2017.
Carbohydrates and Personal Diet Choices | 289
recommended that users complete these activities using a
desktop or laptop computer.
An interactive H5P element has been excluded
rom this version o the text. You can view it
online here:
https://pressbooks.oer.hawaii.edu/
humannutrition2e22/?p=184#h5p-50
290 | Carbohydrates and Personal Diet Choices
CHAPTER 5. LIPIDS
Chapter 5. Lipids | 291
Introduction
E hinu auaneʻi na nuku, he pōmaikaʻi ko laila
Where the mouths are shiny with at ood, prosperity is there
Image by Phu
Thinh Co /
CC BY-SA 2.0
Introduction | 293
Learning Objectives
By the end o this chapter, you will be able to
•
•
Describe the unction and role o lipids in the body
Describe the process o lipid digestion and
absorption
•
Describe tools and approaches or balancing your
diet with lipids
The coconut is considered to be the ‘Tree o Lie’ in the Pacic. The
coconut provided wood or shelter and cratsmanship along with
being a source o hydration, animal eed and income through copra.
It also serves many ecological unctions such as a source or shade,
1
protection rom the wind, and coastal erosion control. A thriving
coconut tree provided Pacic Island amilies with great prosperity.
For many Pacic communities the coconut provided a valuable
source o at to a diet that was generally low in at as the major
nutrient ound in the mature coconut is at. As you read urther, you
will learn the dierent types o ats, their essential roles in the body,
and the potential health consequences and benets o diets rich in
particular lipids. You will be better equipped to decide the best way
to get your nutritional punch rom various ats in your diet.
Lipids are important molecules that serve dierent roles in the
human body. A common misconception is that at is simply
attening. However, at is probably the reason we are all here.
Throughout history, there have been many instances when ood was
1. Snowdon W, Osborn T. (2003). Coconut It’s role in
health. Secretariat o the Pacic.
294 | Introduction
scarce. Our ability to store excess caloric energy as at or uture
usage allowed us to continue as a species during these times o
amine. So, normal at reserves are a signal that metabolic processes
are ecient and a person is healthy.
Lipids are a amily o organic compounds that are mostly insoluble
in water. Composed o ats and oils, lipids are molecules that yield
high energy and have a chemical composition mainly o carbon,
hydrogen, and oxygen. Lipids perorm three primary biological
unctions within the body they serve as structural components o
cell membranes, unction as energy storehouses, and unction as
important signaling molecules.
The three main types o lipids are triglycerides, phospholipids,
and sterols. Triglycerides make up more than 95 percent o lipids
in the diet and are commonly ound in ried oods, vegetable oil,
butter, whole milk, cheese, cream cheese, and some meats.
Naturally occurring triglycerides are ound in many oods, including
avocados, olives, corn, and nuts. We commonly call the triglycerides
in our ood “ats” and “oils.” Fats are lipids that are solid at room
temperature, whereas oils are liquid. As with most ats, triglycerides
do not dissolve in water. The terms ats, oils, and triglycerides are
discretionary and can be used interchangeably. In this chapter when
we use the word at, we are reerring to triglycerides.
Phospholipids make up only about 2 percent o dietary lipids.
They are water-soluble and are ound in both plants and animals.
Phospholipids are crucial or building the protective barrier, or
membrane, around your body’s cells. In act, phospholipids are
synthesized in the body to orm cell and organelle membranes. In
blood and body fuids, phospholipids orm structures in which at is
enclosed and transported throughout the bloodstream.
Sterols are the least common type o lipid. Cholesterol is perhaps
the best well-known sterol. Though cholesterol has a notorious
reputation, the body gets only a small amount o its cholesterol
through ood—the body produces most o it. Cholesterol is an
important component o the cell membrane and is required or the
synthesis o sex hormones, and bile salts.
Introduction | 295
Later in this chapter, we will examine each o these lipids in more
detail and discover how their dierent structures unction to keep
your body working.
Figure 5.1
Types o
Lipids
Image by
Allison
Calabrese /
CC BY 4.0
Learning Activities
Technology Note The second edition o the Human
Nutrition Open Educational Resource (OER) textbook
eatures interactive learning activities. These activities are
available in the web-based textbook and not available in the
downloadable versions (EPUB, Digital PDF, Print_PDF, or
Open Document).
Learning activities may be used across various mobile
devices, however, or the best user experience it is strongly
296 | Introduction
recommended that users complete these activities using a
desktop or laptop computer.
An interactive H5P element has been excluded
rom this version o the text. You can view it
online here:
https://pressbooks.oer.hawaii.edu/
humannutrition2e22/?p=189#h5p-51
Introduction | 297
The Functions of Lipids in
the Body
Storing Energy
The excess energy rom the ood we eat is digested and
incorporated into adipose tissue, or atty tissue. Most o the energy
required by the human body is provided by carbohydrates and
lipids. As discussed in the Carbohydrates chapter, glucose is stored
in the body as glycogen. While glycogen provides a ready source o
energy, lipids primarily unction as an energy reserve. As you may
recall, glycogen is quite bulky with heavy water content, thus the
body cannot store too much or long. Alternatively, ats are packed
together tightly without water and store ar greater amounts o
energy in a reduced space. A at gram is densely concentrated with
energy—it contains more than double the amount o energy than a
gram o carbohydrate. Energy is needed to power the muscles or
all the physical work and play an average person or child engages in.
For instance, the stored energy in muscles propels an athlete down
the track, spurs a dancer’s legs to showcase the latest ancy steps,
and keeps all the moving parts o the body unctioning smoothly.
Unlike other body cells that can store at in limited supplies, at
cells are specialized or at storage and are able to expand almost
indenitely in size. An overabundance o adipose tissue can result
in undue stress on the body and can be detrimental to your health.
A serious impact o excess at is the accumulation o too much
cholesterol in the arterial wall, which can thicken the walls o
arteries and lead to cardiovascular disease. Thus, while some body
at is critical to our survival and good health, in large quantities it
can be a deterrent to maintaining good health.
298 | The Functions o Lipids in the
Body
Regulating and Signaling
Triglycerides control the body’s internal climate, maintaining
constant temperature. Those who don’t have enough at in their
bodies tend to eel cold sooner, are oten atigued, and have
pressure sores on their skin rom atty acid deciency. Triglycerides
also help the body produce and regulate hormones. For example,
adipose tissue secretes the hormone leptin, which regulates
appetite. In the reproductive system, atty acids are required or
proper reproductive health. Women who lack proper amounts may
stop menstruating and become inertile. Omega-3 and omega-6
essential atty acids help regulate cholesterol and blood clotting
and control infammation in the joints, tissues, and bloodstream.
Fats also play important unctional roles in sustaining nerve impulse
transmission,
memory
storage,
and
tissue
structure.
More
specically in the brain, lipids are ocal to brain activity in structure
and in unction. They help orm nerve cell membranes, insulate
neurons, and acilitate the signaling o electrical impulses
throughout the brain.
Insulating and Protecting
Did you know that up to 30 percent o body weight is comprised o
at tissue? Some o this is made up o visceral at or adipose tissue
surrounding delicate organs. Vital organs such as the heart, kidneys,
and liver are protected by visceral at. The composition o the brain
is outstandingly 60 percent at, demonstrating the major structural
role that at serves within the body. You may be most amiliar with
subcutaneous at, or at underneath the skin. This blanket layer
o tissue insulates the body rom extreme temperatures and helps
keep the internal climate under control. It pads our hands and
buttocks and prevents riction, as these areas requently come in
The Functions o Lipids in the Body | 299
contact with hard suraces. It also gives the body the extra padding
required when engaging in physically demanding activities such as
ice- or roller skating, horseback riding, or snowboarding.
Aiding Digestion and Increasing Bioavailability
The dietary ats in the oods we eat break down in our digestive
systems and begin the transport o precious micronutrients. By
carrying at-soluble nutrients through the digestive process,
intestinal absorption is improved. This improved absorption is also
known as increased bioavailability. Fat-soluble nutrients are
especially important or good health and exhibit a variety o
unctions. Vitamins A, D, E, and K—the at-soluble vitamins—are
mainly ound in oods containing at. Some at-soluble vitamins
(such as vitamin A) are also ound in naturally at-ree oods such
as green leay vegetables, carrots, and broccoli. These vitamins are
best absorbed when combined with oods containing at. Fats also
increase
the
bioavailability
o
compounds
known
as
phytochemicals, which are plant constituents such as lycopene
(ound in tomatoes) and beta-carotene (ound in carrots).
Phytochemicals are believed to promote health and well-being. As a
result, eating tomatoes with olive oil or salad dressing will acilitate
lycopene absorption. Other essential nutrients, such as essential
atty acids, are constituents o the ats themselves and serve as
building blocks o a cell.
300 | The Functions o Lipids in the Body
Figure 5.2
Food Sources
o Omega 3’s
Note that removing the lipid elements rom ood also takes away
the ood’s at-soluble vitamin content. When products such as grain
and dairy are processed, these essential nutrients are lost.
Manuacturers replace these nutrients through a process called
enrichment.
Learning Activities
Technology Note The second edition o the Human
Nutrition Open Educational Resource (OER) textbook
eatures interactive learning activities. These activities are
available in the web-based textbook and not available in the
downloadable versions (EPUB, Digital PDF, Print_PDF, or
Open Document).
Learning activities may be used across various mobile
devices, however, or the best user experience it is strongly
The Functions o Lipids in the Body | 301
recommended that users complete these activities using a
desktop or laptop computer.
An interactive H5P element has been excluded
rom this version o the text. You can view it
online here:
https://pressbooks.oer.hawaii.edu/
humannutrition2e22/?p=192#h5p-52
An interactive H5P element has been excluded
rom this version o the text. You can view it
online here:
https://pressbooks.oer.hawaii.edu/
humannutrition2e22/?p=192#h5p-53
302 | The Functions o Lipids in the Body
The Role of Lipids in Food
High Energy Source
Fat-rich oods naturally have a high caloric density. Foods that are
high in at contain more calories than oods high in protein or
carbohydrates. As a result, high-at oods are a convenient source
o energy. For example, 1 gram o at or oil provides 9 kilocalories
o energy, compared with 4 kilocalories ound in 1 gram o
carbohydrate or protein. Depending on the level o physical activity
and on nutritional needs, at requirements vary greatly rom person
to person. When energy needs are high, the body welcomes the
high-caloric density o ats. For instance, inants and growing
children require proper amounts o at to support normal growth
and development. I an inant or child is given a low-at diet or
an extended period, growth and development will not progress
normally. Other individuals with high-energy needs are athletes,
people who have physically demanding jobs, and those recuperating
rom illness.
When the body has used all o its calories rom carbohydrates
(this can occur ater just twenty minutes o exercise), it initiates
at usage. A proessional swimmer must consume large amounts
o ood energy to meet the demands o swimming long distances,
so eating at-rich oods makes sense. In contrast, i a person who
leads a sedentary liestyle eats the same high-density at oods, they
will intake more at calories than their body requires within just a
ew bites. Use caution—consumption o calories over and beyond
energy requirements is a contributing actor to obesity.
The Role o Lipids in Food | 303
Smell and Taste
Fat contains dissolved compounds that contribute to mouthwatering aromas and favors. Fat also adds texture to ood. Baked
oods are supple and moist. Frying oods locks in favor and lessens
cooking time. How long does it take you to recall the smell o your
avorite ood cooking? What would a meal be without that savory
aroma to delight your senses and heighten your preparedness or
eating a meal?
Fat plays another valuable role in nutrition. Fat contributes to
satiety, or the sensation o ullness. When atty oods are swallowed
the body responds by enabling the processes controlling digestion
to retard the movement o ood along the digestive tract, thus
promoting an overall sense o ullness. Otentimes beore the eeling
o ullness arrives, people overindulge in at-rich oods, nding the
delectable taste irresistible. Indeed, the very things that make atrich oods attractive also make them a hindrance to maintaining a
healthul diet.
304 | The Role o Lipids in Food
Tools for Change
There are many
sources o omega-3 oods.
It is important to strike a proper balance between
omega-3 and omega-6 ats in your diet. Research suggests
that a diet that is too high in omega-6 ats distorts the
balance o proinfammatory agents, promoting chronic
infammation and causing the potential or health problems
such as asthma, arthritis, allergies, or diabetes. Omega-6
ats compete with omega-3 ats or enzymes and will
actually replace omega-3 ats. The typical western diet is
characterized by an excessive consumption o oods high in
omega-6 atty acids. To gain proper balance between the
two, increase your omega-3 at intake by eating more atty
sh or other sources o omega-3 atty acids at least two
times per week.
The Role o Lipids in Food | 305
Learning Activities
Technology Note The second edition o the Human
Nutrition Open Educational Resource (OER) textbook
eatures interactive learning activities. These activities are
available in the web-based textbook and not available in the
downloadable versions (EPUB, Digital PDF, Print_PDF, or
Open Document).
Learning activities may be used across various mobile
devices, however, or the best user experience it is strongly
recommended that users complete these activities using a
desktop or laptop computer.
An interactive H5P element has been excluded
rom this version o the text. You can view it
online here:
https://pressbooks.oer.hawaii.edu/
humannutrition2e22/?p=195#h5p-54
306 | The Role o Lipids in Food
How Lipids Work
Lipids are unique organic compounds, each serving key roles and
perorming specic unctions within the body. As we discuss the
various types o lipids (triglycerides, phospholipids, and sterols) in
urther detail, we will compare their structures and unctions an...
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