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Worksheet 4-2: Glycemic Index and Glycemic Load
Glycemic Index
Factors
Glycemic Load
A method of classifying foods according to
their potential for raising blood glucose as
determined by the rate of their absorption.
Definition
A method of using the glycemic index as the
basis for understanding the inter-related effects
of glucose and insulin.
For the following foods, please calculate the glycemic load (GL) and indicate whether it is low or high.
Glycemic Load (GL) = Glycemic Index (GI) of food/100 Net carbs (# of grams of CHO per serving)
Food
GI
Net Carbs
GL
GL Level
Apple (1 med.)
38
16
Watermelon (1 c.)
72
11
White rice (1 c.)
64
52
Sugar (1 Tbsp.)
68
12
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Worksheet 4-3: Hidden Sugars—What Is Your Sugar IQ?
For each of the following food items, indicate the relative sugar (carbohydrate) content, amount of kcalories that are
provided, and whether or not you consider the item to be a significant source of sugar in your diet (circle “Yes” or
“No”). Use the Food Composition Table in the back of your textbook.
Food item
Relative sugar content
Amount of kcal
Significant source of
sugar in your diet?
12-oz. cola/soda
Yes No
8 ounces instant
unsweetened tea
Yes No
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Worksheet 4-4: Check Your Carbohydrate Choices
Most of the energy we receive from foods comes from carbohydrates. Healthy choices provide complex
carbohydrates or naturally occurring simple carbohydrates, rich in water-soluble vitamins and dietary fiber. A diet
that is consistently low in dietary fiber and high in added sugar can lead to health problems. Look at these examples
of related foods and identify which are most similar to your food choices.
High in fiber/
low in added sugar
Apple with peel
1. Do you select whole-grain products and fresh fruits and vegetables regularly?
2. Do you choose foods that increase your intake of fiber and limit your intake of sugars?
Pumpernickel bread
Bagel, plain
Danish pastry
Corn on the cob
Creamed corn
Frosted corn flakes
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Worksheet 4-5: Chapter 4 Crossword Puzzle
1
2
3
4
5
6
7
8
9
10
11
12
Across
Down
5. Location where the majority of carbohydrate
absorption occurs
9. Adequate dietary fiber intake may protect the body
from developing _____ cancer.
11. Location where carbohydrate digestion begins
12. Classification system that quantifies how foods
impact blood glucose levels
3. Lactase deficiency can lead to diarrhea and
abdominal pain and is referred to as _____.
for maintaining healthy blood glucose levels
6. Nonstarch polysaccharides that the body cannot
consuming _____ fiber.
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Handout 4-1: Glycemic Index of Selected Foods
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Handout 4-2: Alternatives to Sugar
Almost everyone finds pleasure in sweet foods—after all, the taste preference for sweets is inborn. To a child, the
sweeter the food, the better. In adults, this preference is somewhat diminished, but most adults still enjoy an
occasional sweet food or beverage. Because they want to control weight gain, blood glucose, and dental caries,
many consumers turn to alternative sweeteners to help them limit kcalories and minimize sugar intake. In doing so,
they encounter two sets of alternative sweeteners: artificial sweeteners and sugar replacers.
Artificial Sweeteners
The Food and Drug Administration (FDA) has approved the use of several artificial sweeteners—saccharin,
aspartame, acesulfame potassium (acesulfame-K), sucralose, and neotame. Two others are awaiting FDA
approval—alitame and cyclamate. Another—tagatose—did not need approval because it is generally recognized as a
safe ingredient. These artificial sweeteners are sometimes called nonnutritive sweeteners because they provide
virtually no energy. Table 1 provides general details about each of these sweeteners.
Table 1: Sweeteners
Sweeteners
Relative
Sweetness a
Energy
(kcal/g)
Acceptable
Daily
Intake
Average Amount
to Replace 1 tsp
Sugar
Approved Uses
Approved Sweeteners
Saccharin
(Sweet ‘n Low)
450
0
5 mg/kg
body
weight
12 mg
Tabletop sweeteners, wide
range of foods, beverages,
cosmetics, and pharmaceutical
products
jams and jellies, syrups
Tagatose
(Nutralose)
0.8
1.5
7.5 g/day
1 tsp
Baked goods, beverages,
cereals, chewing gum,
confections, dairy products,
dietary supplements, health
bars, tabletop sweetener
Sweeteners with Approval Pending
Proposed Uses
Alitame
2000
4 e
—
Beverages, baked goods,
tabletop sweeteners, frozen
desserts
Sucralose
General purpose sweetener for
70
a Relative sweetness is determined by comparing the approximate sweetness of a sugar substitute with the sweetness of pure
sucrose, which has been defined as 1.0. Chemical structure, temperature, acidity, and other flavors of the foods in which the
substance occurs all influence relative sweetness.
Saccharin, acesulfame-K, and sucralose are not metabolized in the body; in contrast, the body digests aspartame as a
protein. In fact, aspartame yields energy (4 kcalories per gram, as does protein), but because so little is used, its
energy contribution is negligible.
Some consumers have challenged the safety of using artificial sweeteners. Considering that all substances are toxic
at some dose, it is little surprise that large doses of artificial sweeteners (or their components or metabolic by–
products) have toxic effects. The question to ask is whether their ingestion is safe for human beings in quantities
people normally use (and potentially abuse).
Saccharin
Saccharin, used for over 100 years in the United States, is currently used by some 50 million people—primarily in
soft drinks, secondarily as a tabletop sweetener. Saccharin is rapidly excreted in the urine and does not accumulate
in the body.
Aspartame
Aspartame is a simple chemical compound made of components common to many foods: two amino acids
(phenylalanine and aspartic acid) and a methyl group (CH3). Figure 1 shows its chemical structure. The flavors of
the components give no clue to the combined effect; one of them tastes bitter, and the other is tasteless, but the
combination creates a product that is 200 times sweeter than sucrose.
Figure 1: Structure of Aspartame
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In the digestive tract, enzymes split aspartame into its three component parts. The body absorbs the two amino acids
and uses them just as if they had come from food protein, which is made entirely of amino acids, including these
two.
During metabolism in the body, the methyl group momentarily becomes methyl alcohol (methanol)—a potentially
toxic compound (see Figure 2). (This breakdown also occurs in aspartame-sweetened beverages when they are
stored at warm temperatures over time. The amount of methanol produced may be safe to consume, but a person
may not want to, considering that the beverage has lost its sweetness.) In the body, enzymes convert methanol to
formaldehyde, another toxic compound. Finally, formaldehyde is broken down to carbon dioxide. Before aspartame
could be approved, the quantities of these products generated during metabolism had to be determined, and they
were found to fall below the threshold at which they would cause harm. In fact, ounce for ounce, tomato juice yields
six times as much methanol as a diet soda.
Figure 2: Metabolism of Aspartame
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decrease their threshold for seizures; this does not appear to be a problem when intakes are within recommended
amounts.
Acesulfame-K
Because acesulfame potassium (acesulfame-K) passes through the body unchanged, it does not provide any energy
nor does it increase the intake of potassium. Acesulfame-K is approved for use in the United States, Canada, and
more than 60 other countries.
Sucralose
Tagatose
The FDA granted the fructose relative tagatose the status of “generally recognized as safe,” making it available as a
low-kcalorie sweetener for a variety of foods and beverages. This monosaccharide is naturally found in only a few
foods, but it can be derived from lactose. Unlike fructose or lactose, however, 80 percent of tagatose remains
Alitame and Cyclamate
FDA approval for alitame and cyclamate is still pending. To date, no safety issues have been raised for alitame, and
it has been approved for use in other countries. In contrast, cyclamate has been battling safety issues for 50 years.
Approved by the FDA in 1949, cyclamate was banned in 1969 principally on the basis of one study indicating that it
caused bladder cancer in rats.
The National Research Council has reviewed dozens of studies on cyclamate and concluded that neither cyclamate
nor its metabolites cause cancer. The council did, however, recommend further research to determine if heavy or
long-term use poses risks. Although cyclamate does not initiate cancer, it may promote cancer development once it
is started. The FDA currently has no policy on substances that enhance the cancer-causing activities of other
substances, but it is unlikely to approve cyclamate soon, if at all. Agencies in more than 50 other countries,
including Canada, have approved cyclamate.
Acceptable Daily Intake
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Table 2: Average Aspartame Contents of Selected Foods
Food
Aspartame (mg)
12 oz diet soft drink
170
Artificial Sweeteners and Weight Control
The rate of obesity in the United States has been rising for decades. Foods and beverages sweetened with artificial
sweeteners were among the first products developed to help people control their weight. Using intense sweeteners,
such as aspartame, instead of sugar lowers the energy density of foods and beverages. Most studies find no
difference in hunger and no compensation in food intakes when diet soft drinks replace regular ones.3 In this way,
people who eat or drink artificially sweetened products can lower their energy intakes and expect modest weight
losses.4
When studying the effects of artificial sweeteners on food intake and body weight, researchers ask different
Stevia—An Herbal Alternative
The herb stevia is a shrub whose leaves have long been used by the people of South America to sweeten their
beverages. In the United States, the highly-purified stevia product rebaudioside A is a “generally recognized as safe”
sweetening additive. Stevia (the plant) may be sold as a dietary supplement, but not used as a food additive. This
herbal sweetener’s popularity has grown sharply in recent years—from $210.6 million in sales in 2010 to $1.192
billion in 2011.5
Sugar Replacers
Some “sugar–free” or reduced-kcalorie products contain sugar replacers.6 The term sugar replacers describes the
Table 3: Sugar Replacers
Sugar Alcohols
Relative Sweetness
Energy (kcal/g)
Approved Uses
Erythritol
0.7
0.4
Beverages, frozen dairy desserts, baked goods,
chewing gum, candies
Isomalt
0.5
2.0
Candies, chewing gum, ice cream, jams and
jellies, frostings, beverages, baked goods
jams and jellies, frostings, baked goods
8 oz powdered drink
100
8 oz sugar-free fruit yogurt
124
4 oz gelatin dessert
1 packet sweetener
74
Sugar Alcohols
Relative Sweetness
Energy (kcal/g)
Approved Uses
health products
Sugar alcohols evoke a low glycemic response. The body absorbs sugar alcohols slowly; consequently, they are
slower to enter the bloodstream than other sugars. Common side effects include intestinal gas, abdominal
discomfort, and diarrhea. For this reason, regulations require food labels to state “Excess consumption may have a
laxative effect” if reasonable consumption of that food could result in the daily ingestion of 50 grams of a sugar
alcohol.
Figure 3: Sugar Alternatives on Food Labels
For persons choosing to use artificial sweeteners, the American Dietetic Association wisely advises that they be used
in moderation and only as part of a well-balanced, nutritious diet. The dietary principles of moderation and variety
help to reduce the possible risks associated with any food. The sugar replacers, like the artificial sweeteners, can
occupy a place in the diet, and provided they are used in moderation, they will do no harm. In fact, they can help, by
providing an alternative to sugar for people with diabetes, by inhibiting caries-causing bacteria, and by limiting
energy intake. People may find it appropriate to use all three sweeteners at times: artificial sweeteners, sugar
replacers, and sugar itself.
References
1. M. Soffritti and coauthors, Aspartame induces lymphomas and leukaemias in rats, European Journal of
Oncology 10 (2005): 107-116.
Mannitol
Bulking agent, chewing gum
Sorbitol
Special dietary foods, candies, gums