This document provides an overview of carbohydrates, including simple and complex carbohydrates. Simple carbohydrates include monosaccharides like glucose, fructose, and galactose, and disaccharides like sucrose, lactose, and maltose. Complex carbohydrates are polysaccharides including glycogen, starches, and fibers. Carbohydrates are digested and absorbed in the gastrointestinal tract. Blood glucose levels are regulated by insulin and glucagon. Dietary fibers provide various health benefits. Recommendations are provided for daily carbohydrate and fiber intake. Alternative sweeteners like sugar alcohols and artificial sweeteners are also discussed.

1. Chapter 4
THE CARBOHYDRATES:
Sugars, Starches &
Fibers

2. Carbohydrates
(CH2O)n
• Simple carbohydrates
–Monosaccharides (single sugars)
–Disaccharides (double sugars)
• Complex carbohydrates
– Polysaccharides (many sugars)
Copyright 2005 Wadsworth Group, a division of Thomson Learning

3. Simple Carbohydrates
Monosaccharides
(C6H12O6)
Glucose
Fructose
Galactose
Copyright 2005 Wadsworth Group, a division of Thomson Learning

4. Monosaccharides
Glucose – dextrose or blood sugar
1. Primary fuel for the body
2. Found in all disaccharides &
polysaccharides

5. Monosaccharides
Fructose – fruit sugar
1. Found in fruit, honey,
syrup
2. Converts to glucose
in the body

6. Monosaccharides
Galactose – part of lactose
1. Found in milk
2. Converts to glucose
in the body

7. Simple Carbohydrates
Disaccharides
Maltose
Sucrose
Lactose
Copyright 2005 Wadsworth Group, a division of Thomson Learning

8. Disaccharides
Sucrose – table sugar
1. Glucose + Fructose
2. Refined from sugar beets &
cane

9. Disaccharides
Lactose – milk sugar
1. Glucose + Galactose
2. Lactose intolerance – missing
digestive enzyme needed to
split into two monodisaccharide
parts to absorb it

10. Disaccharides
Maltose – malt sugar
1. Glucose + Glucose
2. Found in germinating seeds &
used in fermentation to produce
malted beverages (beer,
whiskey)

11. Condensation

12. Hydrolysis

13. Complex Carbohydrates
Polysaccharides
Glycogen
Starches
Fibers
Copyright 2005 Wadsworth Group, a division of Thomson Learning

14. Polysaccharides
Glycogen – long chains of glucose
found in animals
1. Stored in liver & muscles
2. Helps maintain blood glucose
and important source of “quick
energy”, esp. during exercise
(lasts only about 12 hrs)

15. Polysaccharides
Starch – long chains of glucose
found in plants
1. Cereal grains (wheat, rice,
corn, etc.), legumes (beans &
peas), and root vegetables
(potatoes, yams)

16. Polysaccharides
Fiber – mostly indigestible CHO;
gums, mucilages, lignin
1. Component of plant cell walls
2. Classified according to solubility
in water
3. Abundant in whole grains,
legumes, fruits and vegetables

17. Fibers
Insoluble – nonviscous;
cellulose, lignins
Soluble – viscous & fermentable;
pectins, gums,
mucilages

18. Digestion
• Mouth
–Salivary amylase
• Stomach
–Fibers and satiety
• Small Intestine
-Maltase, sucrase, lactase

19. Digestion
• Pancreas
–Pancreatic amylase
• Large Intestine
-Fermentation of viscous fibers
 Water, gas, short-chain fatty
acid production

20. Carbohydrate Digestion
in the GI Tract

21. Absorption

22. Metabolism
Glucose in the Body
• Used for energy – fuels most of the body’s
cells
• Stored as glycogen – 1/3 in the liver and
2/3 in muscles
• Made from protein – gluconeogenesis
• Converted to fat – when in excess of
body’s needs

23. Constancy of Blood Glucose
• Regulating hormones – maintain
glucose homeostasis
1. Insulin – moves glucose from
the blood into cells
2. Glucagon – signals the liver to
release glucose into the blood
3. Epinephrine – released when
emergency fuel needed

24. Maintaining Blood Glucose Homeostasis

25. Constancy of Blood Glucose
• Diabetes
–Type 1 diabetes
•Failure of insulin production
–Type 2 diabetes
•Obesity
• Hypoglycemia
–Rare in healthy people
• Glycemic response
–Glycemic index

26. Glycemic Index

27. Health Effects of Sugar
• Sugar in excess
1. Contains no nutrients and may
contribute to malnutrition
2. Causes dental caries (tooth decay)
3. Does not cause, but can contribute
to: obesity, diabetes, heart
disease, & behavorial problems

28. Accusations Against Sugars
• Sugar causes
obesity
• Sugar causes
heart disease

29. Accusations Against Sugars
• Sugar causes misbehavior in children
and criminal behavior in adults
• Sugar causes cravings and addictions
–serotonin

30. Recommended Intakes of
Sugars
• DRI
–No more than 25% of total daily
energy intake
-Limit added sugars to <10% of
total energy intake
Copyright 2005 Wadsworth Group, a division of Thomson Learning

31. Health Effects
• Complex carbohydrates &
fiber may reduce
the risk of:
-Heart disease
-Diabetes
-GI health
-Cancer
-Weight
Management

32. Health Effects
How?
• Diets high in complex CHO tend to
be:
1. Lower in fat and calories
2. Higher in fiber, vitamins, &
minerals

33. Soluble Fibers
• Lower blood cholesterol by binding
dietary cholesterol so less absorbed
• Slow glucose absorption
• Slow transit of food through upper GI
tract
• Holds moisture in stools, softening
them
• Lower risk of heart disease
• Lower risk of diabetes

34. Soluble Fibers
• Gums & mucilages, pectins,
psyllium
• Sources
–Whole-grains, fruits, legumes,
seeds and husks, vegetables
–Extracted and used as food
additives

35. Insoluble Fibers
• Increase fecal weight - helps form
soft, bulky stools which improves
G.I. motility & reduces risk of
constipation, hemorrhoids,
diverticulosis & colon cancer
• Speed fecal passage through colon
• Provide bulk and feelings of fullness
(satiety)

36. Insoluble Fibers
• Cellulose, lignins, hemiculloses
• Sources
–Brown rice, fruits, legumes, seeds,
vegetables, wheat bran, whole
grains
–Extracted and used as food
additives

37. Recommended Intakes
of Carbohydrates & Fibers
• RDA for carbohydrate
–130 g/day
–45% - 65% total daily energy
intake with emphasis on complex
-Daily Value: 300 g/day
• Fiber
–Daily Value: 25 g/day
–AI: 14 g/1000 kcal/day

38. Dietary Recommendations
Example:
If 2000 kcal diet, then:
1100-1200 kcals as CHO
(275-300 grams)
with < 200 kcals as “added sugar”
(50 grams)
One 12 oz. soft drink has 36-40 gms sugar
0ne tsp. sugar weighs 4 gms = 9-10 tsps!

39. Alternative Sweeteners
Two Categories
1. Sugar Alcohols – mannitol, sorbitol,
xylitol
2. Artificial sweeteners – sugar substitutes
(calorie-free); in moderation, useful for
blood sugar & weight control

40. Alternative Sweeteners
Sugar Alcohols
1. CHOs that provide less energy than
sucrose (2-3 kcals/gm) because not
completely absorbed
2. May cause gas, abdominal discomfort,
diarrhea
3. Less cariogenic than sugar

42. Alternative Sweeteners
Artificial Sweeteners
1. Saccharin = “Sweet ‘N Low” or
“Sugar Twin”
2. Aspartame = “Equal” or “Nutrasweet”
must avoid if have phenylketonuria
3. Acesulfame-K = “Sunette” or “Sweet
One”
4. Sucralose = “Splenda”

45. Alternatives to Sugar
• Acceptable Daily Intake (ADI)
• Artificial sweeteners and weight
control
• Saccharine and cancer
• Aspartame and PKU

46. Sugar Alternatives on Food Labels

47. Alcoholic Beverages
• Rule of thumb to figure calories per
ounce for wines and distilled spirits
Wine: Multiply the “percent of alcohol by
volume” by two to obtain calories/ounce
Example: Zinfandel is 12.5% alcohol by
volume, 12.5 X 2 = 25 calories/ounce
Distilled Spirits (hard liquor): Proof minus 15
to obtain calories per ounce
Example: 80 proof whiskey – 15 = 65
calories per ounce