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Chapter 4:
Carbohydrates
Plants Synthesize Glucose
“Sugars”
Simple-one or two sugar units
Monosaccharides
 Disaccharies

Starch or fibers-digestibility
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Large, more complex structures
Monosaccharides
Glucose
Dextrose or blood sugar
 Major mono found in the body

Fructose

Fruit sugar “high fructose corn
syrup”
Galactose

Milk
Disaccharides
Maltose + maltase= glucose + glucose
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Fermentation
Alcohol production
Sucrose + sucrace= glucose+ fructose

Sugar
Lactose + lactase= galactose + glucose

Milk products
Complex Carbohydrates
Polysaccharides: Starch & glycogen
Amylose-long straight chain
Amylopectin-highly complex branched
chain
Dietary fiber-cellulose
Glycogen
Storage form of CHO for animals & humans
Structure similar to amylopectin
More sites for enzyme action & storage
Dietary Fiber
Undigested plant food
Body cannot break the bonds
Insoluble fiber
Cellulos, hemicellulose, lignin
 Not fermented by the bacteria in the colon

Soluble fiber
Gum, Pectin, Mucilage
 Fruit, vegetable, rice bran, psyllium seed

Soluble and Insoluble
Fiber
Health Benefits of
Dietary Fiber
Absorbs & holds water
Soften stool
Larger stool promotes peristalsis
Promotes regularity-oligosaccharides
Lower risk for cardiovascular disease
Decrease hemorrhoids and diverticula
CHO in Food
Types of Sweeteners
High-fructose corn syrup
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cornstarch treated with acid and enzymes
conversion of glucose into fructose
same degree of sweetness as sucrose
cheaper & used in many food products
Brown sugar, maple syrup, honey
Sugar alcohols (2.6 kcals/gm)

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Sorbitol & xylitol
Absorbed & metabolized slower-fewer calories
Large amount causes diarrhea
Sugar Substitutes
Saccharin-pink
Aspartame-blue
Sucralose-yellow
Neotame
Acesulfame-K
Tagatose
Functions of Carbohydrate
Supplies energy & sweetness
Protein sparing & prevent ketosis
Regulating glucose
 Glycemic
index
 Glycemic load
Recommended CHO Intake
No RDA (yet)
Consume at least 130 gm to prevent
ketosis
National Cholesterol Education Program
recommends 45-65-0% of kcal from
CHO
Current intake is ~60%
The kind of CHO matters
Recommended Dietary
Fiber Intake
25 gm of fiber/day for women
38 gm of fiber/day for men
About 14 gm/1000 kcals
Children: age +5gm/day
Ave. U.S. intake: ~16 gm/day
Too much fiber (>60 gm/d) will:



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require extra intake of fluid
bind to some minerals
develop phytobezoars
fills the stomach of a young child quickly
Recommendation for
Simple Sugar Intake
Low nutrient density
Recommends no more than 10% of
total kcal/day (50 grams)
Ave. U.S. intake: 16% of total kcal/day
Added to food and beverages
during processing
Serving sizes! 6.5 g 20 oz.
High Sugar Diets
Empty calories
Soda replacing milk
Calories adding to excess
Dental caries

exposure to teeth
High glycemic index
Blood glucose response of a given food
 Influence by various factors
