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Chapter 2Chapter 2Carbohydrates

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Chapter 2 Chapter 2

Lesson 2.1 Lesson 2.1

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Key ConceptsKey Concepts

• Carbohydrate foods provide practical energy (calorie) sources because of their availability, relatively low cost, and storage capacity.

• Carbohydrate structures vary from simple to complex, so they can provide both quick and extended energy for the body.

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Importance of Carbohydrates Importance of Carbohydrates

• Basic fuel source

• Widely available and easily grown

• Relatively low in cost

• Easily stored

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Classes of CarbohydratesClasses of Carbohydrates

• Monosaccharides Glucose Fructose Galactose

(Cont'd…)

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Classes of CarbohydratesClasses of Carbohydrates(…Cont’d)

• Disaccharides Sucrose Lactose Maltose

(Cont'd…)

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Classes of CarbohydratesClasses of Carbohydrates(…Cont’d)

• Polysaccharides Starch Glycogen

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Summary of Carbohydrate Summary of Carbohydrate ClassesClasses

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Chapter 2 Chapter 2

Lesson 2.2 Lesson 2.2

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Key ConceptsKey Concepts

• Dietary fiber, an indigestible carbohydrate, serves separately as a body regulatory agent.

• Carbohydrate foods provide practical energy (calorie) sources because of their availability, relatively low cost, and storage capacity.

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Dietary FiberDietary Fiber

• Not digestible

• Important in health promotion and disease prevention

• Cellulose Remains undigested in the GI tract and

provides bulk to a diet Bulk helps move the food mass through the

intestine

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Dietary FiberDietary Fiber(…Cont’d)

• Noncellulose polysaccharides Absorb water and swell to a larger bulk

• Lignin Only noncarbohydrate type of dietary fiber

(Cont'd…)

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Dietary FiberDietary Fiber(…Cont’d)

• Divided into two groups based on solubility

• Dietary fiber provided in whole grains, legumes, vegetables, fruits

• Many health organizations recommend increasing intake of dietary fibers

(Cont'd…)

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Dietary FiberDietary Fiber(…Cont’d)

• Sudden increases can result in gas, bloating, constipation

• Excessive amounts of dietary fiber can trap small amounts of minerals and prevent absorption into GI tract

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Summary of Dietary Fiber Summary of Dietary Fiber ClassesClasses

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Other SweetenersOther Sweeteners

• Nutritive sweeteners Sugar alcohols (sorbitol, mannitol, xylitol)

• Nonnutritive sweeteners Artificial sweeteners in food

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Sweetness of Sugars and Sweetness of Sugars and Artificial SweetenersArtificial Sweeteners

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Energy Function of Energy Function of CarbohydratesCarbohydrates

• Basic fuel supply Energy for physical activities and all work of

body cells

• Reserve fuel supply Provided by glycogen Maintains normal blood glucose level

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Special Tissue Functions of Special Tissue Functions of CarbohydratesCarbohydrates

• Liver Glycogen reserves protect cells from

depressed metabolic function

• Protein and fat Carbohydrates regulate proteins and fat

(Cont'd…)

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Special Tissue Functions of Special Tissue Functions of CarbohydratesCarbohydrates

(…Cont’d)

• Heart Glycogen is vital emergency fuel for heart

muscle

• Central nervous system Brain dependent on minute-to-minute supply

of glucose

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Food Sources of Food Sources of CarbohydratesCarbohydrates

• Starches Provide fundamental complex carbohydrates

• Sugars High-sugar diets carry health risks

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Carbohydrate Content of Carbohydrate Content of FoodsFoods

(Cont'd…)

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Carbohydrate Content of Carbohydrate Content of FoodsFoods

(…Cont’d)

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Digestion of CarbohydratesDigestion of Carbohydrates

• Mouth Mechanical or muscle functions break food

mass into smaller particles

• Stomach Peristalsis continues mechanical digestive

process

(Cont'd…)

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Digestion of CarbohydratesDigestion of Carbohydrates(…Cont’d)

• Small intestine Peristalsis continues mechanical digestions Pancreatic secretions Intestinal secretions

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Summary of Carbohydrate Summary of Carbohydrate DigestionDigestion

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Body Needs for Body Needs for CarbohydratesCarbohydrates

• Dietary Reference Intakes 45%-65% of adult’s total caloric intake should

come from carbohydrate foods Limit sugar to no more than 25% of calories

consumed

• Dietary Guidelines for Americans Does not outline specifics for caloric

consumption or where kilocalories should come from