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Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

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Page 1: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Carbohydrates

Part One:

A. Classification

B. Digestion & Absorption of CHO

Page 2: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Carbohydrate Is Made by Photosynthesis

CHO

Page 3: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Carbohydrate Classifications

Simple CHO = “Sugars”– Monosaccharides: single sugar unit

– Disaccharides: two sugar units linked together

Complex CHO= Starch, glycogen, fiber– Polysaccharides: many sugar units linked

together

Page 4: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Simple CHO: Sugars Monosaccharides

Disaccharides

Page 5: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO
Page 6: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

condensation

hydrolysis

Page 7: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Simple Sugars, Cont. What is sugar good for? When is sugar considered to be “bad?”

Page 8: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

10% recommendation

– (current U.S. 24%) high sugar diet can change in fat

distribution toward central adiposity binge trigger in some, inhibitor in others –

highly individual

Page 9: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Sugar on the Food Label

fructose/levulose glucose/dextrose honey/invert sugar

fruit juice concentrate corn syrup corn sweetener molasses raw sugar turbinado sugar

Page 10: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Sugar Alcohols

E.g. mannitol, sorbitol, xylitol Considered “sugar free” sweeteners,

but still almost the same kcals as sugar Sugar free candy -- diarrhea if eaten in

excess

Page 11: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

A word about lactose: milk sugarand lactose intolerance

Enzyme lactase splits lactose into glu-gal in the small intestine

Lactase deficiency causes trouble digesting milk products

Page 12: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Different from milk allergy, immune rx to casein

Page 13: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Carbohydrate Classifications

Simple CHO = “Sugars”– Monosaccharides: single sugar unit– Disaccharides: two sugar units linked

together

Complex CHO= Starch, glycogen, fiber– Polysaccharides: many sugar units

linked together

Page 14: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Complex CHO: Polysaccharides:Several to Hundreds of ____________ Units Linked Together

Starch –

Glycogen –

Fiber –

Page 15: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO
Page 16: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Starch Long straight or branched chains of

hundreds of __________________ units Sources:

– Richest source:

– Legumes

– Tubers

Page 17: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

When eaten, ALL starches are broken down enzymatically to ______________– (blue dots!)

One to 4 hours after a meal, all starch __________________

Page 18: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO
Page 19: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Glycogen Storage form of CHO in animals. Not

found in diet. More complex and more highly branched

than starch–

Limited capacity for storage–

Page 20: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Muscle Glycogen–

Liver Glycogen–

Page 21: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Fiber

Typical U.S. diet:

Most fibers are polysaccharides but–

Page 22: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Most common fibers: cellulose, hemicellulose, and pectin. Also gums, mucilages, and lignins

Sources:

Page 23: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO
Page 24: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Whole Vs. Refined Grains Whole grains Label:

Page 25: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Refined grains Label:

Sources:

Page 26: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

“Enriched” When bran and germ are removed,

several vitamins/minerals also “enriched,”

Shoot for at least half of your grains to be from whole grain sources

Page 27: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO
Page 28: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Soluble vs. Insoluble fiber Soluble fiber

– foods: barley, fruits (apples), legumes, oats, oat bran, rye, seeds, vegetables, nuts

Health benefits: –

– lowers serum cholesterol

– stool bulk/softening

Page 29: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO
Page 30: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO
Page 31: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Insoluble fiber – Foods: brown rice/whole grains/wheat

bran, fruits, legumes, seeds, veggies Health benefits:

– – Speeds transit through intestines

– delayed starch hydrolysis: slowed glu absorption

Page 32: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO
Page 33: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

If you have a low-fiber diet, add fiber gradually!

What about fiber supplements?

Page 34: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Carbohydrates

Digestion and absorption of CHO

Page 35: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Dietary CHO = starch, sugar, and fiber

Page 36: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

D&A of CHO Mouth

starch Salivary amylase dextrins & maltose

glu-glu-glu-glu-glu-glu-glu-glu-glu x100

glu-glu-glu-glu-glu-glu

glu-glu

Page 37: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Stomach –

–Mechanical digestion continues in stomach, but

Page 38: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Small Intestine

Starch and dextrins

Pancreatic amylasemaltose

glu-glu-glu-glu-glu-glu

glu-glu

Page 39: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Last phase: The brushborder cells of the small intestine.

Enzymes in these cells break down ___________________ to _____________________.

maltose

lactose

sucrose

(maltase)

(lactase)

(sucrase)

glu & ________

glu & ________

glu & ________

Page 40: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Monosaccharides are ABSORBED–

– In liver, fru and gal are converted to glu

– ____________ then regulates the release of glu back into the bloodstream for transport to tissues.

Page 41: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO
Page 42: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Large Intestine (colon)

Fiber – (absorbed & used for E, 0-2kcals/g of

fiber)

– (Cellulose and lignin completely pass through in feces)

Page 43: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

So now we have glucose in the liver and the bloodstream. If glu is to fuel the tissues, how is it done?

“Glucose-dependent tissues” rely on glucose for fuel (not fat) – Brain, nervous system, retina, etc.

***

Page 44: Carbohydrates Part One: A. Classification B. Digestion & Absorption of CHO

Average person enough CHO stored to last ________________ hours

Since we can’t store much, need to rely on dietary CHO.