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Nutrition Chp 3


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II. Why we need carbs
for energy
III. Simple carbs
sugars, available carbs
1. Monosaccharide
a. Different sweetness
b. Provide E
c. Have general CnH2nOn
d. ready to go quickly absorbed
i. Glucose
1. monosacc
2. Essential E source
3. One of 2 sugars in disaccharides

blood sugar⬝ or dextrose
ii. Fructose
fruit sugar⬝ or levulose
1. monosacc
2. sweetest
3. same form, glucose diff structure
4. honey, cereal, fruits, soft drinks
iii. galactose
1. monosacc
2. part of disaccharide lactose
3. rarely occurs by itself
2. Disaccharide
a. Pairs of monosaccs linked together
b. Condensationes
c. Hydrolysis ÷es --- occurs in digestion
d. Glucose + monsacc
e. Derives from plants except lactose
i. Maltose
malt sugar”
2. has 2 glucose units – alcohol
3. whenever starch breaks ↓
a. carb digestion

ii. sucrose
1. glucose + fructose
2. fruits, veggies, grain
3. sugars (powdered, white, brown)

iii. lactose
1. galactose + glucose
2. main part of milk
3. “milk sugar”

Complex Carbohydrates
1. starches and fibers
2. polysaccharides
2. polysaccharides
a. ed of straight/branches monosaccs
b. Several monosaccs linked together

Glycogen, starches, fibers
i. Glycogen
1. many glucoses linked together as highly branched chains  fast hydrolysis
2. stored in liver and muscles as a form of glucose
3. not sig food source of carbs
4. not complex carbs in food
5. storage form of glucose ing E for humans
6. found limitedly in meat, some plants

ii. starches
1. plant polysaccs composed of glucose
2. storage form of glucose  E for humans
3. available carb (simple carb)
4. most of glucose supply
5. all starchy foods come from plants, beans, grains, wheat/rice
6. Amylopectin – a component of starch, other is glucose
iii. fibers
1. most are polysaccs
2. no contain monosaccs  no E
3. soluble fibers and insoluble fibers
3. soluble fibers
dissolve in water, ex pectin (thicken jelly)
a. viscous – gel like
b. fermentable – degree
that bacteria can break ↓
fibers to frags
c. fruits, oatmeal, barley, legumes
d. sponge - absorbs
e. decreases cholesterol, 5-10 g/day
4. insoluble fibers
a. nonviscous, less fermented
b. whole grains, veggies
c. ↑ bowel movements, increases motility, makes food LEAVE
d. don't dissolve in H20
characs of fibers
5. from plants
6. veggies, fruits, grains, beans
7. each has diff struct
structures of fiber
a. cellulose
b. Hemicelluloses
c. Pectins
e. Mucilages
f. Lignin
g. Resistant starches
fibers from plants
a. nonstarch polysaccs --- not digested by humans
b. unavailable carbs b/c can’t break ↓
c. cant be broken ↓ by digestive enzymes like starches
a. cellulose
i. plant cell walls
ii.  no broken ↓ humans
b. Hemicelluloses
i. Main pt cereal fibers
ii. Made up monosaccs and branching monosaccs
c. Pectins
i. Backbone of one type of monsacc
ii. Veggies and fruits (citrus)
iii. Thicken jelly, keep salad dressing ÷ing
d. Gums
i. Plant secretion
ii. Addititives to thicken foods
e. Mucilages
i. +ed to foods as stabilizers
f. Lignin
i. Nonpolysacc
ii. 3-d structure  strength
iii. Woody taste in veggies
g. Resistant starches
i. Escape digestion/absorption
How carbs are digested
in mouth
1. in mouth – saliva, chewing, amylase,
a. amylase – enzyme that hydrolyzes amylose, breaks ↓ carbs
i. amylose – form of starch
ii. hydrolyzes starch to maltose
iii. very little digestion
how carbs digested
in stomach
bolus, stomach acid and protein digesting enzymes -> stop amylase and salivary enzymes
a. ->es satiety
b. hydrochloric acid churns food
how carbs digested
in small intestine
most of work of carb digestion, pancreatic amylase (breaks ↓ polysaccs to disaccs), enzymes take apart specific disaccs
a. maltase  two glucoses
b. sucrase  one glucose + one fructose
c. lactase  one gluclose + one galactose
d. now, all polysaccs/disacs are monosaccs
how carbs digested
in large intestine
1-4 hours, all sugs/starches digested,
a. fibers only ones left
i. attract H20  soft poo
carb absorption
in SI,
monosaccs enter capillaries of intestinal villi --- monosaccs travel to liver thru portal vein
3. galactose and fructose ed into glucose
carb metabolism glucose as glycogen
a.liver stores 1/3 of body’s total glycogen
b.after meal, blood glucose ↑es
i. condensation →ing long branches glycogen
c.blood glucose ↓es
i.liver cells hydrolysis
ii.single molecules, bloodstream
d.glucose supplies E to other areas regardless of recent meal
e.muscles stores glycogen (other 2/3s)
I. use in exercise
2. using glucose for E
a. fuel, breaks in ½
b. can us eother nutrients, fat & ptein but not as easy
c. liver only uses for a few hours
3. making glucose from Protein
a. protein has other jobs and fat = no
b. gluconeogenesis – making glucose from noncarb source  don’t want this
c. protein sparing action –carb/fat ing E, allows ptein used real purpose
d. need 50-100 g carbs/day
e. 45-65%
4. making ketone bodies from fat frags
a. when lack carbs, ketone bodies form incomplete break ↓ of fat, when excess 
i. ketosis
1. ↑ level of ketone, disturbs pH balance
5. how many carbs do you need?
a. 45-65%
b. 225-325 g --- 900-1300 cal
c. RDA 130 g
d. DV 300 g
e. Calculate total
Lactose Intolerance
i. Inability to digest milk sugar lactose
ii. Different than milk allergy
VIII. Maintaining Blood Glucose
regulators of blood glucose
a. insulin
hormone, released in response to ↑ levels blood glucose
i. purpose: remove glucose from blood into muscle/fat cells

allows cells to absorb blood glucose and store as glycogen in liver

regulates blood glucose
b. glucagon
i. when blood glucose ↓es (b/t meals), pancreas es glucagon
ii. es ↑ blood glucose, signals liver to release glucose storage
a. Epinephrine
fight or flight⬝ hormone, acts quickly, adrenaline

regulator of blood glucose
4. diabetes
a. disorder of carb metab, inad/ineffect insulin
i. type 1 diabetes
1. less common
2. pancreas fails  insulin, unknown cause
ii. type 2 diabetes
1. more common
2. cells don’t respond insulin
3. effect of obesity
4. prevent how? Healthy body weight
5. hypoglycemia
a. blood glucose ↓es dramatically es mini attack
b. effect of poorly controlled diabetes
c. rare in healthy ppl
6. glycemic index
a. way of classifying foods to potential to ↑ blood glucose
a. Nutritive sweeteners
– sweeteners that  E, includes sugars/sugar replacers
b. Hyperactivity
has been disproven, sugar no link to ADD/ADHD
i. Inattentive/impulsive behavior ↑ freq than age bracket
c. Recommendation sugar
i. No upper limit, no > 25%
d. Health threat sugar
i. Dental caries
ii. Might displace other nutrient needs
iii. Natural sugars ok: veggies, fruits
V. Effects of Fibers
a. Weight manage, ↓ blood cholest,
b. Prevents
i. Colon cancer, diabetes, homerrhoids, appendicitis, diverticulosis
c. Excessive amts fiber
i. Displaces E and nut-dense foods
ii. →es intestinal probs
iii. Interfere w/ mineral absorp
d. How much fiber we need?
i. 23-30 g

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