Nutrient Review: The Energy Nutrients:
Carbohydrates, Protein and Fat
Ingestion, Digestion, Absorption, Transport, Storage, Utilization, Excretion:
Physiology of the GIT; digestion in mouth and stomach, absorption primarily
in small intestine.
Nutrients in the Cell:
Energy: the capacity to do work. Energy in food is chemical energy -in
body changed to mechanical, electrical and heat energy. In cell, C-H bonds
break, combine with O2=CO2+H2O+ energy. If energy is not used from the CHO,
protein or fat, body rearranges the molecules to form storage energy, glycogen
and adipose tissue (fat). Energy food provides is measured in Kcalories in U.S.;
in Europe in Kilojoules (calories X 4.18 = kilojoules).
How energy is used:
I. Carbohydrates ( ___ kcalories / gram)
a. Definition: organic cmpds made up of C, H, and O. Two
classifications: simple sugars (mono and disaccharides), and starches (complex CHO or polysaccharides). Recommend that
_________ % of
calories come from CHO, and <_________of calories come from refined sugars.
b. Structure and Functions: CHO are the primary energy source for the body; glucose is the body's preferred energy source. CHO are the major source of calories for the world's population.
1. Monosaccharides: 1
CHO molecule
___________:
_____________:
_____________:
2. Disaccharides: 2 CHO molecules
_________:
_________:
_________:
3. Polysaccharides:
complex CHO,
polymers with
a few hundred to a few thousand monosaccharides joined by glycosidic
linkages; can
be straight or branched chains.
3 most
important for humans:
_______:
primarily long chains of interlocking glucose units; enzyme in small intestine hydroyzes
carbon chains to form
glucose, absorbed and used in cells for energy.
_______: storage form of glucose, in muscle and liver. Available during short
fasts, sleep, and
athletes for top performance; Hydrolysis in cells releases glucose for energy.
__________: polysaccharides unaffected by cooking, mashing, chopping.
Adults need
______ g / day. 2 types:
1. Soluble - dissolves in water, produces a gel; slows glu absorption and may be
helpful in treatment of DM, decrease risk of CVD. Sources: beans,oats, apples,
gums, mucilages,
broccoli, corn, oranges, potatoes, seaweeds, plant secretions,
pectins, psyllium.
2. Insoluble - not digested, won't dissolve in water; increases stool bulk and
decreases
transit time, so less opportunity for fecal mutagens to interact with intestinal
epithelial
c
cells thus decreasing risk of cancer; prevents constipation and hemorrhoids, CVD.
Sources: cellulose, most hemicelluloses, lignan - plants such as wheat, rice
bran, seeds,
nuts, whole grains, brown rice, vegetables and fruits.
Other Polysaccharides:
Alcohol: __calories per gram, or ___ calories per ml; toxic to brain
and liver; can
easily be converted in the body to fat.
Sweetners: FDA tested as GRAS; sweetness varies with product; sugar
alcohols:
sorbitol, xylitol, mannitol give 1.6-3 calories per gram; nonnutrive sweetners
no calories - saccharin, aspartame (NutraSweet) safe limit = to ____ cans
soda/day.
II. Protein ____calories / gram;
contain C, H, O, N, and sometimes minerals like _________..
a. Definition: necessary for growth and
maintenance of all body tissues; most abundant organic
molecule in the cells and fundamental
for cell structure and function; used in blood transport
of nutrients also. All proteins are
constructed with a limited assortment of amino acids _______.
__ amino acids are termed essential,
since they cannot be produced in the body. Recommend
_________% of calories come from protein.
b. Protein functions
1. Growth of new tissue (muscle)
2. Use as building material for maintenance and repair
3. Essential for hormones and enzymes
4. Essential in the formation of antibodies
5. Essential for red blood cell production
6. Provides energy:
c. Protein digestion, absorption,
transport; protein balance
Proteins are broken down with enzymes
(proteinases) in stomach and proximal small
intestine; absorbed into blood stream
into an amino acid pool. From here the AA are used
for anabolism (tissue synthesis), or
deaminated for energy or converted to fat or glycogen.
Catabolism (tissue breakdown) occurs
in illness, injury, starvation;
N balance:
- N balance:
+ N balance:
d. Amino Acids, _____ in
total
1. A protein food that supplies all
the essential (indespensible) amino
acids in sufficient quantities i
is a Complete Protein. __ Essential Amino Acids:
phenylalanine, valine, tryptophan, isoleucine, methionine, leucine, threonine, lysine, histadine
3.
Incomplete Proteins: food sources deficient in________________________AA
Limiting Amino Acid: the AA that is lacking to make the plant food a complete
protein
lysine
(low in corn, cereal, sesame and sunflower seeds),
methionine
(low in legumes, nuts, soybeans, peanuts and greens)
tryptophan
(low in corn, legumes)
4. Vegetarian Diets:
make complete high quality protein by combining 2 or more
incomplete protein sources:
_________ + LEGUMES - rice and beans, lima beans and corn, dried peas and rice
________ + GRAINS - oats and almonds, wheat and sesame
seeds, rice and
pine nuts
_________ + DAIRY- cornflakes and milk, cheese and tortilla,
crackers and cheese
III. Fats (___ kcalories / gram)
1.
Dietary Fat: Recommend _______% of calories come
from fat (children, ______%)
< ____% of calories from saturated fat
Unsaturated Fats: not all C bonds are "saturated" with H; liquid at
room temp. (can
determine degree of saturation by hardness at room temperature); fats and oils
have
varying degrees of saturation, not all saturated or unsaturated.
Provide concentrated sources of calories
Carries essential fatty acids and fat soluble vitamins for absorption
enhances the flavors of foods
provides sustained relief form hunger - satiety
tenderizes and adds moisture to foods, acts as emulsifier for sauces.
A. Monounsaturated fats:
1 point of unsaturation; appear more heart healthy than
saturated fats. _________oil, olive oil, _________oil, some nuts (peanuts, cashews)
B.
Polyunsaturated fats: 2 or more points of unsaturation; ___________ oil,
safflower oil,
______ oil, soybean oil; may have free radical issues increased cancer risk in
large amts
Essential fatty acids are PUFA:
1.(_________) alpha-linolenic acid: needed for brain and nervous
system development,
retina health, may prevent CVD; Used to synthesize EPA and DHA, essential for
premature infants (abundant in breast milk).
Sources: fatty cold water fish like veg oils like mackerel, sardines, tuna,
trout, salmon,
soybean and canola oil, nuts, flax seed.
2. (_________) linoleic acid: needed for cell membranes, hormone and
skin formation
RBC; can synthesize arachadonic acid, which is needed for CNS and prostaglandins;
Sources: veg oils, meats, whole grains, leafy greens, seeds, nuts.
__________________ acid found in dairy products may play a role in cancer
prevention
C.
Saturated Fats: solid at room temp; all C bonds are "saturated"
with H; appear to raise
blood cholesterol levels (LDL) and increase risk for CVD. Recommend less than_____% of
total calories from saturated fats.
Sources: lard, ______ fat, ______ fat, butter, coconut oil, _______ oil
b.
Hydrogenation of vegetable oils: trans fatty acids:
Chemically saturate bonds with H to make liquid oils solid at room temp;
stick margarine, hydrogenated vegetable shortenings, some peanut butters,
commercial muffins, cookies, bagels, cakes, crackers, processed meals.
May increase risk for ____________ same as saturated fats.
D. Dietary Cholesterol: Not as much emphasis in restriction to prevent CVD
as in the
past. Sources: only from foods of ___________ origin, egg yolk, dairy and milk fat,
butter,
meat, fish and poultry
2. Body Lipids
a. made mostly of triglycerides, phospholipids and
sterols; contain C, H, O,
can contain P, N. Have less O than C
and H, so more concentrated in adipose tissue
and yield more energy; intregral part
of cell membranes; serves as a cushion for internal
organs, and provides body insulation
from the cold.
b. Triglycerides: majority of body fat stores (adipose tissue) are in this form;
c. Cholesterol: a sterol, part of estrogen,
testosterone and bile; major component
of nerves and brain; needed to
convert sunlight into Vitamin D in you skin, manufactured in
the liver and all body cells;
is transported in the body by LDL and HDL. Contains ____calories.