Nutrition
The Basis of Healthy Living
Ron Robertson
Classes
A. Carbohydrates - stored
B. Lipids (fats) - stored
C. Proteins - not stored
D. Vitamins - not produced by the body, some
stored, some not
E. Minerals - elements other than C,H, O, N
F. Water
Caloric need
1 food Calorie = 1000 calories = 1 kcal
| Nutrient |
|
U.S. |
% of
calories |
%Goal |
| Protein |
4 Cal/g |
80- 120 g |
10-15 |
12 |
| Carbohydrate |
4 Cal/g |
300-400 |
34-45 |
58 |
| Fat |
9 Cal/g |
100-150 |
30-50 |
30 |
- Basal Metabolic Rate (BMR) - kcal
needed for maintenance of life
- BMR = weight x 10
Digestion
Carbohydrates
- Mouth - salivary amylase (ptyalin) causes
starches to hydrolyze to maltose
- Stomach - no enzymes due to acidity
- Intestinal tract - acidity is neutralized
by secretion from pancreas, other pancreatic juices
hydrolyze poly and disaccharides to mono saccharides
Fats and Oils
Intestinal tract - bile salts emulsify and
allow other enzymes to hydrolyze fat and oil to fatty
acids and glycerol
Protein
- Stomach - pepsin begins hydrolysis
- Intestinal tract - the hydrolysis is
completed to amino acid fragments
After absorption through the intestinal
walls the water soluble products are sent to the liver
for storage and conversion. Glycogen is assembled from
excess glucose, fatty acids are sent for storage or
prepared for metabolism, and amino acids are assembled
into enzymes. The liver is the central nutrient bank of
the body.
Energy Transfer
Energy to drive muscles comes from
ATP Þ ADP + P + energy
Thus ADP must be replenished
ADP + P + energy Þ ATP
How do we get the energy to make ATP?
- Anaerobically (without oxygen)
- Aerobically (with oxygen)
The anaerobic series of complex reactions is
called the Embden-Meyerhof pathway. The aerobic series is called
the Krebs cycle.
Proteins
A. Needed for structure, enzymes, hormones,
transport proteins, antibodies, nucleic acids
B. 10 amino acids essential, meat is a
complete protein, vegetables are not
C. Few problems in U.S. diet
D. Kwashiorkor - protein deficiency disease
Fats
A. Foods contain triglycerides,
phospholipids (a complex lipid), and steroids (cholesterol)
B. The only essential fatty acid is linoleic
acid, an unsaturated C18
fatty acid
C. Uses
- energy
- insulation and padding
- building blocks for other molecules
- store vitamins A, D, E, K
D. Problems
Obesity
- Too much fat and too little carbohydrates
lead to ketosis - too many ketones from breakdown of fats
- Hydrogenation of oils to form margarine
produces trans fatty acids in trigylceride; natural fatty
acids are cis. Trans acids are not broken down well and
tend to let cholesterol levels increase in the blood. Cis
acids tie up cholesterol.
E. Fat substitutes
- Simplesse, Olestra, emulsified starch,
emulsified protein
Carbohydrates
A. Energy molecules.
B. Excess digestible carbs are stored as
glycogen, may be converted into fat. Indigestible carbs serve as
roughage.
C. Problems
Lack of undigestible fiber contributes to
diverticulitis, rectal cancer
- Too much digestible carbs (especially
refined sugar) can lead to obesity and diabetes - among
others. One type of diabetes is caused by insufficient
insulin production by the pancreas; another is caused by
excess fat preventing receptors from using insulin
appropriately.
- Refined sugar and flour have removed
coexisting natural nutrients and fiber - a dietary
problem.
Minerals
A. Elements other than C, H, O, N
B. Major minerals - Ca, P, Mg
C. Electrolytes - K, Na, Cl
D. Trace - Fe, I, Zn, Cu, Mn, Mo, Se, Cr, F,
Co, Ni, V, Si, Sn, As, Cd
E. Uses
- Enzyme components
- Structural components
- Electrolyte balance (Ca/P = 2.5/1) (K/Na
>1/1) Problems result with excess Na - high blood
pressure, water retention
- Transport
Vitamins
A. Organic components that are needed in
small amounts and function as catalysts
B. Not synthesized, must be ingested, and
are absorbed directly without digestion.
C. Fat-soluble = A, D, E, F, K
These are stored and should not be ingested in megadoses.
- A - prevention of infection by bacteria by
maintenance of mucous
- D - absorption of calcium
- E - antioxidant with varied uses; involved
in proper functioning of the kidneys, lungs, liver,
genitals; protects integrity of cell membranes
- F - essential fatty acid for production of
prostaglandins
- K - blood clotting
D. Water-soluble = B, C
These are not stored, must be ingested daily. Much fewer problems
with megadoses.
- B complex- growth and energy production
- C - antioxidant; involvement in the immune
system through production of interferon
Why Should You Eat A Balanced
Diet?
Thousands of virtually unknown chemicals
"phytochemicals" are produced by plants in small
quantities. These chemicals are natural anticarcinogens and
provide one of the best advantages of the balanced diet. (Newsweek,
April, 94)
1. Tomatoes - keep carcinogens from forming
2. Broccoli - boot carcinogens out of cells
3. Cabbage - disarms carcinogens
4. Garlic and onions - protect against
stomach cancer
5. Soybeans - prevent tiny tumors from
growing
6. Hot chili peppers - keep carcinogens
from binding to DNA
Food Additives
A. Maintain or improve nutritional value
- Add iodide to salt
- Add Vitamin D to milk
- Add Vitamin A to margarine
- Add Vitamin B to cereals
B. Maintain fresheness, color, flavor
- Tie up metal ions that catalyze
decompositon reactions- sequestrants (EDTA, citric acid)
- Antioxidants - Keeps fats and oils from
turning rancid (BHA, BHT, ascorbic acid, lecithin)
- Prevent spoilage caused by molds,
bacteria, fungi, etc. (sodium nitrite, salt, sodium
benzoate, sodium propionate)
C. Processing or preparation aid
- Emulsifiers, stabilizers, thickeners (
carrageenan and other polysaccharides, cholic acid in egg
yolks, polysorbate 80)
- Hygroscopic agents ( calcium silicate,
silicon dioxide, magnesium silicate)
- Retain moisture ( glycerine in candy)
D. Make foods more appealing
- Colors - most are synthetic and are
produced from crude oil
- Flavorings - oil of wintergreen,
peppermint, orange, lemon, etc.
- Flavor enhancer - monosodium glutamate
E. Sweeteners
Sucrose
Glucose
Sorbital
Saccharin
Aspartame
