In this pyramid level are complex carbohydrates. Carbohydrates are

derived mainly from plants, including foods such as fruits, vegetables,

pasta, rice, legumes (beans), and other grains fall in this category.

Carbohydrates are very important to the body since they are the primary

source of energy. Some body tissues, such as red blood cells and most parts

of the brain, can only use carbohydrate (glucose) for energy. You should

eat 6-11 servings of carbohydrates each day, comprising 55-65% of your

diet.

Carbohydrates are broken down by the bbody into glucose, which is a

form of sugar that is carried in the blood and transferred to cells for

energy. Some carbohydrates, such as pasta and bread, have been labeled

fattening. This, however, can be said of all foods, no matter their

nutritional makeup. When a person consumes too many calories, the excess

will be stored as body fat, whether the foods were carbohydrates, proteins,

or fats.

Complex carbohydrates are long chains of glucose molecules. They are

usually comprised of starches, which is the product of ccarbohydrate storage

in plants. The major source of complex carbohydrates are whole grain

products, such as whole wheat bread, brown rice, pasta, and beans.

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In fruits and vegetables are a lot of vitamins. The chemical

structures of the vitamins are all known, and all of them have been

synthesized; the vitamins in foods are identical to the synthetic ones. A

well-balanced diet usually satisfies the minimum vitamin requirements of

human beings. The Recommended Dietary Allowance (RDA) of each vitamin is

the standard guideline put forward by the Food and Nutrition Board,

National Academy of Sciences-National Research Council. It is based on the

nutritional needs of an average, healthy person. Different amounts may be

recommended for children, older people, lactating mothers, or people

dealing with an ongoing disease process.

   Vitamins were originally classified according to their solubility in

water or fats, and as more and more were discovered they were also

classified alphabetically. The fat-soluble vitamins are A, D, E, and K; the

B complex and C vitamins are water soluble. A group of substances that

decrease blood capillary fragility, called the vitamin P group, are no

longer considered to be vitamins.

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What does it do? Vitamin A is a fat-soluble vitamin with four major

functions in the body: (1) It helps cells reproduce normally—a process

called differentiation (cells that have not properly differentiated are

more likely to undergo pre-cancerous changes). (2) It is required for

vision; vitamin A maintains healthy cells in various structures of the eye

and is required for the transduction of light into nerve signals in the

retina. (3) It is required for normal growth and development of the embryo

and fetus, influencing genes that determine the sequential development of

organs in embryonic development. (4) It may be required for normal

reproductive function, with influences on the function and development of

sperm, ovaries and placenta.

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What does it do? Vitamin C is a water-soluble vitamin that has a number of

biological functions. Acting as an antioxidant, one of vitamin C’s

important functions is to protect LDL cholesterol from oxidative damage.

(Only when LDL is damaged does cholesterol appear to lead to heart disease,

and vitamin C may be one of the most important antioxidant protectors of

LDL.) Vitamin C may also protect against heart disease by reducing the

stiffness of arteries and the tendency of platelets to clump together.

Vitamin C is needed to make collagen, the „glue“ that strengthens many

parts of the body, such as muscles and blood vessels. Vitamin C also plays

important roles in wound healing and as a natural antihistamine. This

vitamin also aids in the formation of liver bile and helps to fight viruses

and to detoxify alcohol and other substances.

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Vitamin E (tocopherol) occurs in at least seven molecular forms,

designated alpha-, beta-, gamma-, delta-, epsilon-, zeta-, and eta-

tocopherol; all exist as light yellow, viscous oils. The best source is

vegetable oils. Other sources include green leafy vegetables, wheat germ,

and eggs. Tocopherol is necessary for the maintenance of cell membranes. It

is a potent antioxidant ; numerous studies have pointed to a protective

effect against arterial plaque buildup and cancer. It is helpful in the

relief of intermittent claudication (calf pain) and in preventing problems

peculiar to premature infants. In large doses, it has an anticoagulant

effect.

In this level are a lot of calcium. Calcium is the mineral in your

body that makes up your bones and keeps them strong. Ninety-nine percent of

the calcium in your body is stored in your bones and teeth. The remaining

1% is in your blood and soft tissues and is essential for life and health.

Without this tiny 1% of calcium, your muscles wouldn’t contract correctly,

your blood wouldn’t clot and your nerves wouldn’t carry messages.

It is mainly the calcium in your diet that spares, or protects, the

calcium in your bones. In addition to their structural role, your bones are

your emergency supply of calcium. Your body actually tears down and builds

bone all of the time in order to make its calcium available for your body’s

functions. If you don’t get enough calcium from the food you eat, your body

automatically takes the calcium you need from your bones. If your body

continues to tear down more bone than it replaces over a period of years to

get calcium, your bones become weak and break easily. This leads to the

crippling bone disease called „osteoporosis.“

Protein molecule that consists of but a single polypeptide chain is

said to be monomeric; proteins made up of more than one polypeptide chain,

as many of the large ones are, are called oligomeric. Based upon chemical

composition, proteins are divided into two major classes: simple proteins,

which are composed of only amino acids, and conjugated proteins, which are

composed of amino acids and additional organic and inorganic groupings,

certain of which are called prosthetic groups . Conjugated proteins include

glycoproteins , which contain carbohydrates; lipoproteins, which contain

lipids; and nucleoproteins, which contain nucleic acids.

    Classified by biological function, proteins include the enzymes,

which are responsible for catalyzing the thousands of chemical reactions of

the living cell; keratin, elastin, and collagen, which are important types

of structural, or support, proteins; hemoglobin and other gas transport

proteins; ovalbumin, casein, and other nutrient molecules; antibodies,

which are molecules of the immune system (see immunity ); protein hormones,

which regulate metabolism; and proteins that perform mechanical work, such

as actin and myosin, the contractile muscle proteins.

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Fats and cholesterol have important functions in the body. Fats and

oils are also called lipids. Fats are the most concentrated source of food

energy. Per gram, fats have over twice as many calories as protein or

carbohydrates. Fats supply nine calories per gram, whereas carbohydrates

(sugars and starches) and protein supply four calories per gram. Our bodies

store excess dietary fats in fat cells to meet later energy needs. Excess

dietary carbohydrates and protein also are converted into fat by our bodies

and stored ffor later use.

In addition to supplying energy, fats have several important

functions. Fats give foods their characteristic flavors. Fats help provide

a feeling of satiety, or fullness. Dietary fats carry the fat-soluble

vitamins A, D, E, and K. Fats are also a source of the essential fatty

acids, linoleic acid and linolenic acid. Because the body cannot make these

essential fatty acids, they must be provided in the diet.

Cholesterol is often confused with fat. Cholesterol is not a

triglyceride, but a sterol. Sterols are fat-like compounds, made in the

body and found in foods. Cholesterol is part of the protective layer around

nerve fibers and is a building block for cell walls. Cholesterol is also

needed for the production of certain hormones, vitamin D, and bile.

Often ffat and cholesterol are present together in food. However, the

fat content of a food does not necessarily parallel cholesterol content.

For example, vegetable oils that contain no cholesterol are still 100% fat.

Further, chicken and fish may contain less fat than some cuts of beef, but

the cholesterol content is similar. Cholesterol is present in muscle tissue

as well as fat.