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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 body 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 carbohydrate 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