Each vitamin has specific
functions. If levels of a particular vitamin are
inadequate, a deficiency disease results.
Vitamin A helps in the
formation and maintenance of healthy teeth, skeletal and
soft tissue, mucous membranes, and skin. It is also known
as retinol because it generates the pigments that are
necessary for the working of the retina. It promotes good
vision, especially in dim light. Vitamin A may also be
required for reproduction and breast-feeding.
Beta-carotene is a precursor to vitamin A that has
antioxidant properties, helping the body deal with
unstable chemicals called free radicals.
Thiamine (B-1) helps the
body cells convert carbohydrates into energy. It is also
essential for the functioning of the heart and for healthy
nerve cells, including those in the brain.
Riboflavin (B-2) works with
the other B vitamins and is important for body growth and
red blood cell production. Similar to thiamine, it helps
in releasing energy from carbohydrates.
Niacin is a B vitamin that
helps maintain healthy skin and nerves. It is also
important for the conversion of food to energy and may
have cholesterol-lowering effects.
Vitamin B-6 is also known as
pyridoxine. The more protein a person eats, the more
vitamin B-6 is required to help the body use the protein.
It aids in the formation of red blood cells and in the
maintenance of normal brain function. It also assists in
the synthesizing of antibodies in the immune system.
Vitamin B-12, like the other
B vitamins, is important for metabolism. It, too, helps in
the formation of red blood cells and in the maintenance of
the central nervous system.
Pantothenic acid is
essential for the metabolism of food. It is also essential
in the synthesis of hormones and cholesterol. Biotin is
essential for the metabolism of proteins and
carbohydrates, and in the synthesis of hormones and
cholesterol. Cholesterol is needed for the functioning of
cell membranes, particularly in the brain.
Folate (folic acid) works
with vitamin B-12 in the production of red blood cells. It
is necessary for the synthesis of DNA, which controls
heredity as well as tissue growth and cell function. Any
woman who may become pregnant should be sure to consume
enough folate -- low levels of this substance are
associated with devastating birth defects such as spina
bifida. Many foods are now fortified with folic acid to
help reduce the level of such birth defects.
Vitamin C, also called
ascorbic acid, promotes healthy teeth and gums, helps in
the absorption of iron, and helps maintain normal
connective tissue. It also promotes wound healing and is
an antioxidant.
Vitamin D is also known as
the "sunshine vitamin," since it is manufactured by the
body after being exposed to sunshine. Ten to 15 minutes of
sunshine three times per week is adequate to produce the
body's requirement of vitamin D. This vitamin promotes the
body's absorption of calcium, which is essential for the
normal development and maintenance of healthy teeth and
bones. It also helps maintain adequate blood levels of
calcium and phosphorus, which are minerals necessary for
many functions.
Vitamin E is also known as
tocopherol and is an antioxidant. It is also important in
the formation of red blood cells and the use of vitamin K.
Vitamin K is known as the
clotting vitamin, because without it blood would not
coagulate. Some studies indicate that it helps in
maintaining strong bones in the elderly.
There are 13 vitamins
essential for bodily functions: Vitamins A, C, D, E, K,
and the B vitamins (thiamine, riboflavin, niacin,
pantothenic acid, biotin, vitamin B-6, vitamin B-12, and
folate). They all can be obtained from food, and vitamin D
and vitamin K can be synthesized by the body.
Fat Soluble Vitamins
Vitamin A is found in milk,
cheese, cream, liver, kidney, and cod and halibut fish
oils. Because most of these sources are high in saturated
fat and cholesterol, vegetable sources of a vitamin A
precursor called beta-carotene may be a better choice.
Beta-carotene comes from carrots, pumpkin, sweet potatoes,
winter squashes, cantaloupe, pink grapefruit, apricots,
broccoli, and spinach. The more intense the color of a
fruit or vegetable, the higher the beta-carotene content.
Vitamin D is found in
cheese, butter, margarine, cream, fish, oysters, and
fortified milk and cereals. The body can also synthesize
vitamin D when the skin is exposed to sunshine.
Vitamin E is found in wheat
germ, corn, nuts, seeds, olives, spinach, asparagus, and
other green leafy vegetables, vegetable oils, and products
made from vegetable oils, such as margarine.
Vitamin K is found in
cabbage, cauliflower, spinach, soybeans, and cereals.
Bacteria in the intestines normally also produce vitamin
K.
Water Soluble Vitamins
Thiamine (vitamin B-1) is
found in fortified breads, cereals, pasta, whole grains,
lean meats, fish, dried beans, peas, and soybeans. Dairy
products, fruits, and vegetables contain some thiamine as
well.
Niacin (vitamin B-3) is
found in dairy products, poultry, fish, lean meats, nuts,
and eggs. Legumes and enriched breads and cereals also
supply some niacin.
Folate is found in green,
leafy vegetables and many foods are now fortified with it
as well.
Vitamin B-12 is found in
eggs, meat, poultry, shellfish, milk and milk products.
Pantothenic acid and biotin
are found in eggs, fish, dairy products, whole-grain
cereals, legumes, yeast, broccoli and other vegetables in
the cabbage family, white and sweet potatoes, lean beef,
and other foods.
Vitamin C (ascorbic acid) is
found in citrus fruits and their juices, strawberries,
tomatoes, broccoli, turnip greens and other greens, sweet
and white potatoes, and cantaloupe. Most other fruits and
vegetables contain some vitamin C; fish and milk contain
small amounts.
