Vitamins are essential for good health because they regulate chemical reactions in which the body converts food into energy and tissues. There are 13 vitamins: vitamin A; the vitamin B complex, which is a group of 8 vitamins; and vitamins C, D, E, and K. Scientists divide vitamins into two general groups, fat-soluble vitamins and water-soluble vitamins. The fat-soluble vitamins-vitamins A, D, E, and K-dissolve in fats. The vitamins of the B complex and vitamin C dissolve in water. Small amounts of these compounds are needed daily.
Vitamin A is necessary for healthy skin and development of strong bones. Sources of this vitamin include liver, green and yellow vegetables, and milk.
Vitamin B 1, also called thiamine, is necessary for changing starches and sugars into energy. It is found in meat and whole-grain cereals.
Vitamin B 2, also known as riboflavin, is essential for complicated chemical reactions that take place during the body's use of food. Milk, cheese, fish, liver, and green vegetables supply vitamin B 2.
Vitamin B 6, also called pyridoxine, and two other B vitamins known as pantothenic acid and biotin all play a role in chemical reactions essential for growth. Liver, yeast, and many other foods contain these vitamins.
Vitamin B 12 and folic acid, also called folate, are both needed for forming red blood cells and for a healthy nervous system. Vitamin B 12 is found in animal products, especially liver. Folic acid is present in green leafy vegetables. Doctors recommend that all women who are capable of becoming pregnant consume small amounts of folic acid each day to reduce the risk of spina bifida, a serious birth defect.
Niacin is also part of the B complex. Cells need niacin in order to release energy from carbohydrates. Liver, yeast, lean meat, fish, nuts, and legumes contain niacin.
Vitamin C, also called ascorbic acid, is needed for the maintenance of the ligaments, tendons, and other supportive tissue. It is found in fruits and in potatoes.
Vitamin D is necessary for the body's use of calcium. It is present in fish-liver oil and vitamin D-fortified milk. Vitamin D also forms when the skin is exposed to sunlight.
Vitamin E, also known as tocopherol, helps maintain cell membranes. Vegetable oils and whole-grain cereals are especially rich in this vitamin. It is also found in small amounts in most meats, fruits, and vegetables.
Vitamin K is necessary for proper clotting of the blood. Green leafy vegetables contain vitamin K. It is also manufactured by bacteria in the intestine.