The B-complex family of vitamins contains 8 of the 13 essential vitamins needed for good health. B vitamins do everything from assisting the body's metabolism of food to assisting its cell and immune functions. Many B vitamins are available in fish, poultry, meat, eggs, dairy, leafy green vegetables, beans, peas, and enriched breads or cereals. Most B vitamins are water-soluble, so they easily leave the body and must be replenished frequently.
Vitamin B-1: Thiamine
Thiamine plays a role in the body's absorption and conversion of foods containing carbohydrates, in particular for the heart, muscles and nervous system. A thiamine deficiency can cause weakness, fatigue, psychosis and nerve damage. Deficiency of thiamine also causes beriberi, and in alcoholics causes both Korsakov and Wernicke Syndromes.
Vitamin B-2: Riboflavin
Riboflavin's main importance is in assisting the body with growth and the development of red blood cells, and in converting energy from carbohydrates. Riboflavin deficiency is uncommon in the United States. This vitamin is destroyed by exposure to light.
Vitamin B-3: Niacin
Niacin, also known as nicotinic acid, primarily helps with digestion, skin and nerves. Nuts and legumes contain this vitamin, as do other B-vitamin-rich foods. Deficiency of niacin causes pellegra, inflamed skin, digestive problems and mental difficulty. Too much damages the liver, and causes peptic ulcers and skin rashes.
Vitamins B-5 and B-7: Pantothenic Acid and Biotin
Both pantothenic acid and biotin assist with growth and metabolism. They are present in yeast, broccoli, cabbage, and both white and sweet potatoes, in addition to the other B-vitamin foods.
Vitamin B-6: Pyridoxine
Pyridoxine contains more than 100 enzymes needed for healthy protein metabolism. B-6 is extremely important to the functioning of many body systems, including red cell production, the nervous and immune systems, cell growth, oxygenation, neurotransmitters and blood sugar regulation. Its deficiency causes a lower immune response and anemia. As a supplement, vitamin B-6 may help alcoholics who suffer from peripheral neuropathy.
Vitamin B-9: Folate
Folate, or folic acid, is a multifunctional B vitamin because it helps the body create needed proteins, red blood cells and DNA. Taken in pregnancy, it helps prevent birth defects. Folate deficiency causes diarrhea, gray hair, mouth ulcers, peptic ulcers, poor growth, swelling of the tongue and anemia. In addition to the other B foods, folate is present in liver, citrus and shellfish.
Vitamin B-12: Cobalamin
Cobalamin helps with metabolism, the production of blood cells and helps maintain healthy nerve function. People eating a strict vegetarian or vegan diet need to supplement their diets with cobalamin. Deficiency causes numbness in the arms and legs, weakness and loss of balance. Unlike most B-complex vitamins, you can store vitamin B-12 in your liver for use in the future.