Other common name(s): B vitamins; vitamins B1, B2, B3, B5, B6, B7, B9, and B12
Scientific/medical name(s): thiamin (B1), riboflavin (B2), niacin (B3, also called nicotinamide or nicotinic acid amide), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folic acid or folate (B9), cobalamin (B12)
B vitamins are essential for growth, development, and a variety of other bodily functions. They play a major role in the activities of enzymes, proteins that regulate chemical reactions in the body, which are important in turning food into energy and other needed substances. B vitamins are found in plant and animal food sources.
B vitamins are an important part of the diet and are needed to help avoid many health problems. But, there is not enough scientific evidence to know whether B vitamins can reduce the risk of cancer.
People with low folate intake are at increased risk for certain types of cancer. A diet rich in vegetables and enriched grain products containing this vitamin are recommended by some experts in cancer prevention. (See our separate document, Folic Acid, for more information.) Grain products have been enriched with folic acid for more than a decade, and there is now some concern that folic acid supplements may increase the risk of certain cancers.
Supplements are not generally advised except in women of childbearing age and people with restricted food intake.
Available scientific evidence does not support claims that any B vitamin is an effective treatment for people who already have cancer.
How is it promoted for use? Scientists know that B vitamins are part of many important bodily functions:
- Vitamin B1 (thiamin) and vitamin B2 (riboflavin) help the body produce energy and affect enzymes that influence the muscles, nerves, and heart.
- Vitamin B3 (niacin) has a role in energy production in cells and helps keep the skin, nervous system, and digestive system healthy.
- Vitamin B5 (pantothenic acid) influences normal growth and development.
- Vitamin B6 (pyridoxine) helps the body break down protein and helps maintain the health of red blood cells, the nervous system, and parts of the immune system.
- Vitamin B7 (biotin) helps break down protein and carbohydrates and helps the body make hormones.
producing red blood cells.
- Vitamin B12 (cobalamin) plays a role in the body's growth and development. It also has a part in producing blood cells, nervous system function, and how the body uses folic acid and carbohydrates.
Deficiency of certain B vitamins can cause anemia, tiredness, loss of appetite, abdominal pain, depression, numbness and tingling in the arms and legs, muscle cramps, respiratory infections, hair loss, eczema, poor growth in children, and birth defects.
Some alternative medical practitioners claim that deficiencies in B vitamins weaken the immune system and make the body vulnerable to cancer. They recommend high doses of B vitamins as treatments for people with cancer. Many researchers are studying the relationships between vitamin intake and risk of developing certain cancers.