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B Complex Vitamins

Health benefits, common uses, side effects & more

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Updated March 21, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

A vitamin B complex is a dietary supplement that contains all eight of the B vitamins: B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6, B7 (biotin), B9 (folate), B12. Also found naturally in a number foods, B vitamins help the body to produce energy and form red blood cells. Proponents suggest that taking a vitamin B complex may help treat or prevent certain health problems.

Health Benefits of B Complex Supplements

Each B vitamin is essential to certain bodily functions:

  • B1 and B2 are important for healthy functioning of the muscles, nerves, and heart
  • B3 helps regulate the nervous and digestive systems
  • B5 and B12 are required for normal growth and development
  • B6 supports the immune system and aids the body in breaking down protein
  • B7 is involved in the production of hormones
  • B9 helps cells make and maintain DNA

Studies show that taking supplements containing certain B vitamins may benefit your health. For instance:

  • B1 may help prevent kidney disease in people with type 2 diabetes and reduce risk of cataracts
  • B2 may prevent migraines; B3 may lower cholesterol levels
  • B6 may protect against heart disease, relieve PMS symptoms, and alleviate pregnancy-related nausea
  • B9 may help prevent breast cancer, colorectal cancer, and pancreatic cancer, as well as decrease risk of birth defects when taken by pregnant women
  • B12 may lower cervical cancer risk and reduce levels of homocysteine (an amino acid thought to contribute to heart disease when it occurs at elevated levels)

Although few studies have tested the effects of taking a B complex supplement, preliminary research shows that B complex supplements may reduce inflammation in hemodialysis patients and promote periodontal wound healing. However, other research indicates that taking B complex supplements may not reduce risk of cardiovascular disease.

Why Do People Take B Complex Supplements?

Proponents claim that vitamin B complex supplements can help with a variety of health conditions, including:

In addition, many people take a vitamin B complex to increase energy, enhance mood, improve memory, and stimulate the immune system.

Food Sources of B Vitamins

To increase your intake of B complex vitamins, include the following foods in your diet:

 
  • cereals and whole grains (a source of B1, B2, and B3)
  • green leafy vegetables (a source of B2 and B9)
  • eggs (a source of B7 and B12)
  • chicken (a source of B3, B6, and B12)
  • citrus fruits (a source of B9)
  • nuts (a source of B3 and B9)
  • kidney beans (a source of B1 and B2)
  • bananas (a source of B6 and B7)

Vitamin B5 is found in almost all foods.

Side Effects

Although B complex supplements are generally considered safe, they may cause certain side effects, such as skin problems and an increase in blood sugar levels.

When Should You Take a B Complex Supplement?

If you're not getting enough B vitamins from your diet, taking a B complex supplement may be beneficial. Deficiency in B vitamins can cause a number of symptoms, including tiredness, anemia, loss of appetite, depression, abdominal pain, muscle cramps, hair loss, and eczema. Consult your health care provider to find out whether a B complex supplement is right for you.

Sources

American Cancer Society. "Vitamin B Complex". May 2010.

Chang TY, Chou KJ, Tseng CF, Chung HM, Fang HC, Hung YM, Wu MJ, Tzeng HM, Lind CC, Lu KC. "Effects of folic acid and vitamin B complex on serum C-reactive protein and albumin levels in stable hemodialysis patients." Curr Med Res Opin. 2007 Aug;23(8):1879-86.

Clarke R, Lewington S, Sherliker P, Armitage J. "Effects of B-vitamins on plasma homocysteine concentrations and on risk of cardiovascular disease and dementia." Curr Opin Clin Nutr Metab Care. 2007 Jan;10(1):32-9.

Galan P, Kesse-Guyot E, Czernichow S, Briancon S, Blacher J, Hercberg S; SU.FOL.OM3 Collaborative Group. "Effects of B vitamins and omega 3 fatty acids on cardiovascular diseases: a randomised placebo controlled trial." BMJ. 2010 Nov 29;341:c6273. doi: 10.1136/bmj.c6273.

National Institutes of Health. "B Vitamins: Medline Plus". August 2011.

National Institutes of Health. "Folic acid: MedlinePlus Supplements". August 2011.

National Institutes of Health. "Niacin and niacinamide (Vitamin B3): MedlinePlus Supplements". August 2011.

National Institutes of Health. "Pyridoxine (Vitamin B6): MedlinePlus Supplements". August 2011.

National Institutes of Health. "Riboflavin (Vitamin B2): MedlinePlus Supplements". August 2011.

National Institutes of Health. "Thiamine (Vitamin B1): MedlinePlus Supplements". August 2011.

National Institutes of Health. "Vitamin B12: MedlinePlus Supplements". August 2011.

Neiva RF, Al-Shammari K, Nociti FH Jr, Soehren S, Wang HL. "Effects of vitamin-B complex supplementation on periodontal wound healing." J Periodontol. 2005 Jul;76(7):1084-91.

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