All About Vitamin B Complex Vitamins

Published: 13th April 2008
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B complex, once thought to be a single vitamin, is now classified as 12 related water-soluble compounds. Four can be synthesized by the body and include inositol, PABA (para-aminobenzoic acid), choline and lipoic acid. The remaining eight are not made in the body and are considered essential to good health (1).

B1 (thiamine) acts as a coenzyme (2) in metabolizing nutrients. Deficiency has been known to lead to heart and nervous system problems.

B2 (riboflavin) is crucial to co-enzymatic reactions. Inadequate amounts may cause the lining of the mouth and skin to swell.

B3 (niacin) is essential to healthy metabolism. Deficiencies are purported to cause cognitive slowing and inflammation of skin and orifices.

B5 (pantothenic acid) is important to the oxidation of fats and carbohydrates.

B6 (pyridoxine) is an important cofactor for enzymes. Inflammation of the skin and mouth, nausea, vomiting, anemia, fatigue and dizziness can result from deficiency.

B7 (biotin) aids in the healthy reproduction of cells and is crucial to cell and body growth.

B9 (folic acid, folate) is needed for nucleic acid synthesis (the making of genetic material). Too low levels of B9 have been known to result in megaloblastic anemia.

B12 (cobalamin) is also needed for nucleic acid synthesis. Both megaloblastic and pernicious anemia (lower than normal red blood cell count) can result from cobalamin deficiency.

Inositol is a naturally occurring sugar in the body that aids nerve health.

Choline is a constituent of lecithin (a compound which breaks up fat and cholesterol) and essential to fat metabolism.

PABA (para-aminobenzoic acid) helps in metabolizing protein and forming red blood cells.

Lipoic acid functions as an antioxidant in the body to protect cells against free radical damage.

(1) There are 13 vitamins said to be essential for normal cell function, growth and development. Eight are B complex vitamins (source: Medline).

(2) Coenzymes are organic molecules that work in concert with enzymes to utilize vitamins and minerals in the body. They're essential to healthy metabolism.

Sources of B complex

Although prevalent in many foods, natural sources high in B complex vitamins include meat and dairy products.

• Dark green, leafy vegetables are excellent sources of folic acid (B9).

• Cobalamin (B12 - essential to healthy red blood cell count) can be derived only from animal sources. For this reason, strict vegetarians are encouraged toward B complex supplementation.

Unless some type of deficiency is present, or an individual has a problem absorbing B complex vitamins, sufficient amounts of B complex vitamins can be obtained from diet alone. However, B complex supplements are used every day by millions looking to balance diet.

B complex health benefits and claims

B vitamins serve a wide range of health functions. They work both together and separately to ensure a healthy metabolism and aid the body in absorbing and utilizing nutrients. B complex vitamins help maintain the outer cover of nerve cells (myelin) and assist in converting nutrients to energy.

• Together, three members of the B complex group, pyridoxine, cobalamin and folic acid, have been scientifically proven to lower blood homocysteine, a toxic by-product of cellular metabolism associated with heart problems.*

• Research links B complex vitamins to a decrease in neural tube defects and are associated with healthy immune function and normal cell growth and hormone production. B complex may also play a role in fighting free radicals that result in signs of aging. B complex vitamins are said to be essential for healthy skin, hair and nails.*

• Thiamine (B1) is said to be supportive of cognitive function in both younger and older persons.*

• Niacin (B3) may help balance cholesterol and triglyceride levels in the body, resulting in healthy blood glucose levels.*

• Riboflavin (B2) supplementation has been linked to decrease in frequency for those suffering regularly from migraine headaches.*

• Mood problems and mental acuity may be improved through cobalamin (B12) supplementation.

*Statement not evaluated by FDA.

RDI or RDA of B complex

There is no one figure that denotes the cumulative RDA or RDI of B complex vitamins. Each B vitamin has its own recommendation, which varies from source to source and is based on age, gender, overall health and alcohol and nicotine consumption. Some B vitamins such as inositol and choline have no standard RDA or RDI. Because the balance of B complex in the body is often crucial to good health and a deficiency or too high level of any B vitamin might lead to a number of disorders, nutritionists suggest that healthy people refer to charts that exhibit conservative B complex intakes. Others who may be suffering from too much or not enough B complex should consult a physician regarding intake. A preferred Internet source for B complex supplementation amounts is the USDA National Agriculture Library at

B complex deficiency and symptoms

Because B complex vitamins occur in food in abundance, two prevalent ways to become deficient in B complex vitamins are a poor dietary intake of foods which contain B complex vitamins and physical problems absorbing B complex vitamins.

• Poor dietary intake of B complex vitamins (most frequent among strict vegetarians and the malnourished) can be offset with vitamin B supplementation.

• Poor absorption of B complex vitamins may result from thyroid dysfunction and the lack of Intrinsic Factor in the stomach (common to the elderly and those who abuse alcohol and tobacco).

B complex deficiency can occur at varied levels in different individuals. Signs include poor skin, hair and nail health, memory loss, nervousness, profound fatigue, sleep disturbances, nausea, poor appetite, frequent infections and mood disorders. It's advisable to search the Internet for more extensive information regarding the specifics of B complex vitamin deficiency or consult a nutritionist or physician.

B complex toxicity and adverse effects

For the most part, excessive amounts of water-soluble vitamins, such as B complex vitamins, are excreted as waste when not used by the body for energy, resulting in little chance of toxicity when taken in large amounts. Adverse effects of B complex vitamins have been reported as rare and minor. Literature does suggest, however, that:

• Too high levels of niacin (B3) in the body may result in inflammation of the liver and high blood sugar levels.

• High doses of pyridoxine (B6) may inflame the liver as well and damage nerve cells.

It is advisable for those with high blood pressure, chronic health conditions or individuals who take seizure medications to consult a physician prior to starting a regimen of B complex supplementation, as certain drug interactions may result.

Clinical studies and B complex research

Although B complex supplementation is well positioned in the marketplace as a health benefit, findings from both animal and human studies differ and are suggestive. Research uncovered in a report entitled "B Vitamins and Berries and Age-Related Neurodegenerative Disorders" published by the Department of Health & Human Services shows that while animals kept deficient in folate (B12) may suffer from neurological damage in the long term, humans showed little to no positive neural response when given folate supplements vs. placebo.

Reports published in the New England Journal of Medicine suggest:

• That despite reports of B complex vitamins as human brain food, more recent clinical evidence shows no marked improvement in thinking function, memory or overall cognitive awareness in human studies.

• Notwithstanding its ability to lower dangerously high levels of homocysteine (1) in the blood, B complex may have no positive impact on the cardiovascular health of high risk patients.

B complex efficacy and the FDA

The FDA goes as far as to allow dietary supplements that contain folate, vitamin B6 and vitamin B12 a qualified health claim that suggest these B complex vitamins may have health merits - but the evidence is inconclusive. Regardless, research indicates more benefits than risks with B complex supplementation because toxicity and overdose are highly improbable.

For more information on B Complex vitamins, visit


1. Vitamin B Complex. Rebecca J. Frey, Ph.D. and Samuel Uretsky, Pharm.D. The Gale Encyclopedia of Alternative Medicine. Ed. Jacqueline L. Longe. 2nd ed. Detroit: Gale, 2005. 4 vols. Updated July 1, 2006.

2. WebMD Vitamins / Enzymes. 2007.

3. B Vitamins Don't Guard Mental Function. Harvard Reviews of Health News. May 11, 2007 pNA.

4. B Vitamins Don't Prevent Heart Attacks. Harvard Reviews of Health News. May 11, 2007 pNA.

5. B Vitamins and Berries and Age-Related Neurodegenerative Disorders. U.S. Department of Health and Human Services. April 2006.

6. Acu-Cell Nutrition. DRI / RDA for B-Complex Vitamins 2007.

7. B Vitamins and Berries and Age-Related Neurodegenerative Disorders. The U.S. Department of Health & Human Services April 2006.

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