Vitamin B complex

Encyclopedia of Alternative Medicine, Apr 06, 2001 by Judith Turner

In many cases, large doses of water-soluble vitamins can be taken with no ill effects since excessive amounts are readily excreted. However, when niacin is taken at daily doses of over 500 mg (and more often at doses six times as high), liver inflammation may occur. It is generally reversible once the supplementation is stopped. Niacin may also cause difficulty in controlling blood sugar in diabetics. It can increase uric acid levels that will aggravate gout. Those with ulcers could be adversely affected as niacin increases the production of stomach acid. Niacin also lowers blood pressure due to its vasodilatory effect, so should not be taken in conjunction with medications that are used to treat high blood pressure. If the form of niacin known as inositol hexaniacinate is taken instead, problems with flushing, gout, and ulcers, and liver inflammation do not occur bit beneficial effects on cholesterol are maintained.

High doses of pyridoxine may also cause liver inflammation or permanent nerve damage. Megadoses of this vitamin are not necessary or advisable.

Those on medication for seizures, high blood pressure, and Parkinson's disease are at increased risk for interactions. Any person with a chronic health condition, or taking other medications should seek the advice of a health professional before beginning any program of supplementation.

Niacin in large amounts commonly causes flushing and headache, although this can be circumvented by taking it in the form of inositol hexaniacinate. Large doses of riboflavin make the urine turn very bright yellow.

Some medications may be affected by B vitamin supplementation, including those for high blood pressure, Parkinson's disease (such as levodopa, which is inactivated by pantothenic acid) and epileptiform conditions. Folic acid interacts with Dilantin as well as other anticonvulsants. Large amounts of vitamin C taken within an hour of vitamin B supplements will destroy the cobalamin component. Niacin may interfere with control of blood sugar in people on antidiabetic drugs. Isoniazid, a medication to treat tuberculosis, can impair the proper production and utilization of niacin. Antibiotics potentially decrease the level of some B vitamins by killing the bacteria in the digestive tract that produce them.

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