High doses vitamin C: effective and safe [ 24-01-2007 ]

The consumption over longer periods of higher than RDA doses of vitamin C involves a diminished risk of cardiovascular disorders, various forms of cancer and cataract. Moreover, high doses of vitamin C are very safe.

This can be concluded from an on 154 references based review article on the health effects of vitamin C supplementation by Bendich and Langseth, published in the Journal of the American College of Nutrition.

No side effects

According to the article various alleged dangers of vitamin C that have been forwarded in the past, have in the meantime been invalidated. It has been established, for instance, that the allegation, based on an in vitro experiment in the seventies, that vitamin C would lead to a deficiency of vitamin B12, is incorrect and is founded on an error made while carrying out the expermiment in question.

It is of further importance that in several studies no support could be found for the supposition that vitamin C would increase the risk of kidney stones. The high safety rate of this nutrient is also evident from the fact that in 14 different studies, 8 of which were placebo-controlled and double-blind, no adverse side effects, caused by high doses of vitamin-C supplements, have been found. Even the dosage of 10 grams a day over the period of more than one year appeared to be no problem at all.

Iron absorption

It is further worth mentioning that neither these 14 studies, nor 24 others, in which the impact of vitamin C on iron absorption was examined, have come up with indications that oral vitamin-C supplementation would lead to symptoms as a result of an excessive iron absorption. Increased iron absorption occurs especially in persons with a bad iron status, for whom this vitamin C property is extremely valuable. In people with a normal iron status vitamin C is not associated with increasing iron stores in the body.

(The health effects of vitamin C supplementation: a review; Bendich A, Langseth L (Hoffmann La- Roche Inc., Paramus, New Jersey, USA); Journal of the American College of Nutrition, 14(2):124-136)