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March 1, 2007

Vitamins can be harmful?

A study reported, with significant controversy, that some vitamins can actually increase the risk of death:

Some vitamin supplements could do you more harm than good, according to research published on Wednesday in the Journal of the American Medical Association (JAMA).

"Beta carotene, vitamin A, and vitamin E seem to increase the risk of death," said the researchers, operating under the umbrella of the internationally-respected Cochrane Collaboration.

[snip]

To do this, they analysed data from 47 clinical trials conducted since October 2005 comparing beta carotene, vitamin A, vitamin C, vitamin E and selenium.

Those trials involved over 180 000 participants, some of whom were completely healthy, and some of whom already had a specific disease.

"Our systematic review contains a number of findings," said the researchers, who were led by Dr Goran Bjelakovic of the Copenhagen University Hospital.

"Beta carotene, vitamin A and vitamin E given singly or combined with other antioxidant supplements significantly increase mortality.

"There is no evidence that vitamin C may increase longevity. We lack evidence to refute a potential negative effect of vitamin C on survival."

read the rest here.

Nutritionalists immediately rejected the findings and some experts said it's too early to toss out all vitamin pills -- or the possibility that they have some health benefits. Others said the study supports the theory that antioxidants work best when consumed in food rather than pills.

Notably, Donald Berry, chairman of the department of biostatistics at the University of Texas M.D. Anderson Cancer Center, said the analysis persuades him antioxidants have no measurable health benefits, but he disagrees with the researchers' finding of an increase risk of dying.

Finally, here's a great message:

Alice Lichtenstein, a professor of nutrition science and policy at Tufts University who was not involved with the research, said the study's main message is: "Rely on food to get your nutrients."

Posted by Diabetologica at March 1, 2007 12:53 PM