US Researchers Warn Against Taking Excessive Vitamins

LOS ANGELES, May 4, 2010 (Xinhua) --

Taking vitamins or other antioxidant nutritional supplements is beneficial, but taking too many can lead to cancer, according to new research findings released on Tuesday.

"Taking one multivitamin daily is fine, but a lot of people take too much because they think if a little is good, a lot must be better," said Dr. Eduardo Marban, director of the Cedars-Sinai Heart Institute in Los Angeles.

"That is just not the case. If you are taking 10 or 100 times the amount in a daily multivitamin, you may be predisposing your cells to developing cancer, therefore doing yourself more harm than good," Marban said in a news release.

Marban said he made the discovery accidentally while trying to reproduce cardiac stem cells.

While stem cells are often grown in a Petri dish culture composed of 20 percent oxygen, cells growing inside human tissue are exposed to just three to five percent oxygen.

Marban said researchers tried to reduce the high level of Petri dish oxygen by using antioxidants.

"That's when we made the serendipitous discovery that there is a danger zone for the cells exposed to antioxidants to develop genetic abnormalities that predispose to cancer," he said.

The potentially harmful effects apply only to excessive nutritional supplements, not foods that are rich in antioxidants, such as milk, oranges, blueberries and peanuts, according to the study.

Editor: Fang Yang

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