The researchers conducted laboratory experiments on cells taken from the brains of mice. They treated some of the cells with metabolic end products, called quinones, of alpha- and gamma-tocopherol.
When the body breaks down vitamin E, these end products are what enter and act on our cells. However, Ma said that our bodies get rid of most gamma-tocopherol before it ever has a chance to reach its quinone stage.
Still, some nutritional supplement companies make and sell gamma-tocopherol supplements, promoting this version of vitamin E as a good antioxidant source. In theory, taking a vitamin supplement a concentrated form of the vitamin - increases the amount of that substance in the body.
Using laboratory techniques that allowed them to detect the activity of the quinones inside the cells, the researchers found that the gamma-tocopherol quinone formed a compound which destroyed that cell. It did so by preventing proper protein folding in the cells, which causes a cellular response that is involved in a variety of human diseases, including diabetes and Parkinson's disease.
However, the alpha-tocopherol quinone did not kill cells, nor did it interfere with protein folding. The researchers repeated their experiments on kidney cells cultured from monkeys and on skin cells cultured from mice and found similar results.
"We think that gamma-tocopherol may have this kind of damaging effect on nearly every type of cell in the body," Ma said.
While the study doesn't get into the possible effects on health, the researchers raise the point that there is still a great deal that isn't known about how antioxidants act in the body. In order to get to that point, scientists must study how antioxidants and cells interact on their most fundamental levels.
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Contact: Jiyan Ma
Ma.131@osu.edu
614-688-0408
Ohio State University
2-Mar-2006