Vitamin E And Prostate Cancer
October 12, 2011 by staff
Vitamin E And Prostate Cancer, New evidence that taking vitamin E supplements can be hazardous to your health adds to the concern that doctors have a lot of people may be excessive use of vitamins and other supplements.
A new study that followed men who took high doses of vitamin E for five years found that had a slightly higher risk of developing prostate cancer – even after they stopped taking the pills.
The study, published today in the Journal of the American Medical Association, followed over 35,000 men who were randomly assigned to receive daily supplements of vitamin E. The researcher found that over a period of ten years, men an additional one or two out of 100 who took vitamin E is expected to have prostate cancer.
“If you have enough of these vitamins in your system … more does not help any, and much of something like this can be harmful,” study author Dr. Eric Klein of the Cleveland Clinic, told Reuters Health reporter Genevra Pittman.
“People tend to think of vitamins as harmless substances, almost like chicken soup – take a little and can not do harm,” Klein said Lyndsey Tanner of the Associated Press (AP). The study shows that this is not true. “If you have normal levels, the vitamin is probably of no benefit, and if taken in excess, can be damaged.”
The findings follow another recent study suggests that taking too many vitamins and supplements increases the risk of a woman suffering a stroke. “There’s a theme here that taking vitamins is not only useful, but it could be harmful,” in people who are not deficient, Klein told Reuters.
Klein and colleagues examined the long-term effects of vitamin E and selenium on prostate cancer risk in relatively healthy men. The study, SELECT, including 35 533 men from 427 study sites in the U.S., Canada and Puerto Rico, between August 2001 and June 2004.
Eligibility criteria included a prostate-specific antigen test (PSA) measured below a certain level, digital rectal examination not suspicious for prostate cancer, and the age of 50 years for men and 55 for black men .
The primaryanlysis included 34,887 men who were randomly assigned to one of four treatment groups: 8752 received 200 mg of selenium per day, 8737 received 400 IU / day vitamin E, 8702 received two, and 8696 received placebo. The men were scheduled for a planned follow-up from a minimum of 7 years and a maximum of 12 years.
Since the initial report, a total of 521 additional prostate cancers were diagnosed: 113 in the placebo group, 147 in the vitamin E group, 143 in the selenium group and 118 in the combined group. The researchers found that the detection rate of prostate cancer was higher in all treatment groups compared with the placebo group, but was statistically significant only in the group of vitamin E alone.
In total, 529 men in the placebo group developed prostate cancer, 620 men in the vitamin E group developed cancer, 575 in the selenium group and 555 in the combined group. The difference in prostate cancer rates between vitamin E and placebo groups became evident during the year of the participants in the third test.
The researchers calculated that men in the group of 400 IU / day of vitamin E were 17 percent more likely to get prostate cancer than those in the placebo group. The doses are commonly found in over-the-counter supplements, is nearly 20 times the recommended daily amount for adults.
The results mean that for every 1,000 men who took vitamin E, there were 11 additional cases of prostate cancer compared with men taking placebos. Experts say that about 160 of 1,000 U.S. men develop prostate cancer in their lifetime. And the National Cancer Institute says of 241,000 men in the U.S. will be diagnosed with prostate cancer in 2011 and about 34,000 die from it.
The study was stopped in 2008 when researchers noted an increased risk of prostate cancer in men who took vitamin E, but continued their follow-up cancer after having stopped taking the supplements. And the researchers found that the additional risk became clearer with time.
In mid-2011, about seven percent of men who took vitamin E had only managed to prostate cancer, compared with six percent of those assigned to placebo.
The researchers found no excess risk of prostate cancer in men taking only selenium or vitamin E along with selenium.
Klein said it is unclear how vitamin E may increase the risk of prostate cancer, and that not all previous studies have shown that hurt at all. Some have even shown a lower risk of prostate cancer with the use of vitamin E.
The new findings are not definitive proof that vitamin E is to blame for most prostate cancers, but there was nothing that could explain why men who took the supplement were more likely to be diagnosed with the disease.
Prostate cancer researcher Dr. Neil Fleshner, University of Toronto, it was doubtful that vitamin E increases the risk of prostate cancer, and said the result could have been a chance finding, or a “false positive”.
“It is an interesting finding. I’m not sure I believe,” Fleshner told Reuters Health. In any case, vitamin E does not appear to be beneficial for prostate health. “Certainly there is more evidence that vitamin E helps … So why bother?” He said.
However, 13 percent of American men continue to take vitamin E, according to a trade group of supplements.
Men should stop taking large doses and talk to their doctors about the risks and benefits of screening for prostate cancer, said Dr. Otis Brawley, chief medical officer of the American Cancer Society. Smaller doses are probably fine, said Brawley, who was not involved in the investigation.
Than through supplements, vitamin E can be found in nuts, seeds and vegetable oils. It helps the nerves, muscles, blood vessels and immune system function. Vitamin E supplements have been promoted for the prevention of disease, but research has shown that many claims are false and suggested that it may actually increase the risk of some diseases, including heart failure.
“There should be a warning that global … excessive use of vitamins has not been shown to be beneficial and can be quite the opposite,” Brawley said the AP.
Experts generally agree that foods are the best sources of vitamins.
Duffy MacKay of the Council for Responsible Nutrition, a group of supplement manufacturers’ trade, said the study should not be interpreted as questioning the benefits of vitamin E as an essential nutrient, and he said there is no evidence that many Americans do not get enough.
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