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Nutritional supplements shouldn’t be marketed for cancer prevention, experts say

Apr 27th, 2012
Staff Writer

Nutritional supplementsNutritional supplements are used by millions of people for a variety of health purposes, including cancer prevention. But a strongly worded commentary from researchers at the University of California, San Diego, published this week, contends those claims are simply false or, at best, premature.

About half of U.S. adults take supplements. The report, published in the Journal of the National Cancer Institute, notes that there are no randomized, controlled trials attesting to the value of any nutritional supplement for cancer prevention. Randomized, controlled trials are considered the gold standard level of proof in scientific research.

Yet, several randomized, controlled trials have linked nutritional supplements to an increased cancer risk. B-carotene supplements increased the risk of lung cancer among smokers by 39%, and a study of vitamin E supplement consumption found an increased risk of prostate cancer by 17%. Folic acid supplements were found in yet another study to raise the risk of colorectal cancer.

Beliefs about the value of a healthy diet “can be exploited by nutritional supplement manufacturers to suggest cancer-fighting effects of supplements that exceed the objective evidence,” the authors wrote.

The Dietary Supplement Health and Education Act was signed into in 1984 to classify supplements as foods but limited Food and Drug Administration authority over the products. A proposed bill that came before Congress in 2010 to give FDA more authority over supplements failed, the authors noted.

In the meantime, consumers are sometimes misled about both the value of supplements for cancer prevention as well as the potential risks of the products. “. . .Even though the manufacturers of Pill X cannot openly advertise that it prevents prostate cancer, they can create an advertisement that states that prostate cancer is a major health problem, that Pill X has a role to ‘support prostate health,’ ” the authors wrote. Moreover, manufacturers can claim that their compounds may have reduced the presence of prostate cancer cells in a lab culture.

While that assertion may be true, that’s a big jump from assuming supplements protect humans from cancer, the researchers wrote, adding: “. ..Dietary supplements should not be directly or indirectly marketed for cancer prevention.”