Sellers of "natural" dietary supplements, unlike sellers of drugs, have a right under federal law to say that their products help mitigate disease, without good evidence that they do, and have no legal obligation to show that their products are safe and effective for their intended uses before they are marketed.
So, now we have a study showing that taking supplements of Vitamin E -- trumpeted by supplement manufacturers as doing all sorts of healthy things for you -- leads to prostate cancer. The study, reported here in the Journal of the American Medical Association, found that "Dietary supplementation with vitamin E significantly increased the risk of prostate cancer among healthy men."
As Howard Parnes, Chief of the Prostate and Urologic Cancer Research Group Division of Cancer Prevention for the National Cancer Institute, put it:
Just because it’s ‘only a vitamin’ or ‘it’s natural,’ we assume it must be safe. But over and over again, we see that’s not necessarily the case. Not only isn’t it the fountain of youth that some people said, it can be harmful.
Read more about it in this story in the Washington Post.