Can supplements reduce cancer risk?

Here’s an excerpt from the upcoming issue of the New York Buyers’ Club newsletter, THE SUPPLEMENT.

While it covers some of the same territory on supplements and cancer that we’ve posted earlier on this Blog, it’s valuable as an overview of the question, and balances the news of some notable advances in 2007 with notes and cautions at the end.


Can Supplements Reduce Cancer Risk?

The short answer is: Yes—but please read on for important details!

Last year Memorial Sloan-Kettering Cancer Center (not the least informed organization when it comes to cancer) posted on its website the striking news from a study published in 2007: Vitamin D and calcium supplementation reduces cancer risk. This federally-funded investigation had followed more than a thousand post-menopausal women, some of whom were given calcium + vitamin D3 supplements, some just calcium, and some placebo. When researchers looked at the data, they reached this conclusion: “Improving calcium and vitamin D nutritional status substantially reduces all-cancer risk in postmenopausal women.”

A lot of researchers have been studying Vitamin D3 (the form recommended as most active in the human body) in the last few years, and it’s good to see the scientific findings percolating down to the general public. We were impressed by the lead article on Vitamin D in the February 2008 issue of the University of California, Berkeley’s Wellness Letter (a “newsletter of nutrition, fitness, and self-care”). The Wellness Letter is usually quite conservative on the subject of nutritional supplements, but in this case it found the recent research on Vitamin D persuasive enough to recommend that people “consider taking 800 to 1000 IU of supplemental D a day.” (That’s a higher dose than generally suggested in the past.) As the newsletter reports, there’s a new focus on Vitamin D’s multiple benefits, including its potential to “reduce risk of some common cancers.”

And speaking of getting word out to the general public. Tuning into the Martha Stewart Show not long ago, we saw nutrition and integrative medicine guru Dr. Andrew Weill answering a question from a female audience member by making a strong pitch for regular calcium and Vitamin D3 supplementation, even for younger women. Dr. Weill stressed not only the well-known value against osteoporosis, but also the many new findings on Vitamin D3, such as its role in reducing cancer rates.

But Vitamin D is not the only supplement receiving attention for its anti-cancer properties. A 2007 review of several large prostate cancer prevention studies concluded that several interventions, including dietary supplements such as lycopene, alpha-tocopherol and selenium, have now shown convincing evidence of being able to reduce the risk of this cancer in some circumstances. And the author of this article in the Journal of Urology urged doctors caring for men entering the range of age of prostate cancer risk to inform themselves and their patients about these “preventive opportunities.”

Also in 2007, researchers at the University of California, Irvine, published a study showing that a biologically active component of milk thistle (silymarin) has significant effect against liver cancer cells. Of course milk thistle/silymarin has a long tradition of use as a remedy for liver diseases, and is known to protect the liver from drug or alcohol-related injury. The lead author of this article, who has published extensively on viral hepatitis B and C, cirrhosis, and liver cancer, suggests that the particular component of milk thistle studied (silibinin) could potentially be used to prevent development of liver cancer, one of the most common cancers worldwide.

Notes & cautions: Although research on using supplements to decrease risk of cancer moves forward and has already produced some valuable results, note that there are also many concerns about use of vitamins and other supplements during and following cancer treatment. One problem: supplements may interfere with conventional medications and thus disrupt treatment. Furthermore, it’s important to look at dosage, since some studies have found that “megadoses” of vitamins may be harmful to people with certain cancers. In short, while we are encouraged by studies showing the anti-cancer activity of specific supplements—we’ve highlighted D3, silibinin, selenium, lycopene, and alpha tocopherol—no one should take these findings as a blanket endorsement of any level of supplement use under any circumstance whatsoever!

If you have a question about the usefulness of a supplement as an anti-cancer agent, we recommend the Memorial Sloan-Kettering Integrative Medicine website. This web resource came into being because health professionals recognized the widespread use of supplements by people concerned about their cancer risk or already diagnosed with cancer, and wanted to provide them with evidence-based information to guide their choices. This is also the approach of New York Buyers’ Club: we want to bring up-to-date, scientifically-based information to our members so that they can make good choices about supplement use.

Prostate cancer prevention studies: lycopene, alpha-tocopherol, selenium play a prominent role

This review, published in late 2007, concludes that studies of prostate cancer prevention are now maturing to the point where recommendations may soon be in order for reducing cancer risk by supplementing with such promising dietary supplement agents as lycopene, alpha-tocopherol, or selenium. Decreased dietary fat, nonsteroidal anti-inflammatory drugs and selective estrogen receptor modulators are also interventions under review.

Chemoprevention of prostate cancer: agents and study designs

PURPOSE: With the completion of the Prostate Cancer Prevention Trial and the ongoing performance of several additional large-scale prostate cancer prevention trials interest in this intervention has increased. We review promising agents for prostate cancer prevention, clinical trial designs and how these agents may be used clinically. MATERIALS AND METHODS: We reviewed current and completed randomized chemoprevention trials for prostate cancer as well as the most promising agents for which evidence suggests that a decreased prostate cancer risk may result from their use. RESULTS: Evidence suggests that lycopene, decreased dietary fat, antioxidants such as alpha-tocopherol and selenium, nonsteroidal anti-inflammatory drugs and selective estrogen receptor modulators such as toremifene and 5alpha-reductase inhibitors may prove useful for decreasing the risk of prostate cancer in a man. Ongoing studies are examining these agents in the 3 general scenarios of 1) general population studies (finasteride, alpha-tocopherol and selenium), 2) increased prostate specific antigen with negative biopsy (dutasteride) and 3) prostatic intraepithelial neoplasia (toremifene and selenium). CONCLUSIONS: There are many agents that may decrease the risk of prostate cancer. It requires careful study of the agents in specific populations to determine whether risk is reduced, the magnitude of the risk reduction and the spectrum of side effects associated with the agent. Physicians caring for men entering the range of age of prostate cancer risk must be aware of these preventive opportunities.

Citation: Chemoprevention of prostate cancer: agents and study designs.
Thompson IM. J Urol. 2007 Sep;178(3 Pt 2):S9-S13. Epub 2007 Jul 20.