Supplements: Discerning fact from fiction no easy task

Beaver Creek, CO--Driven by demand from U.S. consumers, business is booming for companies that produce dietary and herbal supplements, as well as health foods. Many patients, including those with prostate cancer, take a dizzying array of supplements and alternative therapies. Those who have not yet jumped on the supplement bandwagon frequently ask physicians which supplements they should take or which foods they should eat to ward off or treat prostate cancer.

How should physicians respond?

"Another challenge to both patients and physicians is discerning between the information that is based on scientific evidence versus language that is disguised to sound scientific," Dr. Simoneau said. "In some instances, the information presented may be based on a laboratory experiment with cancer cells on a Petri dish and unrealistically high levels of a nutrient, instead of a legitimate IRB-approved clinical trial."

Vitamin E and selenium: There is very strong evidence as secondary endpoints from prospective randomized trials. The Nutritional Prevention of Cancer Study, a trial of selenium versus placebo for prevention of non-melanoma skin cancer, was negative for its primary endpoint of skin cancer, but it did demonstrate a decrease in prostate cancer as a secondary endpoint (JAMA 1996; 276:1957-63). The Alpha-Tocopherol, Beta Carotene Cancer Prevention Study, which examined beta carotene and vitamin E versus placebo in smokers in a 2×2 trial design, found beta carotene did not reduce lung cancer as hoped, but vitamin E decreased prostate cancer as a secondary endpoint (N Engl J Med 1994; 330:1029-35). Ongoing trials are evaluating these supplements for their efficacy in preventing prostate cancer; notably, the Selenium and Vitamin E Cancer Prevention Trial (SELECT).

Saw palmetto: Numerous trials have reported its benefit in improving symptoms associated with mild BPH, but there is no evidence it is effective in treating or preventing prostate cancer. A recent trial reported no effect in men with moderate to severe BPH (N Engl J Med 2006; 354:557-66).