Labels for dietary supplements can be confusing.
It might be tempting to assume that anything labeled “natural” is safe. But dietary supplements are not usually tested for either effectiveness or safety. Be wary of any claims that offer miraculous results or quick cures—keep in mind that if cancer were a simple disease, it would already be widely cured!
The Office of Dietary Supplements, part of the U.S. National Institutes for Health, is a good resource for information about dietary supplements. The National Center for Complementary and Integrative Health and the American Cancer Society maintain collections of resources about a variety of complementary health practices and products and their safety. “Complementary” practices are non-mainstream methods used along with conventional therapies, which are research-based medical treatments for treating cancer effectively.
Labels for some dietary supplements can be misleading.
There is also a risk that some dietary supplements may be contaminated or contain ingredients that are not included on the product label. One Chinese product called PC-SPES was sold in the United States from 1996 to 2002 as an herbal supplement for prostate health. Many prostate cancer patients who took it suffered blood clotting abnormalities and severe bleeding. It was later found to contain a synthetic estrogen, the blood thinner warfarin, and a non-steroidal anti-inflammatory drug in addition to the herbs on its label.
Some dietary supplements can interfere with cancer therapies.
Some dietary supplements reduce the effectiveness of proven cancer therapies and cause harmful side effects. For example, the herb St. John’s wort can make some cancer drugs less effective. And taking antioxidants during radiation therapy may actually protect cancer cells against the effects of the radiation and prevent the treatment from working. To avoid dangerous interactions, medical guidelines recommend discussing the use of dietary supplements with your health care team. You should tell your doctor about every herb or supplement you take, either as a pill or in some other form.