“When you supplement, particularly one specific type of nutrient, you can upset the metabolic balance, how the body processes those nutrients,” says Denise Snyder, RD, the clinical trials manager at the Duke University School of Nursing and a study co-author.
For the study, published online in the Journal of Cancer Survivorship, Snyder and colleagues asked 753 cancer survivors who were five years or more out from their diagnosis of breast, prostate, or colorectal cancer to answer questions by telephone about their dietary habits and their use of supplements.
Seventy-four percent of the survivors reported taking dietary supplements. Of these:
• 80% took a multivitamin.
• 50% took calcium, vitamin D, or both.
• 41% took antioxidants such as vitamins C and E, carotenoids, selenium, and combinations.
• 29% took fish oil or fatty acid supplements.
• 19% took glucosamine, chondroitin, and combinations.
• 18% took botanicals or herbs.
In general, the healthier the lifestyle, the more likely the survivors were to take supplements. While dietary supplements may help fill in nutrients lacking in a person’s diet—particularly in the diets of seniors, which can fall short—Snyder warns that risks are also associated with supplement use. For instance, she writes in the paper, calcium intakes of 1,500 milligrams or more a day may be associated with an increased risk of aggressive prostate cancer.
The American Institute for Cancer Research and the World Cancer Research Fund recommend against supplements to protect against cancer.
There are little data on the role of supplements in helping cancer survivors remain cancer free, says Andrew Shao, PhD, vice president of scientific and regulatory affairs for the Council for Responsible Nutrition. “Most of the data on nutrient intake in cancer risk is on primary prevention,” that is, preventing a first cancer, he tells WebMD.
For that reason, he says, “The Council does not have a specific recommendation on supplements for cancer survivors.”
—Kathleen Doheny, WebMD Health News, 8/12/08