Dietary supplements are a booming business—Americans are spending approximately $25 billion a year to supplement their diets with products containing vitamins, herbs, and botanicals, as well as other supplements such as glucosamine, probiotics, and fish oils. A variety of studies have shown essential fatty acids to be beneficial; the omega-3 fatty acids found in fish oil—eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)—are especially good. Fish oil has previously been reported to reduce heart disease risk, making its implications in cancer prevention an area of interest. Researchers from the Fred Hutchinson Cancer Research Center recently evaluated what, if any, impact specialty supplements have on breast cancer risk.
In this study, more than 35,000 postmenopausal women completed a 24-page questionnaire to evaluate their use of non-vitamin, non-mineral “specialty” supplements. The women in this study did not have a history of breast cancer and did not have breast cancer when they enrolled in the study. During six years of follow-up, 880 study participants developed breast cancer. Of the specialty supplements used by the women in this study, only fish oil was associated with a reduced risk of breast cancer. Risk of breast cancer was 32% lower among women who regularly used fish oil supplements.
The results of this study will need to be confirmed by additional studies. The researchers note: “Fish oil is a potential candidate for chemoprevention studies. Until that time, it is not recommended for individual use for breast cancer prevention.” Because the full range of effects of many dietary supplements is not well understood, patients should talk with their doctor about any dietary supplements that they are using or considering.
 Brasky TM, Lampe JW, Potter JD et al. Specialty Supplements and Breast Cancer Risk in the VITamins And Lifestyle (VITAL) Cohort, Cancer Epidemiology, Biomarkers & Prevention. 2010; 19(7):1696–708.