In response to a new study, “Effect of Vitamin D and Calcium Supplementation on Cancer Incidence in Older Women,” published online in JAMA, the Council for Responsible Nutrition (CRN), the leading trade association for the dietary supplement and functional food industry, issued the following statement:
Statement by Duffy MacKay, ND, senior vice president, scientific and regulatory affairs, CRN: “The scientific community, health care practitioners and consumers are already aware of the important benefits of vitamin D for good health. This rigorous, well-designed study points to the possibility of more promising news for this popular, and ever-important, nutrient. Conducted in a population of post-menopausal women, the study shows the potential for vitamin D to reduce cancer risk—and we encourage more research in this area.
Although the positive results did not meet statistical significance, the study came very close, showing a 30 percent reduction in cancer risk in the study population. These results are especially heartening in light of one significant limitation of this study: the study subjects had higher baseline vitamin D levels at the beginning of the study compared to the U.S. population, suggesting that the potential benefits of vitamin D supplementation may not have been fully realized. The study raises the question that if the placebo group had been a population of women that was below average for vitamin D levels at baseline, would we have seen this study reach statistical significance?
Additionally, in the post hoc analysis, when the authors eliminated the cancers diagnosed during the first year of the study, presumably cancers that started before the supplements could have had a protective effect, there was a statistically significant 35 percent reduction in cancer risk. Of course, this finding should not be over interpreted, but if supplementing with an essential nutrient could significantly reduce the risk of cancer, it is all the more reason to support more research to build on these findings.
Cancer is multifactorial, but good nutrition in combination with a lifetime of other healthy habits can help to reduce risk of disease. This study is a good reminder to have vitamin D levels checked by your doctor to make sure that you are getting enough of this important nutrient. We recommend that consumers consult their doctor or other healthcare practitioners about all of the dietary supplements they use and manage expectations when it comes to the role dietary supplements play in health maintenance and disease risk reduction.”