The potential health benefits of vitamin D and marine omega-3 fatty acids are receiving increasing attention in both the media and medical field; however, definitive evidence on the health benefits and risks of these supplements is not yet available. Researchers at Brigham and Women's Hospital (BWH) will soon launch the largest randomized trial of vitamin D and omega-3s in the primary prevention of chronic disease.
Adding to the recent Associated Press report on the VITamin D and OmegA-3 TriaL (VITAL), the study's co-leader, JoAnn E. Manson, MD, said, "Vitamin D and omega-3's are two of the most promising nutrients we know of for the prevention of cancer, heart disease, stroke, and many other chronic diseases, but we need large-scale randomized trials to clarify the benefits and risks." Manson, who is also chief of Preventive Medicine at BWH added, "What is most exciting is that these low-cost supplements have the potential of tremendously reducing the burden of chronic disease in this country and throughout the world if they are shown to be effective." She and Julie Buring, ScD, an epidemiologist in the Division of Preventive Medicine at BWH, will co-direct the study.
Researchers are also excited about the possibility of reducing many of the health disparities seen by race and ethnicity. For example, African-Americans have a higher risk of vitamin D deficiency as well as a greater frequency of diabetes, hypertension, and certain types of cancer. "We are excited about the potential of vitamin D to reduce this health gap, but it is important to get answers from clinical trials before recommending mega-doses of this supplement," said Manson.
There is epidemiological evidence that vitamin D and omega-3 may play a role in the prevention of disease, but larger primary prevention trials have not been conducted until now. For vitamin D, previous trials have generally tested low doses and, for omega-3s, trials have been done in high-risk populations. This randomized, double-blind, placebo-controlled clinical trial will enroll 20,000 participants throughout the entire U.S. to determine whether moderate-to-high doses of these supplements can prevent colorectal, breast, prostate, and other cancers, as well as heart disease and stroke. Those eligible for the five-year trial, including women older than 65 and men older than 60 without a prior history of cancer, heart disease, or stroke, will be randomly assigned to take either one or both of the supplements or placebo.
Additional studies will look at whether these nutrients have a role in preventing a wide range of other health conditions. "The trial will be a rich resource for answering questions about the effects of vitamin D and fish oil on myriad health conditions besides cancer and heart disease - from cognitive function to vision disorders to diabetes to bone fractures," said Buring.
Mechanism-wise, both vitamin D and omega-3s have powerful anti-inflammatory effects and also work through multiple other pathways that may have a role in preventing chronic disease. "We are hopeful that this study will provide definitive proof of the effect of these nutrients on several health outcomes," added Buring.
Researchers note that while the potential for vitamin D and omega-3s for reducing chronic diseases is great, it is important to be cautiously optimistic. "We tend to forget the lessons of other nutrients -- many had high hopes for vitamin E, vitamin C, beta-carotene, folic acid, selenium, and other supplements as preventive tools for many diseases, but large-scale trials didn't confirm the hoped-for benefits and even found some risks when consumed at higher levels. Let's not jump on the bandwagon to take mega-doses of these supplements before clinical trials help to clarify their role," Manson said.
The study is funded by the National Institutes of Health through the National Cancer Institute and the National Heart Lung and Blood Institute, as well as through other institutes and agencies that are co-funding the trial.
To learn more about the study, visit www.vitalstudy.org.
