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Vitamin D and Omega-3's Impact on Disease Prevention Video and Transcript

JoAnn E. Manson, MD, DrPH

  • Principal Investigator, VITAL Main Study
  • Chief, Division of Preventive Medicine, Brigham and Women’s Hospital
  • Michael and Lee Bell Professor of Women’s Health, Harvard Medical School

The VITAL trial, the vitamin D and omega-3 trial is a randomized, clinical trial of the effect of vitamin D at a dose of 2,000 IU’s per day and the omega-3s at a dose of 1 gm per day in the preventions of cancer, heart disease and stroke.

The 26,000 participants nationwide are tremendously important for assessing the effect of vitamin D and omega-3s in preventing heart attack, strokes, cancer. You need a very large study population. In fact, you need a population of this size in order to get a clear answer.

So the participants in this trial agree to be assigned at random by a computer to one of four treatment groups. It’s a placebo controlled trial so they may receive active vitamin D or a placebo, active omega-3s or placebo. One active, one placebo or both active, both placebos. There are four different treatment groups.

The Institute of Medicine recommends 600 IUs per day of vitamin D for adults, up until age 70 and 800 IUs a day after age 70. And it’s believed that that is sufficient to provide the bone health benefits, to protect the bones and reduce risk of fractures, osteoporosis, osteomalacia, other bone health problems. However, it’s not known whether giving higher amounts would be of benefit for preventing heart attack, stroke and cancer. We’re testing 2,000 IUs a day in half of the study population and placebo, compared to placebo in the other half—because we feel that 2,000 IUs a day provides a good balance of efficacy and safety based on what’s known from other research and the recommendations of the Institute of Medicine to avoid getting very high intakes of vitamin D—which might have safety issues.

For the omega-3s, we’re testing one gram a day of EPA plus DHA in have of the participants and half for placebo. And the American Heart Association actually recommends 1 gm per day for people who already have a history of heart disease. However, in general, the US population gets only about one-fourth to one-fifth that amount of omega-3s. And there aren’t previous, large-scale randomized trials looking at the omega-s in prevention of first, cardiovascular event or first development of heart attack, stroke, cancer or these other outcomes.

Impact of Vitamin D and Omega-3s on Other Health Conditions

We’re very much interested in the role of vitamin D and omega-3s in improving cognitive function, preventing memory loss, reducing rate of cognitive decline that often occurs with aging. And the evidence from observational studies has been promising for these two interventions.  However, we don’t yet have conclusive evidence about a cause and effect relationship from randomized clinical trials.

There’s also some promising evidence for vitamin D in preventing diabetes and reducing the risk of developing insulin resistance or glucose intolerance. And we are testing vitamin D and omega-3s in terms of effects on blood sugar and effects on insulin sensitivity as well as the development of diabetes. Another area of great interest is autoimmune diseases because both vitamin D and the omega’3s have anti-inflammatory effects.  So we’re looking at the effects of these interventions and the development of autoimmune conditions, rheumatoid arthritis, lupus, some of the autoimmune thyroid diseases and other forms of autoimmune disorders.

Health Disparities and Vitamin D Deficiency

We have nearly 26,000 participants in VITAL from all 50 states. And we have racial, ethnic diversity in the cohort, which is very exciting to us because one of the goals of the VITAL Trial is to see whether vitamin D can reduce some of the health disparities that occur by race and ethnicity. We know that vitamin D deficiency is more common, for example, in African-Americans and there are certain conditions that have been linked to vitamin D deficiency, such as stroke and diabetes and cardiovascular death and prostate cancer, breast cancer mortality and we are very much interested in seeing whether supplementation with vitamin D can reduce some of these health disparities.

Public Health Implications of VITAL Trial

If it’s shown that with 2,000 IUs a day of vitamin D or 1 gm supplementation of EPA DHA, the omega-3s, that there is a reduction in these major chronic diseases—which include heart disease, stroke, cancer or even any one of these major disease outcomes—then this may lead to recommendations, public health recommendations to take supplements of vitamin D, omega-3s in similar amounts in order to reduce these chronic disease risks.

Read BWH's Endocrinology Advances Article: Large Trial Investigates Whether Vitamin D and Omega-3s Can Reduce Risk of CVD and Cancer and Effects on Diabetes, Bone Health, and Other Conditions.


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