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Dietary Supplements: VITAL Research Delves into Potential Benefits

Dietary supplements are widely used but whether they provide true health benefits remains mostly unknown. Researchers at Brigham and Women’s Hospital (BWH) are conducting large and long-term studies, including randomized trials, that may reveal answers. 

Dr. JoAnn Manson, Chief of the Division of Preventive Medicine at Brigham and Women’s Hospital and the Michael and Lee Bell Professor of Women’s Health at Harvard Medical School and colleagues are conducting several research studies investigating whether supplements enhance diet to promote health in both women and men.

“The main purpose of dietary supplements, historically, was to prevent or treat deficiencies of vitamins and minerals to avoid diseases like scurvy and rickets,” explains Dr. Manson. “In recent decades, many people are taking dietary supplements with the hope of reducing their risk of chronic diseases, such as cardiovascular disease or cancer, but such benefits are largely unproven. Although it's reasonable to take a multivitamin or relatively low doses of different nutrients if you’re concerned about your diet, supplements should never be viewed as a substitute for a healthful diet.”  

Also, megadose supplementation (very high dose supplementation of any vitamin, mineral, or other nutrient) may have risks and is not advised unless recommended by your health care provider. Certain individuals do benefit from dietary supplementation, however. “For women of reproductive age and during pregnancy, folic acid is extremely important in preventing neural tube defects and other birth defects. So, these groups should be encouraged to take a supplement that contains folic acid,” says Dr. Manson.

Another example, she explains, is calcium and vitamin D supplementation, which is important for bone health, especially for patients with osteoporosis or a history of osteoporotic fracture. Additionally, people who have lactose intolerance or those who tend to have very low intakes of calcium or vitamin D-fortified foods may benefit from supplementation. “And we need to keep in mind that many older individuals may have an inability to absorb vitamin B12 and may benefit from B12 supplementation,” she adds.

There is a lot more to investigate when it comes to the benefits of dietary supplements.

Among the trials being led by researchers at BWH, is the VITamin D and OmegA-3 Tria(VITAL). VITAL is a 5-year, randomized, double-blind, placebo-controlled trial in 25,871 U.S. men and women investigating whether taking daily dietary supplements of vitamin D (2000 IU) or omega-3 fish oil (Omacor®, 1 gram) reduces the risk of developing cancer, heart disease, and stroke in people without a prior history of these illnesses. 

Ancillary studies of VITAL are evaluating the effect of vitamin D and omega-3 fatty acid supplementation on other outcomes, including diabetes, hypertension, heart failure, cognitive decline, autoimmune diseases (e.g., thyroid disease, rheumatoid arthritis, and lupus), physical disability and falls, bone health and fractures, anemia, macular degeneration, dry eye syndrome, infections, asthma, depression, diabetes-related kidney disease, kidney function in people with hypertension, chronic knee pain symptoms, atrial fibrillation, and others. 

Results of the trial are expected by mid-2018. Visit vitalstudy.org to learn more about the study and the latest updates.  

JoAnn Manson, MD, DrPH, Chief, Division of Preventive Medicine at Brigham and Women’s Hospital (BWH), discusses the need for dietary supplements.