Major study tests primary prevention power of vitamin D and omega-3s
Television news and cereal boxes tout the health benefits of extra vitamin D and omega-3 fatty acids, but exceeding the recommended dietary allowance of either is not a proven way to prevent cancer nor cardiovascular disease. To fill the data gap, the first large randomized trial designed to test these promising nutritional supplements for these two major chronic diseases is underway, with a special Boston cohort.
"More is not necessarily better when it comes to vitamin D," says JoAnn Manson, MD, DrPH (BWH), principal investigator of the VITamin D and OmegA-3 TriaL (VITAL). "We already know it's important for bone health to avoid vitamin D deficiency. But once we get to the threshold of 600 to 800 international units (IU) per day, or a blood level of 20 nanograms, we don't know if getting to higher levels will provide additional benefits or even if the benefits will outweigh the risks," says Manson, the Michael and Lee Bell Professor of Women's Health at HMS.
She and her co-investigators expect VITAL's results to inform individual decisions, clinical recommendations, and public health guidelines about the use of vitamin D and marine omega-3 fatty acid supplements for the primary prevention of cancer and cardiovascular disease.
VITAL is about halfway toward its goal of screening 40,000 volunteers to enroll 20,000 participants, Manson says. In June 2011, the study lowered its age limits to include men 50 or older and women 55 or older. Participants must have no personal history of cancer (except for non-melanoma skin cancer), heart attack or stroke. The demographic change is meant to boost diversity in the study population as well as answer questions about the nutrient's effects in younger age groups. The research team wants to achieve 25 percent African American enrollment, in part because of the higher risks of vitamin D deficiency, certain cancers and cardiovascular events such as stroke in blacks.
Manson encourages study participation by health professionals and staff in the DF/HCC community, as well as healthy family members of people with cancer. These groups tend to understand the importance of research on cancer prevention, to be knowledgeable about the health issues being studied, and to be more dedicated to good compliance with the protocol, she says.
In November 2010, the Institute of Medicine (IOM) increased the Dietary Reference Intakes (DRIs) and set an upper safe boundary of vitamin D that is within VITAL limits. The IOM committee, which included Manson, issued the guidelines to cover the needs of U.S. and Canadian people, including those who get little sun, and emphasized the importance of randomized trials to get conclusive answers about high-dose vitamin D.
In the 2x2 study design, participants are first randomized to vitamin D or a vitamin D placebo, and then to purified omega-3s from fish oil or placebo. VITAL is testing 1 gram a day of omega-3s, a dose recommended by the American Heart Association for heart health. Existing data from laboratory studies and observational research suggest that vitamin D and omega-3s may reduce risk for cancer or cardiovascular disease.
VITAL takes place at a single study site in Boston and is conducted mostly by mail to participants in all 50 states. Study pills are mailed out in calendar packs and participants provide consent for medical record review for health outcomes. A key feature of the trial is a subcohort of 1,000 people within driving distance of the Longwood Medical Area. There, a representative cross-section of the study participants in all four randomized groups will undergo a more detailed assessment. The extra time contributed for the baseline exam and the follow-up visit two years later will be compensated with a small monetary stipend.
The Boston subcohort will support an ancillary study of other health outcomes, including diabetes and glucose tolerance, hypertension, cognitive function, depression, osteoporosis and fracture, physical performance and falls, respiratory function, infections, and rheumatoid arthritis and other autoimmune disorders. These outcomes, as well as cancer, heart disease, and stroke, will also be looked at in the full cohort of 20,000 participants.
VITamin D and OmegA-3 TriaL (VITAL)
JoAnn Manson, MD, DrPH (BWH)
For eligibility criteria, go to NCT01169259 on ClinicalTrials.gov. For additional information, see the VITAL study web site at http://www.vitalstudy.org/. To refer a patient to the trial, contact the project manager at 1-800-388-3963 or firstname.lastname@example.org
— Carol Cruzan Morton