Weight Plays a Role in Vitamin D Health Benefits – Harvard Gazette

New research finds that vitamin D may metabolize differently in those considered overweight, resulting in reduced health benefits.

The study, which appears on JAMA Network Open, is a new analysis of data from the VITAL study, a large national clinical trial led by researchers at Brigham and Women’s Hospital that investigated whether taking vitamin D or marine omega-3 supplements could reduce the risk of developing cancer, heart disease or stroke.

“Analysis of the original VITAL data found that vitamin D supplementation was related to positive effects on several health outcomes, but only among people with a BMI less than 25,” said first author Deirdre K. Tobias, an associate epidemiologist in Brigham’s division of preventive medicine. “Something different appears to be happening with vitamin D metabolism at higher body weights, and this study may help explain the reduced results of supplementation for people with a high body mass index.”

Vitamin D is an essential nutrient involved in many biological processes, in particular it helps our body absorb minerals, such as calcium and magnesium. While some of the vitamin D we need is made in the body from sunlight, vitamin D deficiencies are often treated with supplementation. Evidence from laboratory studies, epidemiological research, and clinical research has also suggested that vitamin D may play a role in the incidence and progression of cancer and cardiovascular disease, and it was this evidence that prompted the original VITAL study.

The VITAL study was a randomized, double-blind, placebo-controlled study of 25,871 US participants, which included men over the age of 50 and women over the age of 55. All participants were free of cancer and cardiovascular disease at enrollment. While the study found little benefit of vitamin D supplementation for preventing cancer, heart attack, or stroke in the overall cohort, there was a statistical correlation between BMI and cancer incidence, cancer mortality, and autoimmune disease incidence. . Other studies suggest similar results for type 2 diabetes.

The new study aimed to investigate this correlation. The researchers analyzed data from 16,515 original study participants who provided blood samples at baseline (before randomization to vitamin D), as well as 2,742 with a follow-up blood sample drawn after two years. The researchers measured total and free vitamin D levels, as well as several other new biomarkers for vitamin D, such as its metabolites, calcium and parathyroid hormone, which helps the body use vitamin D.

“Most studies like this focus on the total vitamin D level in the blood,” said senior author JoAnn E. Manson, chief of the division of preventive medicine at Brigham and principal investigator of VITAL. “The fact that we were able to look at this expanded profile of vitamin D metabolites and new biomarkers has provided us with unique insights into vitamin D availability and activity and whether vitamin D metabolism might be disrupted in some people but not in others”.

The researchers found that vitamin D supplementation increased most biomarkers associated with vitamin D metabolism in people, regardless of their weight. However, these increases were significantly smaller in people with a high body mass index.

“We observed striking differences after two years, indicating an attenuated response to vitamin D supplementation with a higher body mass index,” Tobias said. “This may have clinical implications and potentially explain some of the observed differences in the effectiveness of vitamin D supplementation based on obesity status.”

“This study sheds light on why we are seeing a 30 to 40 percent reduction in deaths from cancer, autoimmune diseases and other outcomes with vitamin D supplementation among those with a lower body mass index, but minimal benefit in those with a higher body mass index, suggesting that it may be possible to achieve benefits in the whole population with more individualized vitamin D dosing,” Manson said. “These nuances make it clear that there’s more to the vitamin D story.”

The authors conclude that VITAL’s findings are a call to action for the research community to continue to explore the potential benefits of vitamin D supplementation for preventing cancer and other diseases and to take BMI into account when evaluating impacts on human health. supplement health.

Disclosures: Co-author Julie Buring said his wife served on the scientific advisory board of Pharmavite, which provided vitamin D and placebos. Additional disclosures can be found in JAMA Network Oquill publication.

Financing: The Vitamin D and Omega-3 trial was supported by National Center for Complementary and Integrative Health grant RO1ATO11729 and, during the intervention phase, was supported by National Cancer Institute grants U01 CA138962 and R01 CA138962; National Heart, Lung, and Blood Institute; Office of Dietary Supplements; National Institute of Neurological Diseases and Stroke; and the National Center for Complementary and Integrative Health. Ancillary studies are supported by grants from multiple institutions, including the National Heart, Lung, and Blood Institute; the National Institute of Diabetes and Digestive and Kidney Diseases; the National Institute on Aging; the National Institute of Arthritis and Musculoskeletal and Skin Diseases; the National Institute of Mental Health; and other. Pharmavite LLC of Northridge, California (vitamin D) and Pronova BioPharma of Norway and BASF (Omacor fish oil) donated the study agents, matching placebos and packaging in the form of calendar packets. Quest Diagnostics measured serum 25-hydroxyvitamin D, parathyroid hormone and other biomarkers at no cost to the study. Dr. LeBoff reported grants from National Institute of Arthritis and Musculoskeletal and Skin Diseases RO1 AR070854 and grants from National Institute of Arthritis and Musculoskeletal and Skin Diseases R01 ARO59775.

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