Vitamin D would protect against cancer and autoimmune or heart diseases. However, the beneficial effect of this nutritional supplementation would actually depend on your BMI.
- According to the Population Dietary Reference, adults need 15 micrograms of vitamin D per day.
- Exposure to the sun for 15 to 20 minutes at the end of the morning or in the afternoon provides an adequate daily intake of vitamin D.
- Vitamin D can also come from food. In France, the main contributing foods are fish and dairy products (19% and 25% of intakes in adults).
Vitamin D is an essential nutrient for the body participating among other things in the absorption of minerals such as calcium and magnesium. It would also help to reduce the risk of cancer or other pathologies. However, researchers from Brigham and Women’s Hospital (USA) assure that this beneficial effect is only visible in people with a BMI of less than 25.
Vitamin D, beneficial for BMIs below 25
Wishing to verify the link between the intake of vitamin D and the incidence of cancer, cardiovascular pathologies or autoimmune diseases, the scientists analyzed the files of 16,515 men and women who participated in a large clinical trial, called VITAL.
The volunteers provided blood samples at the start of the experiment and then two years later after taking vitamin D regularly. The researchers measured the levels of the nutrient as well as its biomarkers; that is to say its metabolites: calcium and parathormone (or parathyroid hormone).
First author Deirdre Tobias explains in the published article JAMA Network Open January 17, 2023: “Analysis of the original VITAL data found that vitamin D supplementation was correlated with positive effects on several health outcomes, but only in people with a BMI of less than 25.” Thus, overweight or obese individuals would not benefit from the protective effect of the food supplement.
Vitamin D is metabolized differently according to weight
The scientific team found that taking vitamin D increased most of its biomarkers, regardless of the individual’s weight. However, these increases were significantly lower in people with a BMI over 25. For the researchers, vitamin D would be metabolized differently at higher body weights.
“We observed striking differences after two years, indicating a blunted response to vitamin D supplementation with higher BMI”says Deirdre Tobias. “This may have clinical implications and potentially explain some of the observed differences in the effectiveness of vitamin D supplementation depending on obesity status.”
Prof. JoAnn E. Manson, who also worked on this project, adds: “This study sheds light on why we are seeing a 30-40% reduction in death from cancer, autoimmune disease and other outcomes with vitamin D supplementation in people with a BMI of less than 25. but minimal benefit in those with a higher BMI. This suggests that it may be possible to achieve population-wide benefits with more personalized vitamin D dosing.”
