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According to an American study, the benefits of vitamin D for health would be less in overweight and obese people. Although the mechanism involved remains to be elucidated, the researchers argue in favor of a personalized dosage of vitamin D.
Are you vitamin D deficient? It is quite possible. According to ANSES, nearly 7 out of 10 French people suffer from a lack of this vitamin, which is nevertheless very useful: vitamin D maintains bone strength, strengthens the immune system, and can reduce the risk of death from cancer. This is why it is often advisable to supplement, especially during the winter.
But a new study provides important new data: overweight or even obese people absorb vitamin D supplements too quickly and do not benefit from its advantages. Bad news when overweight people already combine several risk factors, including cardiovascular.
A rise in very low vitamin levels in overweight people
For the study, the Massachusetts researchers analyzed data from one of the largest vitamin D trials to date, called the VITAL (Vitamin D and Omega-3 Trial) study. As many as 26,000 people who took daily vitamin D supplements were followed for about 5 years on average between 2010 and 2018. Participants were over 50 years old and had no cancer or cardiovascular disease at the start of the study. Half took pills containing 2,000 international units (IU) of vitamin D per day (five times the recommended daily allowance). The other half was placed in the placebo group who took a dummy pill. The results after taking vitamin D showed that the supplemented group had a 20% lower overall risk of death from cancer, although this was not significant.
Towards a personalized dosage of vitamin D?
The Brigham researchers then wanted to see if body weight played a role in this reduction. They then also re-analyzed data from a smaller subset of 16,000 participants who also had blood tests at the start of the trial and up to two years after the start of the study. The sample included 6,600 people who had a body mass index (BMI) in the overweight category and 4,400 who were in the obese or morbidly obese group (the rest were within the normal weight).
The results showed that:
- Both groups saw an increase in vitamin D levels in their blood over the course of the study;
- The increase was significantly higher in the group that was not overweight or obese.
“This study sheds light on why we’re seeing a 30-40% reduction in death from cancer, autoimmune disease, and other outcomes with vitamin D supplementation in people with lower BMIs, but benefit minimal in those with a higher BMI, suggesting that it may be possible to obtain more benefit for the whole population with a more personalized dosage of vitamin D”Manson said.
NO to diets, YES to WW!
The study found that they had significantly lower levels of vitamin D in their blood compared to healthy people taking the same pills. Dr. Deirdre Tobias, an epidemiologist at Brigham and Women’s Hospital who led the research, “We observed striking differences after two years, indicating a blunted response to vitamin D supplementation with higher body mass index (BMI)” established author Dr. Tobias. “It seems that something different is happening with vitamin D metabolism at higher body weights” he continued.
To explain this phenomenon, researchers currently have two theories:
- The fat cells would absorb the vitamin better than the others and could extract more of it from the blood;
- Being overweight could impair the body’s ability to make or process vitamin D, leading to lower levels.
Further studies are planned to confirm these theories, and to learn more about how everyone can benefit from vitamin D.