Largest study of its kind
The research was published by scientists at Brigham and Women’s Hospital, who reviewed the numbers of one of the largest and longest-running studies ever on vitamin D: the so-called VITAL study from the US.
The researchers followed 26,000 American men and women over the age of 50 who received a daily vitamin D supplement for five years to see whether it affected their risk of cancer, heart disease and thrombosis, among other things. None of the participants had cancer or heart disease before the study began.
Search in blood samples
The original figures showed that vitamin D seemed to have various health effects, but only for people with a BMI of less than 25 – so people who are not overweight.
So the hospital researchers decided to look at a subgroup of 16,000 participants who had donated blood samples before the experiment and two years after it started.
They checked the level of vitamin D in the blood, but also looked at small so-called biomarkers that tell us something about the absorption of the vitamin, such as the amount of calcium and the so-called parathormone.
Researcher: ‘Striking difference’
For example, they found that vitamin D supplements lead to higher levels of biomarkers related to vitamin D absorption, regardless of weight. But the uptake turned out to be much lower in participants with a high BMI.
“We observed striking differences after two years, indicating that people with higher BMIs respond more slowly to vitamin D supplements,” says scientist Deirdre Tobias, assistant professor at Harvard School of Public Health. in a press release.
Explanation of key difference
The results suggest there may be many more sides to the story of the important little vitamin than we previously thought, said Joann E. Manson, also one of the study’s scientists.
“This study sheds light on why people with a lower BMI who take a vitamin D supplement experience a 30-40 percent reduction in autoimmune disease, cancer mortality, etc., while people with a high BMI benefit less.” ‘ explains the researcher. According to her, it is useful to tailor the vitamin D dose more to individuals in the future.
The researchers do not indicate what the dose of vitamin D should be for overweight people.
