Dr. Leen Antonio from University Hospitals Leuven in Belgium and a team of European researchers conducted the study. They presented their findings at the 22nd European Congress of Endocrinology (e-ECE 2020) conference in early September.
Vitamin D is important for maintaining healthy bones, as well as protecting against infections and diseases. Vitamin D deficiency is a major global health problem, with estimates suggesting that about 1 billion people have low levels of vitamin D in their blood.
Vitamin D deficiency is particularly common in older people. Also, studies are increasingly showing the importance of vitamin D in protecting against a range of health conditions associated with aging.
Researchers have linked low blood levels of vitamin D with major age-related health problems, including:
- increased risk of death from cardiovascular disease
- type 2 diabetes
- cognitive decline.
There are several forms, or metabolites, of vitamin D in the body. However, the medical community typically uses the total amount of these metabolites to determine people’s vitamin D status.
The body converts the prohormone form, 25-dihydroxy vitamin D, to 1,25-dihydroxy vitamin D, which scientists consider the active form of vitamin D in the body.
However, more than 99% of all metabolites of vitamin D in the blood are bound to proteins, so only a tiny portion of it can be biologically active. This explains why the free, active forms of the vitamin may be a better predictor of current and future health than the total levels.
Dr. Antonio and her team used data from the European Male Aging Study, which researchers collected between 2003 and 2005 from 1,970 men aged 40–79 years.
To investigate whether the free metabolites of vitamin D can better forecast health concerns, the team compared the levels of free and total vitamin D in the men’s bodies with their current health status, considering their age, body mass index (BMI), and lifestyle.
The findings demonstrated that even though both free and bound vitamin D metabolites were linked to a higher risk of death, only free 25-hydroxyvitamin D was predictive of future health problems and not free 1,25-dihydroxy vitamin D.
“These data further confirm that vitamin D deficiency is associated with a negative impact on general health and can be predictive of a higher risk of death,” explains Dr. Antonio.
While these findings are promising, the study was observational in nature, so the researchers could not determine the underlying mechanisms. Additionally, it was not possible to gather specific information about the causes of the death of the participants.
“Most studies focus on the association between total 25-hydroxyvitamin D levels and age-related disease and mortality. As 1,25-dihydroxy vitamin D is the active form of vitamin D in our body, it was possible it could have been a stronger predictor for disease and mortality. It has also been debated if the total or free vitamin D levels should be measured,” explains Dr. Antonio.
“Our data now suggest that both total and free 25-hydroxyvitamin D levels are the better measures of future health risk in men,” she concludes.
Dr. Antonio and her colleagues are currently finalizing the statistical analysis and paper on their work.
Further investigation into vitamin D levels and their relationship with poor health may be a promising area for future studies.