In a new study, researchers found free, circulating vitamin D levels in the blood may be a better predictor of future health risks in aging men.
The finding suggests the free, precursor form of vitamin D found circulating in the bloodstream is a more accurate predictor of future health and disease risk, than the often measured total vitamin D.
The research was conducted by a team from University Hospitals Leuven in Belgium and elsewhere.
Vitamin D deficiency is linked to multiple serious health conditions as people get older.
The problem is common in Europe, especially in elderly people. It has been linked to a higher risk for developing many aging-related diseases, such as heart disease, cancer and osteoporosis.
However, there are several forms, or metabolites, of vitamin D in the body but it is the total amount of these metabolites that is most often used to assess the vitamin D status of people.
The prohormone, 25-dihydroxyvitamin D is converted to 1,25-dihydroxyvitamin D, which is considered the active form of vitamin D in our body.
More than 99% of all vitamin D metabolites in the blood are bound to proteins, so only a very small fraction is free to be biologically active.
Therefore the free, active forms may be a better predictor of current and future health.
In the study, the team tested whether the free metabolites of vitamin D were better health predictors, using data from 1,970 community-dwelling men, aged 40-79, between 2003 and 2005.
The levels of total and free metabolites of vitamin D were compared with their current health status.
The team found the total levels of both free and bound vitamin D metabolites were linked to a higher risk of death.
However, only free 25-hydroxyvitamin D was predictive of future health problems and not free 1,25-dihydroxyvitamin D.
These findings further confirm that vitamin D deficiency is linked to a negative impact on general health and can be predictive of a higher risk of death.
The team says most studies focus on the association between total 25-hydroxyvitamin D levels and age-related disease and mortality.
As 1,25-dihydroxyvitamin D is the active form of vitamin D in the 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.
The study now suggests that both total and free 25-hydroxyvitamin D levels are the better measures of future health risk in men.
One author of the study is Dr. Leen Antonio.
The study was presented at e-ECE 2020.
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