Popping a daily vitamin D supplement might not protect against or alleviate a number of conditions.
Vitamin D has been rumored to fight certain diseases such as "cancer, cardiovascular disease, diabetes, [and] Parkinson's disease," but new research suggests a deficiency may be a result of the condition as opposed to a contributor, an International Prevention Research Institute news release reported.
The vitamin is known to aid in the uptake of bone formation and calcium, and past studies have noticed inadequate Vitamin D levels had an association with several diseases.
Large trials have been conducted to determine if the two have a causal relationship, and if Vitamin D supplements are beneficial.
"If the health benefits of high vitamin D concentrations shown by data from observational studies are not reproduced in randomised trials (the gold standard method for assessing a causal relation between an exposure and an outcome) then the relation between vitamin D status and disorders are probably the result of confounding or physiological events involved in these disorders," lead author Professor Philippe Autier of the International Prevention Research Institute in Lyon, France, said.
The research team sifted through 290 prospective observational studies and 172 randomized trials to see how it affected conditions not relating to bone health.
The team found that in observational studies there was no confirmed benefit to taking Vitamin D in terms of preventing diseases including cardiovascular events, diabetes, and colorectal cancer.
"What this discrepancy suggests is that decreases in vitamin D levels are a marker of deteriorating health. [Aging] and inflammatory processes involved in disease occurrence and clinical course reduce vitamin D concentrations, which would explain why vitamin D deficiency is reported in a wide range of disorders," Autier said.
Other studies have concluded it is unlikely Vitamin D has an effect on non-skeletal conditions.
"Large [ongoing] clinical trials to assess the effects of vitamin D on non-skeletal health outcomes are therefore justified. It would be a real boon to patients if the results are positive, but unless effect sizes for clinically important outcomes are large, the results will only confirm the neutral effect reported by most clinical trials thus far," a linked Lancet Diabetes & Endocrinology Editorial reported according to the news release.
