The long held belief that Vitamin supplements helped preventing chronic diseases unrelated to the bones is nothing more than fantasy - concluded a research published Friday in The Lancet Diabetes & Endocrinology medical journal.
The study, not only corroborated the scientifically proven importance of vitamin D in health of bones, but also found that the vitamin role in reducing the risk of diseases ranging from cancer to heart disease as shown in 290 observational studies were vastly unconfirmed in 172 randomized controlled trials - the gold standard for establishing causal links.
According to Philippe Autier, lead author and professor at the International Prevention Research Institute in Lyon, France, the discrepancy in findings between the two types of studies suggests that low levels of vitamin D aren't a cause but a consequence of ill health, particularly inflammation linked to many diseases.
"Associations between vitamin D and health disorders reported by investigators of observational studies are not causal," Autier wrote. "Low vitamin D could be the result of inflammatory processes involved in the occurrence and progression of disease."
These results have implications evaluated in about $600 million a year - that is, what almost half of all U.S. adults pay per year for vitamin D pills.
In the study, scientists administered to a randomized controlled trials either treatment or placebo to study participants who don't know which one they're getting to tease out whether the treatment is causing the outcome. In observational studies, there are no such comparison groups.
The randomized trials on vitamin D, Autier said, proved that there was effect ranging from little to none in lowering risk for heart disease, diabetes, infectious diseases and mood disorders, among other conditions. The result stands in stark contrast with the observational studies, which have usually reported moderate to strong effects on these disorders.
In a phone interview, Duffy Mackay, vice president of scientific and regulatory affairs at the Council for Responsible Nutrition, said: "These findings shouldn't be misinterpreted, that vitamin D has no value. This doesn't change the fact that we have recommended intake levels backed by the science around bone health, which is rock solid."
