Today the media has been fanning the outcome of a review that doesn’t think much of vitamin D supplementation. Some quick dismantling is required.
Prof Philippe Autier, from the International Prevention Research Institute in Lyon, carried out a review of data from 290 prospective observational studies and 172 randomised trials looking at the effects of vitamin D levels on health outcomes, excluding bone health, up to December 2012.
Stop, stop! The vast majority of reviews from time immemorial to present day rely on data that has three problems: use of vitamin D2, non-physiological dosages and deeply conservative recommended vitamin D levels.
…[T]he results of the clinical trials – where participants were given vitamin D supplements – found no reduction in risk, even in people who started out with low vitamin D levels.
Well, people with low vitamin D levels will probably find negligible improvement on the long-established RDA.
…[Autier said:] “Ageing and inflammatory processes involved in disease occurrence… reduce vitamin D concentrations, which would explain why vitamin D deficiency is reported in a wide range of disorders.”
Sure, illnesses reduce vitamin D levels, but for that reason one should not rule out vitamin D deficiency as an initial enabler of disease too.
…Peter Selby, consultant physician and honorary professor of metabolic bone disease at Manchester Royal Infirmary, said the French review was limited.
“It could very well be that the apparent negative results of this study have been obtained simply because they have not been looking at people with sufficient degree of vitamin D insufficiency to have any meaningful biological effect.”
This can be true, but, as above, I think the historical RDA negates most studies. Vitamin D work since the last 10-15yrs is often of the most value.
The Scientific Advisory Committee on Nutrition (SACN), an independent group of scientific experts who advise the government on nutrition, is currently reviewing the dietary recommendations for vitamin D for all population groups in the UK.
Don’t hold your breath over SACN! Act now!
[Source: BBC News]