Vitamin D supplements are recommended for young children and the elderly
Scientists have cast doubt on the value of vitamin D supplements to protect against diseases such as cancers, diabetes and dementia.
Writing in The Lancet Diabetes and Endocrinology, French researchers suggest low vitamin D levels do not cause ill health, although they did not look at bone diseases. More clinical trials on non-skeletal diseases are needed, they say.Vitamin D supplements are recommended for certain groups.
Recent evidence has shown it may also have a role to play in preventing non-bone-related diseases such as Parkinson's, dementia, cancers and inflammatory diseases. 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.
"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."
More research
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."