According to a published report in The Lancet Diabetes and Endocrinology, French researchers suggest low vitamin D levels do not cause ill health, however they confirm that additional clinical trials on non-skeletal diseases are required.
Recommended as a supplement for certain groups, recent evidence has shown Vitamin D may have a role to play in preventing non-bone-related diseases such as demetia, Parkinson's, inflammatory diseases and cancers.
Prof Philippe Autier, based at Lyon’s International Prevention Research Institute, conducted a data evaluation from almost 300 prospective observational studies and over 170 randomised trials investigating the effects of vitamin D levels on health outcomes, excluding bone health, up to December 2012.
A high number of the observational studies did suggest high vitamin D intake had benefits, such as risk reduction of cardiovascular events by up to 58%, diabetes by up to 38% and colorectal cancer by up to 33%. In comparison to this data however, the results of the clinical trials found no reduction in risk, even in people with low vitamin D levels, with additional analysis of recent randomised trials finding no positive effect of vitamin D supplements on diseases occurring.
Prof Autier commented that this discrepancy suggested decreases in vitamin D levels were a marker of deteriorating health, and since ageing and inflammatory processes involved in disease occurrence reduced vitamin D concentrations, it would explain why vitamin D deficiency is reported in a wide range of disorders.
The vitamin D supplement recommendation in the UK extends to groups at higher risk of deficiency, all pregnant and breastfeeding women, children under five years old, people aged over 65, and people at risk of not getting enough exposure to sunlight which includes people who wear full-body coverings. Furthermore, skin and pale-skinned people are also known to be at higher risk and in recent years, a four-fold increase in the diagnosis of the bone disease rickets has been registered in the UK.
Dr Colin Michie, consultant senior lecturer in paediatrics and chair of the nutrition committee at the Royal College of Paediatrics and Child Health, emphasised that for almost a century, the vitamin’s benefits were known to include improvement in bone health, preventing hypocalcemic seizure and rickets in people with deficient vitamin D levels. He added that the review excluded the measurement of bone health and was thus not contributing to the problem in the UK.
Consultant physician and honorary professor of metabolic bone disease at Manchester Royal Infirmary Peter Selby also found the French study to be limited, suggesting the apparent negative results of this review had been obtained by not includeing people with a high enough vitamin D insufficiency to have any meaningful biological effect. He did however agree with the authors saying more interventional research looking at disease outcomes was necessary.
The independent group of scientific experts who advise the government on nutrition, the Scientific Advisory Committee on Nutrition (SACN) is in the process of reviewing the dietary recommendations for vitamin D for all population groups in the UK with their report to go out for public consultation in 2014.
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6 December 2013