November 23, 2016

expert reaction to two articles discussing the evidence on the benefits of taking vitamin D supplements to prevent disease

The benefits and harms of taking vitamin D supplements for disease prevention are discussed in two articles in The BMJ.

Prof. David Richardson, Founder and Director of DPR Nutrition Limited (a company that provides specialist consultancy on food science and nutrition), & Visiting Professor of Food Bioscience, University of Reading, said:

“I agree with the comments from Louis Levy. Failure to address low vitamin D status during childhood, adolescence, for women of childbearing age and in the elderly could have serious long term implications for public health. There is clearly a need to consider all policy solutions to ensure adequacy of vitamin D intake, including the promotion of targeted supplementation. Action is needed now in the face of growing evidence of a high prevalence of vitamin D insufficiency. Such action should not be delayed by the current scientific debate about thresholds of 25(OH)D for optimal function and health. The evidence for supplementary vitamin D was included in the EFSA Scientific Opinion on Dietary Reference Values Oct 2016 and also in the EU authorised disease risk reduction health claim for vitamin D and risk of falling and fractures based on the EFSA evaluation of the evidence.

“Tim Spector should be aware of the scientific opinion of the European Food Safety Authority (EFSA) published on the 28th October 2016. EFSA considered changes in bone mineral density (BMD), bone mineral content (BMC) and fracture risk as additional health outcomes in its assessment, and set a target serum 25(OH)D concentration of 50nmol/L. The subsequent recommendation was for an Acceptable Intake (AI) of 15 micrograms of vitamin D per day for all population groups at which the majority of the population will achieve the target level of 50 nmol/L of 25(OH)D when exposure to sunlight is minimal. The SACN considered a serum concentration of 25(OH)D of 25 nmol/L to represent a ‘population protective level.’ i.e. a concentration that individuals in the UK should be above, throughout the year, in terms of protecting muscular skeletal health.

“In my opinion, there is a lack of coherence regarding the sets of recommendations and use of terminology. There is likely to be confusion among doctors, health professionals, consumers and industry alike. The recommendation from the SACN and Public Health England for 10 microgram per day are to be welcomed, but this amount of vitamin D recommended should be considered modest when compared with the amounts stated by the EFSA Scientific Panel of 15 micrograms per day vitamin D for musculoskeletal health outcomes.”

Prof. Martin Hewison, member of the Society for Endocrinology & Professor of Molecular Endocrinology, University of Birmingham, said:

“In this analysis of multiple studies, the authors conclude that vitamin D supplementation provides no additional health benefits to normal healthy adults. Whilst this was a comprehensive overview of vitamin D and human health, the authors emphasise that many of the studies they analysed involved subjects who had enough vitamin D to begin with.

“The authors point out that the benefits of vitamin D are only likely to be observed for individuals who are vitamin D-deficient. There is still some debate about what levels of vitamin D count as deficiency, and this varies according to the disease being studied.

“However, irrespective of the target level for vitamin D-sufficiency it is clear that people in the UK are at high risk of vitamin D-deficiency, particularly in winter. The Science Advisory Council on Nutrition (SACN) recommends taking vitamin D supplements for the whole UK population to prevent vitamin D-deficiency. SACN indicated that their recommendations were particularly relevant for people at high risk of deficiency: those with darker skin from African, Afro-Caribbean and South Asian backgrounds; people who are confined indoors, and people who cover up their skin while outdoors.  The level of vitamin D intake recommended by SACN is 10μg per day, a relatively low but safe level of supplementation.

“Finally, it is important to recognise that some aspects of vitamin D function that have shown the most promise biologically have not been properly studied in clinical trials. Indeed, in some cases, such as autoimmune diseases including diabetes, prevention trials are very difficult, if not impossible, to carry out. The take home message is that we need to know more about how vitamin D works before planning new clinical trials to assess its health benefits. In the meantime, Public Health England’s vitamin D recommendations are conservative and sensible and people should be following them.”

‘Should adults take vitamin D supplements to prevent disease?’ by Bolland et al. & ‘Should healthy people take a vitamin D supplement in winter months?’ by Spector & Levy published in The BMJ on Wednesday 23rd November. 

Declared interests

Prof. David Richardson: “I was a member of the UK Department of Health Committee on Medical Aspects of Food and Nutrition Policy (COMA) that preceded the SACN. I also Managing Director of a Specialist Consultancy DPRNutrition Ltd that provides advice to the food and food supplements industries, trade associations and government departments nationally and internationally.”

Prof. Martin Hewison: No conflicts of interest declared.