Tuesday, 07 March 2017
There has been more exposure about Vitamin D in the media recently and there are now numerous supplements available on prescription, from chemists and to purchase over the internet to boost us with the “sunshine vitamin”.
I currently recommend that all my patients take vitamin D supplements, which differs to guidance I have given in the past. Previously, I only recommended vitamin D to those people who had a diagnosed deficiency or those patients who have a greater risk of vitamin D deficiency (for example pregnant women, certain ethnic groups). This change is due to the Public Health England announcement in July 2016 that 10mcg of vitamin D should be given daily to everyone over one year of age to help keep healthy bones, teeth and muscles.1 This was based on the advice of the Scientific Advisory Committee on Nutrition (SACN).2
Vitamin D promotes the absorption of calcium and phosphate from the gut, which are needed for the mineralisation of bones. Low vitamin D levels can cause calcium to be released from the bones, leading to de-mineralised, weak bones. In adults, vitamin D deficiency can cause osteomalacia. This can lead to bone and muscle pain, proximal myopathy and even pathological fractures. In children, vitamin D deficiency can cause rickets: growing bones are not adequately mineralised and become soft and deformed.
There are many other conditions that have been attributed to low vitamin D, such as cancers and cardiovascular disease, but the evidence for the link with these non-musculoskeletal conditions is actually still not clear. It is not known whether low vitamin D levels is more a marker of poor health rather than a cause of poor health.
A recent article in the BMJ showed that regular vitamin D supplements can result in a reduction in the number of people having an acute respiratory tract infection.3 Vitamin D supplementation reduced the risk of acute respiratory tract infection (adjusted odds ratio 0.88, 95% confidence interval 0.81 to 0.96; P for heterogeneity <0.001). Although the media used these results to promote the use of vitamin D more widely, further work needs to be done in this area involving randomised controlled trials which this study was not.
There is now a strong argument for foods in the UK being fortified with vitamin D, which is not expensive and could potentially really improve health.
As GPs, we need to decide whether to endorse the current advice and we also need to define what part we should play in providing supplementation of vitamin D. Should we be prescribing vitamin D for our patients or should we be encouraging our patients to buy it themselves?
- PHE publishes new advice on vitamin D. Public Health England, July 2016
- SACN vitamin D and health report. Scientific Advisory Committee on Nutrition, July 2016
- Martineau AR, Jolliffe DA, Hooper RL, et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ 2017;356:i6583