Vitamin D deficiency has been associated with an ever expanding list of diseases, and with this has come almost tonic-like claims for vitamin D supplementation. In observational studies, low vitamin D status has been associated with increased risk of multiple sclerosis, type 1 and type 2 diabetes, cardiovascular disease, colon cancer, breast cancer, autoimmunity, and allergy.1 The UK government has advised that all pregnant women, and children under 5 years, should take 400 IU vitamin D daily; a recent news story, however, reported a survey conducted by a charity which suggested that only 26% of pregnant women and 46% of healthcare professionals are aware of these guidelines.2 The most recent musculoskeletal trend seems to be the attribution of childhood problems such as Blount’s disease and slipped femoral epiphyses to vitamin D deficiency and the incorrect conflation of rickets with low serum calcidiol (25-hydroxyvitamin D₃) concentrations.3 So are health professionals causing ill health through their lack of awareness and advocacy of vitamin D supplementation?

The high profile news coverage and the enthusiastic promotion of the results of observational studies as though they proved …