Rickets in children and osteomalacia in adults are the classic manifestations of profound vitamin D deficiency. In recent years, however, non-musculoskeletal conditions—including cancer, metabolic syndrome, infectious and autoimmune disorders—have also been found to be associated with low vitamin D levels.1 The spectrum of these common disorders is of particular concern because observational studies have demonstrated that vitamin D insufficiency is widespread in many northern regions of the world, including industrialised countries.2 3 The increasing prevalence of disorders linked to vitamin D deficiency is reflected in the several hundred children with rickets treated each year in the UK.4 However, these children represent a small proportion of the individuals with a suboptimal vitamin D status in the UK population.1 3 5

A recent nationwide survey in the United Kingdom showed that more than 50% of the adult population have insufficient levels of vitamin D and that 16% have severe deficiency during winter and spring.5 The survey also demonstrated a gradient of prevalence across the UK, with highest rates in Scotland, northern England, and Northern Ireland.5 People with pigmented skin are at high risk, …