It is widely established that vitamin D is critical for bone health. There is also an increasing body of evidence from observational studies that low levels of vitamin D are associated with a range of other disorders, including cancer and cardiovascular disease. People in temperate climates are often deficient in vitamin D, particularly in wintertime. The key question is whether there is sufficient evidence to justify supplementing vitamin D intakes for all. In this 'Controversy in Medicine', two international experts argue the case 'for' and 'against' universal vitamin D supplementation.
