Scientists often liken the process of discovery to doing a jigsaw. At first, few pieces fit and the picture is a mystery. Then suddenly two or three pieces lock together and an image starts to take shape.
This is what is happening in the study of apparently unrelated, chronic diseases such as multiple sclerosis, schizophrenia, diabetes and asthma. These conditions are increasingly common both in the UK and elsewhere; their causes have puzzled doctors and scientists for decades. Now pieces of the jigsaw are starting to fit together – and they focus on vitamin D which is produced naturally in the skin when exposed to sunlight.
A deficiency in this crucial vitamin, thanks to our increasingly indoor lifestyles, is already blamed for the reappearance of rickets, the painful and deforming bone disease in children, in the UK. But gradually, evidence is emerging that links low vitamin D levels to a rise in a whole host of “modern” diseases, some of which were virtually unheard of in the pre-industrial era.