Vitamin D is essential in a number of biochemical roles in the human body, perhaps the best known is that of being involved in the process in which calcium in taken up for growth and maintenance of bone structure.
Vit.D is relatively hard to acquire naturally through dietary sources, only the oily fishes providing high levels. The human body synthesises Vit.D, but the process depends on exposure of the skin to the ultraviolet component of sunlight, and the question which has arisen in recent years is that of whether or not we now get adequate exposure to UV?
It is clearly the case that weather conditions during UK winters greatly limit the number of days when we actually have significant levels of sunlight. Moreover, our current lifestyles mean that many people spend more of their working and leisure time indoors than was probably the case in the past. Additionally, over the last 20 years we have been repeated told that exposure to the UV component of sunlight increases the risk of skin cancer, so that we need to “cover up” or use sunscreen with a high skin protection factor (SPF). Attempts to assess the effect of sunscreen use on Vit.D production have been inconclusive; some reports suggest that sunscreen has little effect while others suggest that they greatly reduce Vit.D production.
The American and Canadian governments have started adding Vit.D to various foods like milk, margarine and breakfast cereals, but this is not yet happening in the UK. However, Vit.D supplements can be obtained either by prescription or purchased from vitamin suppliers. The possibility is that the Brits are ‘behind the curve’ on this issue.