Background

Vitamin D is essential for health, supporting bone strength, immune function and metabolism. Unlike most vitamins, it is mainly produced in the skin in response to sunlight, so levels vary by season, location and time spent outdoors. Vitamin D deficiency is common in Europe, especially in winter, yet people differ widely in how their levels respond to sunlight. Until now, the strong influence of sunlight has made it difficult to untangle the smaller role of genetics in these differences. 

Research

In this study, led by Trinity College Dublin researchers Prof Lina Zgaga and Dr Rasha Shraim, in collaboration with FutureNeuro researchers at Maynooth University Prof Lorna Lopez and Dr Cathy Wyse, genetic data from over 330,000 UK Biobank participants were combined with satellite data measuring daily UVB sunlight exposure at each person’s home address. This enabled a precise estimate of individual sunlight exposure before vitamin D levels were measured. 

By analysing genetics alongside sunlight exposure, the team identified more than 300 genetic variants linked to vitamin D status, including over 30 genes not previously associated with it. Several of these genes are involved in circadian rhythm, metabolism, and how vitamin D and other substances are processed in the body. 

Potential Impact

These findings bring us closer to personalised vitamin D recommendations, where supplementation could one day be tailored to an individual’s genetics and environment. More broadly, the study highlights how combining genetic and environmental data can uncover insights into health and disease that would be missed by studying either alone.