Background

Vitamin D is essential for good health, supporting bone strength, immune function and metabolism. Unlike most vitamins, it is largely produced in the skin in response to sunlight, meaning vitamin D levels change with the seasons and vary depending on where people live and how much time they spend outdoors. Vitamin D deficiency is common in Europe, particularly in winter, but people differ greatly in how their vitamin D levels respond to sunlight. Until now, it has been difficult to understand how genetics contributes to these differences because the strong effects of sunlight can mask smaller genetic influences.

Research

In this study lead by researchers in Trinity College Dublin Professor Lina Zgaga and Dr Rasha Shraim, in collaboration with FutureNeuro researchers at Maynooth University Professor Lorna Lopez and Dr Cathy Wyse, combined genetic data from over 330,000 people in the UK Biobank with detailed satellite data measuring daily UVB sunlight exposure at each participant’s home address. This allowed them to calculate a precise estimate of how much sunlight each person was exposed to before their vitamin D levels were measured.

By analysing genes and sunlight exposure together, the team identified more than 300 genetic variants linked to vitamin D status, including over 30 genes not previously known to be involved. Some of these genes are related to circadian rhythm (the body’s internal clock), metabolism, and how substances such as hormones and vitamin D are processed and excreted by the body.

Potential Impact

These findings move us closer to personalised vitamin D recommendations, where supplementation advice could one day be tailored to a person’s genetics and their environment. More broadly, the study shows how combining genetic and environmental data can reveal new insights into health and disease that would be missed by studying genes or environment alone.