Study finds links between vitamin D, fat and cholesterol metabolism, and genes that control the body’s internal biological clock. Vitamin D is often described as the “sunshine vitamin” because our bodies produce it when skin is exposed to sunlight. It plays an important role in bone health and many other aspects of wellbeing, including helping to protect against Multiple Sclerosis. Yet even people who live in the same place, experience similar weather and lead similar lifestyles can have very different vitamin D levels in their blood. This large genetic study helps explain why.Scientists have long known that both genes and environment influence vitamin D levels. Previous genetic studies identified more than 140 genetic variants linked to vitamin D, but these explained only a small part of the differences between people, much less than sunlight exposure. This raised an important question: do genes and sunlight act independently, or do they work together?A major challenge has been how sunlight exposure is measured. Many studies simply rely on the season when a blood sample is taken as a stand‑in for ultraviolet B (UVB) exposure. However, UVB levels vary greatly from day to day and place to place due to factors such as latitude, cloud cover and weather. Grouping all of this variation into broad seasons can hide important biological effects. To overcome this problem, researchers used historical satellite data to calculate personalised UVB exposure for each participant based on where they lived and the sunlight they experienced in the months before their blood was taken. This produced a much more accurate estimate of real sunlight exposure than had been used before.Using this approach, the study analysed data from nearly 339,000 UK Biobank participants of White British ancestry. Researchers examined millions of genetic variants to see how they influenced vitamin D levels on their own and in combination with sunlight exposure.The results showed that genes and sunlight strongly interact. In total, more than 300 genetic variants were linked to vitamin D levels, including 162 that had not been identified previously. Importantly, genetic effects were much more visible in people with higher UVB exposure. Rather than cancelling out genetic differences, sunlight revealed them. To check the validity of the findings, the analysis was repeated in the data from ORCADES, which provided replication.The study also found links between vitamin D, fat and cholesterol metabolism, and genes that control the body’s internal biological clock. Several key signals came from circadian rhythm genes, suggesting vitamin D may be involved in how the body responds to daily and seasonal changes in the environment.Overall, the findings show that vitamin D sits at the intersection of sunlight, genetics, metabolism and the body clock. It also highlights the importance of measuring the environment (what we are exposed to) precisely when studying how genes affect health.This paper was published in Nature Communications. To read more visit:Genome wide gene–environment interaction study uncovers 162 vitamin D status variants using a precise ambient UVB measure This article was published on 2026-05-11
