A new study from Trinity College Dublin sheds light on the complexities of achieving optimal vitamin D status across diverse populations. Despite substantial research on the determinants of vitamin D, levels of vitamin D deficiency remain high. The study was recently published in the journal Clinical Nutrition.

The authors analysed data from half a million participants from the UK and for each person, they calculated the individualised estimate of ambient ultraviolet-B (UVB) level, which is the wavelength of sunlight that induces vitamin D synthesis in the skin. 

A comprehensive analysis of key determinants of vitamin D and their interactions revealed novel insights. The first key insight is that ambient UVB emerges as a critical predictor of vitamin D status, even in a place like the UK, which receives relatively little sunlight. The second is that age, sex, body mass index (BMI), cholesterol level and vitamin D supplementation significantly influence how individuals respond to UVB. For example, as BMI and age increase, the amount of vitamin D produced in response to UVB decreases.

The research team believes that its findings are largely generalisable for Ireland, with both populations (Irish versus British) quite similar biologically/genetically, as well as other conditions – most notably the level of UVB light but also other lifestyle factors such as diet.

Dr Margaret Brennan, research assistant with the Department of Public Health and Primary Care, School of Medicine, TCD and first author, said: “We hope this work can highlight the significant differences in vitamin D levels among different ethnic groups at northern latitudes and contribute to efforts to address the long-standing population health issue of vitamin D deficiency.”

The principal investigator, Prof Lina Zgaga, associate professor of epidemiology, Department of Public Health and Primary Care, School of Medicine, TCD, said: “We believe our findings have significant implications for the development of tailored recommendations for vitamin D supplementation. Our study underscores the need to move away from a one-size-fits-all approach towards personalised strategies for epitomising vitamin D status.”