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Is Vitamin D Supplementation Really One-Size-Fits-All?

A vitamin D capsule.
Credit: Michele Blackwell/Unsplash
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A new study has shed light on factors surrounding vitamin D supplementation across diverse populations. The research suggests the need for personalized approaches to supplementation to help reduce vitamin D deficiency, which remains widespread despite extensive research.

The study is published in Clinical Nutrition.

Tackling vitamin D deficiency with supplementation

Vitamin D is incredibly important for our bodies, helping to keep our bones, teeth and muscles healthy – yet deficiency is incredibly common.

Vitamin D is produced in the skin following exposure to ultraviolet-B (UVB) radiation from the sun. Skin pigment, such as melanin, limits UVB penetration and vitamin D synthesis in the skin. Consequently, in places like Europe, the prevalence of vitamin D deficiency varies from 13–40% but can be as much as 3- to 71-fold higher in darker-skinned individuals compared to white ethnicities.

Many health agencies recommend supplementing vitamin D, especially during the darker winter months. However, these recommendations typically follow a one-size-fits-all approach, despite many factors influencing vitamin D synthesis in the skin including ambient sunlight intensity, age and skin tone.

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Studies have found profound differences in vitamin D status between and within populations. In a new study, researchers hypothesized that predicting vitamin D status could be improved by accounting for ambient UVB radiation and interaction with other key determinants of vitamin D.

Not as simple as one-size-fits-all?

The researchers harnessed data from half a million Asian, Black and White participants from the UK Biobank – specifically, data on vitamin D levels obtained from participants’ blood samples. The researchers then estimated the ambient UVB doses for each person depending on their place of residence in the 135 days leading up to their blood draw.

The researchers found that ambient UVB was a key predictor for vitamin D levels for all ethnicities, even in places that – like the UK – receive relatively little sunlight. Vitamin D deficiency was common, particularly among non-White participants.

Other factors were also found to influence how people’s bodies responded to UVB, such as age, sex, body mass index (BMI), cholesterol levels and vitamin D supplementation. For example, with increasing age and BMI, vitamin D production in response to UVB was found to decrease.

"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,” said the study’s lead author Dr. Margaret M. Brennan, a research assistant in the Department of Public Health and Primary Care in Trinity College Dublin’s School of Medicine.

“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 personalized strategies for optimizing vitamin D status,” said study co-author Professor Lina Zgaga, an associate professor of epidemiology at Trinity College Dublin.

The authors also highlight that improved methods of predicting vitamin D levels could help develop more nuanced approaches to supplementation, helping to limit deficiency in a range of populations.

“Our study also highlights the effect that natural environmental factors, like sunlight, can have on our health,” explained study co-author and PhD candidate Rasha Shraim. “We hope that our approach encourages future researchers and public health bodies to integrate these factors into their health and disease work.”

Reference: Brennan MM, Geffen J van, Weele M van, Zgaga L, Shraim R. Ambient ultraviolet-B radiation, supplements and other factors interact to impact vitamin D status differently depending on ethnicity: A cross-sectional study. Clin Nutr. 2024;43(6):1308-1317. doi: 10.1016/j.clnu.2024.04.006

This article is a rework of a press release issued by Trinity College Dublin. Material has been edited for length and content.