A Newcastle University-led screening study of nearly 300 adults in northern Britain found persistently high rates of low vitamin D in older people and adults from minoritized ethnic groups, with little evidence that summer months substantially improved levels.
Researchers at Newcastle University analyzed vitamin D screening results from 299 people enrolled during a clinical-trial recruitment period running from December 2024 to August 2025.
The analysis focused on two study strata: older adults aged 65 and over (168 participants) and adults from minoritized ethnic groups aged 18 and over (147 participants). In the older-adult group, 54.8% were classified as having insufficient vitamin D (described in the paper as “low or deficient”). In the minoritized-ethnic group, 72.1% were classified as insufficient.
The researchers reported little variation by month in the older-adult group and no seasonal change in the share of participants who were insufficient among the minoritized-ethnic group across winter, spring and summer. In their discussion, the authors said the findings challenge the assumption that summer sunlight reliably restores vitamin D status, noting that deficiency rates in older adults remained high even in summer.
Bernard M. Corfe, a Newcastle University professor and one of the study’s authors, said the results suggest that relying on sunlight alone may not be enough for some higher-risk groups and that year-round approaches may be needed.
The study was published in the European Journal of Clinical Nutrition. The authors reported that the project was wholly funded by BetterYou Ltd, and stated that the sponsor was not involved in the study design, delivery or interpretation of the data, which they said was carried out by Newcastle University.
The researchers said further work is needed to determine the most effective strategies to improve vitamin D status in at-risk groups.
