New research from Newcastle University indicates that seasonal sunlight is not a reliable remedy for vitamin D deficiency, particularly for older adults and individuals from minoritized ethnic backgrounds. Published in the European Journal of Clinical Nutrition on May 19, 2026, the study found that vitamin D insufficiency remained a persistent, year-round issue for these groups, even throughout the peak summer months.
Why Summer Sun Doesn’t Guarantee Vitamin D Recovery
Many people believe that increased sun exposure during the summer naturally replenishes vitamin D levels after the darker winter months. However, the study, which monitored nearly 300 participants, suggests this assumption is flawed. According to Bernard Corfe, Professor of Human Nutrition and Health at Newcastle University and co-leader of the study, the findings show that vitamin D levels did not improve during the summer months when a recovery would typically be expected.
This reality is especially pronounced in northern regions where sunlight is weaker for much of the year. The body’s ability to synthesize vitamin D from ultraviolet B (UVB) rays is hindered by several factors, including skin pigmentation, the use of sunscreen, clothing choices, and age. As people get older, their skin becomes less efficient at producing the vitamin, making reliance on sunlight alone an unreliable health strategy.
Vitamin D is essential for maintaining strong bones, supporting muscle function, and ensuring the immune system operates correctly. Chronic low levels are linked to conditions such as osteoporosis, rickets, and muscle weakness.
The Disproportionate Impact on High-Risk Groups
The study highlights a significant public health blind spot. Over half of the participants aged 65 and older were found to have insufficient vitamin D levels. The rates of insufficiency were even higher among participants from minoritized ethnic backgrounds. Because these levels remained consistently low throughout the year, the research suggests that vitamin D insufficiency is a quiet, persistent health challenge that does not simply disappear with the arrival of warmer weather.
The researchers, led by the team at Newcastle University, emphasize that individuals in these higher-risk categories cannot assume that spending more time outdoors in the summer will solve the problem. Instead, the findings point toward a need for more consistent, year-round strategies to maintain healthy vitamin D status.
What Should Change in Public Health Policy?
To address these findings, researchers are calling for a shift in how vitamin D deficiency is managed within the healthcare system. The study suggests that clearer public guidance, routine discussions during primary care visits, and targeted supplementation could help mitigate long-term health risks. The next phase of this research will focus on personalized and culturally appropriate approaches to improve vitamin D levels, including tailored dietary guidance.
It is important to note that the study, titled “Circannual prevalence of vitamin D insufficiency in older and minoritized ethnic adults in Northern Britain: screening outcomes from a clinical trial (ISRCTN13778806),” was funded by Better You Ltd. The university confirmed that the funder was not involved in the study design, delivery, or interpretation of the data.
Frequently Asked Questions
- Can I get enough vitamin D just by being outside in the summer?
Not necessarily. According to researchers at Newcastle University, older adults and people from minoritized ethnic backgrounds often show consistently low levels of vitamin D even during the summer months. - Why is it harder to get vitamin D as I get older?
As people age, their skin becomes less efficient at producing vitamin D in response to UVB sunlight exposure. - What are the risks of low vitamin D levels?
Low levels can contribute to muscle weakness, impaired immune function, rickets, and osteoporosis.
If you are concerned about your vitamin D levels, consult your primary care physician. Do not rely solely on seasonal changes in weather to manage your nutritional health.
Are you concerned about your vitamin D levels? Have you discussed supplementation with your healthcare provider? Share your thoughts in the comments below or subscribe to our health newsletter for the latest updates on nutritional research.
