Sunlight alone may not be enough, particularly for older adults
For generations, the rhythm of sunlight and health has been understood as a seasonal bargain: winter takes, summer restores. But researchers at Newcastle University have found that for older adults and people from minoritized ethnic backgrounds in northern Britain, that bargain was never on the table. A study tracking nearly 300 participants reveals that vitamin D deficiency persists year-round in these groups, unmoved by summer sun, pointing to a quiet public health failure hiding in plain sight.
- More than half of adults over 65 in the study showed insufficient vitamin D levels throughout the entire year — not just in winter — and rates were even higher among minoritized ethnic groups.
- Summer brought almost no improvement: the expected seasonal recovery never arrived, exposing a fundamental flaw in the 'just get more sun' approach to public health guidance.
- Biology and geography conspire against these groups — older skin produces vitamin D less efficiently, higher melanin reduces UV absorption, and northern latitudes deliver weaker sunlight even at peak summer.
- The consequences accumulate silently: weakened bones, muscle deterioration, and diminished immune function erode quality of life without dramatic warning signs.
- Researchers are now calling for year-round supplementation, routine screening in primary care, and culturally tailored health strategies to replace the one-size-fits-all seasonal advice that has consistently failed vulnerable populations.
The idea that summer sun replenishes what winter takes away seems intuitive — but for many people in northern Britain, that cycle simply doesn't hold. A Newcastle University study published in the European Journal of Clinical Nutrition tracked nearly 300 participants and found that older adults and people from minoritized ethnic backgrounds maintained stubbornly low vitamin D levels throughout the year, even during the sunniest months.
What surprised researchers most was not winter deficiency — that was expected — but the near-total absence of summer recovery. More than half of adults aged 65 and older had insufficient levels year-round, with even higher rates among minoritized ethnic groups. The reasons are layered: aging reduces the skin's ability to synthesize vitamin D, higher melanin concentrations slow UV absorption, and northern England's lower sun angle weakens ultraviolet rays even in summer. Clothing, indoor time, and sunscreen compound the effect.
The health consequences are serious but slow-moving — gradual bone loss, muscle weakening, and diminished immune resilience that rarely announce themselves until significant damage is done. Professor Bernard Corfe, one of the study's leaders, was direct: telling higher-risk groups to spend more time outside in summer is advice that simply doesn't work for them.
The research points toward a different approach — one built on year-round supplementation, routine vitamin D screening in primary care, and health strategies designed around the actual needs of diverse communities. The next phase of the work will develop personalized, culturally appropriate guidance, moving away from the universal assumptions that have quietly failed these populations for too long.
The assumption seems reasonable enough: winter drains your vitamin D, summer restores it. Spend a few months in the sun, and your body bounces back. But researchers at Newcastle University have found that for millions of people, that seasonal cycle simply doesn't work. For older adults and people from minoritized ethnic backgrounds living in northern Britain, vitamin D levels stay stubbornly low all year long—even when the sun is at its strongest.
The study, published in the European Journal of Clinical Nutrition, tracked nearly 300 participants and found something that upended a widely held belief about how our bodies work. More than half of adults aged 65 and older had insufficient vitamin D levels throughout the year. Among participants from minoritized ethnic groups, the rates climbed even higher. What struck the researchers most was not that these groups were deficient in winter—that was expected—but that summer brought almost no improvement. The vitamin D boost that should have arrived with longer days and stronger sunlight never materialized.
The reasons are rooted in biology and geography. Vitamin D is produced when ultraviolet B rays from the sun penetrate the skin, but that process is far from simple. Age matters: older adults produce vitamin D less efficiently than younger people. Skin pigmentation plays a role too. So does where you live. In northern regions like the North of England, the sun sits lower in the sky for much of the year, and its rays are weaker. Clothing, sunscreen use, and time spent indoors all factor in. For some people, the combination of these factors means that even a sunny summer day doesn't generate enough vitamin D to move the needle.
The health stakes are real. Vitamin D is essential for calcium absorption and bone health. Deficiency has been linked to osteoporosis, rickets, muscle weakness, and compromised immune function. Researchers are still investigating other potential connections to chronic disease, but the foundation is clear: low vitamin D is not a minor problem. It is a persistent one, and it is hitting the most vulnerable people hardest.
Bernard Corfe, a professor of human nutrition and health at Newcastle and one of the study's leaders, put it plainly: the findings suggest that sunlight alone may not be enough, particularly for older adults and those from minoritized ethnic backgrounds. The old advice—get outside more in summer—misses the mark for these groups. "If you are in a higher-risk group, you can't assume that spending more time outdoors in summer will solve the problem," Corfe said. "We need to be thinking about more consistent, year-round ways to support healthy vitamin D levels."
What the study reveals is a public health blind spot. Vitamin D deficiency in these populations has been largely invisible, perhaps because it doesn't announce itself loudly. There are no dramatic symptoms, no sudden crisis. Instead, it is a slow erosion of bone density, a gradual weakening of muscle, a quiet dimming of immune resilience. The research suggests that clearer guidance, routine screening during primary care visits, and appropriate supplementation could help. The next phase of the work will focus on personalized, culturally appropriate strategies—tailored dietary guidance and healthcare approaches designed to meet the actual needs of diverse communities, not the one-size-fits-all assumptions that have failed them so far.
Citações Notáveis
For people living in places like the North of England, sunlight alone may not be enough, particularly for older adults and those from minoritized ethnic backgrounds.— Bernard Corfe, Professor of Human Nutrition and Health, Newcastle University
If you are in a higher-risk group, you can't assume that spending more time outdoors in summer will solve the problem. We need to be thinking about more consistent, year-round ways to support healthy vitamin D levels.— Bernard Corfe
A Conversa do Hearth Outra perspectiva sobre a história
Why does summer not help these groups the way it helps others?
It's not that summer doesn't help at all—it's that the help is too small to matter. An older person's skin produces vitamin D less efficiently. If you have darker skin pigmentation, you need more sun exposure to generate the same amount. And in northern Britain, even summer sun is weak. The combination means you might get a small bump, but not enough to cross the threshold from deficient to sufficient.
So it's not about behavior. It's not that older people or people from ethnic minorities aren't going outside enough.
Exactly. That's the trap in the old advice. It assumes the problem is behavioral—go outside more. But the research shows the problem is biological and geographic. You can't will your way out of it by spending more time in the sun.
What does year-round support actually look like?
The study doesn't prescribe a single answer, but the direction is clear: supplementation, dietary guidance, and healthcare conversations that happen regularly, not just when someone complains of symptoms. And crucially, approaches that are designed with these communities in mind, not imposed from outside.
Why has this been invisible for so long?
Vitamin D deficiency doesn't cause acute illness. It's a slow accumulation of risk—weaker bones, weaker immunity, muscle loss. It doesn't show up in an emergency room. And if you're already marginalized in healthcare, you're less likely to be screened for it in the first place.
What changes if this research gets attention?
The most immediate change would be screening. If doctors routinely checked vitamin D levels in older patients and patients from minoritized groups, they could intervene early. But the bigger shift is philosophical: stop assuming that seasonal sun exposure solves the problem, and start building year-round strategies.