Slowing Ageing with Vitamin D

Slowing Ageing with Vitamin D: New Study Reveals Remarkable Results—But One Size Doesn’t Fit All

After a rare and welcome stretch of sunshine here in Scotland, it might seem counterintuitive to talk about vitamin D deficiency. But while the past few weeks have brought brighter skies, they don’t erase what we know from decades of clinical observation and research: most of us are still not getting enough vitamin D to support long-term health and resilience—especially in the winter months, and especially if genetics are working against us.

A major new study published in The American Journal of Clinical Nutrition adds powerful evidence to something we've long suspected in functional medicine: vitamin D may actually slow down biological ageing.

The Study: 1,071 People, 4 Years, and 3 Years of Ageing Slowed

Researchers followed 1,071 participants over four years, supplementing one group with vitamin D3 and marine omega-3 fatty acids. They measured the length of telomeres—the protective caps on the ends of our chromosomes that get shorter as we age.

Telomeres work like the plastic tips on the ends of shoelaces, preventing our chromosomes from fraying or sticking to each other. The shorter they get, the more our cells struggle to function properly. Short telomeres are associated with everything from heart disease and cognitive decline to a shorter lifespan overall.

What they found was remarkable: in the placebo group, telomeres shortened significantly. But in the group receiving vitamin D3, telomere loss was significantly slowed. The estimated biological ageing difference between groups? Equivalent to three years. In just four years, the vitamin D group essentially aged one year less.

The benefits didn’t stop there—C-reactive protein (CRP), a key marker of inflammation, also dropped in those taking vitamin D. And because chronic inflammation is tightly linked to accelerated ageing and disease, this finding is just as significant.

Why Personalised Dosing Matters

This isn’t about everyone rushing out to buy high-dose vitamin D. It’s about understanding how your body processes it. Some people—due to genetics, particularly variations in the vitamin D receptor (VDR)—struggle to absorb and use vitamin D efficiently. These individuals may need a much higher dose to get the same benefit.

Without personalised dosing, someone with a VDR variant might be walking around with what looks like a “normal” vitamin D level on paper—but still experiencing symptoms of deficiency: low mood, poor immune function, fatigue, joint pain, and more.

Scotland’s Sunshine Paradox

Yes, we’ve had an unusually sunny spring. But our latitude means that for most of the year, the sun simply isn’t strong enough to produce adequate vitamin D through the skin—especially if you’re older, have darker skin, cover up for cultural reasons, or work indoors.

One sunny spell doesn’t reverse a winter of depletion. In fact, most people in Scotland start spring with vitamin D levels that are still low—and for those with VDR issues, topping up naturally can take much longer.

What Should You Do?

1. Test your vitamin D levels regularly, especially at the end of winter and again in late summer.
2. Consider VDR genetic testing if you’ve struggled to maintain optimal levels or respond to supplementation.
3. Tailor your dose: standard UK recommendations (400–800 IU) may be too low for many people. In our clinic, some need 2,000–4,000 IU daily, monitored carefully.
4. Support absorption: vitamin D is fat-soluble—pair it with food that contains healthy fats for best uptake.
5. Track your inflammation: markers like CRP and homocysteine can help show whether your vitamin D is doing its job.

In Summary

This isn’t just about taking a supplement—it’s about using science to slow ageing and reduce inflammation in a way that’s tailored to you. The data is clear: with the right form and dose of vitamin D, you could be protecting your DNA, preserving your cellular health, and potentially gaining years of vitality.

Even in a sunny spell, we need to look deeper than the weather.

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