Can Vitamin D Slow Aging? A New Study Says Yes – But There's a Catch

Science Alert ^ | September 01, 2025 | Dervla Kelly

[Red Badger]

Vitamin D supplements could help protect the caps on our chromosomes that slow aging, sparking hopes the sunshine vitamin might keep us healthier for longer, a recent study suggests.

The researchers discovered that taking 2,000 IU (international units, a standard measure for vitamins) of vitamin D daily helped maintain telomeres – the tiny structures that act like plastic caps on shoelaces, protecting our DNA from damage every time cells divide.

Telomeres sit at the end of each of our 46 chromosomes, shortening every time a cell copies itself. When they become too short, cells can no longer divide and eventually die.

Related: Green Tea And a Vitamin Supplement Could Protect Against Alzheimer's

Scientists have linked shorter telomeres to some of our most feared diseases of aging, including cancer, heart disease and osteoarthritis. Smoking, chronic stress and depression all appear to speed up telomere shortening, while inflammatory processes in the body also take their toll.

Beyond strong bones

It is well known that vitamin D is essential for bone health, helping our bodies absorb calcium. Children, teenagers and people with darker skin or limited sun exposure particularly need adequate levels to build and maintain strong bones.

But vitamin D also powers our immune system. A review of evidence found that vitamin D supplements can cut respiratory infections, especially in people who are deficient.

Early research even suggests it might help prevent autoimmune diseases like rheumatoid arthritis, lupus and multiple sclerosis, though more trials are needed.

Since inflammation damages telomeres, vitamin D's anti-inflammatory effects could explain its protective role.

In this recent study, from Augusta University in the US, the researchers followed 1,031 people with an average age of 65 for five years, measuring their telomeres at the start, after two years, and after four years. Half took 2,000 IU of vitamin D daily, while the other half received a placebo.

The results showed that telomeres were preserved by 140 base pairs in the vitamin D group, compared with a placebo. To put this in context, previous research found that telomeres naturally shorten by about 460 base pairs over a decade, suggesting vitamin D's protective effect could be genuinely meaningful.

This isn't the first promising finding. Earlier studies have reported similar benefits, while the Mediterranean diet – rich in anti-inflammatory nutrients – has also been linked to longer telomeres.

The catch

But there are some important points to note. Some researchers warn that extremely long telomeres might actually increase disease risk, suggesting there's a sweet spot we don't yet understand.

There's also no agreement on the right dose. The Augusta researchers used 2,000 IU daily – much higher than the current recommended intake of 600 IU for under-70s and 800 IU for older adults. Yet other research suggests just 400 IU might help prevent colds.

Experts say the optimal dose probably depends on individual factors, including existing vitamin D levels, overall nutrition and how the vitamin interacts with other nutrients.

Although these findings are exciting, it's too early to start popping high-dose vitamin D in the hope of slowing aging. The strongest evidence for healthy aging still points to the basics: a balanced diet, regular exercise, quality sleep, not smoking and managing stress, all of which naturally support telomere health.

However, if you're deficient in vitamin D or at risk of poor bone health, supplements remain a sensible choice backed by decades of research.

As scientists continue unravelling the mysteries of aging, vitamin D's role in keeping our cellular clocks ticking may prove to be just one piece of a much larger puzzle.

Dervla Kelly, Associate Professor, Pharmacology, University of Limerick

[TTFX]

Not from this article, but other publicaciones suggest that the optimal level is 32 ng/ml.

People who have a level of 50 ng/ml or higher have more kidney stones.

[TTFX]

I believe your doctor is correct.

[aMorePerfectUnion]

Apparently, there are a number of variables, with some populations exceeding 100 through sun exposure.

Highest Vitamin D Levels

• Indigenous populations in Tanzania, such as the Maasai and Hadzabe, have some of the highest recorded mean serum 25(OH)D levels, with studies reporting averages over 106 nmol/L, and pregnant Maasai women averaging up to 138.5 nmol/L.
• Vietnam has mean levels around 92 nmol/L for men and 75 nmol/L for women, which are also among the highest globally outside of Africa.
• Populations in the Gambia also show higher-than-global-average vitamin D levels, with mean values around 91 nmol/L in women aged 45–80.
Key Factors Influencing High Levels

• Sunlight exposure is the main reason, as these populations often live near the equator with abundant year-round sun and engage in outdoor lifestyles.
• Minimal clothing restrictions allow for more skin exposure to ultraviolet B, promoting natural vitamin D synthesis.
• Diets with some fish and non-industrialized habits may also support higher vitamin D status in some Asian populations, like Japan and Vietnam

[aMorePerfectUnion]

Vitamin D blood levels just over 32 ng/mL are not directly linked to a higher risk of kidney stones in the general population, according to current evidence.
Vitamin D, Calcium, and Kidney Stone Formation
• Vitamin D increases intestinal calcium absorption, and high levels may theoretically raise blood and urinary calcium, a known risk factor for calcium kidney stones.
• However, most studies show that typical supplementation or blood levels just above 32 ng/mL do not significantly increase urine calcium or kidney stone risk in healthy individuals.
• Doses that achieve serum levels over 32 ng/mL, which are within the normal range for sufficiency, are not associated with increased kidney stone formation unless accompanied by excessive calcium intake or underlying conditions like hypercalciuria or kidney stone history.
Study Findings and Clinical Practice
• Large cohort studies and randomized trials found no significant association between vitamin D supplementation (even up to 4000 IU daily) and kidney stone formation in people without prior stones or hypercalciuria.
• Some individuals, especially those with a history of kidney stones or pre-existing hypercalciuria, may be at higher risk when taking high doses of vitamin D, so clinical monitoring is recommended in these cases.
• Combined calcium and vitamin D supplements may increase kidney stone risk, but vitamin D alone shows little effect

Via Perplexity AI

[TTFX]

This is my source that those with a level of 50 ng/ml or higher are more likely to have kidney stones:

Increased Incidence of Nephrolithiasis (N) in Lifeguards (LG) in Israel
https://link.springer.com/chapter/10.1007/978-1-4615-9167-2_51

AI might have missed this study.

[TTFX]

Indigenous populations in Tanzania, such as the Maasai and Hadzabe, have some of the highest recorded mean serum 25(OH)D levels, with studies reporting averages over 106 nmol/L, and pregnant Maasai women averaging up to 138.5 nmol/L.

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Note that 138.5 nmol/L is 55.5 ng/ml. Source:

https://www.grassrootshealth.net/project/ng-ml-nmol-l-converter/

[aMorePerfectUnion]

Great catch! Thank you for pointing it out

[Hyman Roth]

I take sheep urine injections to slow my aging.

[Red Badger]

Well, it will work. Death stops aging in its tracks.................