The late Dr Michael Mosley, renowned for his work on health and wellbeing, emphasized the powerful benefits of Vitamin D not only for mental health but also for reducing the risk of dementia.
On BBC Radio 4’s Just One Thing with Michael Mosley, the doctor—who passed away in May 2024—revealed, “In the winter, I take this tiny little pill every day,” referring to Vitamin D supplements. He described how the UK’s low sunlight exposure during winter months leads to insufficient Vitamin D production in the skin.
Dr Mosley highlighted that this inexpensive supplement could boost the immune system, making individuals less susceptible to colds and respiratory infections. Importantly, he pointed to mounting scientific evidence suggesting that higher doses of Vitamin D may help protect against cognitive decline and dementia.
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Vitamin D’s discovery dates back to the 1920s, with its critical role historically linked to strengthening bones by aiding calcium absorption—dramatically reducing conditions like rickets. Yet, Dr Mosley noted that emerging research shows Vitamin D has far-reaching health impacts because its receptors are found in nearly every cell of the body.
Supporting this, Dr David Llewellyn from the University of Exeter cited a large American population study involving over 1,600 participants. The study found that people deficient in Vitamin D were more than 50% more likely to develop Alzheimer’s or dementia. Those with severe deficiency faced a 125% higher risk.
“This was the first compelling evidence linking low blood Vitamin D levels to dementia risk,” Dr Llewellyn explained. He further revealed that Vitamin D appears to influence Alzheimer’s pathology by helping break down harmful brain proteins like amyloid plaques and tau. It may also protect the brain’s blood supply and reduce inflammation, potentially benefiting vascular dementia cases.
In the UK, sunlight exposure from late March to early autumn is usually enough for most people to produce sufficient Vitamin D naturally. However, winters bring weaker and shorter days, limiting this natural production and leading to widespread deficiency. Some groups are particularly vulnerable, including people with darker skin, who produce less Vitamin D for the same UV exposure, and older adults, whose skin’s ability to synthesize Vitamin D declines with age.
Statistics reveal that over half of people of South Asian descent in the UK suffer Vitamin D deficiency in winter, and more than 50% of older adults fall below recommended levels.
The NHS recommends that, because it is difficult to get enough Vitamin D from food alone, everyone—including pregnant and breastfeeding women—should consider daily Vitamin D supplements containing 10 micrograms during autumn and winter months. Most people can meet their Vitamin D needs through sunlight and diet from late March until the end of September, but supplementation during the darker months is important.
Importantly, the NHS advises not to exceed 100 micrograms (4,000 IU) of Vitamin D daily, as higher doses can be harmful irrespective of age or condition.
Dr Mosley’s exceptional endorsement of Vitamin D as a “cheap, little supplement” underlines its significance in both immune support and long-term brain health, making it a simple but effective safeguard against dementia.