The late Dr Michael Mosley emphasized the benefits of vitamin D as a simple and effective way to enhance mental health and reduce the risk of dementia. During an episode of BBC Radio 4’s Just One Thing with Michael Mosley, he shared his personal practice of taking a small vitamin D supplement daily during the winter months, when natural sunlight is scarce in the UK.
Dr Mosley explained that vitamin D, best known for supporting bone health by aiding calcium absorption, offers far greater advantages. “Scientists have discovered vitamin D receptors in nearly all the cells of our body,” he noted, which suggests wide-reaching health benefits beyond just bones.
Citing research led by Professor David Llewellyn of the University of Exeter, Mosley highlighted a large American study tracking over 1,600 people. The study found that individuals with vitamin D deficiency were over 50% more likely to develop Alzheimer’s or dementia. Those with severe deficiency faced more than double the risk. Professor Llewellyn described this as “the first compelling evidence to link low levels of vitamin D in the blood to an increased risk of dementia.”
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Vitamin D may help protect the brain by breaking down abnormal protein buildups such as amyloid plaques and tau, which are associated with Alzheimer’s disease. Furthermore, it appears to safeguard the brain’s blood supply and reduce inflammation, potentially mitigating other forms of dementia like vascular dementia.
Vitamin D deficiency is widespread in the UK during autumn and winter because sunlight—the primary source for natural production—is insufficient. This deficiency is particularly common among people with darker skin and older adults, as their bodies generate less vitamin D from sun exposure.
The NHS advises that most individuals, including pregnant and breastfeeding women, consider taking a daily vitamin D supplement containing 10 micrograms from autumn through winter. Between late March and September, most can rely on sunlight and a balanced diet for their vitamin D needs. However, it warns against exceeding 100 micrograms (4,000 IU) daily, as this could be harmful.
Given its affordability and potential to support both immune and cognitive health, vitamin D supplementation during the darker months may offer a simple yet powerful strategy to reduce the risk of dementia.