A daily dose of Vitamin D could help protect against Alzheimer’s, experts discover

Taking a daily Vitamin D supplement could help protect against dementia, a new study suggests.

Researchers found that people with higher levels of the vitamin in midlife had lower levels of a key Alzheimer’s-related protein in the brain years later.

The protein, known as tau, is strongly linked to the disease, with build-up thought to help drive it.

‘These results suggest that higher Vitamin D levels in midlife may offer protection against developing these tau deposits in the brain,’ said Martin David Mulligan from the University of Galway in Ireland.

‘Low Vitamin D levels could potentially be a risk factor that could be modified to reduce the risk of dementia.’

The research followed 793 people with an average age of 39 who did not have dementia. All participants had their blood Vitamin D levels measured at the start of the study.

Brain scans were performed an average of 16 years later to measure tau and amyloid beta proteins, both markers of Alzheimer’s disease.

High Vitamin D levels were defined as above 30 nanograms per millilitre – a level most experts say is enough for good bone and overall health. Around a third of participants were below this, and just five per cent were regularly taking supplements.

The researchers also took into account factors such as age, sex, and symptoms of depression, which can all influence both vitamin D levels and dementia risk.

The study, published in Neurology Open Access, found that higher Vitamin D levels were linked to lower tau protein, but there was no connection with amyloid beta.

‘These findings are promising, as they suggest a link between higher Vitamin D levels in early middle age and lower tau burden 16 years later,’ Mulligan said. ‘Midlife is a time where risk factor modification can have a greater impact.’

A limitation of the study is that Vitamin D levels were measured only once.

Often called the ‘sunshine vitamin’, Vitamin D is unique because the body can produce it when exposed to sunlight. It acts more like a hormone than a traditional vitamin, influencing many processes in the body.

Health experts recommend adults over 65 take a daily supplement of 10 micrograms of Vitamin D, especially if they are frail, housebound, or get little sun exposure.

As we age, cells gradually become damaged and release chemicals that drive inflammation, while the body becomes less able to repair itself. This increases the risk of illnesses such as cancer, dementia, and heart disease.

Scientists are exploring whether it is possible to slow or even reverse this biological ageing process. A recent study found that taking a daily multivitamin may slow the body’s biological clock.

Researchers found that older adults who took the supplements every day for two years aged more slowly at a cellular level – an effect roughly equal to reducing their biological age by about four months.

The findings, published in the journal Nature Medicine, showed that participants who took the multivitamin experienced slower ageing across five DNA-based ageing measures compared with those taking a placebo.

The trial was led by researchers at Massachusetts General Brigham using data from the COSMOS trial, a large US study investigating the health effects of supplements.

Scientists say the findings suggest multivitamins could be a simple, accessible way to support healthier ageing, although the benefits were modest.