Ella Scott
Supplement researchers have suggested that a commonly used pill could help reduce the risk of dementia.
Dementia is a progressive neurological condition that is one of the leading causes of death in the UK.
According to statistics published by the Office for National Statistics, more than 68,000 people died from the disease in 2025 - accounting for around one in six deaths.
The decline in brain function causes memory loss, problem-solving issues, and a person’s ability to perform daily activities, as per the World Health Organization (WHO).
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While dementia and Alzheimer’s cannot be completely prevented, the NHS reported that living a healthy life can help reduce your risk of developing them.
This includes eating a balanced diet following the Eatwell Guide, managing your weight, exercising regularly, and reducing alcohol consumption.
According to experts, maintaining high vitamin D levels in midlife may also help mitigate dementia risk.
A new study published in Neurology Open Access suggested that people with a good amount of the supplement in their system have lower tau protein levels.
Elevated tau protein levels in cerebrospinal fluid (CSF) or blood act as key biomarkers for Alzheimer’s disease and neurodegeneration, often detectable 20 years before symptoms, as per Alzheimer’s Research UK.
Researchers concluded that vitamin D and tau protein levels were linked after analysing data from 793 adults who were around 39 years old between 2002 and 2005.
Initially, experts measured each participant’s blood levels of vitamin D.
16 years later, participants underwent brain scans to evaluate levels of tau and also amyloid beta - another protein associated with Alzheimer’s disease.
Five percent of this cohort reported taking a vitamin D supplement.
Following the second brain scan, the experts said that those with a higher stockpile of vitamin D in midlife were more likely to be protected from developing tau deposits in the brain.
According to study author Martin David Mulligan, a PhD candidate at the University of Galway, the research may suggest that ‘low vitamin D levels could potentially be a risk factor that could be modified and treated to reduce the risk of dementia’.
“These results are promising, as they suggest an association between higher vitamin D levels in early middle age and lower tau burden on average 16 years later. Midlife is a time where risk factor modification can have a greater impact.”
While the results initially seemed positive, EatingWell has identified some limitations.
The first is that participants’ vitamin D levels wreak havoc on only measured one at the beginning of the study and again 16 years later.
Researchers failed to track changes in supplement status over time, which could affect long-term outcomes, experts at the website explained.
The second issue was that people who exhibited higher vitamin D levels may have had other health behaviours that contributed to better brain health.
“Although researchers adjusted for many variables, unmeasured factors,” it was stated.
The NHS advises that anyone over the age of one should consume around 10 micrograms (mcg) of vitamin D a day.
This can be achieved by going outside in the sunshine, eating foods - such as fatty fish, egg yolks, and fortified products, including milk, orange juice, and cereal - and taking a supplement if necessary.
Most of these dietary add-ons come in pill, liquid, or powder form, and can help to prevent rickets and osteomalacia, according to a 2022 study published in the Nature journal.
Be sure to contact your doctor before you start self-supplementing with the ‘sunshine vitamin’.
If you don’t, then you could run the risk of experiencing vitamin D toxicity, which causes excessive calcium buildup (hypercalcaemia).
The essential nutrient may also interfere with medications, including statins, thiazide diuretics, and magnesium.