Dementia and the Role of Vitamin D Supplements
What do we know?
Vitamin D is naturally made in the skin when we are exposed to sunlight; we get 80% of the vitamin this way. It is also found in some foods, such as oily fish and egg yolks. In the UK winter when sunlight is lower and we cover up to keep warm we can become deficient in Vitamin D. This is particularly true for people with darker skin. Higher rating sun creams can also reduce our ability to make Vitamin D.
In the UK the NHS recommends that all adults take 10 microgram (400 international units) daily[i], through autumn and winter. The American National Institute of Health recommends 600iu.
Vitamin D is found in foods such as oily fish.
Vitamin D helps regulate calcium to keep bone, teeth and muscles healthy
Low Vitamin D levels are also associated with a greater risk of developing Dementia and Alzheimer’s’ Disease.[ii]
[i] https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/
[ii] Vitamin D deficiency is associated with increased risk of Alzheimer’s disease and dementia: evidence from meta-analysis, Liang Shen, Hong-Fang Ji. Nutrition Journal. Aug 2015
What’s new
A recent study followed adults taking Vitamin D supplements for four years. [i] They measured the telomere length. These are the protective ends on the DNA cells. When these are shortened the cell is at risk of developing cancer or dying. They found that Vitamin D protected the cell telomeres and slowed their ageing. The authors concluded that this could be a “promising strategy to counter biological ageing”.
Another study[ii] showed that Vitamin D supplementation was significantly linked to longer Dementia-free survival and 40% lower incidence of Dementia.
Vitamin D Supplements play a role in protecting against Dementia.
And finally a short study[iii] asked nearly 200 adults to take high doses of Vitamin D daily (5000iu) for nine months. This level is normally not recommended as it can cause high calcium levels and kidney stones. The treated group were less likely to need to attend A&E or be admitted to hospital.
[i] Vitamin D supplementation and leukocyte telomere length. H Zhu et al. American Journal of Clinical Nutrition. May 2025.
[ii] Vitamin D supplementation and incident dementia: Effects of sex, APOE, and baseline cognitive status, Z Ismail et al. Alzheimer’s and Dementia: Diag, Assess and Dis Monitoring, March 2023.
[iii] Healthcare Costs and Healthcare Utilization Outcomes of Vitamin D3 Supplementation at 5000 IU Daily During a 10.9 month Observation Period within a Pragmatic Randomized Clinical Trial. P LaRicca et al, Nutrients. Oct 2023.
What should we do?
It makes perfect sense to follow the guidance and take these supplements. They are safe and cheap. They are easily available from the supermarket pharmacy aisle or any pharmacy. These are the only supplements that I use.
