Matthew Messer

Matthew Messer


One of the gravest illnesses of our time is dementia, for which there is currently no effective treatment. A recent study suggests that vitamin D supplementation may help prevent the onset of the disease.

What is dementia?

Dementia is the deterioration of cognitive abilities - thinking, remembering and reasoning - to the point where it interferes with the patient's daily life.

More than 50 million people worldwide currently live with dementia and, with life expectancy increasing, this number could almost triple by 2050. As there is currently no effective drug to treat dementia that can halt or reverse the progression of the disease, more and more therapies are being investigated to prevent it, including vitamin D consumption.

How might vitamin D help?

Vitamin D is involved in the clearance of beta-amyloid (Aβ) plaques (1) and protects the nervous system in other ways. Low levels have been linked to the risk of dementia and Alzheimer's disease. (2)

Clinical trials to date on vitamin D supplementation have had mixed results, but some studies have reported that vitamin D improved cognitive function. (3) Although a recent review summarizing the results of previous studies found insufficient evidence that vitamin D supplementation can be used to prevent Alzheimer's disease, (4) this is not at all surprising for this type of disease. They usually take decades to develop, so the short duration and follow-up time of trials is not sufficient to observe a significant response. In addition, the dose of vitamin D used and the baseline intake of participants can vary considerably.

However, a recent study has found very positive results: those who supplemented with vitamin D were significantly more protected against the onset of dementia. (5)

Results of the new study

A total of 12388 participants, aged ~72 years on average, were followed for 10 years. They were divided into two groups based on whether or not they supplemented with vitamin D.

Vitamin D was supplemented in three different ways: vitamin D3 alone, vitamin D3 supplemented with calcium, or vitamin D2. There was no significant difference in the effectiveness of the different forms.

Vitamin D supplementation reduced the incidence of dementia by 40%, and in women the risk was reduced even more significantly by 49%.

In participants who had normal cognitive abilities, vitamin D was much more effective in helping to maintain their state than in those who already had mild cognitive impairment.

Additionally, those who supplemented with vitamin D also lived longer on average: after 5 years, 83.6% of those in the vitamin D supplementation group were still alive, compared to 68.4% of the other group.

These results have been adjusted for age at the outset of the study, gender, education, cognitive status, depression and genetics, so regardless of these factors; vitamin D was able to reduce the onset of the disease by 40%.


Based on this observational study, vitamin D supplementation significantly reduces the risk of dementia and plays an important role in preserving our cognitive abilities.

  1. Mizwicki MT, Menegaz D, Zhang J, Barrientos-Durán A, Tse S, Cashman JR, Griffin PR, Fiala M. Genomic and nongenomic signaling induced by 1α,25(OH)2-vitamin D3 promotes the recovery of amyloid-β phagocytosis by Alzheimer's disease macrophages. J Alzheimers Dis. 2012;29(1):51-62. doi: 10.3233/JAD-2012-110560. PMID: 22207005.
  2. Shen L, Ji HF. Vitamin D deficiency is associated with increased risk of Alzheimer's disease and dementia: evidence from meta-analysis. Nutr J. 2015 Aug 1;14:76. doi: 10.1186/s12937-015-0063-7. PMID: 26231781; PMCID: PMC4522102.
  3. Jia J, Hu J, Huo X, Miao R, Zhang Y, Ma F. Effects of vitamin D supplementation on cognitive function and blood Aβ-related biomarkers in older adults with Alzheimer's disease: a randomised, double-blind, placebo-controlled trial. J Neurol Neurosurg Psychiatry. 2019 Dec;90(12):1347-1352. doi: 10.1136/jnnp-2018-320199. Epub 2019 Jul 11. PMID: 31296588.
  4. Du Y, Liang F, Zhang L, Liu J, Dou H. Vitamin D Supplement for Prevention of Alzheimer's Disease: A Systematic Review and Meta-Analysis. Am J Ther. 2020 Dec 26;28(6):e638-e648. doi: 10.1097/MJT.0000000000001302. PMID: 33395056.
  5. Ghahremani M, Smith EE, Chen HY, Creese B, Goodarzi Z, Ismail Z. Vitamin D supplementation and incident dementia: Effects of sex, APOE, and baseline cognitive status. Alzheimers Dement (Amst). 2023 Mar 1;15(1):e12404. doi: 10.1002/dad2.12404. PMID: 36874594; PMCID: PMC9976297.

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