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Is Vitamin D Deficiency Driving Dementia?

Is Vitamin D Deficiency Driving Dementia? Hello everyone, I hope you are well. In today’s post, I will be sharing a press release from the FoodForTheBrain Foundation. Is Vitamin D Deficiency Driving Dementia? Everyone knows that vitamin D is vital for healthy bones and a stronger immune system, but could low levels be a significant driver of Alzheimer’s and age-related cognitive decline? New research suggests that the levels of vitamin D commonly found in the UK are accelerating cognitive decline and increasing the risk of a dementia diagnosis and that supplementing with vitamin D, especially in the winter, can reduce future dementia risk.

Is Vitamin D Deficiency Driving Dementia?

Vitamin D deficiency is well known to increase future risk of Alzheimer’s disease.[1] In a study in France, those with low vitamin D levels below 50 nmol/L had a nearly three-fold increased risk of Alzheimer’s [2]. Over sixty per cent of people in the UK have lower levels than this.[3]

Supplements also help ward off dementia, according to a large-scale study earlier this year involving over twelve thousand dementia-free 70+ year-olds.[4] More than a third (37%) took vitamin D supplements, and those that did had a 40% lower incidence of dementia.

Professor Zahinoor Ismail of the University of Calgary and the University of Exeter, who led the research, said: “We know that vitamin D has some effects in the brain that could have implications for reducing dementia. Overall, we found evidence to suggest that earlier supplementation might be particularly beneficial before the onset of cognitive decline.”

Vitamin D expert Dr William Grant (PhD), advisor to the prevention charity, says we’ve vastly underestimated the importance of vitamin D on the brain and how much you need.

“All the evidence regarding cardiometabolic diseases, cancer, diabetes, infectious diseases and pregnancy outcomes shows that you need a blood level of vitamin D above 75 nmol/L to be healthy, and the same is proving true for the brain. This optimal level is impossible to achieve without supplementation in the winter. I recommend every adult and teenager supplement themselves with at least 1000 to 3000iu daily from October to March, in line with a recent review by 35 vitamin D researchers.[5] The degree of obesity, darker skin colour[6] and living further North[7] increases need[8]. The UK government’s recommendation of 400iu (10 mcg) a day is not enough for optimal brain health. Supplementing 800iu (20 mcg) a day for 12 months has already improved cognitive function, but you need more than this to achieve anything close to an optimal level.[9]” says Dr Grant.

Vitamin D test

Vitamin D Levels Test Home Kit

“If you’re not supplementing with vitamin D in the winter, then you may be heading for cognitive decline.” However, the British Nutrition Foundation says only 8% of UK adults take vitamin D in the winter.[10]

Under the direction of Dr Grant, has launched a research project to test blood vitamin D levels using a home test kit and cognitive function with a free online Cognitive Function Test. Having already tested over 400,000 people’s cognitive function, the aim is to measure their vitamin D levels now. This will help to establish the vitamin D level you need to stay free from dementia, says Dr Grant, who is director of the Sunlight, Nutrition and Health Research Centre in San Francisco.

If you’d like to participate in this research and discover your vitamin D level and cognitive function, visit the project. The free online Cognitive Function Test also works out what is driving your future dementia risk generally (that is, other than vitamin D) and gives you advice on what to do to reduce your risk. The free test is available at

I hope you enjoyed that.

Talk soon.


The Food for the Brain Foundation ( is an educational and research charity on dementia prevention. It’s a free online validated Cognitive Function Test, followed by the Dementia Risk Index questionnaire assessing eight drivers of dementia, including ‘brain fats’ and ‘low carbs & GL’, thus identifying those eating too many carbs and not enough brain fats, then advising them what to do.


[1] Chai B et al. Vitamin D deficiency as a risk factor for dementia and Alzheimer’s disease: an updated meta-analysis. BMC Neurol. 2019 Nov 13;19(1):284. doi: 10.1186/s12883-019-1500-6. PMID: 31722673; PMCID: PMC6854782.

[2] Jia J et al. 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] Ghahremani M et al. 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.

[5] Płudowski P et al Guidelines for Preventing and Treating Vitamin D Deficiency: A 2023 Update in Poland. Nutrients. 2023 Jan 30;15(3):695. doi: 10.3390/nu15030695. PMID: 36771403; PMCID: PMC9920487.

[6] Ames BN, Grant WB, Willett WC. Does the High Prevalence of Vitamin D Deficiency in African Americans Contribute to Health Disparities? Nutrients. 2021 Feb 3;13(2):499. doi: 10.3390/nu13020499. PMID: 33546262; PMCID: PMC7913332.

[7] Engelsen O. The relationship between ultraviolet radiation exposure and vitamin D status. Nutrients. 2010 May;2(5):482-95. doi: 10.3390/nu2050482. Epub 2010 May 4. PMID: 22254036; PMCID: PMC3257661.

[8] Ekwaru JPet al.l The importance of body weight for the dose-response relationship of oral vitamin D supplementation and serum 25-hydroxyvitamin D in healthy volunteers. PLoS One. 2014 Nov 5;9(11):e111265Doioi: 10.1371/journal.pone.0111265. PMID: 25372709; PMCID: PMC4220998.

[9] Feart C et al.. Associations of lower vitamin D concentrations with cognitive decline and long-term risk of dementia and Alzheimer’s disease in older adults. Alzheimers Dement. 2017 Nov;13(11):1207-1216. doi: 10.1016/j.jalz.2017.03.003. Epub 2017 May 16. PMID: 28522216.

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  • Luna S

    What an interesting topic, It is amazing what our bodies do & have different vitamin deficiencies can affect us. It is so important to keep up on vitamins especially with how a lot of diets aren’t really the best diets anymore.

  • Karletta

    A very informative and important article. Vitamin D came to my attention at the outset of the pandemic. I’ve been taking it but your article prompted me to considering testing.

  • Stephanie

    I really should get tested for what vitamins I lack. I take a multi-vitamin daily but I wouldn’t know if I was lacking in vitamin D (or any other).

  • Maria Azanha

    Wow, I needed to find your article! I was unaware of the link between dementia and vitamin D deficiency. Unfortunately, my father is affected by this debilitating disease…

  • Bryan Carey

    I didn’t know there was a connection between dementia and lack of vitamin D! I feel like I am in good shape, however, as I drink a good deal of Vitamin D enhanced milk and I spend a fair amount of time in the sun. Living on the Gulf coast helps, since we have more sun than most places.

  • Beth

    This makes so much sense to me. Our bodies need an adequate amount of so many different vitamins and minerals. If we don’t get what we need over the long-term, things can go wrong.

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