Dementia if you lack vitamin D? Half of it is...It depends on gender and genotype

Jul 07, 2025

Dementia if you lack vitamin D? Half of it is...It depends on gender and genotype
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A research team led by Professor Kim Ki-woong of the Department of Mental Health at Seoul National University Bundang Hospital said the common belief that vitamin D deficiency increases the risk of cognitive decline does not apply equally to everyone, but is only valid for women who do not have the 'APOE ε4 genotype' (apodiprotein E eta type 4).

Vitamin D is a nutrient that plays an important role in strengthening bones and maintaining muscle function and immune response by controlling the absorption of calcium and phosphorus, and it has been continuously found to contribute to maintaining the function of brain neurons, controlling inflammation, and protecting nerves, drawing attention as a key factor in determining brain health in old age.

In fact, observational studies have been steadily reported in countries around the world, such as the United States, Europe, and Korea, that vitamin D deficiency has a higher risk of cognitive decline, and this argument has become more convincing, and today vitamin D has gained recognition as a nutrient that helps cognitive function to the extent that it has been nicknamed 'brain vitamin'.




The problem is that most of the studies conducted so far explain only a simple correlation between vitamin D and cognitive function, and many opposite studies have been reported that there is no connection at all.

Accordingly, it is difficult for academia to generalize the existing theory that vitamin D deficiency lowers cognitive function to the entire population group, and it is gaining weight with the opinion that certain conditions are needed. However, this has also remained controversial as it has yet to be clarified.

In response, the research team conducted a large-scale long-term follow-up study to conduct regular cognitive function tests (MMSE) and blood vitamin D concentration tests for 10 years on 1,547 elderly people with normal cognitive function to find answers on who and under what circumstances vitamin D deficiency affects cognitive function.




As a result, it was confirmed that the group in which vitamin D affects cognitive decline was clearly divided according to gender and genotype.

First, men had low vitamin D levels, but there was no significant difference in the rate of cognitive decline compared to those who did not, and among women, those with genotype 'APOE ε4' suggesting the risk of Alzheimer's disease were not affected. Considering that about 15% of women have the genotype, it can be interpreted that vitamin D deficiency does not act as a factor for cognitive decline in virtually more than half of the population, including men and these women.

Conversely, women without the APOE ε4 genotype were found to have significantly accelerated cognitive decline in the group with low vitamin D levels by approximately 0.14 points per year (out of 30 points).




Usually, the APOE ε4 genotype is interpreted as a strong risk factor for Alzheimer's disease, and the research team explains that vitamin D deficiency does not have a great influence if the genotype is possessed, and on the contrary, vitamin D deficiency becomes an important variable if it is not.

This study is the world's first prospective study that considers both gender and APOE genotype classification, which can be confirmed by simple blood tests, and is significant in that it has carefully monitored more than 1,000 participants for an average of more than eight years to specifically identify the conditions under which vitamin D deficiency affects cognitive decline.

Professor Kim Ki-woong said, "The effect of vitamin D deficiency on cognitive function varies greatly by genotype and gender, and not everyone needs to take nutritional supplements for fear of this."According to the results of the study, active vitamin D management from the beginning in APOE ε4 non-bearing women who are vulnerable to vitamin D deficiency will be of great help in preventing dementia." Meanwhile, the study was recently published in the global journal 『Clinical Nutrition』.



Dementia if you lack vitamin D? Half of it is...It depends on gender and genotype
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This article was translated by Naver AI translator.