Vitamin D May Affect Alzheimer’s Development

Research indicates a significant association between low levels of vitamin D and an increased risk of developing dementia and Alzheimer’s disease in older populations.

Observational data suggests that vitamin D deficiency may play a role in cognitive deterioration, with severe deficiencies correlating to a substantially higher risk of cognitive decline.

Study Findings on Vitamin D and Dementia Risk

A major study published in the August 6, 2014, issue of Neurology, the medical journal of the American Academy of Neurology, examined the blood levels of 1,658 people over the age of 65 who were initially dementia-free.

After an average period of six years, 171 participants developed dementia and 102 developed Alzheimer’s disease.

The researchers found that individuals with low levels of vitamin D faced a 53 percent increased risk of developing dementia compared to those with normal levels.

For those classified as severely deficient, the risk of developing dementia increased by 125 percent.

Similar trends were observed regarding Alzheimer’s disease. People with lower vitamin D levels were nearly 70 percent more likely to develop the disease, while those with severe deficiency were over 120 percent more likely to develop Alzheimer’s.

These results remained consistent after the researchers adjusted for other risk factors, including alcohol consumption, smoking, and education.

Mechanisms and Sources of Vitamin D

Vitamin D is obtained through several primary channels, including sun exposure, dietary intake, and supplementation.

Dietary sources of vitamin D include eggs, cheese, milk, and fatty fish such as mackerel, tuna, or salmon.

Review literature on the neuroprotective roles of vitamin D explores its impact on cognitive health and its potential therapeutic use in addressing cognitive decline.

Current research focuses on bridging the gap between the observed association of low vitamin D levels and the specific neuroprotective mechanisms that may prevent cognitive deterioration.

Current Scientific Consensus and Limitations

While observational studies consistently link low vitamin D to increased risk, the exact nature of the relationship remains a subject of ongoing study.

A dose-response meta-analysis of observational studies published on September 10, 2025, in Front Neurol, noted that the relationship between serum vitamin D levels and dementia risk remains unclear.

Because these findings are based on observational data, they establish a correlation rather than a direct cause-and-effect relationship.

Clinical trials are now needed to establish whether eating foods such as oily fish or taking vitamin D supplements can delay or even prevent the onset of Alzheimer’s disease and dementia.

David J. Llewellyn, PhD, University of Exeter Medical School

The scientific community continues to investigate whether vitamin D can lower specific risk markers for Alzheimer’s disease to determine if supplementation provides a viable preventative strategy.