Vitamin D: Anti-Dementia?

Vitamin D

Vitamin D

Via Instapundit, “New Study Supports Links Between Dementia And Vitamin D Deficiency” in IFLScience:

Adding to an ever-growing body of evidence, a new study has found that vitamin D deficiency is associated with a substantially increased risk of developing Alzheimer’s and dementia. While previous studies have drawn similar conclusions, this is the largest, most robust study carried out to date. The results have been published in the journal Neurology.

Vitamin D is an essential vitamin that is produced by the body upon exposure of the skin to sunlight, but it can also be found in small amounts in certain foods such as oily fish. It plays a variety of roles in the body and over recent years our understanding of how it helps to maintain optimum health has dramatically increased. For example, it’s thought to reduce the risk of certain bone diseases, bacterial and viral infections and autoimmune diseases.

Interestingly, some studies have hinted that vitamin D may play a neuroprotective role. In support of this idea, several recent studies have found links between vitamin D deficiency and the risk of dementia and cognitive decline. However, one study also found no associations in men.

To find out more, an international team of researchers, headed by scientists at the University of Exeter, enrolled 1,658 adults aged 65 and over who were able to walk unaided and were free from dementia, cardiovascular disease and stroke. Vitamin D levels were assessed at the start of the study and the participants were then followed for six years in order to investigate who went on to develop Alzheimer’s or other forms of dementia.

The researchers discovered that participants with a moderate vitamin D deficiency had a 53% increased risk of developing any form of dementia, and those with a severe deficiency had a 125% increased risk. Similar results were also found for the risk of developing Alzheimer’s, which is the most common form of dementia. Interestingly, they found that there was a threshold level of 50nmol/L vitamin D in the serum, below which the risk of dementia and Alzheimer’s was markedly increased.

While this shows vitamin D deficiency is associated with increased risk of dementia, it does not prove causation; it’s possible that since oily fish contain lots of D, the Omega-3 fatty acids and other components of fish oil, which has already been shown to reduce dementia, are responsible, since people who regularly eat oily fish won’t suffer D deficiencies. And any number of other cofactors may play a role.

What’s the story on vitamin D supplements? A few years ago, medical professionals themselves were taking 2000-4000 IUDs every day believing these larger doses would be protective against a variety of degenerative diseases. The evidence since is inconclusive. Here are some studies:

Vitamin D and Cardiometabolic Outcomes: A Systematic Review
Vitamin D and calcium: a systematic review of health outcomes.
Vitamin D supplementation for prevention of mortality in adults.
The effect of vitamin D supplementation on skeletal, vascular, or cancer outcomes: a trial sequential meta-analysis

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