Dr. Rhonda Patrick

And so one might say, well,

people that are vitamin D deficient might just be less healthy.

They might be going out in the sun less, they're exercising less.

And so vitamin D deficiency might just be biomarking some other health factor.

So that is a, I would say, pretty relevant argument, but we also have a whole host of other data to support the link between vitamin D deficiency and dementia risk and Alzheimer's disease risk.

So for example,

With these observational studies, we can look at what's called Mendelian randomization.

This is a way to use genetics to look at how something in the environment can affect an outcome.

In this case, there's many different genes that regulate the ability of your body to produce vitamin D3 and convert it into the steroid hormone.

And some people do that less effectively because they have a certain variation in those genes that are not doing it quite as well.

And so you can look at genetically low vitamin D levels.

In other words, you just look at someone's genes.

And if they have a certain variation of that vitamin D converting gene that makes it not as effective, you put them into the low vitamin D group because we know people with those genes actually do have low vitamin D. And then you compare them to people that have the normal functioning genes that don't make them have low vitamin D levels.

They don't have low 125-hydroxyvitamin D, which is the actual steroid hormone.

And then you look at the risk for dementia and Alzheimer's disease.

And so what's been shown is that genetically low vitamin D levels increase dementia risk by up to 54%.

Again, this is really confirming that observational data, which really can't really show causation.

And so it strengthens that data, but then you can go a step further and you can look at other studies that have shown vitamin D deficiency actually accelerates brain aging.

So there have been studies that have shown, that have looked by fMRI,

at what's called white matter hyperintensities.