Summary
Vitamin D supplementation cut dementia risk by 40% in a 12,000-person study. Learn why nearly 70% of Americans are deficient, how age and body fat tank your levels, and the blood markers you should actually be tracking for brain protection.
Key Points
- Nearly 70% of Americans have insufficient vitamin D levels (below 30 ng/mL)
- Vitamin D users had 40% lower dementia risk in 12,388-person study
- Higher vitamin D levels correlate with less white matter brain damage
- Age reduces vitamin D production—70-year-olds make 4x less than 20-year-olds
- Body fat stores vitamin D, reducing bioavailability in overweight individuals
- Sunscreen and darker skin pigmentation reduce vitamin D synthesis
- Northern latitudes have months with no UVB radiation reaching the surface
Key Moments
Vitamin D cuts dementia risk by 40% over a decade
A study of 12,000+ adults found vitamin D supplementation was associated with 40% lower dementia risk over 10 years.
"And using vitamin D3 was associated with a 37% lower risk of dementia. And then using vitamin D2, which is the plant version, was actually associated with a 50% lower risk of dementia. Using combined forms of vitamin D was associated with a 50% lower risk. So I think here in concluding thoughts, overall, not only the findings of this study, but the other studies that I talked about really do give strong support to this idea that everyone should probably be supplementing with at least some vitamin D to make sure they're avoiding deficiency. And I mentioned, as I mentioned earlier, deficiency is a widespread problem in the United States. Up to 70% of people are either deficient or insufficient. So getting a simple blood test is one of the best things you can do. Measure your 25-hydroxyvitamin D levels. This is the precursor to the active steroid hormone, 125-hydroxyvitamin D. And you want to have your 25-hydroxyvitamin D levels between 30 to 60 nanograms per milliliter is a great, I would say, level to have your vitamin D levels. You don't really want to go above 80 nanograms per milliliter. Then you start getting into a pretty high range. Most people can take a supplement in the range of 2,000 to 4,000 IUs a day, depending on where your blood levels are at, and keep their vitamin D levels within that, you know, 40 to 60 range. So it's good to kind of do an annual vitamin D blood test just to make sure you're not taking too much or to make sure that you're actually taking enough to raise your levels into that sweet spot. And lastly, I just want to mention how vitamin D can support brain health. So vitamin D can enhance the removal of amyloid beta. This is a protein that's linked to Alzheimer's disease by promoting its efflux from the brain. Now, I mentioned in that study, it was a randomized controlled trial. And people that were giving it 800 IUs of vitamin D a day, people that already had Alzheimer's disease, it lowered their amyloid beta plaque burden. Vitamin D also is an immune modulator. So vitamin D receptors on microglia and astrocytes in the brain help reduce excess neuroinflammation. So it basically helps lower the pro-inflammatory cytokine response in the brain. We know that neuroinflammation plays a major, major role in the cause of dementia and Alzheimer's disease. Vitamin D also upregulates a variety of neurotrophic factors, including nerve growth factor and also brain-derived neurotrophic factors. So this is helping support neurotransmitters, supporting learning and memory. And then lastly, vitamin D also decreases oxidative stress. It's been shown in the mild cognitive impairment trial that I mentioned earlier. This was a randomized controlled trial. Those individuals that took vitamin D also had decreased levels of various markers of oxidative stress compared to people that were given the placebo. And so oxidative stress is an indirect way that can lead to a variety of inflammatory processes and stuff in the brain as well. So there's several different mechanisms by which vitamin D can support brain health. And again, it's pretty simple to get a vitamin D test and to take a relatively inexpensive vitamin D supplement as well. I'm Dr. Rhonda Patrick, and I'll talk to you soon."
