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A Neurologist's Top Tip For Preventing Alzheimer's? Healthy Vitamin D Levels

Senior Woman smelling fresh herbs in her kitchen in pots that she planted
Image by Trinette Reed / Stocksy
October 22, 2022
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According to a scientific review that came out earlier this year, approximately 6.5 million U.S. adults1 over 65 are living with Alzheimer's disease. Unfortunately, that number is predicted to grow to 13.8 million within the next 40 years.

So, what gives? Why is cognitive decline on the rise? And how the heck do we stop it in its tracks?

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According to neurologist Dale Bredesen, M.D., author of the New York Times bestselling book The End of Alzheimer's, one surprising factor has a serious impact on your risk for developing Alzheimer's: your vitamin D status.

Vitamin D levels and Alzheimer's disease.

Vitamin D is an essential vitamin that's required for a plethora of vital functions throughout the body, including cognitive health and neuroprotection. And like Alzheimer's, vitamin D deficiency is shockingly prevalent in the U.S. A whopping 29% of adults are deficient in vitamin D, and another 41% are insufficient in the critical nutrient.

Growing evidence suggests vitamin D deficiency and cognitive decline are intrinsically linked:

In a 2019 BMC Neurology meta-analysis2 of 21,784 participants, researchers found significant associations between vitamin D deficiency and both dementia and Alzheimer's disease.

How vitamin D helps prevent cognitive decline.

In fact, in a recent episode of the mindbodygreen podcast, Bredesen explains that dangerously low levels of vitamin D [i.e., 25(OH)D serum test results at or below 20 ng/ml—the clinical cutoff for vitamin D deficiency] is one of the main contributing factors of cognitive decline he sees in his patients.

"It is surprisingly common to see people come in with cognitive decline and their vitamin D level is 19 or 20 [ng/ml]," he shares.

How did these individuals become vitamin D deficient in the first place? According to Bredesen, it's a combination of lifestyle habits and nutritional choices: "They're living indoors, they're not getting out enough, they're not taking vitamin D, or they're not absorbing the vitamin D they are taking." 

While getting outdoors and spending some time in the sun—safely, of course—is always recommended, the sun isn't a historically reliable source of vitamin D. (And for the record, diet isn't either!)

So, we're left with supplementation. But as Bredesen stated, some people are taking vitamin D supplements and seeing no improvement to their D levels—or their cognitive function.

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What to look for in a quality vitamin D supplement.

Here are the three biggest challenges in getting enough vitamin D from supplementation:

  • Form
  • Dose
  • Bioavailability
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You need to make sure you're taking the superior form of this essential vitamin (D3) in an efficacious dose (5,000 IU) that will actually help you raise and maintain truly optimal levels.

Because it's a fat-soluble vitamin, taking your vitamin D alongside a dietary fat is absolutely critical to aid absorption and enhance bioavailability. (Bonus points if the healthy fat is built right into your supplement!)

Need some help finding a product that fits the bill? Check out our roundup of the best vitamin D supplements.

The takeaway.

While scientists still aren't 100% sure what causes Alzheimer's or dementia, neurologists have found that maintaining healthy vitamin D levels can help prevent cognitive decline.

An easy way to help maintain cognitive function later in life? Take an effective vitamin D3 supplement—your future self will thank you for supporting your brain health and longevity.

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