Taking This Daily Vitamin Could Slash Dementia Risk By 40%, Research Suggests
Dementia impacts millions of older adults, but researchers are still learning how, exactly, to prevent this devastating illness. Now, research suggests that increasing your intake of one specific vitamin may help.
Of course, dementia is a complicated condition, so just making one change might not completely shift your odds of developing it. But these findings are "significant," scientists say. Here's what the study found, plus what a geriatrician wants you to know.
Meet the experts: David Merrill, MD, PhD, is a geriatric psychiatrist at Providence Saint John’s Health Center in Santa Monica, California, and the Singleton Endowed Chair in Integrative Brain Health. Brigitte Zeitlin, RD, is a certified nutritionist and founder of BZ Nutrition.
What did the study find?
The study, which was published in the journal Alzheimer’s & Dementia Diagnosis, Assessment, & Disease Monitoring in 2023, analyzed the impact of vitamin D on the development of dementia in nearly 12,500 older adults who participated in the National Alzheimer’s Coordinating Center. None of the participants had dementia at the start of the study.
The researchers broke the groups down into people who took a vitamin D supplement and those who didn’t during the study. The researchers discovered that people who took vitamin D had a 40% lower risk of developing dementia than those who didn’t take a supplement. They also had a 15% higher five-year survival rate.
Of the study participants, women were at a higher risk of developing dementia than men, but they also had a better response to the vitamin D intervention—women who took it had a 49% lower risk of developing dementia than those who didn’t.
Finally, 75% of those who developed dementia didn’t have exposure to vitamin D.
“Across all formulations, vitamin D exposure was associated with significantly longer dementia-free survival and lower dementia incidence rate than no exposure,” the researchers concluded.
Why could vitamin D help prevent dementia?
The study didn’t explain why there was a link between taking vitamin D and a lower risk of developing dementia. However, there are some theories.
Vitamin D influences a lot of cellular functions in the body—so it’s possible that mild deficiencies can impact the development of aging-related brain changes, says David Merrill, MD, PhD, a geriatric psychiatrist at Providence Saint John’s Health Center in Santa Monica, California.
Vitamin D also helps clear beta amyloid, a protein that plays a role in Alzheimer’s disease, Merrill points out. This is “the same mechanism targeted by new prescription drugs in Alzheimer’s disease,” he says.
Vitamin D might also slow the buildup of tau tangles, which are another hallmark of Alzheimer’s, he adds.
How much vitamin D should I get per day?
The recommended daily allowance of vitamin D varies by person. However, most adults should get 600 international units (IU) daily, while adults 70 and up should have 800 IU of the nutrient, according to the National Institutes of Health (NIH).
How can I get more vitamin D?
Your body produces vitamin D when you’re exposed to sunlight, making that an easy way to get more in your life. However, there are supplements available. (Just check in with your doctor before taking the vitamin to make sure it doesn’t interact with anything else you might be taking.)
But Merrill stresses that taking vitamin D alone won't keep you from developing dementia. “No single factor will be sufficient to keep the brain intact with aging,” he says.
Instead, do your best to be healthy overall, which will support good brain health as you age.
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