Vitamin D Could Reduce Your Dementia Risk, New Study Says

caucasian woman riding bicycle near beach, vitamin d
Vitamin D Could Reduce Dementia RiskPeter Griffith - Getty Images
  • A new study involving 12,000 participants over age 70 found that those taking a vitamin D supplement were less likely to receive a dementia diagnosis.

  • Experts explain the importance of getting sunshine to meet your vitamin D needs, and point out the many other health benefits of this nutrient.

The list of vitamin D benefits is wide-ranging, from lower incidence of depression and certain cancers to decreased severity of COVID-19 symptoms. Now, a large-scale study is adding another major benefit to that list: potentially lower risk of dementia.

Looking at more than 12,000 participants over age 70 in an Alzheimer’s study who were assessed over a 10-year timeframe, researchers found that those taking vitamin D—about 37 percent of the group—were less likely to be diagnosed with dementia within that decade. For the group who was diagnosed with dementia, participants taking the vitamin tended to show symptoms later than participants who didn’t take a supplement.

Effects were significantly greater in women, and were especially pronounced in those with normal cognition compared to participants who had mild cognitive impairment at the start—implying that the vitamin is particularly good as a preventive step rather than part of treatment.

In terms of mechanism, the researchers noted that vitamin D has previously been shown assist in the clearance of amyloid in the brain. Accumulation of amyloid, which is a type of plaque, is one of the key signs of Alzheimer's disease.

The study focused on the effects of supplements, but don’t underestimate the effect of getting vitamin D the old-fashioned way, with a strategic amount of sun exposure, according to Michael Holick, M.D., Ph.D., director of the Bone Health Care Clinic at Boston University Medical Center.

Although he wasn’t involved in the recent study, Holick has done extensive research on vitamin D and its effects, and told Bicycling that it only takes about 10 to 20 minutes daily of direct sunshine to get a vitamin D boost. After that, be sure to use sunscreen if you’re outside for longer, to lower skin cancer risk. It’s best to get sun on shoulders, arms, or legs instead of your back or face, he added, because the latter are more prone to cancer risk.

“There are beneficial biological processes that occur with sunshine that you won’t get with vitamin D supplements alone” he said. “Best of all, it doesn’t take much to kick off these processes.”

You can also get a boost from foods that are rich with vitamin D, such as salmon, tuna, eggs, and mushrooms. You’ll see the vitamin added to milk, too, because it makes the calcium in dairy more easily absorbed.

In addition to helping with brain health, vitamin D has been shown to have a breadth of other advantages, Holick said. The list includes improvement in mood, better cardiovascular function, lower blood pressure, and deeper sleep.

Of course, there’s also bone health, an important consideration for cyclists because the sport has been associated with low bone mass and higher risk of osteoporosis. For example, older research found Tour de France riders’ bones were up to 17 percent less dense than their non-cycling peers.

All of that taken together should nudge people toward getting more vitamin D, either in the form of sunshine, supplements, nutrition, or all three.

“It’s impossible to overstate how important vitamin D is for the health of your body and brain,” said Holick. “We see that across all ages, but when you get older, it becomes even more crucial.”

If you do opt for supplements, there’s still some debate on how much vitamin D you need daily. The recommended daily allowance is 600 IU, but the Endocrine Society suggests consuming potentially much higher levels of 1,500 to 2,000 IU daily. (The upper limit of vitamin D is 4,000 IU, according to the National Institutes of Health.)

If you’re concerned that you may be vitamin D deficient, talk to your healthcare provider and get your levels checked. They can easily spot whether you’re lacking on this important vitamin.

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