Reviewed by We all want to live longer, healthier lives. And while science hasn’t quite discovered a magic cure-all to keep you young, new research suggests a popular supplement may at least help support your brain as you age: Vitamin D. While the supplement is often associated with sunlight and supporting your immune system, a growing body of research suggests it may have brain benefits as well.
A new study published in the journal Sleep Medicine suggests that older adults with certain health complications who took vitamin D ended up doing better on a cognitive test than those who weren’t on the supplement. It’s a bit of a stretch to say that means this supplement will boost your brainpower as you age, but this, in conjunction with existing research, suggests that vitamin D could play a role in healthy brain aging.
Whether you’ve been eyeing vitamin D for your brain health or just want to do what you can to keep yourself sharp as you get older, experts say the results are worth paying attention to. Here’s why.
Meet the experts: Jessica Cording, RD, author of The Little Book of Game Changers; Sandra Zhang, RDN, a dietitian at the Frances Stern Nutrition Center at Tufts Medical Center; and Victoria Pak, PhD, study co-author and associate professor at the Emory Nell Hodgson Woodruff School of Nursing.
What did the study find?
For the cross-sectional study, researchers looked at 54 older adults who were diagnosed with mild cognitive impairment and disturbed sleep, or were suspected to have these health complications. Researchers had each participant take the Montreal Cognitive Assessment, which is a 10-minute cognitive screening test. They compared those results against the participants’ vitamin D supplement use.
After crunching the numbers, the researchers found that participants who took 5,000 international units (IU) or more of vitamin D a day scored more than 13% higher on the cognitive test than those who didn’t take the supplement. That held true, even when the researchers adjusted for other factors like BMI, age, and education.
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The researchers concluded that their 'findings suggest that taking higher doses of daily vitamin D supplementation is associated with better overall cognitive performance in this population.'
Why might vitamin D support cognition as you age?
This isn’t the first study to link vitamin D with better cognition. Research published in the Alzheimer’s & Dementia Diagnosis, Assessment, & Disease Monitoring journal in 2023 analysed the impact of vitamin D on dementia risk in nearly 12,500 older adults. There, the researchers discovered that people who took a vitamin D supplement had a 40% lower risk of developing dementia than those who didn’t take a supplement. Women, who were at a higher risk of developing dementia than men, had a 49% lower risk of developing dementia if they took vitamin D than those who didn’t take the supplement.
It’s important to point out that this latest study was small and observational, meaning we can't say for sure that taking more than 5,000 IU of vitamin D daily will boost your brain as you age. But experts say there may still be something worth paying attention to here.
'Vitamin D plays a role in brain health, including brain-cell function and inflammation,' says Sandra Zhang, a dietitian at the Frances Stern Nutrition Center at Tufts Medical Center. 'Low vitamin D levels have also been linked with poorer cognitive health, although we don't know yet if supplementation directly improves cognition.'
Vitamin D has 'long been known' to play a role in brain function, agrees nutritionist Jessica Cording, author of The Little Book of Game Changers. 'When levels are low, things like memory, focus, and mood may be impacted,' she says.
Vitamin D receptors are found in the brain, notes Victoria Pak, PhD, study co-author and associate professor at the Emory Nell Hodgson Woodruff School of Nursing. 'Research suggests that inflammation can increase with age and may be associated with cognitive decline,' she says. 'These are some of the reasons why the relationship between vitamin D and cognitive health is worth studying further.'
Should everyone take vitamin D for brain health?
While we cannot say for certain that taking a vitamin D supplement will improve cognition, we do know that vitamin D is incredibly important for our bones, teeth and muscles, which is why the NHS says that everyone should consider taking a daily supplement containing 10 micrograms of vitamin D during autumn and winter (from October to early March).
This is because during those months our bodies are not able to make all the vitamin D we need from sunlight exposure alone.
Eating foods that contain vitamin D or are fortified with the nutrient, like fatty fish, UV-treated mushrooms, and fortified milks, can also top up your stores, but generally don't provide enough.
The only way to know for sure if you’re low in vitamin D is to get your levels checked via a blood test, Cording points out. Zhang also flags that 5,000 IU daily is a high dose (10 micrograms is equivalent to 400 IU), making it important to check in with a healthcare provider before putting yourself on it.
'Our findings are encouraging, but they’re still preliminary and come from people with signs of cognitive impairment who also had sleep disturbances,' Pak says.
If you’re curious about your vitamin D status and its potential impact on your health, talk to your GP. They can get you tested, establish a baseline, and make personalised recommendations from there.
Carina Hsieh, MPH, is the deputy features editor of Women’s Health. She has more than a decade’s worth of experience working in media and has covered everything from beauty, fashion, travel, lifestyle, pets, to health.
She began her career as an intern in the fashion closet at Cosmopolitan where she worked her way up to Senior Sex & Relationships Editor. While covering women’s health there, she discovered her passion for health service journalism and took a break to get her Masters in Public Health. Post-grad school, she worked as a freelance writer and as The Daily Beast’s first Beauty, Health, and Wellness Reporter.
Carina is an alum of the Fashion Institute of Technology and the Yale School of Public Health. She and her French Bulldog, Bao Bao, split their time between Brooklyn and Connecticut. She enjoys reformer Pilates, (slow) running, and smelling the fancy toiletries in boutique fitness class locker rooms.
