Reviewed by Dietitian Jessica Ball, M.S., RD
Credit: Getty Images. EatingWell Design. Background: Michela Buttignol.
Key Points
Omega-3s, especially DHA, support brain health. Fatty fish may be the best source, but supplements can help, too.
Vitamin D deficiency is linked to cognitive decline. Check your levels to assess supplement need.
Low vitamin B12 levels can harm memory and thinking, especially for older adults.
Dementia risk is shaped by a mix of factors. Some you can’t change—like age, genetics and family history—and many you can, from sleep and exercise to what’s on your plate. And while diet, sleep and exercise are great areas to focus on, supplements are another area worth a closer look.
Experts say supplements aren’t a magic bullet, but a few have been studied for their potential to support cognitive aging, especially when they help correct an underlying deficiency. “I generally approach supplements cautiously and individually rather than universally recommending them for everyone,” says Jon Stewart Hao Dy, M.D. “I am most optimistic about correcting deficiencies rather than promoting aggressive supplementation in otherwise-healthy individuals with no clinically and laboratory proven deficiencies,” he adds. In other words, the strongest case for supplementation is when blood work shows you actually need it—not as a preventive guess.
Before adding a supplement to your routine, it’s a good idea to talk with a health care provider, especially if you take prescription medications, have a chronic health condition or follow a special diet. We spoke with experts in neurology and cognitive aging to better understand which supplements may be worth considering—and what to know before adding them to your routine.
1. Omega-3 Fatty Acids
Of the supplements studied for brain health, omega-3 fatty acids—particularly docosahexaenoic acid (DHA)—tend to come up most often.
“DHA is an important structural component of neuronal cell membranes, and it may help support our brain’s vascular system and anti-inflammatory pathways involved in brain aging,” says Dy.
In 2023, a large meta-analysis of 48 studies and more than 103,000 participants found that higher dietary intake of omega-3s was linked to roughly a 20% lower risk of dementia or cognitive decline, with DHA showing the strongest effect.
That said, the research isn’t entirely consistent—a 2026 analysis even raised questions about whether supplementing in older adults offers the same benefit as getting omega-3s from food. “Getting omega-3s from foods like fatty fish comes with protein, vitamins and a broader array of nutrients linked to better brain and heart health,” says Allison B. Reiss, M.D., a member of the Medical, Scientific & Memory Screening Advisory Board for the Alzheimer’s Foundation of America. Still, the bulk of the evidence points in a favorable direction for cognitive health, particularly when DHA and EPA come from your diet.
Fatty fish like salmon, sardines and mackerel are excellent sources of EPA and DHA. If you don’t eat fish regularly—or follow a vegetarian or vegan eating pattern—an omega-3 supplement may help fill the gap, but it’s worth discussing with a health care provider first.
2. Vitamin D
This fat-soluble vitamin may also have a potential role in supporting brain health as you age.
“Vitamin D receptors are found throughout the brain, and deficiency is directly linked to poor concentration, brain fog and long-term cognitive decline,” says Fawad Mian, M.D., a board-certified neurologist and sleep specialist. Beyond those day-to-day effects, vitamin D also helps regulate inflammation, immune function and the clearance of amyloid-beta. This protein can build up in the brain and is linked to Alzheimer’s disease.
A 2024 meta-analysis of prospective cohort studies found that vitamin D deficiency was associated with a 1.42 times higher risk of dementia and a 1.57 times higher risk of Alzheimer’s disease.
That said, observational research consistently links low vitamin D status with worse cognitive outcomes, but large trials haven’t confirmed that taking a vitamin D supplement prevents dementia. The strongest case for supplementation is to correct a deficiency, which is common—especially among older adults, people with limited sun exposure and those who follow a vegan or vegetarian diet.
“A lot of us have low vitamin D levels,” says Reiss. “It is hard to get vitamin D from food alone, so checking your levels is a good idea,” she adds. A simple blood test can tell you where you stand.
Fatty fish, egg yolks and fortified foods like milk and some cereals can also help boost your intake, but for many people, food and sunlight alone may not be enough.
3. Vitamin B12
Vitamin B12 may not get the same attention as omega-3s or vitamin D, but it stands out as one of the most important nutrients to keep an eye on—particularly as you age.
“Vitamin B12 deficiency can severely affect the brain with symptoms of brain fog, poor memory, slowed thinking, depression and cognitive decline,” says Reiss. “Low levels of B12 are linked to loss of brain volume,” she adds. The reassuring news is that, unlike many causes of cognitive decline, a B12 deficiency is often reversible once it’s identified and treated.
A 2021 study co-authored by Dy examined patients with mild cognitive impairment and found that low vitamin B12 and vitamin D levels were common in this group. While the authors emphasized that this is an association rather than proof that deficiency causes dementia, the findings confirm the importance of checking your levels.
Older adults are particularly vulnerable to B12 deficiency because stomach acid production tends to decline with age, which makes it harder for the body to absorb B12 from food. Certain medications can also lower levels. Reiss notes that the diabetes drug metformin can induce B12 deficiency, so people taking it should be monitored. People who follow a vegan or vegetarian diet are another group at higher risk, since B12 is found naturally almost exclusively in animal products.
Animal products like fish, meat, eggs and dairy are the main natural sources of B12. Fortified foods—including some plant milks, nutritional yeast and breakfast cereals—can also help, and a supplement may be appropriate if your levels are low or your diet is limited.
Other Tips for Lowering Dementia Risk
Supplements may offer extra support in some cases, but the strongest tools for protecting your brain are the habits you build every day. As Dy puts it, “Brain health is not determined by a single supplement, food or habit alone, but rather by long-term patterns repeated consistently over many years.” Here are a few habits experts recommend focusing on:
Move your body regularly. Aerobic exercise boosts blood flow to the brain and stimulates brain-derived neurotrophic factor (BDNF), a protein that helps brain cells grow and connect. “Studies show this actually increases grey matter and expands the hippocampus, the part of the brain where memories are made and stored,” says Mian. Aim for at least 150 minutes of moderate-intensity activity per week.
Prioritize quality sleep. “Our glymphatic system helps flush out the proteins that cause Alzheimer’s, and this system is most active during sleep,” says Mian. Experts recommend aiming for seven to nine hours of sleep a night, and addressing issues like snoring or sleep apnea that can interfere with this restorative process.
Follow a brain-healthy eating pattern. Eating patterns like the Mediterranean diet and MIND diet emphasize vegetables, fruits, whole grains, beans, fish, nuts and olive oil, while limiting saturated fat and added sugar. Both have been linked to a lower risk of cognitive decline.
Stay socially and mentally engaged. Spending time with others, learning new skills or picking up a hobby may help build cognitive reserve—a kind of mental buffer that helps the brain stay resilient with age.
Our Expert Take
Supplements may play a supporting role in brain health, but they aren’t a substitute for the daily habits that protect cognition over time. The strongest case for any supplement is correcting a known deficiency—particularly omega-3 fatty acids, vitamin D and vitamin B12, which experts identified as the most evidence-backed nutrients for cognitive aging. If you’re considering adding one, talk with a health care provider about checking your levels first.
Beyond what you take, what you do day-to-day matters just as much. Regular movement, quality sleep, a brain-healthy eating pattern and social connection are all habits with strong links to long-term brain health. None of these alone can prevent dementia—but consistently practiced over years, they’re the most powerful tools you have for staying sharp as you age.
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