After 50, the Right Plant-Based Diet May Boost Brain Health

A study of nearly 93,000 adults finds that whole plant foods like vegetables, fruit and whole grains are linked to lower dementia risk

Donna Freydkin,

AARP

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Published April 10, 2026

artistic representation of a brain made from green leafy vegetables to symbolize brain-healthy nutrition

Leafy greens like spinach, lettuce and kale are rich in nutrients linked to better brain health and a lower risk of cognitive decline.

Ilia Biriukov/Dreamstime

Key takeaways

Whole, minimally processed plant foods lower dementia risk; refined grains and sugary drinks raise it, even though both count as “plant-based.”
Diet changes after 50 still make a difference.
Cutting back on refined grains and sugary foods and replacing them with vegetables, whole fruits, legumes and whole grains can meaningfully shift long-term brain health.

Not all plant-based diets are equal.

People who eat more whole, minimally processed plant foods like leafy greens, fruit, whole grains and nuts face a lower risk of dementia over time. People who consume more refined grains, sugary drinks and juices face a higher risk, according to a large new study published in Neurology. It tracked nearly 93,000 adults for more than a decade and found that the types of plant-based foods participants chose to eat shaped their long-term brain health.

Over the course of the study, those with the highest overall plant-based diet scores had a 12 percent lower risk of Alzheimer’s disease and related dementias compared with those who had the lowest scores. But those who ate more unhealthy plant-based foods saw their risk tick up.

The message is clear for adults 50 and older: Switching to a plant-based diet is not enough. The quality of the plants you eat makes a difference.

"Not all plant based foods are equal. A salad with olive oil and nuts supports your brain. A bag of chips and sugary cereal is also plant based, but it harms your brain," says Dr. Majid Fotuhi, a neuroscientist and adjunct professor at the Johns Hopkins University Mind/Brain Institute. "The key is quality. Choose whole and natural foods instead of processed and refined ones."

Why this matters after 50

Participants in the study were not young adults experimenting with trendy new diets. They were between 45 and 75 at the start, with an average age of just over 59.

Those who leaned into whole, minimally processed plant foods had a lower risk of developing dementia over the 10-year study.

Changes to diets also made a noticeable difference. Cutting back on less healthy plant foods was linked to lower risk, while adding more of them was linked to higher risk.

The takeaway is practical. You do not need to totally clean out your fridge. But swapping out refined grains and sugary foods for vegetables, whole fruits, beans and whole grains lines up with a meaningful shift in dementia risk over time. Small changes can lead to big results.

The difference between “healthy” and “unhealthy” plant foods

The study breaks plant-based eating into two categories.

Healthy plant foods include minimally processed vegetables, whole fruits, whole grains, nuts and legumes. These foods are rich in fiber, antioxidants and nutrients tied to brain health.

Unhealthy plant foods include refined grains — such as white flour, white pasta and white rice — as well as sugary drinks and fruit juices. These are often ultraprocessed; high in sugar, fat and salt; and low in protein and fiber.

Both groups are plant-based. Only one was linked to lower dementia risk. In the most basic terms, a diet built on white bread, chips and sweetened drinks meets the definition of being plant-based. But it does not deliver the benefits you get from eating broccoli or spinach.

That distinction is backed up by a separate body of research focused specifically on fruits and vegetables. In two long-running studies of more than 10,000 adults 50 and older, higher intake of whole fruits and vegetables was linked to better cognitive function and a slower rate of decline over time. The strongest associations were seen with green leafy vegetables, cruciferous vegetables and dark-colored vegetables.

What to change now

The findings do not call for a strict diet. They point to targeted shifts. Start with what is already in your routine and adjust the quality of what you’re eating.

Swap refined grains for whole grains: Choose brown rice, oats or whole-grain bread instead of white versions.

Eat fruit; don’t drink it: Whole fruit retains fiber that helps regulate blood sugar. Juice does not.

Build meals around vegetables and legumes: Leafy greens, beans and lentils show up consistently in healthier patterns.

Watch packaged “plant-based” foods: Many, like meat alternatives, are highly processed and fall into the same category as the foods linked to higher risk.

Ready to cook with brain-healthy foods? Start by browsing our collection of delicious, nourishing recipes. We even offer meal plans so you can follow a week of Mediterranean eating or a high-protein plan. And be sure to read up on Staying Sharp's other pillars of brain health: Be Social, Manage Stress, Restorative Sleep, Engage Your Brain and Ongoing Exercise.

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Donna Freydkin has spent 10-plus years interviewing celebrities for major publications, and has written for a variety of outlets such as USA Today, Allure, Yahoo! and CNN covering topics such as films, family and favorite meals.