9 foods that can boost your brain health — and don't cost more than $1 per serving

• What we eat makes a difference to our brain health.
• Brain doctors Ayesha and Dean Sherzai list 9 favorite foods for boosting cognition.
• Everything on their list is a plant. 

Brain doctors Ayesha and Dean Sherzai have spent their careers investigating how to have a healthy brain.

"We learned that yes, there are things you can do," Mr. Sherzai told Business Insider. "Lifestyle has the most profound effect on brain health, more than anybody could imagine."

One big study the two doctors often reference, which examined the diets of older adults living in public housing and nursing homes around Chicago, showed that those who adhered to a more brain-friendly diet pattern had a 53% lower risk of developing dementia.

"These are unimaginable numbers," Sherzai said. "No protocols, no weird stuff, no vitamin concoction."

It's findings like this that have convinced the "Brain Docs," as they call themselves on social media, to focus on promoting "simple dietary changes" people can make immediately to promote better cognitive health, instead of waiting for drugs to treat the symptoms of dementia later on in life.

"We think that if you take care of brain health, you've taken care of all health," he said. "Everything you need for heart, for liver, for kidney is included in neuro."

9 evidence-backed foods for brain health

Greens

Cost: about $1 for one serving of bagged spinach (2 cups)

Evidence: Getting in at least one serving of leafy greens, like lettuce, spinach, or kale per day is associated with better performance on cognitive tests for competencies like working memory, spatial awareness and perception among older adults. Scientists think there's probably something neuroprotective about the nutrients in the leaves, which include folate, nitrate, and lutein.

Legumes

Cost: $0.50 or less per serving for things like canned chickpeas, black beans, or bagged lentils

Evidence: Studies consistently suggest plant proteins like legumes are good for the aging brain — and nutrition experts suspect that might be in part because they're packed with B vitamins that help keep our nervous system humming along.

Berries

Cost: probably the priciest item on this list, at roughly $3-7 for a carton of fresh berries like strawberries, raspberries, or blackberries. But since a serving of berries is only half a cup, you can still probably squeeze in a serving for $1 or less. You can always opt for (cheaper) frozen berries, which studies show are just as nutritious as the fresh stuff — and sometimes even a little bit more nutritious — because fruits are typically frozen just as they reach peak ripeness.

Evidence: Berries like blueberries, raspberries, and strawberries are rich in chemical compounds that help keep our cells running well. There's evidence to suggest they may also prevent some of the oxidative stress that's associated with cognitive decline, but more research is still needed to better understand the precise link between berry eating and better brain health.

Whole grains

Cost: similar to legumes, generally less (and sometimes far less) than $1 per serving for things like oats, bulgur, corn, millet, quinoa, or brown rice.

Evidence: Whole grains are consistently linked to slower cognitive decline, and experts think that probably has something to do with all the anti-inflammatory effects they have on the body. Whole grains are also great at staving off other health issues, like diabetes, and heart disease, which can accelerate cognitive decline as they impact our vascular health.

Nuts

Cost: varies, but considering a one-pound bag of walnuts or almonds typically costs about $5-6, each serving would be less than $0.50

Evidence: Nuts are thought to be great for your brain in large part because they're loaded with nutrients, including many that naturally improve vascular health and tamp down inflammation. Walnuts are an especially popular choice among nutrition buffs and longevity-seekers because they offer a decent dose of omega-3, which "is the only fat that your brain needs," Sherzai said.

Herbs and spices

Cost: pennies

Evidence: There are various reasons that seasonings can boost cognitive health. A favorite example of many health experts is turmeric, which has nice anti-inflammatory effects and is consistently linked to better cognitive function, but there are also real benefits to various other spices, including cinnamon (anti-inflammatory) and peppers, including black pepper (increases absorption of other nutrients, and may be directly neuroprotective). In general, being able to spice up your dishes in a way that tastes yummy to you also probably means you'll be able to cook more at home and enjoy less processed foods, which is also a boon for overall health and well-being and linked to lower dementia risk.

Seeds

Cost: about $0.35-0.75 per serving for things like chia seeds and pumpkin seeds

Evidence: Much like nuts, seeds are great for the brain because they're full of fiber, healthy fats, key vitamins and minerals, including fatty acids like omega-3.

Crucifers

Cost: between $0.50 and $1 per serving of broccoli or similar brassica veggies, like chard, kale, cauliflower, and Brussels sprouts.

Evidence: These crunchy stalks are well-known health foods because they're great for blood flow. They are consistently linked to less cognitive decline, are great cancer preventers, and lower the incidence of strokes.

Tea

Cost: varies, but generally between $0.10 and $0.60 per cup.

Evidence: Tea leaves are chock-full of various plant compounds that can be beneficial for our long-term health, improving inflammation (a hallmark of dementia) and possibly even lubricating neurotransmission.

You might've noticed that everything on this list is a plant

Experts say it's too simplistic to attempt to break down these natural foods into exhaustive laundry lists of nutritional components that fully explain their health benefits.

While they all do offer vitamins, fiber, and other beneficial compounds, they are also each their own little biological systems, working synergistically with our bodies in ways we may not fully understand.

"The data shows that if you eat more plants and less processed food, you are going to do amazingly," Sherzai said. "It's not about superfood. It's about your dietary pattern."