Simple lessons from popular healthy diets can help prepare you for lifelong mental fitness.

As researchers work to discover the causes and prevention of age-related cognitive decline, a growing body of research points to lifestyle factors, such as diet and exercise, as possible prevention measures. Dementia, characterized by a deterioration of memory and thinking, affects approximately 50 million people worldwide, with 10 million new cases per year, the World Health Organization estimates. Alzheimer's disease, the most common type of dementia, is the sixth leading cause of death in the U.S. and affects 5.7 million Americans, two-thirds of whom are women over age 65.

As the Alzheimer's Association states that deaths from Alzheimer's disease increased 145% between 2000 and 2019, there is a growing sense of urgency to uncover prevention methods that can be practiced from an early age. One way to do that could start with what you eat. "Nutrition plays a huge role in most body functions and how we function, including aging," says Liz Weinandy, M.P.H., RD, a registered dietitian at the Ohio State University Wexner Medical Center. For example, a 2019 study of dementia-free elders published in the journal NeuroImage found that distinct nutrient biomarker patterns were associated with cognitive health and functional brain network efficiency. A 2015 study in the journal Alzheimer's & Dementia showed that adhering to the MIND diet was linked to lower rates of Alzheimer's. And another 2015 study from the same publication found a link between the MIND diet and slower rates of cognitive decline.

healthy brain foods in the shape of a brain
Credit: Getty Images / filo / fcafotodigital

Include Healthy Fats

The brain's composition is one reason that it needs certain nutrients to thrive. The brain is approximately 60% fat, and consuming healthy fats is vital for proper brain development and protection against cognitive decline. Omega-3s, polyunsaturated fats that the body can't make on its own, are one of the more healthful fats that the brain needs. "[Omega-3s] are really important for the stability of a lot of the cells in the brain and for the cells to work properly. We want to keep the brain cells functioning at a high level," Weinandy says. "There are lots of things that influence brain function, but when we talk about diet, omega-3s in particular play a huge role in the phospholipid around the outside of the cells. If the integrity of that cell is not real great, then those cells are compromised and they don't work as well."

Since the brain can't make omega-3s on its own, healthy food sources are essential. Fatty fish are one of the most common sources of omega-3s. For example, a 3.5-ounce serving of mackerel contains more than 5,100 milligrams of omega-3s, as well as 200% of the recommended daily intake of vitamin B12 and 100% of the antioxidant selenium. Nutrient-dense salmon is another popular source of omega-3s, and additionally it contains high levels of vitamins D and B. Omega-3s are also found in chia seeds, walnuts and extra-virgin olive oil.

Omega-6s, however, are a type of polyunsaturated fat that can be obtained only through diet. While the body needs at least some level of omega-6s to protect against chronic disease, too many can increase the risk of harmful inflammation. These fats are typically found in mayonnaise and vegetable oils, such as canola, soybean and sunflower oil. "We need omega-6s. It's an essential fat that we can't make, so we need to take them in for food. The real issue is just that most people are taking way too many sixes in saturated fat, too much of those in and way, way too little of the omega-3s," Weinandy says. An easy way to limit omega-3s is to replace vegetable oil with extra-virgin olive oil. Weinandy also points to B vitamins as essential for brain and nervous system health. These are found in dairy, fatty fish, lean meats, dark leafy greens, whole grains, nuts and seeds.

The nutrient choline, which is produced in small amounts by the liver but is primarily obtained from such foods as eggs, fresh cod, salmon and broccoli, is crucial to memory formation. The brain needs choline to produce the neurotransmitter acetylcholine, which impacts muscle movement, thinking and working memory. Low levels of acetylcholine have been linked to learning and memory impairments, as well as to Alzheimer's and dementia. Foods that promote brain health can also reduce inflammation and oxidative stress, an imbalance between free radicals and antioxidants, which fight infection and lower chronic disease risk.

Try the MIND Diet

If you're looking to strengthen your brain with these nutrients, there's an eating plan for that. Brain-healthy foods are the foundation of the MIND diet, or Mediterranean-DASH Intervention for Neurodegenerative Delay. The goal of the MIND diet is to reduce the risk of disorders, such as Alzheimer's and dementia, and cognitive decline that accompany aging. As the name implies, the MIND diet takes inspiration from the popular Mediterranean and DASH diets, which amplify fruits, vegetables, whole grains, legumes and fatty fish to protect against chronic conditions, such as diabetes and heart disease. These diets are also consistent with the recommendations of the 2020 Dietary Guidelines for Americans from the U.S. Departments of Health and Human Services and Agriculture, which advise a diet of leafy greens, legumes, fruits, whole grains, dairy, learn meats, eggs and fatty fish. The MIND and Mediterranean diets both caution against added sugars, refined grains (such as white bread and pasta), margarine and red meats.

"They took two of the very best diets that have been shown time and time again to be the healthiest," Weinandy says. "They're really very similar, but there are some small differences."

While the Mediterranean and DASH diets both recommend eating a variety of fruits and vegetables, berries specifically are a primary fruit that has been shown to improve brain function. "It's more of a precise diet that's really targeted toward brain function. It's a pretty comprehensive approach to eating," Weinandy says. A recent study in Annals of Neurology, for example, found that berries were associated with significantly lower rates of cognitive decline among older women. These can be used as a colorful topping for Greek yogurt or as a healthful midday snack. The MIND diet also specifically cautions against high consumption of cheese, advising that it should be limited to about once per week.

Beyond influencing the brain's ability to protect against cognitive decline and disease, nutrition can also influence mood and mental health. For example, the amino acid tryptophan, found in turkey, tofu, chicken and pumpkin seeds, produces the B vitamin niacin, which is vital for creating the neurotransmitter serotonin. A lack of serotonin can worsen overall mood, which increases the risk of mood disorders, such as depression. A 2016 study in the journal Nutrients, for instance, found that emotional processes were inhibited in subjects who had depression or a high risk of developing it when subjects were depleted of tryptophan. Additionally, a 2015 study in the Archives of Psychiatric Nursing found that among 25 healthy young adult subjects, higher doses of dietary tryptophan resulted in significantly less depression and irritability and decreased levels of anxiety.

Likewise, anti-inflammatory properties found in omega-3s, vitamin D and folate have been linked to positive effects on depression and anxiety. A small double-blind study in the Journal of Affective Disorders, for example, found that Parkinson's patients who took fish oil omega-3 supplements presented an improvement in depressive symptoms. And a 2013 meta-analysis in the British Journal of Psychiatry noticed a link between depression and vitamin D in study participants and found that those with vitamin D deficiency are at greater risk for developing depression. "There have been studies looking at these [effects], and it shows that usually healthy food or healthy dietary patterns are also considered as being related to a lower risk of depression, anxiety, those psychological, mental health issues," says Yian Gu, M.D., Ph.D., assistant professor of neurological sciences at Columbia University. However, Gu emphasizes that these effects are difficult to measure in observational studies.

Advanced glycation end products, or AGEs, have also been linked to cognitive function and diseases associated with aging, such as Alzheimer's. AGEs are compounds formed when protein or fat mixes with sugar in the bloodstream, otherwise known as glycation. Diet is considered the largest contributor to the development of AGEs, since AGEs are often found in foods that have been exposed to high temperatures or dry heat, such as grilled, fried, sautéed, barbecued or toasted foods. AGEs also increase oxidative stress and inflammation throughout the body, including in the brain. High levels of AGEs have been associated with Alzheimer's disease, as well as heart disease, diabetes, liver disease, arthritis and high blood pressure. A 2015 study in the Journal of Clinical Endocrinology & Metabolism found that AGEs were associated with diminished cognitive and memory function, including the ability to recall specific words. A 2019 study in the Journal of Alzheimer's Disease found that high concentration of AGEs could "be a predictor of a long-term decline in cognition-related daily living performance" in patients with Alzheimer's disease, the authors wrote. Other studies have shown that foods containing AGEs can induce higher levels of oxidative stress in the brain.

While grilled and roasted meats, full-fat dairy and highly processed foods could increase the amount of AGEs, consuming foods consistent with the MIND diet—fruits, vegetables, whole grains—can lower AGE levels. "It all goes back to the same thing. It's like eating this pretty healthy diet and staying away from those foods that we know are not so healthy," Weinandy says.

How to Get Started

For newcomers, the tenets of the MIND diet can feel overwhelming. Both Gu and Weinandy caution against diving in too quickly and recommend starting slow. "If somebody was just looking at this and if they eat very far from what's recommended, it can seem very daunting to try to do this. And this is where, as dietitians, we always like to see people just take small, gradual steps because, usually, if people try to just dive into something that's very different from what they do currently, it won't last long," Weinandy says. "So instead of failing, I would tell people to look at where they are now." Weinandy recommends incorporating one or two items every one to two weeks. Try replacing a steak at dinner with salmon or lean chicken, or replace a bowl of ice cream for dessert with berries and Greek yogurt. If your morning smoothie usually includes oranges and bananas, consider adding mixed berries and unsweetened almond milk. "Try to make those small shifts in how a person eats and maybe try to trade out some of the red meat for fish or poultry and trade out butter for olive oil. Some of those small shifts can really make a difference over time," Weinandy says.

Making these swaps in between meals is also a gradual step to following the MIND diet. For a brain-healthy snack, consider choosing nuts. A 2018 study in the Journal of Nutrition, Health & Aging of nearly 5,000 Chinese individuals over age 55, for example, found that the long-term high consumption of nuts, including peanuts, was associated with a lower likelihood of having poor cognitive function. Peanuts, which are technically legumes, are high in unsaturated fats, folate, vitamin E, magnesium and potassium, which provide anti-inflammatory, antioxidant and lipid-lowering benefits. To get in more leafy greens, consider adding a side salad to your dinner in place of starchy foods. Just half a cup of spinach contains 1.9 milligrams of the powerful brain-healthy antioxidant vitamin E, or 10% of the daily recommended intake. "This type of healthy diet is not something surprising," says Gu, pointing out that most people are already aware that fruits and vegetables are key components of a full-body healthy-eating plan.

And unlike many fad diets that focus on restrictions and strict counting of calories, carbs and fat, the MIND diet is not an exact science of what you have to eat and when. "You don't have to be exact. There's nothing that says you have to have exactly a certain amount of fish in a certain amount of time," Gu says. "It's not that strict; just take this as a rule of your daily food intake to try to reduce your high fat intake, red meat intake, and to try to increase your vegetable, fish, fruit intake." Gu adds that "if someone is interested in this and they are paying attention to getting this healthy diet, it's not a very hard thing to do. It's just you need to get this in your mind and stick with it." Experts also recommended pairing this dietary pattern with regular exercise to keep the entire body strong as it ages. "Any level of physical activity should be good because it will reduce your time sitting," says Gu.

While the goal in making these dietary changes is to prevent cognitive disorders associated with aging, starting early can pave the way for better brain health later in life. "Alzheimer's disease and dementia are not happening over one night. It takes decades or many, many years for these diseases to develop," Gu says. "When certain pathological changes are already occurring in your brain, it's really hard to reverse the process, so it's really important to prevent that as early as possible."

This article first appeared in EatingWell, Anti-Aging.