A Harvard nutritionist and brain expert shares the 5 foods she eats every day to sharpen her memory and focus - CNBC

As a dietitian, I always tell people to think of the brain as the mastermind behind almost everything — our thoughts, memory, focus, movements, breathing, heartbeat — and that certain foods can help make it stronger, sharper and smarter.

Our brain and diet also play a key role in longevity. According to the National Institute on Aging, what we eat can directly impact inflammation and oxidative stress in our bodies — both of which can affect our risk of neurodegenerative diseases, including Alzheimer's and Parkinson's.

I spoke with Dr. Uma Naidoo, a nutritional psychiatrist, faculty member at Harvard Medical School and author of "This Is Your Brain on Food," about what she eats to sharpen her memory, focus and overall brain health:

1. Extra dark chocolate

Chopped dark chocolate

Julia Malynovska | Twenty20

"Extra dark chocolate is full of antioxidants and cacao flavanols that help preserve the health of brain cells," Naidoo tells CNBC Make It. "It also contains fiber to help reduce brain inflammation and prevent cognitive decline."

A 2020 study looked at how dark chocolate and white chocolate can affect the memory of healthy young adults. Participants who were given dark chocolate had better verbal memory performances two hours after consuming the chocolate, compared to the group that received white chocolate.

Researchers suggested this was due to the higher flavonoid content of the dark chocolate, "which can acutely improve cognitive function in humans."

Extra dark chocolate should be at least 70% cacao or greater, according to Naidoo.

Just don't go overboard with the serving sizes, she says: "One meta-analysis suggests that the optimal amount of dark chocolate consumption for the health of our blood vessels — including the ones that supply blood to the brain — is about 45 grams per week."

2. Berries

Fresh berries

Viktoryia Vinnikava | Twenty20

"Berries are packed with antioxidants, phytonutrients, fiber, vitamins and minerals," says Naidoo. "These nutrients help retain memory, and the fiber content helps feed microbes in the gut to reduce brain inflammation."

She suggests choosing from an assortment of red, blue and black-colored berries. Strawberries, for example, are rich in flavonoids and may help slow down cognitive decline; blueberries contain different types of flavonoids linked with preventing oxidative stress; and blackberries are great sources of antioxidants, which help brain cell health.

"Eating a variety of colorful berries can also reduce symptoms of anxiety and help fend off neurodegenerative diseases like dementia," says Naidoo.

She typically goes for a half or single cup in her daily serving.

3. Turmeric (with black pepper)

Turmeric spice powder

Annmartianova80 | Twenty20

4. Leafy Greens

Plate of spinach

Ekaterina Budinovskya | Twenty20

"Leafy greens are a staple in brain-healthy diets because they contain folate, which is a B vitamin that supports neurodevelopment and neurotransmitter function," explains Naidoo. "Folate deficiency has been tied to increased symptoms of depression as well as cognitive aging."

Naidoo says her favorite leafy greens include:

• Arugula
• Dandelion greens
• Spinach
• Swiss chard
• Watercress

Not a salad fan? You can also enjoy them as creative ingredients in your favorite dishes, like pasta, burritos or as a pizza topping.

5. Fermented foods

Yogurt bowl

David Tanke | Twenty20

Fermentation involves adding foods to a culture of microorganisms that then feed on the sugars in the food. This creates other products, such as lactic acid, that can generate gut-friendly bacteria.

"We have what's called a gut-brain connection," says Naidoo. "So when we eat fermented foods and boost our gut health, we may also improve our cognitive function."

She likes to eat homemade kimchi as a snack with celery sticks, or combine it with salads for extra texture and flavor. Some other fermented foods Naidoo recommends:

• Sauerkraut
• Miso
• Kombucha
• Kefir
• Yogurt

However, large amounts of fermented foods can make you bloated. "If you feel uncomfortable, cut back on your intake until your gut and body adjust," Naidoo advises.

You'll also want to double-check the food labels to ensure that what you're buying is actually fermented. Typically, you'll see a label that mentions "live active cultures."

Lauren Armstrong is a dietitian and nutrition coach. She was also a nutritionist for The Women, Infant and Children (WIC) program. Lauren received her bachelor's degree in dietetics from Western Michigan University and has written for several publications, including Livestrong and HealthDay.

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A Harvard nutritionist and brain expert shares the 5 foods she eats every day to sharpen her memory and focus - CNBC
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