But this line of thinking isn't exactly true based on what researchers have learned about brain health over the past decade. A wealth of scientific studies are connecting certain food and lifestyle habits with neurogenesis, the process by which new neurons grow in the brain. It's a topic psychiatrist Drew Ramsey, MD talks about in his book, Eat to Beat Depression and Anxiety ($22), and means that we can actively protect ourselves from cognitive decline—at least in part. Encouraging, right? The key, of course, is knowing how to do it.
How are brain cells destroyed?
Before we get into brain cell growth, it's helpful to know what exactly kills them off in the first place. Dr. Ramsey says this comes down to high levels of chronic inflammation. While small doses of short-term inflammation can actually be beneficial, experiencing high-levels of inflammation for extended periods of time can be damaging to the brain (and the body as a whole, TBH).
"Scientific research has been very clear that excess inflammation affects the circuits in the brain," Dr. Ramsey says. Inflammation not only disrupts brain circuity, it actively kills brain cells, too. He explains that an inflamed brain leads to brain fog, anxiety, depression, low energy, and (over a long period of time) cognitive decline and disease. What causes long-term inflammation? Chronic stress, eating a lot of processed sugar, processed meat, and refined carbs, and not getting enough sleep are some of the major causes.
Something else chronic inflammation does is prohibit neurogenesis, the key process for producing new brain cells, says neurologist Faye Begeti, MD, PhD. (It's important to note that most of the scientific studies on neurogenesis have been done in mice—very few have been done in humans—so knowledge around the process is still limited, says Dr. Begeti.) "The brain is shielded by a blood-brain barrier. This barrier can become leaky, but this would only happen in prolonged, systemic inflammatory states rather than a simple cough or cold."
Watch the video below to learn more about the connection between diet and inflammation:
How the human brain grows new cells
Okay, so we can blame excess inflammation for killing brain cells. How do we get them back? Actively working to fight off inflammation. This not only prevents neurons from dying, it actively leads to brain cell growth, as well, according to Dr. Ramsey.
When it comes to brain cell growth, though, it's important to understand the connection between neurogenesis and neuroplasticity—two words that sound similar, but mean different things—says Dr. Begeti. While neurogenesis refers to new brain cell growth, she explains that neuroplasticity is where existing neurons grow and form different connections with each other. "Kind of like interweaving branches from nearby trees," she says. "Neuroplasticity is vital for shaping our brain into who we are, learning, and recovering from diseases, like a stroke." Neuroplasticity is how existing and new brain cells are all communicating with each other; that's why both are important, Dr. Begeti adds.
From what doctors can tell, it seems that neurogenesis only happens in two parts of the brain, the hippocampus being one of them. (The other is the olfactory bulb, linked to smell.) Dr. Ramsey explains that the hippocampus is the part of the brain responsible for emotional health as well as memory function, remembering old memories as well as creating new ones. Because of this, neurogenesis is key for staying mentally sharp and emotionally balanced. And that's where what you eat and your daily habits can come in.
Food and lifestyle habits that promote neurogenesis
A healthy diet, consistent good sleep, and regular workouts are all beneficial for the hippocampus, studies have shown. "Exercise, socialization, and environmental enrichment—which means having plenty of stimulating activities—increases neurogenesis but these studies have only been done in mice, as it is difficult to study [brain cell growth] in humans," Dr. Begeti says. This means that while there likely is a strong connection, more human studies need to be done to confirm it.
Though, some nutrients have been linked to benefitting the brain through neurogenesis in humans, according to Dr. Ramsey: omega-3 fatty acids (found in foods like fish, nuts and seeds, and soybeans), phytonutrients (natural compounds found in plants such as vegetables, fruit, whole grains, and legumes), B vitamins (found in meat, dairy, whole grains, dark leafy greens, citrus fruits, avocado, banana, nuts and seeds, and legumes), zinc (found in lean meats, eggs, seafood, lentils, nuts and seeds, and soy), and magnesium (found in whole grains, soy, nuts and seeds, legumes, and dark chocolate). This is one reason why so many doctors are into the Mediterranean diet, which emphasizes all the foods mentioned here.
Watch the video below to learn more about the Mediterranean diet, which is rich in the nutrients associated with neurogenesis:
Besides all the nutrients mentioned above, Dr. Ramsey says there's a specific brain chemical that plays a role in neuroplasticity and brain cell growth: BDNF, which is a neurotrophin, aka a type of protein that helps brain cells grow and survive. "Some say that BDNF is a lot like 'Miracle-Gro for the brain'—a fertilizing biomolecule that supports the birth of new brain cells and synapses during development," he says in his book. He also says that besides helping with brain cell growth, BNDF works to protect the mind from toxins.
Want to boost your BDNF production? Dr. Ramsey says regularly eating foods with omega-3 fatty acids is key. (Yep, the nutrient is doubly good for brain health.) He says flavonoids, a type of antioxidant found in green tea, berries, kale, tomatoes, dark chocolate, and nuts (except for macadamia nuts and Brazil nuts), are also linked to spurring more BDNF production in the brain.
Working all the aforementioned foods into your diet will likely benefit your hippocampus, but Dr. Ramsey says doing what you can to keep excess inflammation away in general is important too, since it's what kills precious neurons. When it comes to food, cooking with anti-inflammatory spices such as turmeric, rosemary, and ginger can help. So can prioritizing getting enough fiber. In terms of lifestyle, Dr. Ramsey says stress management, good sleep, and regular movement are all key. However, Dr. Begeti says it's important to acknowledge that there are still many unknowns surrounding cognitive decline. While diet and lifestyle habits are connected, they are just one piece of the puzzle. If someone does get dementia later in life, it's certainly not their fault.
When it does come to prioritizing these healthy practices, remember that embracing a "mind-over-matter" mindset can help make new habits stick. "Knowing that we can actively grow the size of our brain is really empowering to me personally," Dr. Ramsey says. "It motivates me to make choices to eat nutrient-rich foods, meditate, and exercise. It's not always easy to do those things consistently, but when you know how it's affecting your brain, it's very motivating."
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