Food makes us happy. Ice cream, burgers, pasta, ramen, sushi, cheesecakes… we love it. All foodies know how much of a difference a good meal can do to our mood. Yet, despite our love for sweets and fast food, there seems to always be a consensus on what constitutes “healthy'', and our favorite food isn't part of it. There also seems to be some sort of obligation imposed on us to eat our veggies and fruits. But why? Beyond the obvious health reasons - protection against cancer, diabetes, heart disease, etc, good nutrition also has a huge impact on our brain and mental health.
The brain is the most complex part of our human body, and it has the responsibility to monitor our activities, and daily operations, and communicate with other organs to control their functions. In the brain, there are cells called neurons, which are the fundamental units of the brain and nervous system, responsible for coordinating with other organs to receive sensory input from the external world, and for sending motor commands to our muscles. Neurons also communicate with the glial cells, cells that work to support and protect neurons by supplying nutrients to neurons and destroying microbes that infect the nervous system. The brain is also responsible for our thinking, learning, memorizing, planning, concentration, etc. Therefore, communication through neurons and other brain cells is important as it allows us to perform cognitive and physical tasks and plays a huge role in our emotions, thinking and behaviors.
So how does nutrition relate to the brain?
A healthy diet can lead to the production of new neurons, in a process called neurogenesis. A healthy diet can also increase synaptic plasticity, which refers to the number of connections between neurons, improving thinking, learning, and memory. These are controlled by the hippocampus, a part of the brain responsible for regulating memory and neurogenesis. The Brain-derived neurotrophic factor, which is strongly expressed in the hippocampus, provides the instructions to create a protein found in the brain and protect neurons from dying, increase neurogenesis, and overall improve our cognitive abilities. A healthy diet can lead to increased levels of BDNF, improving neurogenesis on the campus, which can cause an improvement in our memory, learning, mood, and mental health.
A diet rich in refined sugars and saturated fats may cause your body to release excess stress hormones which can activate the microglia and astrocytes, leading to inflammation in parts of the brain. This may inhibit the formation of new neurons, and inflammation in parts of the brain may affect brain functions and cognitive abilities. Studies have shown a relationship between diets with high refined sugars and impaired brain function and even contribute to disorders like depression.
In addition to that, the food you eat can affect how you feel. Neurotransmitters like serotonin help control our moods, regulate appetite, sleep, and hinder pain. Around 95% of our serotonin is produced in our gastrointestinal tract, which is lined with a hundred million neurons, so the inner workings of our digestive system not only digest food, it also affects our emotions. Studies comparing the Mediterranean diet and traditional Japanese diet to a typical “western” diet have found a 25%-35% lower chance of depression in those who have a traditional diet. This difference may be accounted for by the high vegetables, unprocessed food, fruits, fish, seafood, and limited refined foods and sugars in these traditional meals.
What accounts for “healthy” then? Is that all we can eat?
At the end of the day, no one magic food can prevent cognitive decline or improve brain functions. Nutritionists emphasize having a balanced diet, typically including fruits, whole grains, vegetables, and healthy fats (rather than saturated fats). Green leafy vegetables (containing vitamin K, folate, and lutein), fatty fish (source of omega-3 fatty acids, healthy fat), nuts (contain omega-3 fatty acids and antioxidants), whole grains (includes vitamin E), avocados (source of healthful unsaturated fat) are all foods that can be beneficial to our brain. Of course, that is not to say we should cut all of our favorite foods from our diet, but being mindful of how dietary choices can affect our brain is important. Remember, balance is key!
Citations:
“12 Best Brain Foods: Memory, Concentration, and Brain Health.” Medical News Today, MediLexicon International, https://www.medicalnewstoday.com/articles/324044#kale.
Authors Richard J. Addante, et al. “Healthy Meal, Happy Brain: How Diet Affects Brain Functioning.” Frontiers for Young Minds, https://kids.frontiersin.org/articles/10.3389/frym.2021.578214.
Avery, Aspen. “How Nutrition Impacts the Brain and Mental Health.” The Whole U, 2 Mar. 2020, https://thewholeu.uw.edu/2020/03/02/nnm-2020-nutrition-and-the-brain/.
“Foods Linked to Better Brainpower.” Harvard Health, 6 Mar. 2021, https://www.health.harvard.edu/healthbeat/foods-linked-to-better-brainpower.
MD, Eva Selhub. “Nutritional Psychiatry: Your Brain on Food.” Harvard Health, 26 Mar. 2020, https://www.health.harvard.edu/blog/nutritional-psychiatry-your-brain-on-food-201511168626.