Nutrition and Mental Health: Are Fish and Fruit Making Me Happy?

Most people are aware of the impact a healthy diet has on their physical health. But how many people know the impact that healthy eating can have on their mental health? 

Nutritional psychiatry is an intersection of the fields of nutrition and mental health, providing an opportunity to learn more about how what we eat impacts our mental wellbeing. Keep in mind, the information we are learning about this topic provides a support system - not a replacement - for traditional methods of treating anxiety and depression. Let’s dig in.

Researchers agree that specific dietary patterns have been linked to positive impacts on mental health. A traditional Mediterranean diet, the DASH diet (Dietary Approaches to Stop Hypertension) or similar diets that are rich in fruit, vegetables, whole grains and healthy fats have been associated with fewer depression and anxiety issues. Conversely, the typical Westernized diet - high in added sugars, saturated fat, ultraprocessed foods and low in fiber, vegetables and fruit - has the opposite effect. It seems that our brain, like the rest of our body, thrives on the nutrients found in healthy foods.  It’s thought that specific nutrients may play a role in mental health, but to what extent is not certain. Either way, researchers agree that our diet as a whole likely plays a bigger role in our mental health than individual nutrients. 

The Details: How Does Nutrition Impact Our Brain? 

The Microbiome-Gut-Brain axis

As mentioned in my blog Your Gut Microbiome: Little Bugs, Big Impact, the gut microbiome plays a vital role in our overall health, including our mental health. The microbiome-gut-brain axis is a two way communication pathway between our gut and our brain. It’s a complex system that involves the gut microbiome, neurotransmitters (chemical messengers found in the gut and the brain), the vagus nerve (a nerve that plays a role in digestion, among other things), our central nervous system and the enteric nervous system in our gastrointestinal tract. These components all work together so that our gut and brain can send signals to each other. These signals are influenced by the bacteria in our gut microbiome, which in turn are influenced by the food we eat. Put differently, the food we eat  influences the communication between our gut and brain, which then impacts mood and mental health. 

Fiber is an important part of this process.  Fiber  is fermented by our gut bacteria, resulting in the production of substances called short chain fatty acids (SCFA). These substances play various roles in neurotransmitter production and act in an anti-inflammatory fashion in the brain.

Neurotransmitter Production

Serotonin, dopamine and GABA are a few examples of neurotransmitters that impact mental health. Omega 3 fats, B vitamins, zinc, vitamin D and the amino acid tryptophan all play a role in the production of neurotransmitters. Inadequate intake of these nutrients disrupt the manufacturing pathway, resulting in negative consequences regarding mood and cognition. 

Inflammation, Blood Sugar Control and Insulin Resistance

Inflammation in the brain is a known risk factor for poor mental health. Diets that promote whole body inflammation (those high in saturated fats, refined carbohydrates and added sugars) also contribute to inflammation in the brain, as does high blood sugar and insulin resistance.Controlling blood sugar levels and preventing insulin resistance through diet and exercise are known to help with depression and anxiety. 

Brain Mitochondria

Mitochondria are cell components frequently referred to as the “powerhouse” of the cell. The health of our brain’s mitochondria is linked to multiple mental health conditions including depression, anxiety, bipolar disorder and schizophrenia, and is impacted by what we eat. Low levels of antioxidants such as vitamin C and zinc, as well as decreased intake of omega-3 fats and B vitamins place our mitochondria at risk for damage. Consuming enough antioxidants, omega 3 fats, as well as polyphenols (vegetables, fruit, whole grains) can help to minimize this damage and ultimately protect one’s mental health. 

BDNF

BDNF, brain derived neurotrophic factor, works with our brain mitochondria as a critical chemical necessary for maintaining the health of nerve cells, promoting brain plasticity (the brain's ability to change and adapt), and is impacted by what we eat. Healthy diets, such as the Mediterranean diet, help to maintain levels of BDNF while a Westernized diet has been shown to suppress it. Research has linked low levels of BDNF and major depressive disorder. (Fun fact: exercise is also a great way to keep your mitochondria healthy and  increase the BDNF in your brain!)

Brain structure

Fat makes up 50-60% of the dry weight of our brain. It’s essential for the structure of cell membranes and also serves as a protective wrapping around the nerve cells in the brain. Some of the fat that the brain needs to function properly can be made by the brain itself, but we also need polyunsaturated fats in our diet as this is not something that the body can produce. 

Eat These Foods 

As mentioned, a traditional Mediterranean diet and the DASH diet are plant heavy, full of vegetables, fruits, whole grain, nuts, seeds, healthy fats and lean protein and are beneficial for good mental health. The nutrients mentioned above are abundant in these healthy eating patterns and can be found in the following foods.

• Omega 3 fats: DHA and EPA are omega-3 fats found in fatty fish such as salmon, mackerel, herring, sardines, anchovies and tuna. They have a strong link to brain health. Aim for two servings of fatty fish each week.

  • ALA is another type of omega-3 fat that has an anti-inflammatory impact on the brain. Ground flaxseed, chia seeds, hemp seeds, walnuts, canola and soybean oil are all healthy sources of these fats. A daily serving of walnuts or any of the above seeds is a good idea. 

• Vitamin D: Low levels of vitamin D in the body are linked to an increased risk of depression. To increase the vitamin D in your diet, add more dairy products, salmon, egg yolks, and mushrooms. 

• B vitamins: There are a number of B vitamins, and this means they can be found in many foods. Some of the main sources are leafy greens, whole grains, eggs, chickpeas, lentils, pork, fish, dairy and fortified foods such as cereal.  Eating a wide variety of foods will ensure that you get adequate amounts of these vitamins. 

• Fiber is critical for gut health and thus for good mental health. Add whole grains, legumes, lentils, fruits and vegetables to each meal and strive for a goal of 30-35 grams each day. Add a little bit of extra fiber each day; don’t do it all at once!

• Fermented foods are also necessary for good gut health. Try adding kefir, Greek yogurt, kombucha, kimchi, tempeh, miso, sauerkraut or other fermented vegetables to your grocery list. Aim for three servings of fermented foods each day.

• Zinc can be found in oysters, red meat, pumpkin seeds and lentils. Consider adding pumpkin seeds to salads and when cooking replace half of your ground beef with lentils. Or, check out the “all you can eat oyster bar” for a big dose of zinc.

• Polyphenols and antioxidants: Berries, deep colored fruits and vegetables, tea, olive oil, and extra virgin olive oil are all good sources of these  potent plant chemicals. Remember to eat a wide variety of colorful plant products to get the maximum benefit. Make 5 servings of fruits and vegetables your daily goal. 

The food we eat can also have a negative impact on our mental health. To prevent this from happening, limit:

• Added sugar and refined carbohydrates such as white bread, white pasta, white rice, sugary desserts and candy, soda and other sweetened beverages. 

• Fast food.

• Red and processed meat such as hotdogs, sausages and pepperoni.

The Bottom Line

It’s not surprising that the same foods that promote good physical health are also good for our mental health. To get the fiber, healthy fats, micronutrients, phytochemicals and nutritional substrates that appear to help our mental health, fill your plate with a variety of vegetables, fruits, whole grains, nuts, seeds, fatty fish and plant proteins. Keep in mind that the phrase "the whole is greater than the sum of its parts” applies to nutrition and mental health. This means that eating whole foods is a much better choice than using supplements. 

Healthy eating for our brain is just as important as healthy eating for the rest of our body. Would you like more personalized advice or  do you have questions you would like answered? Reach out via my website mbhyneknutrition.com. I’d love to hear from you!