To understand the connection between nutrition and the brain better, we sat down with Uma Naidoo, MD, a board-certified Harvard Nutritional Psychiatrist, professional chef, and nutritional biologist. She is the Founder and Director of the first and only hospital-based Nutritional and Metabolic Psychiatry Service in the United States which is housed at Massachusetts General Hospital (MGH). Dr. Naidoo’s first book, the international bestseller This Is Your Brain on Food has been published in 22 countries and 18 languages. Check out our interview here.
Her two books: This is Your Brain on Food an Calm Your Mind on Food are great easy reads with practical information. We are going to integrate into our eating recommendations.
The vagus nerve travels all the way from the brain stem to the gut-connecting your gut to your central nervous system. It plays a central role in digestion but its' most critical function is carrying critical information via nerve signals from the brain to the gut and vice-versa. The same way chemicals in pills travel from your gut to your brain-which then tells other areas of your body such as reducing inflammation, telling blood vessels to relax-the food you eat and chemicals produced in the gut also reach the brain. Your brain can also reach the gut-it is a 2-way communication system.
The central nervous system produces chemicals like dopamine, serotonin, acetylcholine which are important for mood, thought, and emotion. For example-serotonin is deficient in depressed and anxious people's brains-it also plays a major role in the gut-brain axis. It is important for mood and emotion yet 90% of serotonin receptors are found in the gut. In fact, the brain-serotonin deficit is highly influenced by the gut.
The autonomic nervous system (sympathetic and parasympathetic nervous system and includes the HPA-axis: hypothalamus, pituitary gland, and adrenal gland) is responsible for an array of functions, namely involuntary like breathing, digesting food, heart function. Adrenaline and noradrenaline (epinephrine and norepinephrine) are heavily regulated by the gut influencing our fight or flight and autonomic responses. The HPA-axis produces hormones to stimulate the release of cortisol which is the stress hormone amping up the body to handle stress. It provides a flood of extra energy. The gut plays a major role in this as well.
When chemicals are under or over produced the gut-brain connection is disrupted from its' normal smooth processes. Important things such as mood, concentration, and immunity can be upset. The gut's protective barrier can be compromised allowing harmful chemicals to get to the brain. This chemical chaos gives rise to mental health issues such as depression, anxiety, loss of libido to bipolar and schizophrenia.
The microbiome in our gut is made up of many different types of bacteria. It is estimated that the gut can contain up to a thousand different species of bacteria. Currently, researchers believe 75% of the microbiome is made up of two species types: Firmicutes and Bacteroides. There are good and bad bacteria that remain in balance when we are in good health however, stress, diet, mental and physical issues can change the bacteria in the gut. This creates a ripple effect that results in many negative health effects. For mental health for example, gut bacteria production of neurotransmitters like dopamine, serotonin, glutamate, gamma-aminobutyric acid (GABA)- all critical for mood, memory, attention are impacted.
The two-way reaction with the gut and brain has important evidence. For example, research has shown that two hours' of psychological stress is enough to alter the bacteria in your gut. The theory is the stress response from the HPA-axis sends signals to the gut, changing bacteria behavior and composition.
"the food that enters our stomachs can warm our hearts and change our brains"- Dr. Naidoo (This is Your Brain on Food, page 27).
*Recent research is supporting bacteria species associated with higher quality of life are depleted in depressed subjects while bacteria that cause inflammation are often found in higher numbers.
-Probiotics and Prebiotics: Lactobacillus in particular has been associated with reducing depression. Some good sources of food include: tempeh, miso, sauerkraut, kefir, kimchi, kombucha, mozzarella, buttermilk, and gouda. Some prebiotic rich food include: beans, legumes, oats, bananas, berries, garlic, onions, dandelion greens, asparagus, leeks.
Sugar: the brain requires 62 grams of glucose to function over a 24-hour period. An easy target to achieve with healthy foods. When you consume sugary foods it floods your brain with too much glucose. This leads to inflammation in the brain and ultimately contributes to depression. Watch your carbohydrate intake and select low glycemic index (GI) carbohydrates as they digest slower and create a lower blood glucose reaction. Low GI foods include sweet potatoes, whole grain, green vegetables, chickpeas, and lentils. Sneaky carbohydrates-those with high GI include potatoes, white bread, white rice, honey, and juice.
Sugar replacements like sucralose (splenda), stevia, aspartame, saccharin are linked to depression. They can also be toxic to the brain altering concentrations of mood regulating neurotransmitters. Sucralose has also been shown to increase inflammation.
Fried Foods & Bad Fats: Fried foods are usually prepared in bad fats known to contribute to cardiovascular disease and other issues (margarine, shortening, hydrogenated oils) while good fats (avocados, almonds, olive oil) can prevent disease and support well-being. Research has shown an association with bad fats and depression.
Nitrates: Food such as bacon, salami, sausage, deli meat- meats that are cured may be connected to depression.
Food for Good Mood
Omega-3 Fatty Acids: Omega-3:: alpha-linolenic acid, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), are important for normal body metabolism. They provide the starting point for making hormones that regulate blood clotting, contraction and relaxation of artery walls, and inflammation. We cannot produce them on our own and need to acquire via diet. EPA and DHA play the most critical role in mood disorders. Omega-3 are important for depression, they promote brain health by lowering inflammation. These foods include: fatty fish like salmon, mackerel, tuna, herring, sardines, walnuts, vegetable oils, dark and leafy vegetables can help protect against depression. Other fish not as high in Omega-3 but still have a significant amount because they consume phytoplankton creating omega-3 accumulation includes: bass, tilapia, cod, shellfish. You can also acquire from grass fed beef. Alpha-linolenic acid can be acquired through edamame, walnuts, chia seeds. You can also look for omega-3 fortified foods like eggs, milk, and yogurt.
Omega-6 on the other hand can contribute to depression such as high fat red meat cuts, corn oil, and palm oil.
Folate: Vitamin B9 and B12-legumes, citrus, fruits, bananas, avocados, leafy greens, cruciferous vegetables, asparagus, nuts, seeds, fish, shellfish
Vitamin A: sweet potatoes, carrots, spinach, black-eyed peas
Iron: shellfish, lean red meats, legumes, pumpkin seeds, broccoli
Magnesium: avocados, nuts, seeds, legumes, whole grains
Potassium: sweet potatoes, bananas, mushrooms, oranges, peas, cucumbers
Zinc: seafood, lean beef, poultry
Spices: ORAC or oxygen radical absorbance capacity is a marker of how a spice serves as an antioxidant to help the brain fight off harmful free radicals and prevent oxidative stress. Here is a list of some key ones to consider: saffron (15 mg), turmeric/curcumin (500-1,000 mg/day), oregano,
Lavender, passionflower, chamomile
FOODS:
-Fish, shellfish, grass fed beef, Omega-3 eggs, poultry
-Vegetables: edamame, leafy dark greens, asparagus, avocados, onions, garlic, spinach, carrots, cucumbers, mushrooms, peas
-Fruit: Bananas, citrus fruit, berries
-Nuts, Beans, & Legumes: walnuts, almonds, beans, legumes, chick peas, pumpkin seeds, chia seeds, flax seeds
-Starches: sweet potatoes, whole grain, oats
-Oils: olive oil, walnut oil,
-Others: kombucha, kimchi, sauerkraut, greek yogurt, dark chocolate, saffron, turmeric, oregano, lavender, chamomile.
Eating Style: Mediterranean Eating Pattern
3-9 servings of vegetables
1/2-2 servings of fruit
1-13 servings of cereal (breads, grains)
Up to 8 servings of olive oil
The MEP is a plant based diet abundant in local and seasonal fruits and vegetables and other foods with minimal processing. Sweets are limited and only high quality fats are consumed. There is low to moderate dairy intake, olive oil is the dominant source of fat, protein is mainly seafood, red meat and eggs in smaller quantity. Wine is low to moderate with meals, herbs and spices are used instead of salt to add flavor to foods.