Nutritional psychiatry is a growing medical field that studies the connection between diet and how we feel. We intuitively understand the body-mind connection and how it affects our daily lives. We get butterflies in our stomach when we are nervous, our heart races when we’re excited, and our mood changes when we have digestive issues. This led to researchers to investigate how lifestyle changes can optimize mental and cognitive health.
Cumulative evidence shows an association between poor diets and decreased mental health, such as increases in depression. Cardiovascular deaths are a common cause of death in depressed individuals.
Alternatively, a healthy diet can promote wellness by reducing inflammation and providing essential nutrients for biochemical pathways. For example, following a Mediterranean diet is associated with a decrease in depression. As well, an increase in vegetable and fruit intake is associated with an increase in well-being and happiness scores.
Key Nutrients for Mental Health
Mood-boosting foods provide key nutrients that help with the production of neurotransmitters and bioactive molecules like serotonin, dopamine, and melatonin.
OMEGA-3s AND FATTY FISH – Omega-3s polyunsaturated fatty acids are essential parts of cellular membranes involved in neurotransmission, synaptic plasticity, and inflammation. Low levels of Omega-3s are linked to depression, suicide, and cardiovascular and inflammatory disorders. A strong negative correlation is observed between fatty fish consumption and rates of major depressive disorder, likely caused by a reduction of proinflammatory cytokines found in depressed individuals. The positive effect of Omega-3s on depressive DHA.
Dose: 200 to 2,200 mg per day of EPA Found in salmon, mackerel, tuna, herring, and sardines as well as nuts & seeds (flaxseeds, chia seeds, walnuts)
PROBIOTICS and PREBIOTICS
The gut can influence the brain via the vagus nerve and via the microbiome (the gut bacteria). When the human microbiome is exposed to the detrimental effects of a poor diet, stress, or antibiotics, its physiology changes, resulting in dysbiosis (an imbalance between beneficial and harmful bacteria) and inflammation, often linked to mental illnesses, including anxiety and depression.
We don’t often hear about the fact that intestinal microbes can produce neurotransmitters including serotonin, norepinephrine, and gamma-aminobutyric acid (aka GABA).
This gut-brain connection has led researchers to investigate the use of probiotics in mental health disorders both as a standalone therapy and as an adjunct to commonly prescribed medications.
Although the connection between the gut-brain axis and mental health is getting clinical and scientific attention, there isn’t any consensus yet regarding bacteria strain, dose, and length of intervention. The genus and species that is showing benefits are Lactobacillus (casei, acidophilus, rhamnosus, bulgaricus, brevis, helveticus, salivarius), and Bifidobacterium (longum, breve, bifidum, lactis, infantis).
Food sources with possibly beneficial bacteria: yogurt with live cultures, tempeh, miso, sauerkraut, kefir, kimchi, kombucha, buttermilk, cheddar, Gouda, and mozzarella.
Another promising approach is to introduce PREbiotics that foster the growth of beneficial bacteria.
PREbiotic-rich foods: legumes, oats, bananas, berries, garlic, onions, dandelion greens, asparagus, Jerusalem artichoke, and leeks.
TRYPTOPHAN – This is an essential amino acid for humans, and it helps form serotonin and melatonin. Lower tryptophan levels are consistently associated with a higher risk of poor mental health status. More than 90% of serotonin is manufactured in the gut, highlighting the importance between the gut microbiome composition and its impact on mental health.
Dose: 250 to 425 mg/day — it’s best to take it with a carb!
Food sources include cashews, walnuts, peanuts, almonds, seeds like sesame, pumpkin, sunflower, soybeans and wheat, rice, and corn
L-THEANINE – This amino acid is abundant in green tea and is popular due to its calming effects. Its relaxing effects have been associated with boosting key neurotransmitters that regulate mood, emotions, sleep, and cognition, and enhancing the brain waves for relaxation, focus, and creativity. Daily intake of 250 mg of L-Theanine for 8 wks has been shown to improve depression, anxiety, mood, and sleep. It’s also been shown to control blood pressure increases during high stress.
Dose: 100 to 400 mg/day
Food sources are green, black, and white teas
MAGNESIUM – Magnesium is essential for hundreds of biochemical reactions – half of the people tested showed suboptimal magnesium intake. Studies have shown a correlation between magnesium supplementation and an improvement in depressive symptoms and the promotion of a calming effect.
Dose: 300 to 420 mg/day
Food sources include leafy green vegetables, avocados, legumes, nuts, seeds, and whole grains.
ANTIOXIDANTS – Foods rich in antioxidants reduce free radicals and have been shown to improve mood, and were associated with a reduction in inflammatory markers while showing increases in antioxidative markers like vitamin C & E, lycopene, lutein, and zeaxanthin.
Food sources include most fruits (mostly berries like cranberries & strawberries), dark chocolate, vegetables, and nuts.
VITAMINS & MICRONUTRIENTS
Zinc – sources include seafood, beef, poultry, beans, nuts
Potassium – sweet potatoes, bananas, mushrooms, peas, oranges, and cucumbers
Iron – shellfish, red meat, organ meats, legumes, pumpkin seeds, broccoli, and dark chocolate
B Vitamins – legumes, citrus, bananas, avocados, leafy greens, cruciferous vegetables, asparagus, nuts, seeds, fish, and shellfish
Vitamin A-sweet potatoes, carrots, spinach, blackeye peas
Vitamin C – citrus, cantaloupe, strawberries, broccoli
Selenium – brazil nuts