Good nutrition is associated with improved mood. The relationship between diet and risk of developing depressed mood is probably multi-factorial. Research supports that deficiencies of select nutrients are associated with increased risk of depressed mood, including certain B vitamins, omega-3 fatty acids, vitamin D, zinc, and magnesium.
Foods rich in B-vitamins, especially folate, pyridoxine (B-6), and methyl-cobalamin (B-12) may be especially effective against depressed mood. Foods rich in B-vitamins include whole grains and dark green leafy vegetables. The B vitamins are enzyme co-factors that facilitate the synthesis of neurotransmitters implicated in mood regulation such as serotonin, dopamine, and norepinephrine.
Nutrients enhance mood through a variety of mechanisms.
Some nutrients such as zinc, magnesium and omega-3 fatty acids may promote increased the synthesis of brain-derived neurotropic factor (BDNF) which enhances neuroplasticity, resulting in greater resilience of the brain in the face of stress, which may lead to a reduced risk of depressed mood. Omega-3s and some B vitamins are known to have important anti-inflammatory and neuroprotective roles, which may also contribute to their antidepressant benefits.
More broadly, there is emerging evidence that the microbiome—which consists of microorganisms that populate the large and small intestines—may contribute to general physical and mental health through a variety of mechanisms, some of which may impact neurotransmitters and inflammatory molecules implicated in mood regulation.
The Mediterranean diet and other traditional diets are associated with reduced risk of depressed mood.
Epidemiologic studies show that individuals who consume whole foods (as opposed to processed foods and fast food diets) have reduced risk of developing the depressed mood. For example, individuals who closely adhere to a Mediterranean diet, as well as traditional diets in Norway, Japan, and China, which are rich in vegetables and fish, have a 30% lower risk of developing depressed mood than those with the lowest rate of adherence to a Mediterranean diet.
Food preferences influencing fatty acid consumption may be directly related to different rates of depressed mood when industrialized countries are compared to more traditional cultures. There is an inverse correlation between the risk of depressed mood and fish oil consumption. Countries where fish is an important part of the average diet are characterized by significantly lower rates of depressed mood and suicidality. For example, in Japan, where fish consumption is very high, only 0.12% of the population experiences depressed mood in a given year. In contrast, New Zealanders, who consume relatively little fish, report a 6% annual rate of depression.
Seafood and cruciferous vegetables have the highest 'antidepressant food scores.'
A 2018 systematic review identified 12 essential nutrients that met criteria for antidepressant efficacy: folate, iron, long-chain omega-3 fatty acids (EPA, DHA), magnesium, potassium, selenium, thiamine, vitamin A, vitamin B6, vitamin B12, vitamin C, and zinc (LaChance and Ramsey 2018). Using an FDA database, the authors then identified foods with the highest content of at least one of these nutrients.
Foods with the highest ‘antidepressant food scores’ (AFS) were bivalves such as oysters and mussels, other seafood, organ meats, leafy greens, lettuces, peppers, and cruciferous vegetables such as broccoli, cauliflower, cabbage, kale, and Brussels sprouts. It is significant that while the Mediterranean diet and other traditional diets emphasize the above foods, the average American diet is relatively deficient in nutrient-dense foods that may have significant antidepressant benefits.
Findings of a randomized controlled trial show antidepressant benefits of dietary choices.
Findings of a 12-week single-blind controlled trial of 67 individuals with depressed mood symptoms ranging from mild to severe were randomized to a diet support group versus a social support group (Jacka et al 2017). Individuals in the diet support group received seven individual one-hour sessions and were encouraged to follow diets rich in whole grains, vegetables, fruits, legumes, and low-fat dairy foods. They ate more raw unsalted nuts, fish, lean red meats, eggs, and olive oil while reducing intake of sweets, refined cereals, fried foods, processed foods, and sugary drinks.
Individuals in a control group received the same number of sessions, during which they discussed neutral topics of interest, but they didn't receive psychotherapy, lifestyle advice, or other interventions. Individuals in the diet support group demonstrated significantly greater improvement in depressed mood scores based on standardized outcome measures compared to those in the social support group. Large prospective studies are needed to confirm these findings and determine which dietary choices have optimal antidepressant effects.
Individuals struggling with depressed mood should be encouraged to optimize their diet to ensure adequate consumption of whole foods rich in nutrients that enhance brain function and have antidepressant effects.
Recent studies show that foods with the highest antidepressant benefits include oysters and mussels, other seafood, lean organ meats, leafy greens, lettuce, peppers, and cruciferous vegetables such as broccoli, cauliflower, cabbage, kale, and Brussels sprouts.
Individuals who prefer not to modify their diets with whole foods should be encouraged to take vitamins, minerals or other supplements are known to have antidepressant effects such as omega-3s, B vitamins, vitamin D, and magnesium.