Though a variety of lifestyle factors play a role in mental health, emerging research suggests that dietary patterns and food choices play a significant role in the prevention and treatment of brain-based disorders, specifically depression. No single nutrient or eating plan can cure depression, but the creators of the Antidepressant Food Score have aimed to classify foods and eating patterns best suited to alleviate its development and symptoms. 

Understanding the relationship between diet and depression

Though diet may not cause a direct improvement in mood or depressive symptoms, it can certainly play an important role in mental health. Recent studies have explored the relationship between the intake of individual foods and nutrients and their roles in the etiology of mental health ailments, including depression.[1] In fact, an entire field of medicine (called nutritional psychology) has evolved from evidence that dietary improvements may provide efficacious and accessible treatment for the management of depression.[2] 

The first nutritional guidelines to prevent depression were published in 2018. They recommend following a traditional dietary pattern like the Mediterranean diet, eating foods high in omega-3 fatty acids, and limiting the intake of processed foods high in refined carbohydrates or sugar. [3] The first randomized controlled trial to analyze this diet/depression relationship found that the symptoms of people with moderate-to-severe depression improved significantly when they adhered to this type of eating pattern.[4] The current theory is that such a diet reduces low-grade systemic inflammation, which is commonly seen in individuals with depression.[3] 

What is the Antidepressant Food Score?

The nutritional guidelines for depression prevention were informed by the Antidepressant Food Score (AFS). The AFS was created to identify the most nutrient-dense foods to prevent and promote recovery from depressive disorders and symptoms. [1] The AFS is the first nutrient profiling system created to inform dietary recommendations concerning mental health. This evidence-based approach is based on the density of Antidepressant Nutrients—nutrients shown to be beneficial for the prevention or treatment of depressive disorders in humans. 

Out of the 34 essential nutrients in the diet, 12 are used to establish the Antidepressant Food Score: Omega-3 fatty acids (EPA and DHA), folate, thiamin, vitamin B6, vitamin B12, vitamin C, vitamin A, iron, zinc, selenium, magnesium, and potassium.

• Omega-3 fatty acids (EPA and DHA): Omega-3 fatty acids are some of the basic building blocks of nerve cell membranes and are therefore essential for proper nervous system function. EPA and DHA have anti-inflammatory properties that can play a role in the prevention and treatment of mood disorders.[5]
• B Vitamins - Folate, thiamin, B6, and B12: Vitamin B12 and other B vitamins play roles in producing brain chemicals that influence mood and other brain functions. Low levels of B12 and other B vitamins such as vitamin B6 and folate may be associated with depression.
• Vitamin C and A: Many micronutrients are known for their antioxidant properties. Vitamin C and Vitamin A have strong antioxidant capacities that may have a positive influence on neural pathways.[6]
• Iron: Iron plays a critical role in proper brain neurochemistry. Iron deficiency has been associated with cognitive alterations in adolescents. [7]
• Zinc and selenium: Zinc is important for brain health and the regulation of neurotransmitter pathways. Both zinc and selenium have high antioxidant activity and protect the body from oxidative stress.[7,8]
• Magnesium: Magnesium is a key mineral for optimal brain function. It is considered to be an “anti-stress” mineral because it works to calm the nerves and relax the muscles.
• Potassium: Low blood potassium levels may disrupt the signals that help maintain optimal brain function. However, the link between potassium deficiency and mood disorders remains unclear.[9]

Which foods rank highest in Antidepressant Nutrients?

While animal foods including oysters, mussels, and other shellfish score high on the AFS, plant foods contain the highest density of Antidepressant Nutrients. However, instead of specific foods, creators of the AFS recommend that clinicians and patients managing depression focus on specific food categories.

• Animal foods: bivalves such as oysters and mussels, various kinds of seafood, and organ meats. 
• Plant-based foods: leafy greens, lettuces, peppers, and cruciferous vegetables

Evidence from meta-analyses also shows that diets rich in fruit, vegetables, whole grains, pulses, nuts, and seeds are associated with a reduced risk for depression in observational studies.[5]

Overall dietary pattern appears to have the greatest influence on depressive disorders and symptoms

Epidemiological studies have repeatedly found that “traditional” or “whole foods” dietary patterns similar to the Mediterranean Diet are significantly correlated with a decreased prevalence and incidence of depressive disorders or symptoms.[1] The Mediterranean Diet is a way of eating that is similar to the cuisine of countries along the Mediterranean Sea. While there is no one definition of the Mediterranean diet, it is high in vegetables, fruits, whole grains, beans, nuts and seeds, and olive oil—many of which score high on the AFS. Recent studies report that a Mediterranean Diet can reduce depressive symptoms and improve rates of remission among patients.[5,6] 

• Daily consumption of vegetables, fruits, whole grains, and omega-3s
• Weekly intake of fish, poultry, beans, and eggs
• Moderate portions of dairy products
• Limited intake of red meat

One four-year study of 10,094 university students found that subjects with the highest adherence to a Mediterranean diet pattern had more than a 30% reduced risk of developing depression over the study term compared to those with the lowest adherence to the diet.[6] The observed differences demonstrate great promise for the role diet plays in reducing the risk of developing depression. However, as the evidence analyzing the relationship between diet and mental health grows, additional studies are warranted to determine the use of these findings in clinical care.

A summary of food and antidepressant effects

• Symptoms of people with moderate-to-severe depression improved significantly when they adhered to a Mediterranean diet-style type of eating pattern and limit processed foods
• The Antidepressant Food Score (AFS) was created to identify the most nutrient-dense foods to prevent and promote recovery from depressive disorders and symptoms. It is based on 12 key nutrients.
• Among the highest-scoring AFS foods are bivalves such as oysters and mussels, various seafoods, organ meats, leafy greens, lettuces, peppers, and cruciferous vegetables.

Marianna Moore, MS

References:

[1]LaChance LR, Ramsey D. Antidepressant foods: An evidence-based nutrient profiling system for depression. World J Psychiatry. 2018 Sep 20;8(3):97-104. doi: 10.5498/wjp.v8.i3.97. PMID: 30254980; PMCID: PMC6147775.

[2]Clay, R. A. (2017, September). The link between food and mental health. Monitor on Psychology, 48(8). http://www.apa.org/monitor/2017/09/food-mental-health

[3] Opie RS, Itsiopoulos C, Parletta N, Sanchez-Villegas A, Akbaraly TN, Ruusunen A, Jacka FN. Dietary recommendations for the prevention of depression. Nutr Neurosci. 2017 Apr;20(3):161-171. doi: 10.1179/1476830515Y.0000000043. Epub 2016 Mar 2. PMID: 26317148.

[4] Jacka, F.N., O’Neil, A., Opie, R. et al. A randomised controlled trial of dietary improvement for adults with major depression (the ‘SMILES’ trial). BMC Med 15, 23 (2017). https://doi.org/10.1186/s12916-017-0791-y

[5]Ventriglio, A., Sancassiani, F., Contu, M. P., Latorre, M., Di Slavatore, M., Fornaro, M., & Bhugra, D. (2020). Mediterranean Diet and its Benefits on Health and Mental Health: A Literature Review. Clinical practice and epidemiology in mental health : CP & EMH, 16(Suppl-1), 156–164. https://doi.org/10.2174/1745017902016010156

[6]Sánchez-Villegas A, Delgado-Rodríguez M, Alonso A, et al. Association of the Mediterranean Dietary Pattern With the Incidence of Depression: The Seguimiento Universidad de Navarra/University of Navarra Follow-up (SUN) Cohort. Arch Gen Psychiatry. 2009;66(10):1090–1098. doi:10.1001/archgenpsychiatry.2009.129