What is the Relationship Between Diet and Depression ?

Back in 1946 the world health organization defined the state of health as “a state of complete physical, mental and social well-being and not merely the absence of disease. “One can be in a perfect physical shape, ideal weight and absence of disease but that not necessarily means that they are healthy. Mental health can be just as important as physical health, because it appears that mental health greatly affects physical health.

A state of being healthy: a state of complete physical, mental and social wellbeing and not merely the absence of disease.Definition by the world health organization(WHO).

Depression: depression is not characterized with just sadness, it is weeks or months of such symptoms diminished interest in activities and used to be pleasurable, weight gain or weight loss, fatigue, inappropriate guilt, difficulty concentrating and thoughts of death.1

Good Mental Health: a state of good mental health does not mean absence of depression. Good mental health is associated with mental and psychological wellbeing. Be able to cope with the normal stressors of life, work load and be productively, be able to realize your potential and contribute to the community. Definition from the WHO.

Positive Phycology: positive phycology is focusing on optimal mental and physical health. There is growing amount of evidence showing that positive physiology leads to reduced risk of physical illness. Prospective studies have determined that people who started out happier do indeed end up healthier and live longer.2,3

Physiological tests to assess mood and risk for depression

  • POMS – a profile of mood states, measured levels of anxiety, depression, anger, hostility and confusion. 
  • DASS – depression and anxiety state, hopelessness, less of interest, lack of pleasure, agitation, irritability, impatience to other people.

Relationship between happiness and health

100 people were paid $ 800 to be allowed to have the flu virus dripped on their noses. Participants were evaluated based on POMS score into two groups: at good mental health and not at optimal mental health / unhappy. Researches were curious to evaluate whose immune systems is able to sustain and the virus, happy or unhappy people. Only one if five of the happy people become sick. One in three from the unhappy come down with the flu and became sickThe results show that mental health plays a role in physical health.5

Relationship between different fats and mood

A cross sectional study involving 138 participants compared vegetarians and omnivores, examined the intake of different fats and concluded that vegetarians experienced significantly less negative emotions compared to omnivores due to the lower consumption of saturated fats and the high intake of mono and polyunsaturated fats, based on POMS scoring system.

The researchers suggested that the pro-inflammatory effect of arachidonic acid, found in animal food products, inversely impacts metal health via a cascade of neuro – inflammation to the brain. Quote from the study “Possibly, the mental health of omnivores can be completely compromised by high intake of arachidonic acid. 6Intake of omge-6 fatty acid was associated with increased risk for major depression and suicide in early pregnancy according to another study. 7

Relationship between diet, mental health and productivity

Several studies were conducted in the corporate setting where employees’ diets were switched from a standard American diet to a plant-based diet. The longest study continued four months during which the results showed: greater diet satisfaction than the control group, improved digestion, increased energy, better sleep, improvement in their mental health and overall vitality.8,9

Relationship between healthy eating and pre-existing depression

A systemic review and meta-analysis concluded that healthy dietary indices are associated with much lower rate of depression.4 A lower dietary inflammatory index was associated with lower depression incidence in four longitudinal studies. High intake of processed foods leads to magnesium deficiency leading to reduced serotonin levels. Excessive calcium, glutamine and aspartate greatly worsens major depression. The questions remains what comes first bad diet leaning to depression or depression leading to bad diet. It seems as a vicious cycle depressed people consume bad diet which leads to more depressive episodes.

Relationship between diet and risk of developing new depression

A meta-analysis was conducted to evaluate the relation between dietary patterns and the risk of developing new depression. A literature research was conducted searching MEDLINE and EMBASE databases up to September 2016. In total, 21 studies from ten countries

In prospective studies, a dietary pattern characterized by a high intakes of fruit, vegetables, whole grain, fish, olive oil, low-fat dairy and antioxidants and low intakes of animal foods was associated with a decreased risk of depression.

A dietary pattern characterized by a high consumption of red and/or processed meat, refined grains, sweets, high-fat dairy products, butter, potatoes and high-fat gravy, and low intakes of fruits and vegetables is associated with an increased risk of depression. The results suggest that healthy eating pattern may decrease the risk of depression, whereas western-dietary patterns may increase the risk of depression. 12

Another meta-analysis examined whether adherence to a Mediterranean-based dietary pattern is predictive of depressive symptoms among older adults.Adherence to high quality diet, regardless of the type (Mediterranean or plant-based) was associated with lower risk for depressive symptoms over time 13

Intake of more vegetables is associated with decreased risk of depression

Higher consumption of vegetables can decrease the risk of depression by 62% according to one study. 10A review in the journal of Nutritional Neuroscience concluded that eating lots of fruits and vegetables is considered as “non-invasive, therapeutic means to support brain health.“ 11 Levels of serotonin and dopamine are controlled by an enzyme called monoamine oxidase (MAO), which breaks down dopamine and serotonin. In depressed people the low levels of the happy hormones ( dopamine and serotonin ) are caused by high levels of MAO.

Antidepressant medications are developed to block the action of MAO. Eating berries, grapes, onions and greens containing phytonutrients appear to naturally inhibits the action of MAO. In addition spices such as cloves, oregano, cinnamon and nutmegs. This may explain why plant-based diets eaters have lower levels of depressants.


  1. Facts on Mental Health.” World Health Organization. World Health Organization. Accessed September 28, 2020. https://www.who.int/news-room/facts-in-pictures/detail/mental-health.
  2. Howell, R. T. “Review: Positive Psychological Well-Being Reduces the Risk of Mortality in Both Ill and Healthy Populations.” Evidence-Based Mental Health 12, no. 2 (2009): 41–41. https://doi.org/10.1136/ebmh.12.2.41.
  3. Beezhold, Bonnie L, Carol S Johnston, and Deanna R Daigle. “Vegetarian Diets Are Associated with Healthy Mood States: a Cross-Sectional Study in Seventh Day Adventist Adults.” Nutrition Journal 9, no. 1 (2010). https://doi.org/10.1186/1475-2891-9-26.
  4. Lassale C;Batty GD;Baghdadli A;Jacka F;Sánchez-Villegas A;Kivimäki M;Akbaraly T; “Healthy Dietary Indices and Risk of Depressive Outcomes: a Systematic Review and Meta-Analysis of Observational Studies.” Molecular psychiatry. U.S. National Library of Medicine. Accessed September 28, 2020. https://pubmed.ncbi.nlm.nih.gov/30254236/.
  5. Cohen S, Doyle WJ, Turner RB, Alper CM, Skoner DP. Emotional style and susceptibility to the common cold. Psychosom Med. 2003;65(4):652-7.
  6. Beezhold, Bonnie L, Carol S Johnston, and Deanna R Daigle. “Vegetarian Diets Are Associated with Healthy Mood States: a Cross-Sectional Study in Seventh Day Adventist Adults.” Nutrition Journal 9, no. 1 (2010). https://doi.org/10.1186/1475-2891-9-26.
  7. Vaz, Juliana S, Gilberto Kac, Antonio E Nardi, and Joseph R Hibbeln. “Omega-6 Fatty Acids and Greater Likelihood of Suicide Risk and Major Depression in Early Pregnancy.” Journal of affective disorders. U.S. National Library of Medicine, January 2014. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4239694/.
  8. Katcher, Heather I., Hope R. Ferdowsian, Valerie J. Hoover, Joshua L. Cohen, and Neal D. Barnard. “A Worksite Vegan Nutrition Program Is Well-Accepted and Improves Health-Related Quality of Life and Work Productivity.” Annals of Nutrition and Metabolism 56, no. 4 (2010): 245–52. https://doi.org/10.1159/000288281.
  9. Mishra, S, J Xu, U Agarwal, J Gonzales, S Levin, and N D Barnard. “A Multicenter Randomized Controlled Trial of a Plant-Based Nutrition Program to Reduce Body Weight and Cardiovascular Risk in the Corporate Setting: the GEICO Study.” European Journal of Clinical Nutrition 67, no. 7 (2013): 718–24. https://doi.org/10.1038/ejcn.2013.92.
  10. Tsai, Alan C, Tsui-Lan Chang, and Shu-Hwang Chi. “Frequent Consumption of Vegetables Predicts Lower Risk of Depression in Older Taiwanese – Results of a Prospective Population-Based Study.” Public Health Nutrition 15, no. 6 (2011): 1087–92. https://doi.org/10.1017/s1368980011002977
  11. Gomez-Pinilla F, Nguyen TTJ. Natural mood foods: the actions of polyphenols against psychiatric and cognitive disorders. Nutr Neurosci. 2012;15(3):127-33.
  12. Li, Ye, Mei-Rong Lv, Yan-Jin Wei, Ling Sun, Ji-Xiang Zhang, Huai-Guo Zhang, and Bin Li. “Dietary Patterns and Depression Risk: A Meta-Analysis.” Psychiatry Research 253 (2017): 373–82. https://doi.org/10.1016/j.psychres.2017.04.020.
  13. Skarupski, Kimberly A., C. C. Tangney, H. Li, D. A. Evans, and M. C. Morris. “Mediterranean Diet and Depressive Symptoms among Older Adults over Time.” The journal of nutrition, health & aging 17, no. 5 (2013): 441–45. https://doi.org/10.1007/s12603-012-0437-x.