Diet and Mood Disorders 

The connection between nutrition and mental illnesses of mood is less acknowledged than the negative effect of nutritional deficiencies on physical health. In recent years, nutritional neuropsychology has indicated nutrition is inevitably intertwined with human emotion, behavior, and mood. The newly established International Society for Nutrition Psychiatry Research (ISNPR) aims to understand the relationship between nutrition, metabolism and neuropsychiatric disorders [1]. Epidemiological studies have indicated an unhealthy diet (for example, a meal regimen revolving around fast-food or refined sugar) can increase a person’s risk of depression, while a balanced, healthy diet can protect against such neuropsychiatric disorders [2,3]. 

Macromolecules such as carbohydrates are known to release insulin, which increases the uptake of most amino acids into peripheral tissues, such as muscles. Tryptophan, an amino acid usually present at low levels in the bloodstream regardless of diet, is unaffected by insulin; thus with the secretion of insulin, the ratio of tryptophan to other amino acids drastically increases [4]. Without the competition of other amino acids, tryptophan is rapidly transported across the blood-brain barrier, where it enters the central nervous system and is converted into serotonin [4]. Increases in this “feel-good hormone” is the reason why diets low in carbohydrates often precipitate anhedonic conditions such as seasonal affective disorder (SAD), premenstrual syndrome (PMS), or major depressive disorder (MDD) [4,5]. The glycemic index (GI) is a caveat of this linear association which reveals fruits and vegetables (which have a low GI) tend to provide more long-lasting positive effects on brain chemistry and mood, while the reverse is true for high GI foods, for example processed foods or those high in artificial sugar [5]. 

Many neurotransmitters, which are signal molecules that allow for “communication” between neurons, are derivatives of amino acids. Among amino acids, 12 are made in the body and 8 are acquired from dietary intake. For example, the neurotransmitters dopamine and serotonin, both of which are related to emotional well-being, are synthesized from the amino acids tyrosine and tryptophan, respectively [5]. The extracellular-regulated protein kinase (ERK) pathway has been associated with protective processes such as plasticity and resilience in neuropsychiatric disorders including bipolar disorder and MDD [6]. Using Western blot analyses, researchers found lower levels of proteins within the ERK cascade in the frontal cortex of individuals with mood disorders compared to healthy controls [6]. In a murine model, stimulation of the ERK pathway was induced through administration of lithium or valproate, two commonly used mood stabilizers in the treatment of mood disorders [6]. 

Half of neural gray matter is composed of fatty acids that must be supplied through diet. Omega-6 and omega-3 polyunsaturated fatty acids (PUFAs) are critical in regulating the biochemical aspects of cellular membranes [5]. In a 4-month, double-blind, placebo-controlled study of 30 individuals with bipolar disorder, omega-3 fatty acids improved the course of illness indicated by a significantly longer period of remission for individuals receiving omega-3 treatment compared to placebo [7]. The authors of this study speculated that since omega-3 fatty acids were known to become highly incorporated in neuronal membranes, they could inhibit signal transduction mechanisms in the human central nervous system, much like many pharmacological mood stabilizers [7]. 

In addition, active areas of research include the effect of various vitamins and minerals on mental health and mood disorders. Although certainly many caveats between diet and mood disorders remain, the foundations of nutritional neuroscience provide a preliminary basis for future, more nuanced research, and current information demonstrates the importance of a balanced diet for all aspects of health.


1. ISNPR 2019. (n.d.). International Society for Nutritional Psychiatry Research (ISNPR). Retrieved from  

2. Sánchez-Villegas, A., Toledo, E., Irala, J. de, Ruiz-Canela, M., Pla-Vidal, J., & Martínez-González, M. A. (2012). Fast-food and commercial baked goods consumption and the risk of depression. Public Health Nutrition, 15(3), 424–432.  

3. Jacka, F. N., O’Neil, A., Opie, R., Itsiopoulos, C., Cotton, S., Mohebbi, M., Castle, D., Dash, S., Mihalopoulos, C., Chatterton, M. L., Brazionis, L., Dean, O. M., Hodge, A. M., & Berk, M. (2017). A randomised controlled trial of dietary improvement for adults with major depression (The ‘smiles’ trial). BMC Medicine, 15(1), 23.  

4. Wurtman, R. J., & Wurtman, J. J. (1989). Carbohydrates and depression. Scientific American, 260(1), 68–75. 

5. Rao, T. S. S., Asha, M. R., Ramesh, B. N., & Rao, K. S. J. (2008). Understanding nutrition, depression and mental illnesses. Indian Journal of Psychiatry, 50(2), 77–82. 

6. Yuan, P., Zhou, R., Wang, Y., Li, X., Li, J., Chen, G., Guitart, X., & Manji, H. K. (2010). Altered levels of extracellular signal-regulated kinase signaling proteins in postmortem frontal cortex of individuals with mood disorders and schizophrenia. Journal of Affective Disorders, 124(1), 164–169. 

7. Stoll, A. L., Severus, W. E., Freeman, M. P., Rueter, S., Zboyan, H. A., Diamond, E., Cress, K. K., & Marangell, L. B. (1999). Omega 3 fatty acids in bipolar disorder: A preliminary double-blind, placebo-controlled trial. Archives of General Psychiatry, 56(5), 407–412.