Depression is a leading cause of morbidity and mortality worldwide. First-line treatments include medications and/or therapy. Although many people find benefit in these treatments, others do not achieve full symptom relief. Furthermore, others may be burdened with side effects of antidepressant medications, even if they do help. For these reasons, there is much interest in treatments for depression that have minimal side effects, such as lifestyle modifications. Dietary patterns, for instance, have been researched as potential preventative strategies for depression, as well as adjunctive treatments to antidepressant medications and/or therapy.6 The Mediterranean Diet, in particular, has been widely studied to date. Some studies have demonstrated a decreased risk for depression in groups who adhere to the Mediterranean Diet (MedDiet).3,6,9,11 Additionally, the MedDiet has also been linked to many other health benefits, such as decreased risk of developing cardiovascular disease, cancer, type II diabetes, as well as all cause mortality and greater psychological resilience.2,3
So what exactly is the Mediterranean Diet?
The MedDiet is a dietary pattern that originates from countries bordering the Mediterranean Sea, such as Greece, Spain, and Italy. It consists of using olive oil as a main source of fat, as well as robust consumption of fruits, vegetables, legumes, and seafood. Dairy and red meats are typically minimized. In addition, wine is consumed moderately with meals, and meals are held in a social setting.
Why does the Mediterranean Diet have health benefits?
The health benefits of the MedDiet are likely due to multiple mechanisms. First of all, the MedDiet consists of quality ingredients that supply good nutrition. Frequent consumption of healthy fats, vegetables, fruits, nuts, and oily fish are thought to support brain health because they supply omega-3 fatty acids, vitamins, and minerals. In fact, studies analyzing individual nutrients, such as omega-3 fatty acids, L-methylfolate/folic acid, Vitamin D, and other nutrients, have demonstrated mood benefits in individual research studies.4,13
In addition, the MedDiet may decrease inflammation in the body, which may explain the decreased rates of cancer, cardiovascular disease, Type II diabetes, and depression in groups of people consuming this diet.3,7,11 The anti-inflammatory effect of the MedDiet may be linked, in part, to a high poly-phenol content.3,5,7 Poly-phenols are micro-nutrients from plants that have high antioxidant activity. Red wine, grapes, berries, citrus, and extra virgin olive oil have high contents of poly-phenols, and are ingredients often consumed in the MedDiet.3,5 Interestingly, inflammatory processes in the body are associated with decreased production of a compound called Brain Derived Neurotropic Factor (BDNF).1 This compound is responsible for neuronal growth and survival. It is found to be low in patients with depression.1 Data from a long-term trial investigating the effects of the MedDiet did show decreased risk of low BDNF levels in groups assigned to the MedDiet versus control.12
Lastly, the MedDiet may also exert health benefits by impacting the human microbiota, and allowing more healthy bacteria to thrive in the gut.3,7 Research demonstrates that certain microbiota profiles are linked to better health outcomes, and this includes mental health as well.8 Diets that support a healthy microbiome are typically high in fiber and whole foods, and low in processed foods. Adhering to the MedDiet would help achieve this goal.
Can the Mediterranean Diet impact depression?
There is more evidence than not to suggest that the MedDiet (or similar diets) may benefit those prone to depression. One recently published review article/meta-analysis reviewed multiple studies investigating diet and depression, and did find a link between depression risk and MedDiet.9 Specifically, the data pulled from four longitudinal studies (patients followed over time for an average of 9.1 years) showed lower risk of depression in those with the highest adherence to the MedDiet.9 This is important because a meta-analysis study quantifies results from several published studies, thus pooling data and strengthening overall power to find trends. Not all studies published to date have demonstrated a link between the MedDiet and depression, however, the overall evidence is trending towards an association.
What does this mean for you?
If you struggle from depression, you may benefit from dietary modifications, in addition to standard treatments for depression. Dietary patterns high in fruits, vegetables, whole grains, fish, legumes, antioxidants, and low in animal foods are generally associated with decreased risk of depression.10 One randomized controlled study found that a dietary support group was more effective in reducing depressive symptoms compared to patients enrolled in a social support group.6 The study participants were already receiving some form of therapy, such as psychotherapy, medications, or a combination of both. The dietary intervention included a modified Mediterranean Diet, called the ModiMed Diet. The main modification included 3-4 servings of unprocessed, lean red meat per week, in moderate portions.
Aside from this trial, common sense suggests that a healthy diet is a reasonable lifestyle modification to make. In addition to possible mental health benefits, there are many other health benefits associated with diets rich in legumes, fruits, vegetables, and fish, without much downside.1,2,3 Myriad resources are available to learn how to implement a healthy diet. For a diet specific to mental health, I recommend literature by Dr. Drew Ramsey, who is a leading psychiatrist dedicated to nutritional psychiatry. You may also benefit from consulting with a dietitian.
Works Cited
1. Bocchio-Chiavetto L., Bagnardi, V.; Zanardini, R.; Molteni, R; Nielsen, MG; Placentino, A.; Giovannini C, Rillosi L, Ventriglia M, Riva MA, Gennarelli M. Serum and plasma BDNF levels in major depression: a replication study and meta-analyses. World J Biol Psychiatry. 2010 Sep;11(6):763-73.
2. Bonaccio, M.; Di Castelnuovo, A.; Costanzo, S.; Pounis, G.; Persichillo, M.; Cerletti, C.; Donati, MB.; de Gaetano, G.; Lacoviello, L. Mediterranean-type diet is associated with higher psychological resilience in a general adult population: findings from the Moli-sani study. Eur J Clin Nutr. 2018 Jan;72(1):154-160. doi: 10.1038/ejcn.2017.150.
3. Carlos, S.; De La Fuente-Arrillaga, C.; Bes-Rastrollo, M.; Razquin, C.; Rico-Campà, A.; Martínez-González, M.A.; Ruiz-Canela, M. Mediterranean diet and health outcomes in the SUN Cohort. Nutrients. 2018 Mar 31;10(4).
4. Freeman, M.P. Omega-3 fatty acids in psychiatry: a review. Ann Clin Psychiatry. 2000 Sep;12(3):159-65.
5. Godos, J.; Castellano, S.; Ray, S.; Grosso, G.; Galvano, F. Dietary polyphenol intake and depression: results from the mediterranean healthy eating, Lifestyle and Aging (MEAL) Study. Molecules. 2018 Apr 24;23(5).
6. Jacka, F.; 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.; and Berk, M. A randomised controlled trial of dietary improvement for adults with major depression (the ‘SMILES’ trial). BMC Medicine. 2017 Jan 30;15(1):23.
7. Martínez-González, MÁ .; Ruiz-Canela, M.; Hruby, A.; Liang, L.; Trichopoulou, A.; Hu, F.B. Intervention trials with the mediterranean diet in cardiovascular prevention: Understanding potential mechanisms through metabolomic profiling. J Nutr. 2016 Mar 9.
8. Mörkl, S.; Wagner-Skacel, J.; Lahousen, T.; Lackner, S.; Holasek, S.J.; Bengesser, S.A.; Painold, A.; Holl, A.K.; Reininghaus, E. The role of nutrition and the gut-brain axis in psychiatry: A review of the literature. Neuropsychobiology. 2018 Sep 17:1-9.
9. Lassale, C., Batty, G. D.; 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. 2018 Sept 26 (e-published).
10. Li, Y.; Lv, M.R.; Wei, Y.J.; Sun, L.; Zhang, H.G.; Li, B. Dietary patterns and depression risk: a meta-analysis. Psychiatry Res. 2017, 253, 373-382.
11. Sánchez-Villegas, A.; Martínez-González, M.A.; Estruch, R.; Salas-Salvadó, J.; Corella, D.; Covas, M.I.; Arós, F.; Romaguera, D.; Gómez-Gracia, E.; Lapetra, J.; Pintó, X.; Martínez, J.A.; Lamuela-Raventós, R.M.; Ros, E.; Gea, A.; Wärnberg, J.; Serra-Majem, L. Mediterranean dietary pattern and depression: the PREDIMED randomized trial. BMC Med. 2013 Sep 20;11:208.
12. Sánchez-Villegas, A.; Galbete, C.; Martinez-González, M.A.; Martinez, J.A.; Razquin, C.; Salas-Salvadó, J.; Estruch, R.; Buil-Cosiales, P.; Martí, A. The effect of the Mediterranean diet on plasma brain-derived neurotrophic factor (BDNF) levels: the PREDIMED-NAVARRA randomized trial. Nutr Neurosci. 2011 Sep;14(5):195-201.
13. Sarris, J.; Murphy, J.; Mischoulon, D.; Papakostas, G.I.;, Fava, M.; Berk, M.; Ng, C.H. Adjunctive nutraceuticals for depression: A systematic review and meta-analyses. Am J Psychiatry. 2016 Jun 1;173(6):575-87.