Omega-3 Fatty Acids and Depression: Scientific Evidence and Biological Mechanisms

Abstract

The changing of omega-6/omega-3 polyunsaturated fatty acids (PUFA) in the food supply of Western societies occurred over the last 150 years is thought to promote the pathogenesis of many inflammatory-related diseases, including depressive disorders. Several epidemiological studies reported a significant inverse correlation between intake of oily fish and depression or bipolar disorders. Studies conducted specifically on the association between omega-3 intake and depression reported contrasting results, suggesting that the preventive role of omega-3 PUFA may depend also on other factors, such as overall diet quality and the social environment. Accordingly, tertiary prevention with omega-3 PUFA supplement in depressed patients has reached greater effectiveness during the last recent years, although definitive statements on their use in depression therapy cannot be yet freely asserted. Among the biological properties of omega-3 PUFA, their anti-inflammatory effects and their important role on the structural changing of the brain should be taken into account to better understand the possible pathway through which they can be effective both in preventing or treating depression. However, the problem of how to correct the inadequate supply of omega-3 PUFA in the Westernized countries' diet is a priority in order to set food and health policies and also dietary recommendations for individuals and population groups.

Focus on fatty acids in the neurometabolic pathophysiology of psychiatric disorders

“…Similar to the above cross-sectional data, prospective studies on the relationship between fatty acids and depression show substantial heterogeneity (Lucas et al 2011;Grosso et al 2014;Matsuoka et al 2017). Although other fatty acid classes have also been prospectively studied, most studies again focused on omega-3 fatty acid concentrations or intake.…”

“…Over the past 100-150 years, the ratio of omega-6 to omega-3 fatty acids in our modern Western diets has shown a steep increase from~1-2:1 to~20-30:1. Although alternative explanations have also been suggested (Dehue 2008;Bracke et al 2016), this may have contributed to a suggested parallel rise in burden of disease due to psychiatric disorders (Simopoulos 1999;Muskiet 2010;Hidaka 2012;Grosso et al 2014;van Elst et al 2014). Similar observations in more recently modernizing countries could suggest that history repeats itself (Sun and Ryder 2016).…”

“…This essential nature could underlie several lines of epidemiological evidence suggesting an inverse association between dietary omega-3 fatty acid intake and the prevalence of psychiatric disorders. A first hint of this inverse association was provided in 1998 by ecological evidence showing a lower prevalence of psychiatric disorders in countries where more (fatty) fish is being consumed, the main dietary source of fatty acids (Hibbeln 1998;Hibbeln 2002;Grosso et al 2014). Later, more detailed cross-sectional studies largely supported this ecological evidence (Grosso et al 2016;Li et al 2016).…”

“…Interestingly, historical epidemiological data also suggest an association between an increase in psychiatric disorder prevalence and a decrease in omega-3 fatty acid intake -together with a relative increase in omega-6 fatty acid intake (Grosso et al 2014). Over the past 100-150 years, the ratio of omega-6 to omega-3 fatty acids in our modern Western diets has shown a steep increase from~1-2:1 to~20-30:1.…”

Omega -3 Fatty Acid for Cardiovascular Prevention

“…These effects are often evidenced by improvements in disease biomarker profiles or in health-related outcomes. As a result, they may play an important role to protect against cardiovascular morbidity and mortality, and might be beneficial in rheumatoid arthritis, diabetes, inflammatory diseases, childhood learning and behaviour, cancer prevention, and adult psychiatric and neurodegenerative illnesses [7,[19][20][21][22][23][24]. It has been shown recently that Omega-3 can protect myocardial infarction (MI) from ischemia/reperfusion injury in an isolated rat heart model [25] and promote early metabolic recovery after coronary artery bypass grafting (CABG) surgery [26].…”