EPA + DHA Associated with 25% Lower Risk of Depressive Symptoms in US Adults

There is an extensive accumulation of studies linking low intakes of long-chain or seafood omega-3 fatty acids (seafood omega-3s) with a greater likelihood of developing depressive symptoms. Eating little or no seafood has also been associated with higher risks of this condition across several countries. Investigators have reported that the red blood cells of patients with major depressive illness have significant deficits in DHA. Further, postmortem examination of the frontal cortex in the brains of individuals who died with major depressive illness revealed that only DHA was significantly lower in these individuals compared with those not having the illness. On the positive side, supplementation of patients with depressive illness with modest amounts of EPA or both EPA and DHA has been associated with significant improvements in symptoms and quality of life in several studies. Even though not all studies have observed improvements and the quality of the studies varies, there is sufficient evidence for the American Psychiatric Association to recommend seafood omega-3s or EPA as an adjunct to existing treatments for depressive illness. These fatty acids have the advantages of being economical, free of side effects and without harm. Nevertheless, omega-3s have not been recommended as the sole treatment for this condition. Countries with Western dietary habits and low seafood intakes have higher rates of depressive illness, as reported by the World Health Organization’s World Mental Health Survey Initiative. This study described the U.S. as having the highest rate (8.3%) among 10 developed countries for the 12-month prevalence of a major depressive episode in adults 18 years of age or more. Taking the investigation of major depressive illness a step further, scientists at the University of Rochester, USA, examined in detail the relationship between fish and EPA + DHA consumption and the prevalence of depressive symptoms in the U.S. The population survey was based on data from the National Health and Nutrition Examination Survey (NHANES), a representative sampling of adults and children. It includes periodic physical examinations and interviews and has been conducted continuously since 1999. The researchers observed that total fish intake over a 30-day period was not associated with the occurrence of mild or moderate to severe depressive symptoms, no matter how much fish was consumed. However, they found that eating any breaded fish was associated with a significantly higher risk of depressive symptoms. The disadvantages of consuming breaded fish, which are usually made of lean fish and fried in fats of questionable health quality, have been reported previously. When the investigators analyzed the relationship between the consumption of EPA + DHA and the risk of depressive symptoms, intakes of these fatty acids were associated with a 25% lower likelihood of depressive symptoms. Even considering the limitations of dietary studies, this was a remarkable finding. What makes this study different from most other observational studies is that it represented all adults 20 years of age and older, regardless of their risk. Depressive illness strikes all ages, so these findings suggest that the regular consumption of seafood omega-3s is important throughout life, not just in infancy and aging.