Omega-3 polyunsaturated fatty acids is a generic term that encompasses eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are abundant in fish, and α-linolenic acid, which is abundant in perilla oil. These fatty acids became well known following an epidemiological study conducted in Greenland about 50 years ago. EPA formulations, with their putative prophylactic effect against cardiovascular disease, first became clinically available in the 1990s in Japan. There were reports of their association with mental health, especially depression, and from around the year 2000 several epidemiological studies and clinical trials were conducted. This article introduces the epidemiological studies and clinical trials conducted in Japan and the knowledge gained.
Keywords: clinical trials; depression; epidemiological studies; omega-3 polyunsaturated fatty acids.