Nutrition plays a key role in brain development, mental health, and psychiatric disorders. The role of omega-3 polyunsaturated fatty acids in physical health is well established, and their role in mental health is becoming increasingly evident. Omega-3 fatty acids are involved in a wide range of physiological functions that are related to neurogenesis, neurotransmission, and neuroinflammation; therefore, they play fundamental roles in the development, functioning, and aging of the brain. In humans, dietary deficiencies of omega-3 fatty acids are associated with an increased risk of developing various psychiatric disorders, including depression, bipolar disorder, schizophrenia, dementia, attention-deficit/hyperactivity disorder, and autism. In particular, eicosapentaenoic and docosahexaenoic acid have been linked to the maintenance of mental health, and their deficits have been implicated in the pathophysiology of mental disorders. This may be mediated by the modulation of inflammatory processes and their direct effects on neuronal membrane fluidity and receptor function. However, randomized clinical trials that have investigated the therapeutic effects of omega-3 fatty acids have yielded inconclusive results, thereby limiting the use of these nutrients in psychiatric practice. High-quality clinical trials should be conducted to examine the efficacy of omega-3 fatty acids in preventing and treating mental disorders. The undesirable side effects of omega-3 fatty acid supplementation should also be considered. These effects may become apparent after many years of administration, and therefore, they may not be detected in most cases.

Variety of accessibility to edible species in different regions has climatic and historical roots. In the present study, we try to systematically analyze 28,064 records of relationships between 11,752 edible species and 228 geographic zones by hierarchical clustering. The 228 geographic regions were classified into 11 super groups named as A to K, which were further divided into 39 clusters (CLs). Of them, at least one member of each of 28 CLs is associated to 20 or more edible species according to present information of KNApSAcK DB (http://kanaya.naist.jp/KNApSAcK_World/top.jsp). We examined those 28 CLs and found that majority of the members of each of the 27 CLs (96%) have specific type of climate. Diversity of accessibility to edible species makes it possible to separate 8 geographic regions on continental landmasses namely Mediterraneum, Baltic Sea, Western Europe, Yucatan Peninsula, South America, Africa and Arabian Peninsula, Southeast Asia, and Arctic Ocean; and three archipelagos namely, Caribbean Islands, Southeast Asian Islands and Pacific Islands. In addition, we also examined clusters based on cultural exchanges by colonization and migration and mass movement of people and material by modern transportation and trades as well as biogeographic factors. The era of big data science or data intensive science make it possible to systematically understand the content in huge data and how to acquire suitable data for specific purposes. Human healthcare should be considered on the basis of culture, climate, accessibility of edible foods and preferences, and based on molecular level information of genome and digestive systems.