In this review we discuss the concept of exposome, which consists of groups of factors interacting with one another and exerting their influence on the organism throughout its lifespan. We classified these factors into three main groups: internal environment, lifestyle, external environment. Particularly, we analyzed a dietary influence on the brain function as part of an exposome. We reviewed three types of diets, which vary in their calorie intake and lipid/carbohydrate ratio. We discussed molecular and cellular mechanisms underpinning ketogenic diet, calorie restriction and Western diet action on the brain function. We emphasized the lack of data on how food regimens influence the neuron-astrocyte communication in the brain. A separate chapter is devoted to examining the relationships between various factors of an exposome, which is often overlooked during the research. We propose a novel paradigm to study brain function from the exposome point of view, which implies the consideration of all its factors and their interaction. This complex approach will allow researchers to trace functional relationships at different levels of organization, including molecular, cellular and organ. This will allow systematization of collected data and will initiate the development of therapeutic approaches based on an individual exposome.