The diet, including total intake, composition and frequency is a crucial environmental factor that impacts brain plasticity. Among the highly sensitive environment-responsive structures of the brain is the hippocampus, a region fundamental for learning and memory. Contributing to this knowledge, our group has studied the impact of dietary protein deprivation, caloric restriction as well as the effects of polyphenol-rich foods in the hippocampus of adult rats and during aging. Recently, diet emerged as a possible key modulator of neurogenesis and, consequently, a possible mechanism by which nutrition may impact cognition and mental health. One of the most prevalent types of diet in young populations is the Western diet that has very poor dietary characteristics and unhealthy metabolic consequences. It presents great amounts of sugar and fat, known to adversely affect hippocampal neurogenesis, decrease the neurotrophin brain-derived neurotrophic factor (BDNF) and increase oxidative stress and neuroinflammation. In a Rat model, we will study the consequences of the Western diet on the hippocampus, particularly in neurogenesis, apoptosis and cognition. In order to extrapolate to the human adolescent period we will study young rats, where neurogenesis is very active. After the detailed description of the effects of Western diet on the hippocampus, we will search for other type of diets and dietary antioxidant compounds capable to eliminate or compensate those potential deleterious actions.