Nutrition and fertility.

The first studies about fertility and nutrition date back to the 70ies and already showed a strict relation among female fertility, weight and body composition. However, the mechanisms of this connection started to be explained only after leptin's discovery. According to some authors' opinion, leptin could interact with reproductive axis at multiple sites with stimulatory effects at the hypothalamus and pituitary and stimulatory or inhibitory actions at the gonads. Leptin could play a role in other physiologic processes such as menstruation and pregnancy, and could initiate the complex process of puberty. It has been showed that conditions in which nutritional status is suboptimal, such as eating disorders, exercise induced amenhorrea, functional hypothalamic amenhorrea and polycystic ovarian syndrome, are associated with abnormal leptin levels. These conditions, are characterized by severe changes in body composition and dietary habits. Since leptin is regulated by body composition and dietary factors, (such as energy intake and macronutrient composition), a strict connection between nutritional intake and fertility regulated by leptin is confirmed. This review focuses on the current knowledge about nutritional factors that influence leptin levels. Since clinical and subclinical nutritional imbalance can determine the development and the maintenance of neuroendocrine and metabolic aberrations, studies on fertility need a deeper attention about dietary habits and nutritional status.