The early origins of food preferences: targeting the critical windows of development.

The nutritional environment to which an individual is exposed during the perinatal period plays a crucial role in determining his or her future metabolic health outcomes. Studies in rodent models have demonstrated that excess maternal intake of high-fat and/or high-sugar "junk foods" during pregnancy and lactation can alter the development of the central reward pathway, particularly the opioid and dopamine systems, and program an increased preference for junk foods in the offspring. More recently, there have been attempts to define the critical windows of development during which the opioid and dopamine systems within the reward pathway are most susceptible to alteration and to determine whether it is possible to reverse these effects through nutritional interventions applied later in development. This review discusses the progress made to date in these areas, highlights the apparent importance of sex in determining these effects, and considers the potential implications of the findings from rodent models in the human context.