Nutritional transition is an important public health issue in developing countries, where switch
from undernutrition to overnutrition/obesity is rapidly occurring, often within two or three
generations. Such transition is related to changes in lifestyle, with people having more access
to western high-caloric diets. In developing countries, settings of poverty, poor sanitation and
hygiene are still common, where children are exposed to numerous enteric pathogens, pollutants,
and other biohazards. Populations living under such adverse environments and facing the
nutritional transition may have increased risks for chronic illnesses in later life, including diabetes,
cardiovascular, and neurodegenerative diseases. This opinion paper summarizes novel findings and
recent literature addressing the nutrition transition under adverse environments, including the
gut microbiota-brain axis dysfunction and their lasting effects with deleterious consequences for
later development