The present review addresses the role of food constituents in the aeti
ology of metabolic conditions and chronic diseases, mostly related to
energy metabolism and substrate regulation, such as obesity and non-in
sulin-dependent diabetes mellitus. Second, attention is paid to malnut
rition, a major Cause of mortality and morbidity in-developing countri
es, which may be a cause of concern in Europe because of the increasin
g number of elderly people in the population. Finally, the role of die
t during exercise, a condition of enormous substrate demands, is evalu
ated. Based on a critical evaluation of the existing knowledge in the
literature; implications for future research in relation to functional
foods are discussed.