[Fatty acid metabolism and requirements in childhood].
The metabolism of fatty acids (FA) has a profound impact on the development of the human being. In fact, the lipidic composition of membranes may be modulated by the relative concentrations of available FA. During the last months of the fetal life, an increasing concentration of polyunsaturated very long-chain (VLC) FA is observed from the umbilical cord to the liver and the central nervous system, where they contribute to the qualitative development of the nervous membranes. Therefore, the preterm baby is at particular risk of polyunsaturated VLCFA deficiency. Among polyunsaturated VLCFA, 20:4 n-6 and 22:6 n-3 carry on fundamental roles respectively for cellular growth and visual development. The accretion of VLCFA in the human body is intense also in the term infant during the first months of life. In the period of exclusive milk-feeding fat represents 50% of the daily caloric intake, and the ketonic bodies, resulting from the incremented beta-oxidation of FA, are readily utilized as source of energy by the developing brain. Weaning is now object of study to precise both metabolic needs and dietary intakes of FA families. Recent surveys have revealed that in this period the intakes of linoleic and linolenic acid are at the lower limits of the recommended levels. No upper limit for saturated FA is advisable for the first two years of life.(ABSTRACT TRUNCATED AT 250 WORDS)