RESUMO
Nonglucose carbohydrates such as mannose and inositol are important in early growth and development, although little is known about their metabolism. Our aim in this study was to determine the plasma appearance rates (Ra) for mannose and inositol in newborns as an index of utilization and as an improved guide to supplementation practices. We studied late-preterm (n = 9) and term (n = 5) infants (median 34 wk gestation, range 33-41 wk) using a multiple isotope infusion start time protocol to determine Ra for each carbohydrate. The plasma mannose concentration [median (range)] was 69.83 (48.60-111.75) micromol/L and the Ra was 0.59 (0.42-0.98) micromol x kg(-1) x min(-1) (854 micromol x kg(-1) x d(-1)). The plasma inositol concentration was 175.74 (59.71-300.60) micromol/L and Ra was 1.06 (0.33-1.75) micromol x kg(-1).min(-1) (1521 micromol x kg(-1) x d(-1)). The Ra for mannose and inositol are >10-fold higher than the amounts a breast-fed infant typically ingests, which are approximately 6 micromol x kg(-1) x d(-1) mannose and 150 micromol x kg(-1) x d(-1) inositol. Thus, for both mannose and inositol, the newborn infant must produce these compounds from glucose at rates sufficient to meet nutritional requirements.