Abstract 90

Background. Free amino acids (FAA), although quantitatively non relevant in human milk, may have local and general effects after ingestion. Aim. To investigate the concentrations of FAA in human milk during lactation and standard infant formulas. Methods. Collection of pooled breast milk (hindmilk) from all the feedings over 24 hours in 21 lactating women at colostrum, 29 at 1 month and 25 at 3 months(16 women had the milk sampled at all the three time points). Seven whey-modified starting formulas (ESPGAN indications) and 1 soy-formula have been indagated for FAA content by means of reversed phase liquid chromatography after treatment with fluoroenylmethyl-chloroformate.Results. Total FAA in human milk (mg/dL, medians and range) progressively increased (26, 8-54, at colostrum and 43, 25-63, at 3 months). Among FAA, the sum of glutamic acid and glutamine (Glu+Gln) represented the major fraction, increasing fourfold from colostrum (6, 2-15) up to 3 months(26, 9-45). In the analysed whey-formulas total FAA ranged 7-16, while 31 mg/dL were found in the soy formula. Glu+Gln range 1-2 mg/dL in all formulas.Conclusions. Breastfed and formula-fed infants have different FAA(mainly Glu+Gln) intakes possibly contributing to some functional differences.