Amino acid profiles in diet, plasma and human milk in Mexican rural lactating women

This study was designed to assess the relation between the amino acid patte rn consumed by marginally nourished lactating women, and the amino acid pro files in plasma and milk. Ten lactating women from a Mexican rural communit y, with an age of 19-29 (y), a postpartum time 15 (w), and a weight of 49 ( kg), were studied in a metabolic unit. Experimental diet was similar to the rural habitual diet and it was given for 10 days. On the last 4 days urine , feces, milk and blood samples were collected. Measurement of total nitrog en in urine, feces and diet, and amino acid analysis in diet, plasma and mi lk were performed. Amino acid score of the habitual diet was : Lys as a lim iting amino acid (18.5%), and Phe+Tyr (137.9%) in excess. Lys intake (21.8 +/- 4.6 mg/g protein) was lower than the consumption recommended for lactat ing women (31 mg/g protein). Nitrogen balance was -9.6 +/- 15.4 mg/kg BW/d. Total amino acid concentration in plasma was: 2212.6 +/- 176.4 mu mol/L, w here indispensable and dispensable amino acids were 33% and 67% respectivel y; the most abundant amino acids were Ala, Glu, Gly, Lys and Val; and the l ess abundant were Cys and Asp. Total amino acid concentration in milk was: 24090 +/- 1228 mu mol/L, containing 42% and 58% of indispensable and dispen sable amino acids respectively; the most abundant amino acids were Glu, Pro and Leu, and the less abundant were Cys, Trp, and Met. The results showed a correlation between the concentration of some indispensable amino acids p resent in the diet with those of milk (p<0.05). This study shows novel resu lts about amino acid relation between habitual diet, plasma and milk in rur al lactating women studied in balance conditions. (C) 1999 Elsevier Science Inc.