METHIONINE SUPPLEMENTATION OF SOYA PRODUCTS - EFFECTS ON NITROGEN-BALANCE PARAMETERS

Soybean protein is one of the best quality foods available. Contributi on of soy to human nutrition increases because of its overall positive nutritional profile, low cost, high protein and excellent functional properties. Addition of methionine to rat soybean diets improve biolog ical value of soy protein. Few studies on methionine fortification of soya protein were carried in infants, but fortification of baby formul as with this amino acid is usually found. This study was carried out t o demonstrate in malnourished children that the effect of methionine s upplementation of soya milk and soy isolated protein, as well as to co mpare with their results to cows' milk. A total of 30 malnourished chi ldren, 1 to 3 years old, admitted to our metabolic unit and distribute d in groups of 6 children were studied. They were fed experimental for mulas with cows' milk, soya milk, soya milk plus methionine, soya isol ated and soya isolated plus methionine. Nutrient compositions of formu las were calculated to be similar to mothers' milk. DL-methionine, 1.5 g per 100 g protein content was added to soya milk and soya isolated formulas. Two nitrogen balances, 3 days each, were carried out. Fecal and urinary nitrogen, serum proteins, creatinine and urea in serum and urine were followed during the study. Results showed differences of i ntake and retention of nitrogen between some of the groups, but there were no statistically significant differences on protein absorption in the groups. No differences were demonstrated in serum proteins, total nitrogen and other serum and urine parameters analyzed. Cows' milk fe d children presented the highest nitrogen retention in both balance st udies. The addition of methionine to the soya milk formula increased t he nitrogen retention, not reaching the cows' milk levels and did not have the same effect when added to the isolate soy protein.