PROTEIN-REQUIREMENTS OF INFANTS AND CHILDREN - GROWTH DURING RECOVERYFROM MALNUTRITION

Objective. To evaluate the adequacy of protein intakes now recommended as safe for infants and toddlers. Methods. Subjects were recovering m alnourished infants, age 5.3 to 17.9 months, length age (LA) 2.5 to 6. 4 months, weight age (WA) 1.5 to 5.2 months, weight/ length (W/L) 78% to 100% of National Center for Health Statistics data; and toddlers ag e 11.4 to 31.6 months, LA 6.1 to 17.9 months, WA 3.9 to 12.0 months, W /L 79% to 99%. Infants were assigned at random to formulas with 5.5% 6 .7%, or 8.0% energy as 60:40 whey:casein protein. The 5.5% was based o n FAO-WHO-UNU safe protein and average energy for ages 2.5 to 6.0 mont hs. Toddlers received 4.7% (recommended for 6 to 18 months), 6.4%, or 8.0%. Identical concentrations (weight/kcal) of other nutrients were m aintained; intakes were adjusted weekly to reach, in 90 days, the 50th percentile of weight for a LA 3 months greater than the initial one. Results. Infants consumed 125 +/- 11 (SD), 116 +/- 10, and 126 +/- 14 kcal and 1.7 +/- 0.1, 1.9 +/- 0.2, and 2.5 +/- 0.3 g protein kg(-1) d( -1); gained 2.4 +/- 0.7, 2.9 +/- 0.7, and 2.6 +/- 0.5 months in LA, an d reached a W/L of 105 +/- 5, 103 +/- 6, and 105 +/- 5% of reference. Sum of four fat-folds (Sigma, FF) grew 13.1 +/- 6.9, 10.4 +/- 4.8, and 11.7 +/- 5.3 mm to 325 +/- 5.2, 31.7 +/- 4.7, and 30.5 +/- 5.5 mm; ar m muscle areas (AMA) 57%, 51%, 70% to 1004 +/- 109, 1017 +/- 110, and 1004 +/- 116 mm(2), still low; arm fat areas (AFA) 93%, 66%, and 93% t o higher-than-normal 598 +/- 105, 610 +/- 101, and 541 +/- 116 mm(2). Regression of intake on weight gain estimated energy for maintenance activity to be 81.0 +/- 7.5 (SEM) kcal . kg(-1). d(-1), and cost of g ain (storage + metabolic cost) as 7.6 +/- 1.7 kcal/g, with no signific ant effect of % protein. Toddlers consumed 107 +/- 9, 103 +/- 12, and 105 +/- 10 kcal and 1.3 +/- 0.1, 1.6 +/- 0.2, and 2.1 +/- 0.2 g protei n . kg(-1). d(-1); gained 3.3 +/- 0.7, 2.9 +/- 0.6, and 3.3 +/- 0.7 mo nths in LA; to a W/L of 102 +/-, 102 +/- 3, and 101 +/- 4%. Sigma FF g rew 9.2 +/- 4.0, 7.4 +/- 4.3, and 6.0 +/- 3.8 to 28.9 +/- 5.2, 30.5 +/ - 3.7, and 27.0 +/- 2.7 mm; AMA 31%, 33%, and 34% to 1121 +/- 115, 112 4 +/- 110, and 1117 +/- 120 mm(2); AFA 53%, 44%, and 45% to higher-tha n-normal 578 +/- 106, 636 +/- 99, and 569 +/- 68 mm(2). Cost of mainte nance + activity was 70.8 +/- 3.8 (SEM) kcal . kg(-1). d(-1), that of weight gain 9.7 +/- 1.35 kcal/g, with no effect of % protein. Conclusi ons. Within age groups, there were no significant protein-related diff erences in growth. In both infants and toddlers, high-energy intakes r esulted in mild obesity, with lean body mass still deficient. Protein intakes two SD below the means in the lowest protein/energy cells, 1.5 g . kg(-1). d(-1) for infants and 1.1 g . kg(-1). d(-1) for toddlers, should still be safe for nearly all children of comparable biological ages.