Corinne M. Montandon

Human Milk Protein Does Not Limit Growth of Breast-Fed Infants

BACKGROUND The efficiency with which breast- and formula-fed infants utilize dietary nutrients is likely to provide insight into their relative requirements for the growth process. METHODS We measured longitudinal changes in growth, body composition, and dietary intakes in breast- and formula-fed infants and estimated the gross efficiency with which dietary nitrogen and energy were used for lean body mass and body fat deposition. Lean body mass and body fat were determined in 10 breast-fed and 10 formula-fed infants at 6-week intervals during the first 24 weeks of life by the 18O dilution technique. Dietary nitrogen and energy intakes were determined from the amount of milk and food consumed and the nutrient content of the feedings. The gross efficiency of nutrient utilization was calculated for each infant from the cumulative dietary intake and the change in body composition with time. RESULTS Length and weight gains and lean body mass and body fat accretion during the first 24 weeks of life were similar between breast- and formula-fed infants despite significantly higher nitrogen and energy intakes of the formula-fed group. The gross efficiency of dietary nitrogen utilization for lean body mass deposition was almost two-fold lower in formula- than in breast-fed infants, whereas the efficiency of dietary energy utilization for lean body mass and body fat deposition was similar between groups. Despite apparent differences in the efficiency of nitrogen utilization, there was no association between lean body mass deposition and dietary protein intake, implying that human milk protein does not limit growth quantitatively in breast-fed infants. CONCLUSIONS These differences in nutrient utilization illustrate the biologic adaptability of human infants who are equipped with mechanisms that promote normal growth despite the variability of their nutrient intake.

Marginal dietary protein restriction reduced nonprotein nitrogen, but not protein nitrogen, components of human milk.

OBJECTIVE This study was designed to determine whether marginal dietary protein intakes of lactating women alter their milk production and composition. The study followed the observation that marginal dietary protein intakes lead to significantly negative nitrogen balances in these women. METHODS Twenty-four healthy, mature lactating women were divided evenly into three groups on the basis of postpartum times; 1, 5, or 12 months. Each woman was given a controlled protein diet of either 1.5 (HP) or 1.0 (MP) g/kg body weight/day for 7 to 10 days. Milk production was measured for 72 hours by test weighing the infant before and after feeding. Milk samples from alternate breasts were collected for 24 hours, pooled, and analyzed for their protein nitrogen, nonprotein nitrogen, free and protein-bound amino acid, and lactoferrin concentrations. RESULTS Reduced dietary protein intakes were associated with a decrease (p < 0.05) in the nonprotein nitrogen and total free amino acid fractions of milk. Although urea was unaffected, the concentrations of milk free leucine, phenylalanine, histidine, and ornithine were lower (p < 0.05) in the MP than in the HP group, while the output of leucine and histidine tended to be lower in the MP group. The amount of milk produced, as well as the amounts of protein nitrogen, protein-bound amino acid, and lactoferrin and their concentrations were unaffected by a reduction of dietary protein. CONCLUSIONS Maternal milk production and the protein nitrogen, but not the nonprotein nitrogen, fraction of human milk were relatively well-preserved in the presence of a short-term, marginal reduction of dietary protein.

Formula intake of 1- and 4-month-old infants.

Summary: This study was designed to estimate energy intake in exclusively formula-fed infants. Formula intake of twenty-four 1− and 4-month-old infants was studied for 5 consecutive days; six boys and six girls were in each age group. Intake was estimated by laboratory-determined weights of formula consumed, spilled, and regurgitated. Two additional methods were used to estimate intake in the first nine infants during the 1st day of observation: test-weighing the infant at each feeding and mothers weighing of formula consumed, regurgitated, and spilled at each feeding. No consistent differences were detected among methods, but test-weighing appeared to have the greatest feed-to-feed variability. Intake was estimated to be 747 ± 100 g or 125.5 ± 17 kcal/kg, and 958 ± 131 g or 94.0 ± 13 kcal/kg for 1− and 4-month-old infants, respectively. The day-to-day variability (expressed as the coefficient of variation) was 13 and 15% (CV, g/kg) for 1− and 4-month-old infants, respectively. Between-infant variability of intake was ∼8% (CV, g/kg) for both age groups. Energy intakes of 1-month-old formula-fed infants were similar to published values of breast-fed infants of similar age, but the energy intakes of 4-month-old formula-fed infants were significantly higher than values published for 4-month-old breast-fed infants.

Glycogen storage disease: long-term follow-up of nocturnal intragastric feeding

Nocturnal intragastric feeding of patients with certain hepatic forms of glycogen storage disease has been advocated as an effective treatment, resulting in improved blood chemical values and linear growth. We are reporting the long‐term follow‐up of five patients with glycogen storage disease; three with type Ia, one with type Ib, and one with type III disease. All had improvement in one or more of the following: linear growth, serum glutamic oxaloacetate transaminase, total lipids, cholesterol, phospholipids, or triglycerides. None had significant improvement in venous CO2, serum lactate or urate. One of the patients in this study died after 1.1 years of treatment, and another patient developed hepatocellular carcinoma after 4.4 years of treatment. Nocturnal intragastric feeding, in conjunction with appropriate daytime feeding, is helpful in the management of patients with glycogen storage disease but response to treatment is variable, and it remains to be determined whether the ultimate prognosis of the diseases can be improved.

Case report: failure to thrive in a breast-fed infant is associated with maternal dietary protein and energy restriction.

OBJECTIVE To determine whether failure to thrive in a breast-fed infant could be attributed to altered milk production or composition from a mother who consumed a self-imposed energy- and protein-restricted diet. DESIGN We evaluated the changes in growth and body composition, dietary intakes, and milk production and composition in a mother-infant pair throughout the first postpartum year. SETTING The Childrens Nutrition Research Center Metabolic Research Unit. SUBJECTS A breast-feeding mother-infant pair. MEASURES OF OUTCOME Body composition was measured by total body electrical conductance, dietary intakes by food records, milk production by the test weighing procedure, and milk composition by proximate analyses. RESULTS A marked decline in the infants linear and ponderal growth rates occurred when the mother consumed an energy- (20 kcal.kg-1.d-1) and protein- (0.7 g.kg-1.d-1) restricted diet. The retardation in body weight gain was associated with an arrest of body fat, but not lean body mass, accretion. Maternal milk production showed positive relationships with maternal dietary energy (p < 0.01, r = 0.93) and protein (p < 0.05, r = 0.83) intakes. Milk composition reflected changes consistent with those of weaning rather than a sequela of the mothers diet. CONCLUSIONS We concluded that failure to thrive in a breast-fed infant could be attributed to reduced milk production in conjunction with maternal dietary energy- and protein-restriction and that an assessment of maternal dietary intakes is essential in an evaluation of the breast-fed infant with failure to thrive.

Complementation and Weaning Phases of Lactation

Breastfeeding is recommended as the best feeding choice by most major national and international agencies concerned with maternal-infant health. However, a clear consensus regarding the implementation of this recommendation is not possible because of unresolved issues concerned with the nutrient needs of infancy, maternal physiology, the use of human milk substitutes, the impact of environmental contaminants on milk consumption, and economic and social factors that affect the infant feeding choice made by the mother. There is no agreement, therefore, on the optimal duration of exclusive breastfeeding (1,2). Such guidelines, however, should be an implicit component of current feeding recommendations. The development of guidelines that best meet the needs of the weanling poses a dilemma: the premature introduction of solid foods increases the risk of infectious illnesses and the inappropriately delayed introduction of solid foods may result in stunting and wasting (3,4).

RELATIONSHIPS BETWEEN MILK PRODUCTION AND NUTRIENT INTAKE OR BODY NUTRIENT STORES IN LACTATING ADOLESCENTS. |[dagger]| 25

RELATIONSHIPS BETWEEN MILK PRODUCTION AND NUTRIENT INTAKE OR BODY NUTRIENT STORES IN LACTATING ADOLESCENTS. † 25