Protein intake and metabolism in formula-fed infants given Swedish or Italian weaning foods

Protein and growth during the first year of life: a systematic review and meta-analysis

Dietary protein intake in the first year of life might influence later growth. We conducted a systematic review to investigate the growth effects of interventions based on infant formula composition providing different amounts of protein within the first year of life of healthy term infants; in the absence of other comparable information over the investigated period, a meta-analysis further compared weight or length gain at 120 days from high- (>2.0 g/100 kcal) and low-protein (≤2.0 g/100 kcal) content formula groups. Twelve papers (n = 2275) were included and five of them (n = 677) contributed to the meta-analysis. Most studies compared a high-protein formula, a low-protein formula, and breastfeeding. Evidence from the systematic review was inconclusive due to heterogeneity in design and treatments. In the presence of modest heterogeneity but in the absence of publication bias, the weighted mean difference for weight gain at 120 days was -0.02 g/day (95% CI: -1.41, 1.45); with higher heterogeneity, the weighted MD estimate of length gain at 120 days was 0.004 cm/month (95% CI: -0.26, 0.27). Although limited and underpowered, evidence from the meta-analysis does not support the assumption that high- vs. low-protein content formulas during exclusive milk-feeding lead to different growth outcomes in the first months of life. Prospero registration number: CRD42017058535. IMPACT: The optimal amount of dietary protein that should be given to healthy full-term infants early in life is still debated. Despite heterogeneity in study design, treatments, and outcomes, this systematic review showed that there is no clear-cut effect on the growth of different amounts of protein intake from formulas or complementary feeding. Evidence from the meta-analysis based on the five articles enrolling infants <1 month of life does not support the previous assumption that high- vs. low-protein content formulas during exclusive milk-feeding lead to different growth outcomes in the first 4 months of life.

The Association of Formula Protein Content and Growth in Early Infancy: A Systematic Review and Meta-Analysis

This systematic review aimed to examine differences in growth outcomes between breastfed infants and infants fed with formula with different protein/energy ratios during the first six months of life. We conducted a systematic review in the PubMed, Web of Science, and Springer databases. Twenty clinical trials qualified for inclusion. We extracted data about the growth outcomes of infants who were exclusive breastfed or exclusively infant formula fed in the first six months and used a meta-analysis to pool the finding data. We categorized study formulas into four groups according to their protein content: <1.8, 1.8−2.0, 2.1−2.2, and >2.2 g/100 kcal. In the first month of life, growth was not different between formula- and breastfed infants. During 2−3 months of life, growth was faster in infants who consumed formulas with protein contents higher than 2.0 g/100 kcal. After 3 months, formula-fed infants grew faster than breastfed infants. Our meta-analysis indicated that the growth outcomes of infants fed with infant formula with a relatively low protein/energy ratios, compared with that a relatively high protein/energy ratio, were close to those of breastfed infants.

Protein Concentration in Milk Formula, Growth, and Later Risk of Obesity: A Systematic Review

BACKGROUND

Protein intake may influence important health outcomes in later life.

OBJECTIVE

The objective of this study was to investigate current evidence on the effects of infant formulas and follow-on formulas with different protein concentrations on infants' and children's growth, body composition, and later risk of overweight and obesity.

METHODS

In this systematic review, we searched electronic databases (including MEDLINE, Embase, and the Cochrane Library) up until November 2014 for randomized controlled trials (RCTs). Eligible studies had to include children aged 0-3 y who represented the general population and were fed cow milk-based infant formulas with variations in protein concentration. Control groups received lower-protein cow milk-based formulas (as defined by the authors). The primary outcomes were growth, overweight, obesity, and adiposity. Various time points for outcomes assessment were accepted for inclusion. If possible, a meta-analysis was performed.

RESULTS

Twelve RCTs met our inclusion criteria. Different formula protein concentrations did not affect linear growth other than a transient effect on mean length at 3 mo observed in a meta-analysis of 4 studies (mean difference, - 0.27 cm; 95% CI: -0.52, -0.02). Lower mean weight and weight z scores obtained from the infants fed lower-protein formulas were observed only from 6 to 12 mo of age. Data from one large RCT showed that consumption of a lower-protein infant formula may reduce body mass index at 12 mo of age and later (12 mo, 24 mo, and 6y) and the risk of obesity at 6 y. Effects on body composition remained unclear.

CONCLUSIONS

The current evidence is insufficient for assessing the effects of reducing the protein concentration in infant formulas on long-term outcomes, but, if confirmed, this could be a promising intervention for reducing the risk of overweight and obesity in children. In view of the limited available evidence, more studies replicating effects on long-term health outcomes are needed.

Lower protein content in infant formula reduces BMI and obesity risk at school age: follow-up of a randomized trial

BACKGROUND

Early nutrition is recognized as a target for the effective prevention of childhood obesity. Protein intake was associated with more rapid weight gain during infancy-a known risk factor for later obesity.

OBJECTIVE

We tested whether the reduction of protein in infant formula reduces body mass index (BMI; in kg/m(2)) and the prevalence of obesity at 6 y of age.

DESIGN

The Childhood Obesity Project was conducted as a European multicenter, double-blind, randomized clinical trial that enrolled healthy infants born between October 2002 and July 2004. Formula-fed infants (n = 1090) were randomly assigned to receive higher protein (HP)- or lower protein (LP)-content formula (within recommended amounts) in the first year of life; breastfed infants (n = 588) were enrolled as an observational reference group. We measured the weight and height of 448 (41%) formula-fed children at 6 y of age. BMI was the primary outcome.

RESULTS

HP children had a significantly higher BMI (by 0.51; 95% CI: 0.13, 0.90; P = 0.009) at 6 y of age. The risk of becoming obese in the HP group was 2.43 (95% CI: 1.12, 5.27; P = 0.024) times that in the LP group. There was a tendency for a higher weight in HP children (0.67 kg; 95% CI: -0.04, 1.39 kg; P = 0.064) but no difference in height between the intervention groups. Anthropometric measurements were similar in the LP and breastfed groups.

CONCLUSIONS

Infant formula with a lower protein content reduces BMI and obesity risk at school age. Avoidance of infant foods that provide excessive protein intakes could contribute to a reduction in childhood obesity. This trial was registered at clinicaltrials.gov as NCT00338689.

Methodology for longitudinal assessment of nutrient intake and dietary habits in early childhood in a transnational multicenter study

OBJECTIVES

The aim of this study was to describe developed methods for repeated longitudinal assessment of feeding habits and nutrient intakes of children in a multicenter trial in different European countries and to assess feasibility.

PATIENTS AND METHODS

Nutrient intake and dietary habits of formula-fed and breast-fed infants were assessed in 5 European countries (Belgium, Germany, Italy, Poland, and Spain). Prospective age-adapted 3-day weighed food records were used from birth to 2 years of age (1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 18, and 24 months). Standard operating procedures were developed to check each day's food record for quality. Dietitians were trained by using standardized food records. Data entry and nutrient analyses were performed with a dedicated software developed for this project.

RESULTS

Of 1368 study participants, at least one 3-day food record was available; of 25,367 1-day food records, data on quality could be evaluated. Overall, between 81% and 97% (depending on the country) of the food records had been completed with high accuracy. The implementation of solid foods and regular family foods decreased the recording quality significantly during the 2-year time course (P < 0.001). The standardized training shows coefficients of variation up to a maximum of about 41%, indicating differences in data entry.

CONCLUSIONS

The experiences gathered indicate that collecting dietary and behavioral data in a large number of infants from different cultures is a challenging but feasible task in which permanent supervision and training is vital. However, we conclude that the established methodology is suitable to obtain valuable results on current infant nutrition practice in Europe.

Protein requirements during the first year of life

The composition of human milk provides the model for estimated total protein and essential amino acid requirements during infancy. However, both the total protein content and the concentrations of individual proteins in human milk change throughout the first year of lactation. Recent reassessments of estimated requirements have resulted in lower total protein recommendations and have emphasized the provision of alpha-amino nitrogen because most nonprotein nitrogen is not used for maintenance or tissue deposition. In clinical studies, formulas containing various whey-to-casein ratios and having total protein concentrations in the range of 13-15 g/L were shown to promote adequate growth and to result in biochemical measures of protein nutritional status similar to those in breastfed infants. In the second half of infancy, human milk can provide most of the protein needed, provided a modest protein supply is obtained from weaning foods. In special situations in which greater protein intakes are desired, special preparations of protein might be needed.

Infant feeding: a critical look at infant formulas

Commercially available infant formulas serve as the best alternative to human milk when breastfeeding is not possible. Infant formulas are designed specifically to mimic the composition of human milk or the functional aspects of human milk feeding. This review highlights the issues related to the composition of infant formulas. The most hotly debated issue currently is whether to add long-chain polyunsaturated fatty acids to infant formulas. Other controversial topics include the safety and efficacy of soy-based protein formulas, protein quantity and quality as they relate to the infant's nutritional needs and feeding tolerance, and the replacement of lactose with other carbohydrate sources for specialized infant formulas. Recent modifications in the fat blend of infant formulas have led to improved fat digestibility. However, the full spectrum of benefits associated with the addition of nucleotides awaits further study. Modifications to infant formulas are made when the preponderance of scientific evidence suggests that the compositional change will better meet the nutritional needs of the infant.