Association of Protein Intake during the Second Year of Life with Weight Gain-Related Outcomes in Childhood: A Systematic Review

There is accumulating evidence that early protein intake is related with weight gain in childhood. However, the evidence is mostly limited to the first year of life, whereas the high-weight-gain-velocity period extends up to about 2 years of age. We aimed to investigate whether protein intake during the second year of life is associated with higher weight gain and obesity risk later in childhood. We conducted a systematic review with searches in both PubMed®/MEDLINE® and the Cochrane Central Register of Controlled Trials. Ten studies that assessed a total of 46,170 children were identified. We found moderate-quality evidence of an association of protein intake during the second year of life with fat mass at 2 years and at 7 years. Effects on other outcomes such as body mass index (BMI), obesity risk, or adiposity rebound onset were inconclusive due to both heterogeneity and low evidence. We conclude that higher protein intakes during the second year of life are likely to increase fatness in childhood, but there is limited evidence regarding the association with other outcomes such as body mass index or change in adiposity rebound onset. Further well-designed and adequately powered clinical trials are needed since this issue has considerable public health relevance.

Early Protein Intake Is Associated with Body Composition and Resting Energy Expenditure in Young Adults Born with Very Low Birth Weight

BACKGROUND

Suboptimal nutrition during fetal life and early childhood may be important in early programming of health and disease. Preterm infants born with very low birth weight (VLBW; <1500 g) frequently receive inadequate neonatal nutrition; the long-term consequences are poorly known.

OBJECTIVE

We evaluated the association between early macronutrient intake and body composition in young adults born with VLBW.

METHODS

We collected comprehensive information on daily nutritional intake during the initial hospital stay for 127 participants of the Helsinki Study of Very Low Birth Weight Adults. We calculated mean daily intakes of energy, protein, fat, and carbohydrate during the first 9 wk of life. At the mean age of 22.5 y, the subjects underwent measurements of weight, height, body composition by dual-energy X-ray absorptiometry, and resting energy expenditure. The associations were examined by linear regression.

RESULTS

We found that energy, protein, and fat intakes during the first 3 wk of life, all below current recommendations, predicted adult body composition. When adjusted for sex, age, birth weight SD score, and gestational age, a 1 g · kg(-1) · d(-1) higher protein intake predicted 11.1% higher lean body mass (LBM) (95% CI: 3.7%, 18.9%) and 8.5% higher resting energy expenditure (REE) (95% CI: 0.2%, 17.0%). Among those born before 28 wk of gestation, the numbers were 22.5% (95% CI: 1.9%, 47.4%) for LBM and 22.1% (95% CI: 3.6%, 44.0%) for REE. Similar associations were seen with energy (P = 0.01, P = 0.05) and fat (P < 0.01, P = 0.03) but not with carbohydrate. Energy intake was also associated with BMI (P = 0.01) and fat intake with BMI (P < 0.01) and percentage body fat (P = 0.05). The results were little changed when adjusted for prenatal and postnatal characteristics.

CONCLUSIONS

At relatively low neonatal protein intake levels, additional protein intake is reflected in a healthier body composition, accompanied by a higher metabolic rate, in young adults born with VLBW 20 y earlier.