Advances in the nutrition of preterm infants

A high-protein neonatal formula induces a temporary reduction of adiposity and changes later adipocyte physiology

The high-protein content of formula offered to low-birth weight babies is suspected to increase the risk of obesity later in life. This study assesses the immediate and subsequent effects of a protein intake in excess during suckling on hormonal and metabolic status and adipose tissue features in a porcine model of intrauterine growth restriction. Piglets were fed milk replacers formulated to provide an adequate (AP) or a high (HP) protein supply from day 2 to day 28. A subset of piglets was killed at day 28. After weaning, the remaining piglets had free access to the same solid high-fat diet until day 160. From day 2 to day 28, HP piglets had a greater daily weight gain ( P < 0.05). Relative weight of perirenal adipose tissue (PAT), adipocyte mean diameters, activities of lipogenic enzymes in PAT and subcutaneous adipose tissue (SCAT), and leptinemia were lower ( P < 0.05) in HP piglets than in AP piglets. Genes related to glucose utilization and lipid anabolism in PAT and SCAT were ( P < 0.05) or tended ( P < 0.1) to be downregulated in HP piglets. At day 160, adipocytes were enlarged, whereas lipogenic rates in adipocytes were reduced ( P < 0.05) in SCAT of HP compared with AP pigs. Percent body fat, mRNA levels of genes controlling lipid metabolism, and plasma concentrations of hormones and metabolites were similar in HP and AP pigs. In conclusion, a HP neonatal formula induced a temporary reduction of adiposity and changed adipocyte physiology at peripubertal age.

Body size from birth to adulthood and bone mineral content and density at 31 years of age: results from the northern Finland 1966 birth cohort study

The purpose of this study was to evaluate the association between body size from birth to adulthood and bone mineral content (BMC) and bone mineral density (BMD) at the age of 31 years in a longitudinal study of the Northern Finland birth cohort for 1966. Data were collected at birth, 1, 14, and 31 years. This analysis was restricted to a subsample of individuals (n =1,099) for whom the BMC (g) and BMD measurements (g/cm(2)) were performed on the distal and ultradistal radius by dual-energy X-ray absorptiometry (DXA) at the age of 31 years. Determinants of low BMC and BMD were analyzed using multivariate logistic regression. Growth retardation at birth, being underweight (BMI < or =20.0 kg/m(2)) at 31 years, and having a low calcium intake at 31 years were associated independently with low BMD at 31 years. Additionally, the proportion of subjects with low BMD was higher among those who had low standardized body weight (< or =1 SD) both at birth and at 14 years, and both at 14 and 31 years. Body weight at 31 years was the strongest associating factor of BCM at 31 years. Growth retardation at birth has long-lasting effects on adult bone mineral content and density of the distal and ultradistal radius independently of later body size, although adult body weight seems to be a most important determinant of BMC at the age of 31 years. Thinness and a low calcium intake are associated with low bone mineral content and density at 31 years of age. Further studies are needed to evaluate if these groups are at increased risk of osteoporosis in old age.

Considerations and approaches in determining the protein and energy composition of preterm infant formulas

Optimal early nutritional support is considered a crucial issue in the care of the preterm infant, particularly of those with very low- or extremely low-brithweight. Unfortunately, this goal is seldom satisfactorily attained. Several conditions such as hypoxia, acidosis, patent ductus arteriosus, drug therapy, reduced intestinal motility may interfere with an adequate nutritional delivery in the early neonatal period. Moreover, there is still concern about metabolic and intestinal tolerance of the currently suggested intakes and a lack of uniformity in the nutritional program among different NICUs. Finally, the vast majority of the available preterm formulas are not fully adequate to the real nutritional needs of these infants. Inadequate protein content and inappropriate protein energy ratio of most preterm formulas represent a matter of major concern, since there is a strict relationship between formula composition and the quantity and quality of weight gain. As a consequence there is a need of at least two milk formulas for different preterm infants: one for LBW and VLBW infants, the other for preterm infants weighing >1500 g.