Enhanced-calorie formulas: considerations and options

The Role of Dietary Fats in the Development and Prevention of Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a significant cause of mortality and morbidity in preterm infants. The pathogenesis of NEC is not completely understood; however, intestinal immaturity and excessive immunoreactivity of intestinal mucosa to intraluminal microbes and nutrients appear to have critical roles. Dietary fats are not only the main source of energy for preterm infants, but also exert potent effects on intestinal development, intestinal microbial colonization, immune function, and inflammatory response. Preterm infants have a relatively low capacity to digest and absorb triglyceride fat. Fat may thereby accumulate in the ileum and contribute to the development of NEC by inducing oxidative stress and inflammation. Some fat components, such as long-chain polyunsaturated fatty acids (LC-PUFAs), also exert immunomodulatory roles during the early postnatal period when the immune system is rapidly developing. LC-PUFAs may have the ability to modulate the inflammatory process of NEC, particularly when the balance between n3 and n6 LC-PUFAs derivatives is maintained. Supplementation with n3 LC-PUFAs alone may have limited effect on NEC prevention. In this review, we describe how various fatty acids play different roles in the pathogenesis of NEC in preterm infants.

Nutritional Management for Intolerance to Human Milk Fortifier in a Preterm Small-for-Gestational-Age Infant: a Case Report

Adequate nutrition is extremely crucial for the growth and development of preterm, small-for-gestational-age (SGA) infants owing to an increased risk of postnatal growth failure and poor neurodevelopmental outcome. Despite the beneficial properties of human milk (HM), it should be fortified to prevent extrauterine growth restriction; however, fortification of HM with a bovine-based human milk fortifier (BHMF) may induce feeding intolerance (FI) and necrotizing enterocolitis in preterm newborns. Herein, we have described the nutritional management of a preterm SGA newborn with intolerance to BHMF. A male infant was born at a gestational age of 32 weeks and 5 days, SGA weighing 1,490 grams (< 10th percentile). During BHMF use, he presented with symptoms of FI including abdominal distention, increased gastric residuals, and delayed enteral feeding advancement. Therefore, HM was fortified with carbohydrate powder, whey protein powder, and medium-chain triglycerides oil instead of BHMF to prevent FI and promote weight gain. Caloric density of feeds was increased once every 3 or 4 days by approximately 5 kcal/kg/day until an intake of 100 kcal/kg/day was achieved. Subsequently, his caloric and protein intake increased, growth rate improved, and full enteral feeding was achieved without any further symptom of FI. In conclusion, the symptoms of FI with BHMF in a preterm SGA neonate improved with the administration of a macronutrient fortified HM without compromising his enteral feed advancements, growth rate, and energy or protein intake.

Fat composition in infant formula contributes to the severity of necrotising enterocolitis

Necrotising enterocolitis (NEC) is a devastating disease that typically affects formula-fed premature infants, suggesting that dietary components may influence disease pathogenesis. TAG are the major fat components of infant formula, and their digestion requires pancreatic lipases, which may be naturally deficient in premature neonates. We hypothesise that NEC develops partly from the accumulation of incompletely digested long-chain TAG-containing unsaturated fatty acids within the intestinal epithelial cells, leading to oxidative stress and enterocyte damage. We further hypothesise that the administration of a formula that contains reduced TAG ('pre-digested fat') that do not require lipase action may reduce NEC severity. To test these hypotheses, we induced NEC in neonatal mice using three different fat formulations, namely 'standard fat', 'pre-digested fat' or 'very low fat', and determined that mice fed 'standard fat' developed severe NEC, which was significantly reduced in mice fed 'pre-digested fat' or 'very low fat'. The expression level of the critical fat-digesting enzyme carboxyl ester lipase was significantly lower in the newborn compared with older pups, leading to impaired fat digestion. The accumulation of mal-digested fat resulted in the significant accumulation of fat droplets within the intestinal epithelium of the distal ileum, resulting in the generation of reactive oxygen species and intestinal inflammation. Strikingly, these changes were prevented in pups fed 'pre-digested fat' or 'very low fat' formulas. These findings suggest that nutritional formula containing a pre-digested fat system may overcome the natural lipase deficiency of the premature gut, and serve as a novel approach to prevent NEC.

Nutritional assessment and therapeutic interventions for the preterm infant

All components of assessment contribute to the final decision regarding nutritional status of the infant and the nutritional therapy indicated. One parameter by itself such as nutrient intake, weight change, or a laboratory value cannot clearly determine the total nutritional state of the infant. Achieving appropriate intakes and weight gains are two excellent parameters. Laboratory values can determine if nutrition is tolerated and manipulations are indicated.