World Review of Nutrition and Dietetics最新文献

Recommendations about the nutritional management of preterm infants, especially of extremely low gestational age (or extremely low birth weight) neonates, have been published by a number of pediatric and nutritional organizations. The objectives of these recommendations are to provide nutrients to approximate the rate of growth and composition of weight gain for a normal fetus of the same postmenstrual age, to maintain normal concentrations of blood and tissue nutrients, and to achieve a satisfactory functional development. Achieving these goals requires an understanding of the intrauterine growth rate to be targeted and of the nutrient requirements of preterm infants. Birth weight-based intrauterine curves should be used to monitor postnatal growth of preterm infants in neonatal intensive care units. Although primarily provided by observational studies or historic control studies, data demonstrate that growth and neurodevelopmental outcomes correlate with nutritional intake. The implementation of standardized feeding guidelines reduces nutritional practice variation and facilitates postnatal growth and improved clinical outcomes.

Human milk contains numerous immune-protective components that protect the premature infant from sepsis and necrotizing enterocolitis. Because of these protective effects, human milk is the feeding of choice for the premature infant. However, human milk does not provide adequate amounts of most nutrients for premature infants and must therefore be supplemented (fortified) with nutrients. Commercially available fortifiers provide energy and most nutrients in adequate amounts. The exception is protein, which is present in expressed milk in highly variable amounts and which is not provided in sufficient amounts by most fortifiers. Some liquid fortifiers are higher in protein content than powder fortifiers and provide adequate amounts of protein.

Most infant deaths (99%) occur in developing countries. The 14.9 million infants born prematurely (>11% of all live births) carry a particularly high mortality risk. This chapter discusses strategies to improve neonatal outcome under resource-restricted conditions, with a focus on nutritional interventions. Evidence-based interventions begin before conception with strategies to prevent and treat malnutrition among women of reproductive age, and micronutrient supplementation in pregnancy. As an example, a practically feasibly strategy of feeding very low birth weight infants in South Africa is presented. The use of parenteral nutrition can be limited by feasibility and affordability, but intravenous glucose and electrolytes should generally be provided after birth. Emphasis is put on the use of expressed own mother's milk without or with pasteurization from women without or with HIV infection, respectively, which is complemented by the use of pasteurized donor milk. If human milk fortifiers are not available, calcium and phosphate should be added, and high total daily feed volumes should be strived for, e.g. by frequent feedings. With restricted resources, human milk fortifiers or preterm formula can be used for high-risk groups such as infants with poor growth. Kangaroo mother care and breastfeeding should be actively encouraged.

Ranges of advisable nutrient intakes are presented for populations of fully enterally fed very low birth weight infants, based on current evidence and an intensive discussion with experts in July 2013. Recommended ranges of adequate nutrient intakes are expressed as amounts per kilogram body weight per day and also per 100 kcal energy intake. For many nutrients only limited evidence exists at present to precisely define quantitative ranges of adequate intakes. Future research may lead to better knowledge and modification of recommended intake values.

The microbes in the human intestinal tract interact with the host to form a 'superorganism'. The functional aspects of the host microbe interactions are being increasingly scrutinized and it is becoming evident that this interaction in early life is critical for development of the immune system and metabolic function and aberrations may result in life-long health consequences. Evidence is suggesting that such interactions occur even before birth, where the microbes may be either beneficial or harmful, and possibly even triggering preterm birth. Mode of delivery, use of antibiotics, and other perturbations may have life-long consequences in terms of health and disease. Manipulating the microbiota by use of pro- and prebiotics may offer a means for maintenance of 'healthy' host microbe interactions, but over-exuberance in their use also has the potential to cause harm. Considerable controversy exists concerning the routine use of probiotics in the prevention of necrotizing enterocolitis. This chapter will provide a brief overview of the developing intestinal microbiome and discuss the use of pro- and prebiotics in preterm infants.

Lipids provide infants with most of their energy needs. The major portion of the fat in human milk is found in the form of triglycerides, the phospholipids and cholesterol contributing for only a small proportion of the total fat. Long-chain polyunsaturated fatty acids (LC-PUFAs) are crucial for normal development of the central nervous system and have potential for long-lasting effects that extend beyond the period of dietary insufficiency. Given the limited and highly variable formation of docosahexaenoic acid (DHA) from α-linolenic acid, and because DHA is critical for normal retinal and brain development in the human, DHA should be considered to be conditionally essential during early development. In early enteral studies, the amount of LC-PUFAs administered in formula was chosen to produce the same concentration of arachidonic acid and DHA as in term breast milk. Recent studies report outcome data in preterm infants fed formula with DHA content 2-3 times higher than the current concentration. Overall, these studies show that providing larger amounts of DHA supplements is associated with better neurological outcomes and may provide other health benefits. One study further suggests that the smallest babies are the most vulnerable to DHA deficiency and likely to reap the greatest benefit from high-dose DHA supplementation. Current nutritional management may not provide sufficient amounts of preformed DHA during the parenteral and enteral nutrition periods and in very preterm/very low birth weight infants until due date and higher amounts than those routinely used are likely to be necessary to compensate for intestinal malabsorption, DHA oxidation, and early deficit. Recommendations for the healthcare provider are made in order to prevent lipid and more specifically LC-PUFA deficit. Research should be continued to fill the gaps in knowledge and to further refine the adequate intake for each group of preterm infants.

The perinatal period is critical for human development. The brain of very low birth weight (VLBW, <1,500 g) infants is particularly vulnerable to undernutrition. Enteral nutrition is of major importance for the growth and the development of the gastrointestinal tract, which depends on the amount and composition of feeds. Feeding intolerance and the risk of necrotizing enterocolitis (NEC) are key concerns with enteral nutrition in VLBW infants. Controversies exist on how to feed VLBW infants during the first weeks of life, particularly in extremely low birth weight (ELBW, <1,000 g) infants. Unreasonable concerns lead to iatrogenic malnutrition, gastrointestinal atrophy, and parenteral nutrition-related complications. Many studies in the field of nutrition during the past decade demonstrated that some feeding regimens have significant benefits. There is strong evidence that the use of human milk (HM) reduces the risk of NEC and provides major advantages in VLBW infants. The feeding of fortified HM should be promoted and HM banking should be further developed to allow access to pasteurized donor HM for VLBW infants with an insufficient intake of their own mother's milk. Early enteral feeding should be promoted soon after birth to enhance gastrointestinal maturation, growth and functional development. Continuous- or short-interval intermittent feeding seems to provide better gastrointestinal tolerance and faster achievement of full enteral feeding. Feeding advancements of 20-30 ml/kg/day in VLBW infants ≥1,000 g and of 15-25 ml/kg/day in ELBW infants are reasonable strategies. Any suspicion of feeding intolerance implies short-interval evaluation to decide whether interruption of enteral feeding or its restart after a transient interruption are appropriate. One should always strive for maintaining at least minimal enteral feeding, rather than complete interruption of enteral feeding.

There are 13 nutrients classified as vitamins: 4 'fat-soluble' and 9 'water-soluble'. All are essential to maintain healthy homeostasis and metabolic function. Preterm infants are born with low levels and reduced stores of fat-soluble vitamins. Active placental transfer of water-soluble vitamins ensures high levels at birth, but as they are not stored, levels fall rapidly. All VLBW and ELBW infants require vitamins to be provided soon after birth. Quantifying exact requirements of each vitamin which will meet the needs for all infants is difficult due to a limited evidence base. However, timely prescription of vitamin supplements and awareness of situations where delivery or uptake might be compromised will help to ensure that these vulnerable patients do not suffer from vitamin deficiencies. Multivitamin preparations are available for parenteral and enteral use. Vitamins A, C and E have important functions as antioxidants. Further research is required to understand optimal doses and routes of administration for initial and ongoing nutritional support.

Amino acids and protein are key factors for growth. The neonatal period requires the highest intake in life to meet the demands. Those demands include amino acids for growth, but proteins and amino acids also function as signalling molecules and function as neurotransmitters. Often the nutritional requirements are not met, resulting in a postnatal growth restriction. However, current knowledge on adequate levels of both amino acid as well as protein intake can avoid under nutrition in the direct postnatal phase, avoid the need for subsequent catch-up growth and improve later outcome.