Early feeding of preterm infants and allergic symptoms during childhood

Nutritionally mediated programming of the developing immune system

A growing body of evidence highlights the importance of a mother's nutrition from preconception through lactation in programming the emerging organ systems and homeostatic pathways of her offspring. The developing immune system may be particularly vulnerable. Indeed, examples of nutrition-mediated immune programming can be found in the literature on intra-uterine growth retardation, maternal micronutrient deficiencies, and infant feeding. Current models of immune ontogeny depict a "layered" expansion of increasingly complex defenses, which may be permanently altered by maternal malnutrition. One programming mechanism involves activation of the maternal hypothalamic-pituitary-adrenal axis in response to nutritional stress. Fetal or neonatal exposure to elevated stress hormones is linked in animal studies to permanent changes in neuroendocrine-immune interactions, with diverse manifestations such as an attenuated inflammatory response or reduced resistance to tumor colonization. Maternal malnutrition may also have a direct influence, as evidenced by nutrient-driven epigenetic changes to developing T regulatory cells and subsequent risk of allergy or asthma. A 3rd programming pathway involves placental or breast milk transfer of maternal immune factors with immunomodulatory functions (e.g. cytokines). Maternal malnutrition can directly affect transfer mechanisms or influence the quality or quantity of transferred factors. The public health implications of nutrition-mediated immune programming are of particular importance in the developing world, where prevalent maternal undernutrition is coupled with persistent infectious challenges. However, early alterations to the immune system, resulting from either nutritional deficiencies or excesses, have broad relevance for immune-mediated diseases, such as asthma, and chronic inflammatory conditions like cardiovascular disease.

Glutamine-enriched enteral nutrition in very low birthweight infants and allergic and infectious diseases at 6 years of age

In a previous randomised controlled trial, we found that glutamine-enriched enteral nutrition in 102 very low birthweight (VLBW) infants decreased both the incidence of serious infections in the neonatal period and the risk of atopic dermatitis during the first year of life. We hypothesised that glutamine-enriched enteral nutrition in VLBW infants in the neonatal period influences the risk of allergic and infectious disease at 6 years of age. Eighty-eight of the 102 infants were eligible for the follow-up study (13 died, 1 chromosomal abnormality). Doctor-diagnosed allergic and infectious diseases were assessed by means of validated questionnaires. The association between glutamine-enriched enteral nutrition in the neonatal period and allergic and infectious diseases at 6 years of age was based on univariable and multivariable logistic regression analyses. Seventy-six of the 89 (85%) infants participated, 38 in the original glutamine-supplemented group and 38 in the control group. After adjustment, we found a decreased risk of atopic dermatitis in the glutamine-supplemented group: adjusted odds ratio (aOR) 0.23 [95% CI 0.06, 0.95]. No association between glutamine supplementation and hay fever, recurrent wheeze and asthma was found. A decreased risk of gastrointestinal tract infections was found in the glutamine-supplemented group (aOR) 0.10 [95% CI 0.01, 0.93], but there was no association with upper respiratory, lower respiratory or urinary tract infections. We concluded that glutamine-enriched enteral nutrition in the neonatal period in VLBW infants decreased the risk of atopic dermatitis and gastrointestinal tract infections at 6 years of age.

Hydrolysed milk in preterm infants: an open problem

AIM

To review knowledge about the role, indications and nutritional adequacy of protein hydrolysate formulas (HF) in the preterm newborn.

METHODS

A review of the available literature was carried out.

RESULTS

No data support the use of HF for atopy prevention. HF could have a positive role in the early feeding of very-low-birthweight infants, but several concerns exist about their nutritional adequacy.

CONCLUSION

Further investigations addressing protein and mineral metabolism as well as long-term effects, including neurodevelopment, are needed.

Higher urinary excretion of essential amino acids in preterm infants fed protein hydrolysates

AIM

Protein hydrolysates have been introduced in preterm formulae, but it is not clear whether they are needed for the feeding of preterm infants. We designed a randomized, controlled trial to test the effects of a preterm formula with hydrolysed cow's milk proteins on short-term growth and urinary and plasma amino acids levels.

METHODS

Infants with a birthweight < or = 1750 g and gestational age < or = 34 wk fed a conventional preterm infant formula (formula B) or a hydrolysed formula (formula A). Weight was measured daily; length, head circumference, mid-arm circumference and total skinfold thickness were measured weekly. Blood and urine were analysed for amino acid concentrations at start, 14 and 28 d.

RESULTS

Twenty-one infants met the criteria for randomization. The daily feeding volumes were: formula A 172.8 +/- 5.6 vs formula B 170.1 +/- 2.8 ml/kg/d. Infants fed with formula A showed slower weight gain (17.4 +/- 3.4 vs 20.5 +/- 3.3 g/kg/d; p = 0.045) and lower mean change in Z-scores for weight (-0.18 +/- 0.16 vs 0.00 +/- 0.09; p = 0.009) and for head circumference (-0.06 +/- 0.13 vs 0.06 +/- 0.13; p = 0.049). After 14 d, infants receiving formula A had statistically significant higher urinary levels of essential amino acids compared to infants receiving formula B.

CONCLUSION

Our results support the hypothesis of less nutritional value of hydrolysed versus conventional preterm formulae. Higher renal excretion of essential amino acids may be one of the mechanisms involved. These findings must be confirmed by further studies with larger sample sizes and protein hydrolysates with different degrees of hydrolysis.

Nitrogen utilization and bone mineralization in very low birth weight infants fed partially hydrolyzed preterm formula

Partialy hydrolyzed formulas have been proposed for term and preterm infants, but decreased nitrogen and calcium intestinal absorption rates, together with plasma amino acid imbalances have been reported in preterm infants. We evaluated a new formula with modified nitrogen and calcium sources (glycerophosphate). During their second week of life, 16 preterm infants were randomly assigned to 1 of 2 groups: 9 were fed the new partially hydrolyzed formula and 7 a conventional formula. A nutrient balance was performed at the end of the first month of life. Amino acid concentrations and whole-body mineralization were measured at the end of study period (theoretical term). Birth weight and gestational age (mean +/- SD) were similar in the 2 groups (28.9 +/- 7.0 wks and 1,183 +/- 242 g v 27.7 +/- 1.0 wks and 1,139 +/- 162 g). Median nitrogen absorption rate (85% v 89%; P = .03) was lower in infants fed the new formula than in those fed the conventional one. After correction for difference in nitrogen intake, there was no significant difference in N retained between the 2 groups (P = .11). Plasma amino acid concentrations were also similar in the 2 groups. At theoretical term, median bone mineral content was not significantly different between the 2 groups (50 g/kg v 55 g/kg; P = .17) and it was close to the reference values obtained in term neonates just after birth. As long as nitrogen content is 10% higher in protein hydrolyzed formula than in entire protein formula, appropriate nitrogen retention, plasma amino acid profile can be achieved with the new partially hydrolyzed formula. In both groups, bone mineralization at theoretical term was close to the mineralization observed term neonates just after birth.

[Allergic colitis: clinical and morphological aspects in infants with rectal bleeding]

BACKGROUND

Recent studies indicate the importance of eosinophilis infiltrated in the rectal mucous which jointly with the clinical features can serve to establish the diagnostic of allergic colitis.

AIM

To describe prospectively, the clinical features and morphological abnormalities of the rectal mucosa in patients with rectal bleeding and clinical diagnosis of cow's milk allergy.

METHODS

Clinical features of 20 infants under 6 months of age were described. Morphological findings in rectal mucosa were compared with control group, with suspicion of congenital megacolon.

RESULTS

The mean age of the patients was 97 +/- 47 days, rectal bleeding started before 120 days in 85% of them; 40% were breastfed, 60% cow's milk formula or both. The most striking morphological feature, in 18 patients, was eosinophilic infiltration in the rectal mucosa. There was a significant statistical difference when these values were compared with control group.

CONCLUSIONS

The increased number of eosinophils in the rectal mucosa represent the most important characteristic of allergic colitis, in patients under 6 months, with rectal bleeding, when breastfed, cow's milk formula or both.

Nutritional efficacy of preterm formula with a partially hydrolyzed protein source: a randomized pilot study

BACKGROUND

Decreased nitrogen levels, calcium intestinal absorption rates, and plasma amino acid imbalances were reported for preterm infants who were fed partially hydrolyzed preterm formulas. In this pilot study, we evaluated a new formula with modified nitrogen and calcium sources.

METHODS

During their second week of life, 16 preterm infants were randomly assigned to one of two groups: 9 were fed the new partially hydrolyzed formula and 7 were fed a conventional formula. Nutrient balance was performed at the end of the first month of life. Amino acid concentrations and anthropometric parameters were measured at theoretical term.

RESULTS

Birth weight and gestational age (mean +/- SD) were similar in the two groups (28.9 +/- 7.0 weeks and 1183 +/- 242 g vs. 27.7 +/- 1.0 weeks and 1139 +/- 162 g). Median nitrogen absorption rates (85% vs. 89%; P = 0.03) and biological values (59% vs. 69%; P = 0.13) were lower for infants who were fed the new formula than for those fed the conventional formula. After correction for difference in nitrogen intake, there was no significant difference in nitrogen retained between the two groups (P = 0.11). Plasma amino acid concentrations were also similar in the two groups. Median calcium absorption tended to be higher in the new-formula group than in the conventional-formula group (54% vs. 45%, P = 0.19). At theoretical term, infants fed the conventional formula were heavier than infants fed the new formula (3559 +/- 362 g vs. 3193 +/- 384 g, P = 0.04).

CONCLUSIONS

Because nitrogen content is 10% higher in hydrolyzed-protein formula than in entire-protein formula, appropriate nitrogen retention, plasma amino acid profile, and mineral use can be achieved with the new partially hydrolyzed formula. Further studies with larger groups are needed to evaluate the effect on growth.

Extensive and partial protein hydrolysate preterm formulas: the effect on growth rate, protein metabolism indices, and plasma amino acid concentrations

BACKGROUND

The use of protein hydrolysate preterm formulas is restricted because data on their nutritional adequacy are scarce. The authors evaluated the rate of growth and indices of protein metabolism in low-birth weight infants fed extensive and partial protein hydrolysate preterm formula followed for 12 weeks.

METHODS

A total of 61 low-birth weight infants were assigned randomly to receive extensive protein hydrolysate preterm formula (EH: n = 16), partial protein hydrolysate preterm formula (PH: n = 15), and standard preterm formula (SF; n = 15), or were fed their own mother's fortified breast milk (FBM; n = 15). The infants were investigated at study entry, and at 4, 8, and 12 weeks after study entry.

RESULTS

There were no differences with respect to growth rate (weight gain, increments in length and head circumference), urea, albumin, prealbumin, transferrin, and plasma amino acid concentrations (except for tyrosine on a single occasion) according to the degree of hydrolysis. There were also no differences between groups fed hydrolyzed formulas and SF. However, several differences were found when EH and PH were compared with FBM. Weight gain from the entry to 12 weeks, serum urea at 12 weeks, and total plasma essential amino acids at 8 weeks were significantly higher in groups fed EH and PH than in those fed FBM. In addition, valine was significantly higher in groups fed PH (P < 0.05) than in the group fed FBM at 8 and 12 weeks, tyrosine was higher in EH and PH in comparison with FBM at 4 weeks, and in PH versus FBM at 12 weeks after study entry.

CONCLUSIONS

This study suggests that experimental EH and PH are at least nutritionally equivalent to SFs.

Prematurity at birth reduces the long-term risk of atopy

BACKGROUND

Antigen exposure in early life has long-lasting effects on atopic sensitization. Thus the predisposition to atopy of children born preterm can be assumed to differ from that of children born at term.

OBJECTIVE

The aim of this study was to evaluate the association between premature birth and atopy.

METHODS

At an outpatient clinic, we examined 2 groups of 10-year-old children, 72 who were born preterm (birth weight < 1500 g) and 65 who were born at term (birth weight > 2500 g). The atopy data were collected with a questionnaire, by performing skin prick testing, and by measuring the serum total IgE level, 3 allergen-specific IgE levels, the eosinophil cationic protein level, and the blood eosinophil level. The data on perinatal and neonatal events affecting the preterm children were collected from the hospital records.

RESULTS

By the age of 10 years, the children born preterm had significantly less atopy than the children born at term: 15% versus 31% of children in the 2 groups were defined as having had obvious atopy (P = .03, odds ratio 0.41, 95% CI 0.18-0.93). The mean value of total IgE level was significantly higher in the term group, 74 kU/L versus 41 kU/L (P = .02). By skin prick testing, the children born at term had positive reactions 2 to 3 times more often; 37% versus 17% of children in the groups had at least 1 positive reaction (P = .007).

CONCLUSION

Our data show that prematurity at birth is linked with a decreased long-term risk of atopic sensitization.

Enteral feeding in the preterm infant

In planning enteral feeding in the preterm infant, decisions need to be made regarding the feeding schedule, choice of milk, and the route of administration. Feeds should be commenced within a week after birth beginning with subnutritional quantities. Preterm human milk from the infant's own mother is the milk of choice. When full enteral feeding is established, supplementation with human milk fortifier is recommended. Donor human milk and preterm formula are alternatives. Early establishment of enteral nutrition and maintenance of optimal nutrition during infancy are important as dietary manipulations in preterm infants have potential long-term influences on their health, growth and neurodevelopment.

Myths and facts about breastfeeding: does it prevent later atopic disease?

Exclusive human milk feeding during the first 6 months of life, with delayed introduction of solids, is the recommended feeding for human infants. Human milk reduces the incidence and morbidity related to infection and allergy to cow's milk proteins. Dietary maternal restrictions during (late) pregnancy or lactation cannot be recommended, but may be advised in special cases. A maternal elimination diet seems more effective if associated with environmental hypoallergenic intervention(s). Milk from mothers consuming cow's milk proteins contains small amounts of beta-lactoglobulin, which appear to introduce in the majority of infants both atopic and non-atopic tolerance rather than sensitization. However, it is uncertain whether breastfeeding also reduces the incidence of later atopic disease, since its aetiology is multifactorial.

Metabolic balance studies and plasma amino acid concentrations in preterm infants fed experimental protein hydrolysate preterm formulas

The aim of this study was to investigate absorption and retention of nitrogen, fat, calcium, phosphorus and magnesium, as well as plasma amino acid concentrations in 19 preterm infants fed three experimental protein hydrolysate preterm formulas (PTHF): seven received a preterm formula based on 100% whey hydrolysate protein (PTHF1), seven other infants were fed a preterm formula based on a mixture of 78% whey and 22% casein hydrolysed protein (PTHF2) and a third group of five infants were fed the same type of protein hydrolysate (78/22) enriched with histidine (PTHF3). Metabolic balances (n = 39) and plasma amino acid concentrations (n = 12) in preterm infants fed a standard preterm formula (whey/casein: 60/40) were included as a control group. Amino acid composition of the formulas was determined after complete hydrolysis with 12 N HCl. Compared with the standard preterm formula, the use of protein hydrolysate formulas led to a decrease in nitrogen and phosphorus absorption without modification of retention. Net absorption of calcium and magnesium was not significantly different in the four groups but calcium intake necessary to obtain calcium retention similar to the standard preterm formula was higher in the infants fed the hydrolysate formulas. Plasma amino acid concentrations were related to the amino acid composition of the formulas. Compared with the standard preterm formula, all three protein hydrolysate formulas led to a significant increase in plasma threonine, and a decrease in tyrosine and phenylalanine concentrations. In addition, there was an important reduction in plasma histidine concentrations with PTHF1.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of mucosal immune function in man: potential for GI disease states

The human mucosal immune system is structurally mature and has all the necessary cellular components to generate an immune response at birth. However, in the absence of dietary antigens and bacterial flora, there are no secondary follicles in the Peyer's patches and virtually no immunoglobulin A plasma cells in the lamina propria. Reactive follicle centers develop after birth but it takes 2 years for mucosal IgA plasma cell density to reach adult levels. T cells are present in the epithelium and lamina propria at birth, albeit at a lower frequency than later in life and there are major differences in phenotype between T cells in fetal intestine and postnatal intestine. There is no information on the impact of the massive antigenic challenge at birth on the mucosal immune system. Well-documented deficiencies in the ability of the blood T cells of the neonate to produce interleukin-4 and interferon-gamma may also occur in the intestine. It is still an open question whether it is better to try to prevent immunological sensitization of the newborn by avoiding potential allergens (i.e. cow's milk), or whether early exposure (as happens when premature infants are given formula feeds) might tolerize the infant. Hydrolysed cow's milk formulae are probably less antigenic than whole cow's milk and have been widely used in the treatment of cow's milk allergy. Some thought is now being given as to whether the prophylactic use of hydrolysates can reduce cow's milk allergy in 'at-risk' infants.