Different quantities and quality of fat in milk products given to young children: effects on long chain polyunsaturated fatty acids and trans fatty acids in plasma.

UNLABELLED: In this study we compared plasma contents of long-chain polyunsaturated fatty acids (LC-PUFAs) and trans fatty acids in triglycerides (TG), phospholipids (PL) and cholesterolesters (CE) in young children fed milk diets containing different amounts of linoleic (LA) and alpha-linolenic acid (ALA). Because the diets differed in vitamin A and E content, plasma concentrations of vitamin A and E were also studied. Thirty-seven 1-y-old children were randomly assigned to one of four feeding groups: (1) low-fat milk (LF) (1.0 g cow's milk fat/dL); (2) standard-fat milk (SF) (3.5 g cow's milk fat/dL); (3) partially vegetable fat milk (PVF) (3.5 g fat/dL; 50% vegetable fat from rapeseed oil, 50% milk fat); and (4) full vegetable fat milk (FVF) (3.5 g fat/dL; 100% vegetable fat from palm-, coconut- and soybean oil). We found higher amounts of plasma LA in the FVF group than in the LF and SF groups (p < 0.001) and higher amounts of ALA in the PVF group than in the SF (p < 0.001 in TGs, p < 0.05 in CEs) and LF (p < 0.01 in PLs and CEs, p < 0.05 in TGs) groups. However, amounts of plasma arachidonic acid (AA) were similar between groups as well as the amounts of docosahexaenoic acid (DHA) in CEs and PLs. Total trans FAs were lower in CEs in the PVF and FVF groups than in the SF group (p < 0.05 SF vs PVF; p < 0.01 SF vs FVF). Plasma concentrations of alpha-tocopherol were higher in the FVF group than in the other groups (p < 0.05 FVF vs SF, p < 0.01 FVF vs SF and PVF). CONCLUSION: Children consuming milk diets containing high amounts of vegetable fat present with higher plasma LA and ALA without any effects on amounts of plasma LC-PUFA. The plasma LC-PUFA status is not adversely affected by a low-fat milk diet. AHA and DHA in plasma are not affected by the diets studied, presumably because 15-mo-old children may be able to compensate for dietary influences through endogenous LC-PUFA metabolism.

Iron-fortified and unfortified cow's milk: effects on iron intakes and iron status in young children.

UNLABELLED: Iron intakes and iron status were evaluated in 36 young Swedish children given either iron-fortified or unfortified cow's milk. All children had good iron status and had received breast milk or iron-fortified formulae during infancy. Twenty 1-y-old children were randomized to a diet with iron-fortified milk (7.0 or 14.9 mg Fe l(-1) and 16 to a diet with unfortified milk. The iron intakes in the unfortified group at 15 and 18 mo (mean +/- SD 5.19 +/- 2.29 and 5.84 +/- 1.62 mg d(-1)) were low in relation to Nordic Nutrition Recommendations, while the intakes in the iron-fortified group (10.20 +/- 2.60 and 10.87 +/- 2.79mg d(-1)) were normal in relation to recommendations. The gain (increase) from receiving fortified diet during the study period was at most [upper limit for 95% confidence interval (CI)] 2.6 g l(-1) in blood haemoglobin, 1.9 fl in mean corpuscular volume, 2.7 micromol in serum iron and 4.5% in transferrin iron saturation, and the gain (decrease) was at most (lower limit for 95% CI) 0.29g l(-1) in serum transferrin and 0.9mg l(-1) in serum transferrin receptor (TfR). None of these differences was statistically significant. There was an almost significantly higher increase in serum ferritin (1.4 times higher relation of values at the end compared with the beginning, p = 0.06) and a significantly higher (1.2; p = 0.047) decrease in TfR/ log10 ferritin ratio in the fortified group. CONCLUSION: One-year-old children starting out with good iron status given either iron-fortified or unfortified cow's milk from 12 to 18 mo maintain sufficient iron status during this period. However, children fed unfortified cow's milk have an iron intake which is low in relation to recommendations and the quantitative development of their reserve iron in iron stores seems to be weaker than that of the fortified group. The consequences of this require further study.

Fatty acid content of plasma lipid fractions, blood lipids, and apolipoproteins in children fed milk products containing different quantity and quality of fat.

BACKGROUND: Differences in fatty acid content of plasma lipid fractions and serum lipid concentrations were investigated among young children fed different milk diets composed to achieve a recommended saturated fat intake. METHODS: Thirty-eight healthy children were randomly assigned to one of four feeding groups at 12 months: 1) low-fat milk (1.0 g/dL cow's milk fat); 2) standard-fat milk (3.5 g/dL cow's milk fat); 3) partially vegetable fat milk (3.5 gtat/dL fat; 50% vegetable fat: rapeseed oil); and 4) full vegetable-fat milk (3.5 gtat/dL fat; 100% vegetable fat: palm, coconut, and soy oil). Plasma fatty acids, blood lipids, and apolipoproteins were analyzed at 15 months, and dietary intakes at 12, 15, and 18 months. RESULTS: There were significantly lower percentage contributions of saturated fatty acids in plasma triglycerides in children fed low-fat milk or milk with 50% or 100% vegetable fat than in children fed standard-fat milk. Plasma polyunsaturated fatty acid levels were significantly higher in children fed milks with vegetable fat than in children fed standard-fat milk. Plasma saturated and polyunsaturated fatty acids in triglycerides most closely reflected dietary intake. Blood lipid concentrations were lower in children fed milk with 50% vegetable fat. CONCLUSIONS: Children fed milk with 50% or 100% vegetable fat, together with high vegetable-fat and low milk-fat dairy products have lower percentages of plasma saturated fatty acids and higher percentages of polyunsaturated fatty acids than children fed standard- or low-fat milk and dairy products.

Protein intake and metabolism in formula-fed infants given Swedish or Italian weaning foods.

The aim of the study was to compare protein intake and metabolism between infants from two countries given similar infant formulae but different weaning foods. Healthy Swedish and Italian infants were studied between 3 and 12 mo. Infants in both populations were assigned to 1 of 3 infant formulae, containing 13, 15 or 18/20 g l(-1) of protein, given in addition to Swedish or Italian weaning foods. Protein intake from weaning foods was higher in Italian than in Swedish infants at 6 and 12 mo, whereas protein intake from formula at 6 mo and from formula/milk at 12 mo was similar in both populations. Plasma isoleucine, leucine, lysine, histidine and valine at 6 mo were lower in Italian than in Swedish infants fed formula with 13 g l(-1) of protein. All essential plasma amino acids were similar in Italian and Swedish groups at 12 mo. Serum urea was similar at 6 mo in corresponding formula groups, but was higher at 12 mo in the Italian than in the Swedish formula group. Serum albumin and growth were normal in both populations throughout infancy. In conclusion, formula with protein content of 13 g l(-1) seems to provide sufficient protein intake when combined with Swedish or Italian weaning foods during the second half of infancy, as indicated by normal serum albumin and normal growth. However, the bioavailability of protein and amino acids from weaning foods, in addition to their protein content, should be considered, as indicated by some indices of protein metabolism in the Italian infants.

Fat intake and metabolism in Swedish and Italian infants.

The purpose of the study was to compare fat intake and metabolism between two infant populations from Sweden and Italy given breast milk or similar infant formulas, but different weaning foods. Nutrient intake and fat metabolism were studied prospectively from 3-12 mo in 68 Swedish and 46 Italian healthy infants, breastfed or given similar infant formulas in combination with Swedish or Mediterranean weaning foods. Although nutrient intake and fat metabolism were similar at 6 mo, fat intake was lower at 12 mo in the Italian than in the Swedish formula group (p < 0.001). At 6 and 12 mo, higher dietary ratios of monounsaturated to saturated fatty acids (p < 0.01 and p < 0.001, respectively), and monounsaturated to polyunsaturated fatty acids (p < 0.05, p < 0.001) were found in the Italian than in the Swedish formula group. Total cholesterol and apolipoprotein B were lower at 6 mo (p < 0.01) in Italian breastfed infants than in Swedish ones. Lower concentrations at 6 and 12 mo of total cholesterol (p < 0.05, p < 0.05, respectively), apolipoprotein B (p < 0.05, p < 0.01) and triglycerides (p < 0.001, p < 0.01), and of apolipoprotein A1 (p < 0.01) at 12 mo, were found in the Italian formula group than in the Swedish one. In conclusion, plasma total cholesterol, apolipoprotein B and triglycerides were found to be lower in Italian infants than in Swedish infants during the second half of infancy. These findings may partly result from differences in fat compositions between Swedish and Mediterranean weaning diets and in total fat intake in late infancy. Differences in duration of breastfeeding and possibly in breast milk composition may also have influenced our results.

Macronutrient and energy intakes in young children fed milk products containing different quantities and qualities of fat and protein.

BACKGROUND: Milk is the major source of protein and saturated fats in the diet after infancy. In the present study, the effects of different fat and protein quantity as well as fat quality in milk and dairy products on nutrient intake and growth in young children were determined. METHODS: Thirty-eight healthy children were randomly assigned to one of four feeding groups at 12 months of age: 1) Low-fat milk (1.0 g fat/dl, 3.3 g protein/dl); 2) standard-fat milk (3.5 g fat/dl, 3.3 g protein/dl); 3) partially vegetable fat and protein-reduced milk (3.5 g fat/dl, 50% vegetable; 2.2 g protein/dl); and 4) full-vegetable-fat milk (3.5 g fat/dl, 100% vegetable; 3.0 g protein/dl). Nutrient intake and growth were measured at 12, 15, and 18 months. RESULTS: The protein intake was significantly reduced with the protein-reduced milks. The intake of saturated fat was significantly lower with low-fat milk (11% of energy) or milks containing vegetable fat (13%) than in standard-fat milk (19.6%). However, the total fat intake was below 30% of energy in low-fat milk, whereas the total fat intake remained more than 30% in the other groups. Energy intake and growth were similar in all groups. CONCLUSIONS: A modified milk with reduced protein content for young children results in protein intakes closer to recommendations. A modified milk with either 50% or 100% vegetable fat and dairy products with low milk fat and high vegetable fat content results in intakes of total and saturated fats closer to international recommendations, compared with standard or low-fat milk and dairy products.

Individualized protein fortification of human milk for preterm infants: comparison of ultrafiltrated human milk protein and a bovine whey fortifier.

BACKGROUND: To improve the nutritional management of pre-term infants, a new individualized human milk fortification system based on presupplementation milk protein analyses was evaluated. METHODS: In an open, prospective, randomized multicenter study, 32 healthy preterm infants (birth weights, 920-1750 g) were enrolled at a mean of 21 days of age (range, 9-36 days) when tolerating exclusive enteral feedings of 150 ml/kg per day. All infants were fed human milk and were randomly allocated to fortification with a bovine whey protein fortifier (n = 16) or ultrafiltrated human milk protein (n = 16). All human milk was analyzed for protein content before fortification with the goal of a daily protein intake of 3.5 g/kg. During the study period (mean, 24 days) daily aliquots of the fortified milk were obtained for subsequent analyses of the protein content. RESULTS: Both fortifiers were well tolerated, and growth gain in weight, length, and head circumference, as well as final preprandial concentrations of serum urea, transthyretin, transferrin, and albumin were similar in both groups. The ultimate estimated protein intake was equivalent in both groups (mean 3.1+/-0.1 g/kg per day). Serum amino acid profiles were similar in both feeding groups, except for threonine (significantly higher in the bovine fortifier group) and proline and ornithine (significantly higher in the human milk protein group). CONCLUSIONS: Protein analyses of the milk before individual fortification provides a new tool for an individualized feeding system of the preterm infant. The bovine whey protein fortifier attained biochemical and growth results similar to those found in infants fed human milk protein exclusively with the corresponding protein intakes.

Plasma lipids and apolipoproteins in breastfed and formula-fed Swedish infants.

This study was carried out to compare plasma lipid pattern in breastfed and formula-fed infants and the effects of exchanging breast milk for formula and of introducing weaning foods. Healthy infants, exclusively breastfed at least until 3 mo, were at this age randomly assigned to infant formulas with similar fat composition. Formula was gradually introduced when breastfeeding was discontinued. One group continued to breastfeed beyond 6 mo of age. All infants received the same weaning foods and were studied between 3 and 12 mo of age. Decreased plasma concentrations of total and low-density lipoprotein cholesterol (TC, LDL-C), apolipoprotein B (apo B) and A1 (p < 0.001), and of high-density lipoprotein cholesterol (p < 0.05) were found when breast milk was exchanged for formula before 6 mo. At this age plasma TC, LDL-C and apo B were lower in formula-fed than in breastfed infants (p < 0.001). These plasma lipids then increased (p < 0.01) when the intake of formula decreased and that of weaning foods increased. However, plasma TC and/or LDL-C remained lower at 12 mo in formula-fed than in breastfed infants (p < 0.05). Our results indicate that the plasma lipid profile of infants is highly responsive to the dietary nutrient intake, as indicated by the decrease in plasma lipids and apolipoproteins when breast milk was exchanged for formula and by the increase in these concentrations when the intake of weaning foods gradually increased.

Higher concentrations of serum transferrin receptor in children than in adults.

BACKGROUND: The serum transferrin receptor (TfR) concentration in adults is suggested to provide a sensitive measure of iron depletion and together with the serum ferritin concentration to indicate the entire range of iron status, from iron deficiency to iron overload. However, little is known about TfR concentrations in children. OBJECTIVE: Our objective was to compare serum TfR and ferritin concentrations and their ratios in children and adults and look for correlations between TfR concentrations and other measures of iron status. DESIGN: Our study groups were healthy 1-y-old infants (n = 36), 11-12-y-old prepubertal boys (n = 35), and 20-39-y-old men (n = 40). RESULTS: TfR concentrations were higher in infants (x; 95% reference interval: 7.8 mg/L; 4.5, 11.1) than in prepubertal boys (7.0 mg/L; 4.7, 9.2) and higher in prepubertal boys than in men (5.8 mg/L; 3.1, 8.5). Geometric mean TfR-ferritin ratios were higher in infants (316; 95% reference interval: 94, 1059) than in prepubertal boys (219; 78, 614) and higher in prepubertal boys than in men (72; 23, 223). By multiple linear regression analysis, the best predictors of TfR concentration were serum iron (P = 0.004) and log serum ferritin (P < 0.0001), both being inverse correlations (R2 = 0.32). Mean corpuscular volume, blood hemoglobin, transferrin iron saturation, transferrin, and even age seemed to not have an influence on the TfR concentration and erythropoiesis was not a determinant of TfR concentration. CONCLUSIONS: Low serum ferritin and iron concentrations, even within the normal physiologic range, result in high TfR concentrations. The lower the iron stores, the stronger the influence of ferritin on TfR. A high TfR concentration in children, especially in infants, is a response to physiologically low iron stores. Age-specific reference concentrations for TfR are needed.

Protein and amino acid metabolism in three- to twelve-month-old infants fed human milk or formulas with varying protein concentrations.

BACKGROUND: The metabolic response to different protein intakes from breast milk and/or formulas varying in protein concentrations, in combination with supplementary foods, has not been studied in infants who are in the second half of infancy. METHODS: Healthy infants, exclusively breast-fed until 3 months old, were randomly assigned to one of three groups, F13, F15, or F18, and were given formulas with 13, 15, or 18 g/l of protein, respectively. Infants breast-fed (B) and mixed-fed (M) (breast milk and formula) at 6 months formed the fourth and fifth groups. All infants received the same supplementary foods and were studied from ages 3 to 12 months. RESULTS: The concentrations of albumin, prealbumin, and transferrin were similar in all groups. At 6 months, serum and urine urea concentrations were lower in B and M, compared with urea levels in the formula-fed groups of infants. At 12 months, urine urea was lower in B + M than it was in F18. At 6 months, plasma concentrations of phenylalanine, tyrosine, and methionine were higher in all formula-fed groups; and those of valine. isoleucine, and threonine were higher in F18 and F15 than they were in B and M. Plasma concentrations of methionine, valine, and threonine were higher in F18 than in F13. At 12 months, plasma levels of tyrosine, methionine, valine, isoleucine, and leucine were higher in F18 than they were in B + M. CONCLUSION: Many indexes of protein metabolism were similar in groups F13, B, and M, particularly at 6 months. In contrast, the provision of a formula with 18 g/l of protein resulted in a different metabolic pattern, which could indicate unnecessarily high protein intakes.

Growth and nutrient intake in three- to twelve-month-old infants fed human milk or formulas with varying protein concentrations.

BACKGROUND: Results on growth and nutrient intake in infants in the second half of infancy fed human milk or formulas with varying protein concentrations in combination with supplementary foods have not previously been reported. METHODS: Seventy-one healthy infants were studied from 3 to 12 months of age. They were exclusively breast-fed until 3 months and were then randomly assigned to one of three feeding groups, F13, F15, or F18, indicating formulas with 13, 15 or 18 g/l of protein, respectively. Formula was gradually introduced when breast-feeding was terminated. Infants fed breast milk only were included in the breast-fed group, and those with breast milk and formula were included in the mixed-fed group. The same supplementary foods were provided to all infants. RESULTS: There were no differences in growth between the feeding groups. Total protein intake exceeded minimum recommendations in all groups at all ages and was higher at 6 months in F18 than in F13 (2.3 vs. 1.9 g/kg per day; p < 0.01), whereas formula protein intake was higher at all ages in F18 compared with F13. Intake of protein from supplementary foods increased, but that from formula decreased between 6 and 12 months in all groups. CONCLUSIONS: Intake of breast milk or infant formula with 13 g/l of protein along with high-protein supplementary foods provided enough protein with no adverse effect on growth. Infants fed formulas with higher protein concentrations had similar growth, despite higher intakes of formula protein.

Taurine supplementation prevents hyperaminoacidemia in growing term infants fed high-protein cow's milk formula.

Blood urea nitrogen (BUN) and plasma and urine amino acid concentrations were compared between three cohorts of healthy growing term infants who were breast-fed (BF) or randomly assigned to one of two formulas either taurine non-supplemented (FF) or taurine supplemented (FF + T). The infants were studied from 2 to 12 weeks of age. Weight gain and growth in length was normal and similar in all three feeding groups during the study interval. At 12 weeks BUN was significantly higher in the FF group than in the BF and FF + T groups, 16.5 mg/dl vs 7.0 and 7.3 mg/dl, respectively. Total plasma amino acids (FF group: 240.5 +/- 110.1 mumoles/dl; BF group 180.1 +/- 28.7 mumoles/dl; FF + T group: 182.3 +/- 89.4 mumoles/dl) and total essential amino acids (FF group: 89.8 +/- 37.3 mumoles/dl; BF group: 56.1 +/- 16.3 mumoles/dl; FF + T group: 53.0 +/- 24.2 mumoles/dl). The urine amino acid concentrations reflected the plasma levels in all groups. These results indicate that taurine supplementation to a high protein formula lowers BUN levels and the plasma urine amino acid concentrations by some yet unknown mechanism to concentrations similar to those found in breast-fed infants with a much lower protein intake.

Impact of solid food on plasma arachidonic and docosahexaenoic acid status of term infants at 8 months of age.

We studied healthy term infants at 6 and 8 months of age to assess the effect of fat-containing solid foods (mashed veal, chicken, and pork provided in ready-to-feed cans) on plasma long-chain polyunsaturated fatty acid (LCP) status. Twenty-one infants were breast-fed and 49 were formula-fed. The fat of the formula contained 16.2% linoleic acid and 2.3% alpha-linolenic acid but no LCPs. The solid-food intake was assessed with a 7-day dietary record. Blood samples were obtained at 6 and 8 months of age, and the fatty acid composition of plasma cholesteryl esters (CE) and phospholipids (PL) were analyzed with capillary gas liquid chromatography. The solid food-derived fat intake was higher in the formula-fed than in the breast-fed group at 6 months, and it increased significantly in both groups (from 0.15 to 0.39 g/kg/day and from 0.24 to 0.43 g/kg/day in breast-fed and formula-fed groups, respectively). The relative plasma concentrations of arachidonic acid (20:4n-6) and docosahexaenoic acid (22:6n-3) were significantly lower in the formula-fed than in the breast-fed group at both 6 and 8 months. In the formula-fed group at 8 months, the proportion of solid food-derived fat correlated positively with plasma 20:4n-6, and the mean percentage of PL-20:4n-6 were 8.0% (95% confidence interval, 7.4-8.5) and 9.0% (8.3-9.7) in its lowest and highest quartiles, respectively. In the breast-fed group, solid food-derived fat intake had no effect on plasma 20:4n-6. The two groups were similar in that solid-food fat had no effect on plasma PL- or CE-22:6n-3. In conclusion, the introduction of meat containing solid foods to formula-fed infants increases their plasma 20:4n-6, but not to levels found in breast-fed infants. Further studies are needed to establish an optimal fatty acid composition of solid foods during weaning.

Protein nutrition during infancy. An update.

Good nutrition is essential during the critical period of infancy to promote the child's optimal growth and development. Proteins in human milk are discussed. Protein requirement and recommended dietary intake of healthy term infants during the first 6 months are reviewed. Recommendations for protein content in infant starting formulas and weaning are also discussed.

Fortification of human milk: evaluation of a novel fortification scheme and of a new fortifier.

Human milk fed to very-low-birth-weight infants must be fortified with protein, minerals, and vitamins. We tested a new fortification regimen in which the amount of fortifier was adjusted on the basis of frequent determinations of serum urea nitrogen (SUN). A newly formulated fortifier based on bovine milk proteins was employed either in the new fashion (regimen ADJ) or in the conventional fixed proportion (regimen FIX). Using the fixed proportion, the study also compared the new fortifier with a fortifier based on human milk protein (regimen HMP). Twelve infants were studied with each of the three regimens; nearly all completed 3 weeks of study. Protein intake was generally higher in ADJ than FIX; the difference was significant (p < 0.01) during week 2. Weight gain was somewhat (but not significantly) greater in regimen ADJ (32.3 g/d or 18.8 g/kg/d) than in regimen FIX (30.0 g/d or 18.3 g/kg/d). SUN was higher in ADJ than in FIX, and several other serum chemical values (calcium, phosphorus, potassium) tended to be higher, probably reflecting higher intakes of these nutrients with ADJ than with FIX. Plasma concentrations of several amino acids were higher in ADJ than FIX, but none, including threonine, were outside the physiological range. In comparing regimen FIX to regimen HMP, infants on FIX received similar intakes of protein and showed slightly but not significantly more rapid weight gain. Concentrations of SUN were lower with FIX, but other serum chemical values, including amino acids, were generally similar to HMP. We conclude that use of the new adjustable fortification regimen is feasible and safe and that it should be studied further. It produced the expected increases in nutrient intakes and growth. The new bovine milk-based fortifier appears to be equivalent to the human milk-based fortifier.

Heat treatment of infant formula: effect on postprandial serum alpha-amino-nitrogen concentrations in very-low-birth-weight infants.

Several different types of heat treatment are used in the production of commercial infant formulas. The extent of heat treatment can have different physicochemical effects on the milk proteins and will affect their solubility and digestibility. In the present study, 40 very-low-birth-weight infants were randomized at the age of 2 weeks to be given one test feed of either fresh, human milk protein-fortified human milk, a conventional canned sterilized liquid formula, a spray-dried powder formula, or an ultra-high-temperature (UHT)-treated liquid formula. The mean volume of the nasogastric test feed was adjusted so that protein intake was the same in each study group (0.45 g/kg). Venous blood samples were taken preprandially and at 30, 60, and 120 min after the test meal. alpha-amino-nitrogen in serum was assayed by the ninhydrin reaction. The concentration of alpha-amino-nitrogen rose rapidly after the fortified human milk feed, reaching a peak at 30 min. After the peak was reached, the serum values progressively declined, reaching baseline values at 120 min after the start of the test meal. The areas under the curve for all formulas were significantly different from that found for fortified human milk. At 30 min, all formulas had significantly lower alpha-amino-nitrogen values than fortified human milk; at 60 min, all formulas had significantly higher mean concentrations than fortified human milk. At 120 min, none of the formula-fed infants had reached baseline values; in particular, canned sterilized formula was still significantly above baseline values.(ABSTRACT TRUNCATED AT 250 WORDS)

Postmenstrual age correlates to indices of protein metabolism in very low birth weight infants.

In 14 infants who were normal in weight for gestational age and 14 infants who were small for gestational age, the plasma essential amino acid profiles and serum urea concentrations were studied between the 30th and 46th weeks of postmenstrual age. All infants were of very low birth weight (< 1,500 g) and were fed with fresh human milk fortified with 6 g freeze-dried human milk per 100 ml (mean protein intake 3.1 g/kg/day, mean energy intake 130 kcal/kg/day). With the exception of threonine, all measured plasma essential amino acid concentrations increased significantly with increasing postmenstrual age (appropriate for gestational age infants: r = 0.861, p < 0.01; small for gestational age infants: r = 0.772, p < 0.001). No differences in this increase could be found between the infants who were small or appropriate for gestational age. The serum urea concentrations also increased with increasing postmenstrual age without differences between the study groups (appropriate for gestational age infants: r = 0.658, p < 0.01; small for gestational age infants: r = 0.604, p < 0.05). The results indicate that very low birth weight infants of similar weights may have very different protein requirements, depending on their postmenstrual ages. Thus, postmenstrual age is of greater importance than birth weight when protein nutrition is planned for very low birth weight infants.

Macromolecular absorption in small-for-gestational-age infants.

Using human alpha-lactalbumin as a marker protein, macromolecular absorption was studied in 40 preterm infants, appropriate for gestational age (AGA), in 12 AGA term infants and in 18 preterm infants, small for gestational age (SGA). The absorption of alpha-lactalbumin was measured as concentration in serum after a human milk feed and expressed as micrograms alpha-lactalbumin/l serum/l human milk/kg body weight on day 7, 14, 21 and 42 after delivery. The serum concentration of alpha-lactalbumin was correlated negatively with maturity and postnatal age. In the SGA infants, the concentration of alpha-lactalbumin was significantly higher than in the AGA infants of similar gestational age. The data show that intrauterine growth retardation causes a delayed postnatal decrease in macromolecular absorption. This may indicate delayed intestinal maturation.