Iron absorption from infant milk formula and the optimal level of iron supplementation

Thirty healthy infants, aged 11-13 months, were studied with regard to the iron absorption from proprietary milk formula. The infants were divided into three groups (I-III) depending on the concentration of iron in the formula: 0.8 (I), 6.8 (II), and 12.8 (III) mg/l, respectively. The calculated amount of iron absorbed per test dose of 50 ml of milk averaged 5 microgram (I), 32 microgram (II), and 43 microgram (III). Group I differed significantly from groups II and III. No correlation was found between iron absorption and hemoglobin, MCV, serum transferrin saturation or serum ferritin within the range of normal values. Our findings suggest that at least 7 mg of iron as ferrous sulphate per litre of formula is required to prevent iron deficiency.     

Effect of iron fortification of infant formula on trace mineral absorption

This study was designed to examine whether iron fortification of infant formulas has an effect on utilization of other nutrients, particularly the trace elements zinc and copper. Metabolic balance studies were performed with seven normal infants who were between 43 and 420 days of age. Two formulas of nearly identical composition except for iron concentration (10.2 and 2.5 mg/L) were fed. Each infant had four balance studies performed, two while being fed formula 10.2 and two while being fed formula 2.5, in an alternating sequence. No effect of formula iron concentration was evident on absorption and/or retention of nitrogen, fat, calcium, and magnesium. Although absorption of phosphorus was significantly (p less than 0.05) less with formula 10.2 than formula 2.5, the difference was trivial. No effect on absorption of zinc was seen. However, absorption of copper was only 13.4% (SD 13.0) of intake when formula 10.2 was fed, compared with 27.5% (SD 15.3) of intake when formula 2.5 was fed. The difference was statistically significant (p less than 0.01). We conclude that iron in amounts present in iron-fortified formulas has a measurable effect on copper utilization. Because the magnitude of the effect is relatively small, we doubt that the finding is clinically relevant.     

Iron fortification of infant foods. A decade of change

A survey of iron-fortified commercial foods commonly marketed for consumption by infants was conducted in 1972 and again in 1982. Positive changes had occurred in infant formulas and cereals during that decade, in availability of fortifying iron, level of fortification, and label information. Miscellaneous iron-containing products, cookies, and crackers were unreliable sources of dietary iron in both 1972 and 1982. Availability of fortifying iron in regular cereals had improved by 1982, though 10 percent lacked the label information. Fortified infant formulas and cereals contribute iron of high bioavailability to the typical infant diet in amounts equal to the USRDA. Food manufacturers need to continue to apply knowledge gained through research to sustain the lessened but still highly prevalent incidence of anemia in 1-2-year old children.     

Iron status of children in southern Sweden: effects of cow's milk and follow-on formula

AIM: The objective of the study was to investigate iron status in children in relation to intake of cow's milk and follow-on formula. METHODS: In all, 367 healthy 2.5-y-old children were enrolled in the study. The amounts of cow's milk and formula consumed were recorded. B-haemoglobin, S-ferritin, S-iron, total iron binding capacity and mean corpuscular volume were analysed. RESULTS: Seven percent of the children had iron deficiency anaemia (Hb <110g/l) and 10% had S-ferritin < 12 microg/l. Furthermore, 10% of the children were iron deficient, with or without anaemia. Children with iron deficiency had a higher intake of cow's milk (382 ml, 95% confidence interval (CI) 294-496, vs. 257 ml, CI 232-272, p < 0.0001), and fewer consumed follow-on formula (11% vs. 43%, p= 0.0002) compared to those with sufficient iron. CONCLUSION: Iron deficiency is still common during childhood in Sweden. Intake of cow's milk is significantly higher in children with iron deficiency. In contrast, iron deficiency is less frequent among those consuming follow-on     

The effect of iron in formula milk after 6 months of age.

Ninety two normal birthweight infants aged 6 months entered a double blind controlled trial which compared a follow on formula milk with no added iron against the same formula milk containing 1.2 mg of iron per 100 ml. There was no significant difference in the social class or demographic characteristics of the two treatment groups or in the proportion of each group completing the trial. There was no difference between the two groups in the quantity of milk taken but the amounts taken lessened between 6 and 18 months of age. There was no difference between the two groups with respect to mean haemoglobin and median serum ferritin at 6, 9, 12, 15, and 18 months of age. Very few infants developed iron deficiency anaemia in either group but there was a tendency for serum ferritin levels to fall between 6 and 18 months of age in both groups. The results suggest that iron added to follow on milk was not an important source of dietary iron in the infants studied.     

Vitamin E status in preterm infants fed human milk or infant formula

Vitamin E status was assessed in 36 infants with birth weights less than 1500 gm who were assigned randomly to receive one of three sources of nutrition: milk obtained from mothers of preterm infants (preterm milk), mature human milk, or infant formula. Infants in each dietary group were further assigned randomly to receive iron supplementation (2 mg/kg/day) beginning at 2 weeks or to receive no iron supplementation. All infants received a standard multivitamin, providing 4.1 mg alpha-tocopherol daily. Serum vitamin E concentrations at 6 weeks were significantly related both to type of milk (P less than 0.0001) and to iron supplementation (P less than 0.05). Infants fed preterm milk had significantly higher serum vitamin E levels than did infants fed mature human milk, and both groups had significantly higher levels than did those fed formula. Ratios of serum vitamin E/total lipid were also significantly greater for infants fed human milks than for those fed formula. The addition of iron to all three diets resulted in significantly lower serum vitamin E levels at 6 weeks (P less than 0.05); however, only in the group fed formula was there evidence of vitamin E deficiency. Preterm milk with routine multivitamin supplementation uniformly resulted in vitamin E sufficiency in VLBW infants whether or not iron was administered.     

Diet and faecal flora in the newborn: breast milk and infant formula.

This study examined the faecal flora on days 4, 14, and 28 of 17 breast fed babies and 26 bottle fed babies receiving a modern infant formula based on demineralized whey. Generally among breast fed babies bifidobacteria and staphylococci were the predominant organisms, whereas in the formula fed babies the predominant organisms were enterococci, coliforms, and clostridia. Despite the extensive modification of cows'' milk to make an infant formula resemble human breast milk, the results are very similar to those previously reported with unmodified cows'' milk baby feeds. The exact dietary factor responsible for these microbiological differences is unclear and in succeeding papers we have looked at the effects of protein quality, in particular the content of whey proteins, casein, and lactoferrin.     

High protein pre-term infant formula: effect on nutrient balance, metabolic status and growth

Several lines of evidence suggest that formula with protein content of 3.0 g/100 kcal does not fully meet the protein needs of very-low-birth weight infants. Our purpose was to compare nitrogen balance, metabolic status and growth in infants fed a standard (3.0 g/100 kcal; RegPro) and high (3.6 g/100 kcal; HiPro) protein infant formula. Infants were fed both formulas, each formula for one week in balanced cross-over design. Metabolic status was monitored throughout. Nutrient balance and plasma amino acids were determined at the end of each week. Data were analysed using a linear mixed model. Eighteen infants were studied. Nine infants received the RegPro and nine received HiPro formula first. Nitrogen intake, absorption and retention were greater with the HiPro formula. None of the infants developed uremia or metabolic acidosis but retinol-binding-protein and weight gain were greater with the HiPro formula. Increased protein accretion paralleled by better weight gain without evidence of metabolic stress indicates that a formula with a protein content of 3.6 g/100 kcal better meets protein needs in these rapidly-growing infants. Further studies are needed to determine whether these short-term outcomes will be translated into long-term benefits.     

Microwave heating of infant formula and breast milk

Heating infant formula and breast milk in a microwave oven has become a common practice in many households. A review of the literature is presented to ascertain if there is evidence to support the safety of this practice, as well as to determine if microwaving affects the nutritional content of the heated milk. The results of a local community's survey are presented, which assesses parental use of microwave ovens in the heating of infant formula and parents' knowledge of the potential hazards of this practice.     

The effect of iron in formula milk after 6 months of age

Ninety two normal birthweight infants aged 6 months entered a double blind controlled trial which compared a follow on formula milk with no added iron against the same formula milk containing 1.2 mg of iron per 100 ml. There was no significant difference in the social class or demographic characteristics of the two treatment groups or in the proportion of each group completing the trial. There was no difference between the two groups in the quantity of milk taken but the amounts taken lessened between 6 and 18 months of age. There was no difference between the two groups with respect to mean haemoglobin and median serum ferritin at 6, 9, 12, 15, and 18 months of age. Very few infants developed iron deficiency anaemia in either group but there was a tendency for serum ferritin levels to fall between 6 and 18 months of age in both groups. The results suggest that iron added to follow on milk was not an important source of dietary iron in the infants studied.     

Iron status with different infant feeding regimens: relevance to screening and prevention of iron deficiency

The objective of this study was to evaluate the benefit of screening for anemia in infants in relation to their previous diet. The iron status of 854 nine-month-old infants on three different feeding regimens and on a regimen including iron dextran injection was determined by analysis of hemoglobin, serum ferritin, and erythrocyte protoporphyrin levels and of serum transferrin saturation. Infants were categorized as having iron deficiency if two or three of the three biochemical test results were abnormal and as having iron deficiency anemia if, in addition, the hemoglobin level was less than 110 gm/L. The prevalence of iron deficiency was highest in infants fed cow milk formula without added iron (37.5%), intermediate in the group fed human milk (26.5%), much lower in those fed cow milk formula with added iron (8.0%), and virtually absent in those injected with iron dextran (1.3%). The corresponding values for iron deficiency anemia were 20.2%, 14.7%, 0.6%, and 0%, respectively. The use of iron supplements is therefore justified in infants fed cow milk formula without added iron, even when there is no biochemical evidence of iron deficiency. The low prevalence of iron deficiency in the group fed iron-fortified formula appears to make it unnecessary to screen routinely for anemia in such infants. These results also support the recommendation that infants who are exclusively fed human milk for 9 months need an additional source of iron after about 6 months of age.     

Prebiotic effect of fructo-oligosaccharide supplemented term infant formula at two concentrations compared with unsupplemented formula and human milk

BACKGROUND: Human milk components, including oligosaccharides, affect the gastrointestinal flora of infants. Previous studies in adults have demonstrated that fructo-oligosaccharides increase potentially beneficial fecal bacteria, including bifidobacteria. The purpose of this study was to determine the prebiotic effect of infant formula supplemented with fructo-oligosaccharides. METHODS: Healthy term infants 2 to 6 weeks of age were enrolled in a 5-week, prospective, randomized, crossover, single-site study with a nonrandomized human milk comparator group. Washout weeks preceded and followed a week of feeding with fructo-oligosaccharide-supplemented formula (1.5 or 3.0 g/L). Stool specimens were quantitatively cultured weekly for bacteroides, lactobacilli, bifidobacteria, clostridia and enterococci and were tested for Clostridium difficile toxin. RESULTS: Seventy-two of 87 infants completed the trial; 58 were formula fed and 14 were human milk fed. Mean counts of bifidobacteria and lactobacilli were similar in all groups at entry and no group experienced a significant change in counts with fructo-oligosaccharide supplementation. After 7 days of fructo-oligosaccharide supplementation the bifidobacteria counts were greater in the 1.5 g/L fructo-oligosaccharide formula group than in the human milk fed or 3.0 g/L fructo-oligosaccharide formula groups. Formula-fed infants had higher counts of enterococci and bacteroides before fructo-oligosaccharide supplementation, and these counts did not change after supplementation. Clostridium counts increased 7 days after supplementation in the 1.5 g/L fructo-oligosaccharide formula group (P = 0.0356). No human milk fed infants had C. difficile toxin in stools. Fructo-oligosaccharide (3.0 g/L) supplementation resulted in more frequent and significantly softer stools. CONCLUSIONS: Infant formula supplemented with 1.5 or 3.0 g/L fructo-oligosaccharides was safe but had minimal effect on fecal flora and C. difficile toxin.     

Antiviral and antibacterial lipids in human milk and infant formula feeds.

Human milk and two infant formula feeds were tested for antiviral and antibacterial activity before being given to 21 low birthweight (LBW) infants; neither was present. When samples were aspirated from the stomachs of the infants within one to three hours of feeding, however, they reduced titres of enveloped virus and also killed both Staphylococcus epidermidis and Escherichia coli. The lipid fraction of the gastric aspirate from an infant who had been given human milk as well as those from four infants who had been given a conventional LBW infant formula feed, showed antiviral and antibacterial activities at least equal to the activities of the unfractionated aspirates. There was no consistent difference in antiviral or antibacterial activity of either the stomach aspirates or the lipid fractions of these aspirates between infants given human milk and those given formula feeds. The antiviral and antibacterial activities of the gastric aspirates seem to result from intragastric production of monoglycerides and fatty acids from the triglyceride content of the ingested feeds.     

Rice protein-based infant formula: current status and future development

Rice is the world's leading staple cereal food and is the major source of protein for many parts of the world. Rice is among the first solid foods fed to infants in many cultures, in part because of its hypoallergenicity from lack of gluten. Nutritional quality of rice protein compares favorably with other cereal proteins including wheat, oat and barley. It is rich in methionine and cystine, although as is the case for other cereals, it is an incomplete protein source for human infants with lysine and threonine being the primary limiting amino acids. Fortification of rice proteins with these two limiting amino acids improves its protein quality. Rice protein-based infant formulas (RPF) were initially based on high protein rice flours, but more recently are based on rice protein concentrates, isolates or hydrolysates, fortified with lysine and threonine. Hypoallergenicity efficacy, particularly for hydrolyzed rice protein-based formulas, has been reported, and limited data indicated that rice protein based infant formula may provide potentially adequate alternative if standard milk- or soy protein-based formulas are not tolerated. Unlike the rice-protein based infant formula, rice beverage formulas made from rice flour are nutritionally inadequate for infants. Reports have indicated stunted growth in infants/children fed rice beverage formulas. Future development for the RPF include those based on genetically improved rice with high lysine and threonine content, supplementation with appropriate mineral and fat blend, and long-term clinical studies in infants to confirm its efficacy and safety.     

Evaluation of the effect of a fiber-enriched formula on infant colic.

Because infants with colic appear to have abdominal pain similar to that of adults with irritable bowel syndrome, who may benefit from the addition of fiber to their diet, we tested whether fiber added to infant formula would alleviate colic. Twenty-seven normal, term infants (aged 2 to 8 weeks; 14 girls) with colic, defined as crying plus fussing for more than 3 hours a day for at least 3 days of a 6-day baseline period, were enrolled. Infants were randomly assigned in 9-day periods to a sequence of placebo (Isomil formula) followed by fiber-supplemented formula (Isomil plus soy polysaccharide) (n = 12) or the reverse (n = 15). Daily diaries of crying, fussing, sleeping, formula, intake, and stooling were kept. Twenty-two infants completed three lactulose breath hydrogen tests at the end of the baseline period and after each study period. The crossover trial was followed by 30 to 35 days of use of the study formula chosen by the parents as most beneficial but unknown to the investigators. Growth was monitored throughout. Serum cholesterol, calcium, phosphate, albumin, iron, and zinc concentrations were measured at the conclusion. There were no significant differences in average daily time spent by the infants in fussing and crying during ingestion of the fiber-supplemented formula. However, parents of 18 of 27 infants chose fiber-supplemented formula as most beneficial in ameliorating symptoms of colic. While the infants were consuming fiber-supplemented formula, stool frequency increased, and breath hydrogen excretion increased significantly, in response to lactulose. Growth and serum biochemical measurements were normal in all infants. Supplementation of infant formula with the level of soy polysaccharide used in this study may have reduced crying and fussing in some infants but did not affect colicky behavior in the majority of infants, who continued to cry and fuss excessively.