Evaluation of nitrite contamination in baby foods and infant formulas marketed in Turkey

Nitrites are responsible for methemoglobinemia, to which infants younger than 6 months are thought to be the most susceptible population. This study aimed to detect whether there was any nitrite contamination in infant formulas and baby foods marketed in Turkey and to estimate possible toxicological risks in this sensitive physiological period. For this purpose, the samples were randomly collected and divided into four groups: milk-based, cereal-based, vegetable-based, and fruit-based. An easy and reliable spectrophotometric method was used by modifying the Griess method. The average nitrite contamination was found to be 204.07±65.80 µg/g in 42 samples, with 1,073 µg/g maximum. According to the results, baby and infant formulas include various nitrite levels; nitrite contamination might come from several sources during manufacturing, and so extreme attention must be given throughout the manufacturing process of food for infants.     

Aluminum and bone disorders: with specific reference to aluminum contamination of infant nutrients

Aluminum (Al) impairment of bone matrix formation and mineralization may be mediated by its direct effect on bone cells or indirectly by its effect on parathyroid hormone and calcium metabolism. Its toxic effects are proportional to tissue Al load. Al contamination of nutrients depends on the amount of Al present naturally in chemicals or from the manufacturing process. Intravenous calcium, phosphorus, and albumin solutions have high Al (greater than 500 micrograms/L), whereas crystalline amino acid, sterile water, and dextrose water have low Al (less than 50 micrograms/L) content. Enteral nutrients including human and whole cow milk have low Al, whereas highly processed infant formulas with multiple additives, such as soy formula, preterm infant formula, and formulas for specific disorders are heavily contaminated with Al. Healthy adults are in zero balance for Al. The gastrointestinal tract excludes greater than 95% of dietary Al, and kidney is the dominant organ for Al excretion. However, even with normal renal function, only 30-60% of an Al load from parenteral nutrition is excreted in the urine, resulting in tissue accumulation of Al. The risk for Al toxicity is greatest in infants with chronic renal insufficiency, recipients of long term parenteral nutrition, i.e., no gut barrier to Al loading, and preterm infants with low Al binding capacity. The rapid growth of the infant would theoretically potentiate Al toxicity in all infants, although the critical level of Al loading causing bone disorders is not known. To minimize tissue burden, Al content of infant nutrients should be similar to "background" levels, i.e., similar to whole milk (less than 50 micrograms/L).     

1,25-Dihydroxy-vitamin D in infant formulas

A method is described for determining 1,25-dihydroxyvitamin D in infant formulas without using high pressure liquid chromatography to separate the vitamin D metabolites. After preparative chromatography with Silica Sep Pak and C18-Sep Pak cartridges the dihydroxylated vitamin D metabolite was quantified in a specific protein binding assay. The concentration of 1,25-dihydroxyvitamin D found was in a range between 2.5 and 11.3 pg/ml.     

Amino acid profile of milk-based infant formulas

The protein content and amino acid profile of three milk-based infant formulas, two of which were powdered (adapted and follow-on) and the third liquid, were determined to check their compliance with the EU directive and to evaluate whether or not they fulfil an infant's nutritional needs. To obtain the amino acid profile proteins were subjected to acid hydrolysis, prior to which the sulfur-containing amino acids were oxidized with performic acid. The amino acids were derivatized with phenylisothiocyanate (PITC) and then determined by ion-pair reverse phase high performance liquid chromatography (HPLC) In the case of tryptophan a basic hydrolysis was applied and there was no need of derivatization. The protein contents of the analysed formulas were in the ranges established by the EU directive for these products and the amino acid contents were in the ranges reported by other authors for these types of formulas. In all cases the tryptophan content determined the value of the chemical score, which was always lower than 80% of the reference protein but in the ranges reported by other authors. The analysed adapted infant formula provides amino acids in amounts higher than the established nutritional requirements.     

Advances in nutritional modifications of infant formulas

Modifications to infant formulas are continually being made as the components of human milk are characterized and as the nutrient needs of diverse groups of infants are identified. Formulas with long-chain polyunsaturated fatty acids added in amounts similar to those in human milk have recently become available in the United States; infants fed these formulas or human milk have higher tissue concentrations of long-chain polyunsaturated fatty acids and reportedly have better visual acuity than do infants fed nonsupplemented formulas. Selenium, an important antioxidant, is present in higher concentrations in human milk than in non-fortified cow milk-based formula, and the selenium intakes of infants fed nonfortified formulas are reported to be at or below recommended levels. Blood selenium concentrations and plasma glutathione peroxidase activity are higher in infants fed selenium-supplemented formulas or human milk than in infants fed non-fortified formulas. Nucleotides and their related products play key roles in many biological processes. Although nucleotides can be synthesized endogenously, they are considered "conditionally essential." Nucleotide concentrations in human milk are higher than in unsupplemented cow milk-based formulas, and studies in animals and human infants suggest that dietary nucleotides play a role in the development of the gastrointestinal and immune systems. Formulas for preterm infants after hospital discharge are designed to meet the needs of a population in whom growth failure is common. Several studies have shown that preterm infants fed nutrient-enriched formulas after hospital discharge have higher rates of catch-up growth than do infants fed standard term-infant formulas.     

Fatty acid composition of prepared infant formulas

The fatty acid composition of eight American, eight European, and four Japanese prepared infant formulas were determined and compared with fat sources listed on labels. Unsaturated fatty acids ranged from 20 to 83 per cent of the total. Generally, the fatty acid composition was consistent with the types of ingredients used; those with corn or soy oil had the highest levels of unsaturated fat, and those with milk fat the lowest; formulas of mixed composition fell in between. The formulas were compared with values for the fatty acid composition of human milk in the literature.     

Amino acid profile of milk-based infant formulas

The protein content and amino acid profile of three milk-based infant formulas, two of which were powdered (adapted and follow-on) and the third liquid, were determined to check their compliance with the EU directive and to evaluate whether or not they fulfil an infant's nutritional needs. To obtain the amino acid profile proteins were subjected to acid hydrolysis, prior to which the sulfur-containing amino acids were oxidized with performic acid. The amino acids were derivatized with phenylisothiocyanate (PITC) and then determined by ion-pair reverse phase high performance liquid chromatography (HPLC) In the case of tryptophan a basic hydrolysis was applied and there was no need of derivatization. The protein contents of the analysed formulas were in the ranges established by the EU directive for these products and the amino acid contents were in the ranges reported by other authors for these types of formulas. In all cases the tryptophan content determined the value of the chemical score, which was always lower than 80% of the reference protein but in the ranges reported by other authors. The analysed adapted infant formula provides amino acids in amounts higher than the established nutritional requirements.     

Microbial contamination of enteral feeding formulas and diarrhea

Twenty-five medical and surgical patients receiving liquid ready-to-use sterile enteral formulas were evaluated prospectively to investigate the relation of diarrhea to serum albumin level, total lymphocyte count, delayed hypersensitivity to purified protein derivative, antibiotic therapy, administration rate and site of enteral formula, and microbial contamination of enteral feeds. Formulas were administered to 6 patients with hang times of up to 6 h by pump-assisted continuous drip and to 19 patients with hang times of up to 3 h as a bolus feeding. Samples of formulas for microbial culture were obtained aseptically before and after feeding on the first and eighth day of the study period. The incidence of microbial contamination of the formula before and after feeding was 1 of 49 samples (2.0%) and 10 of 48 samples (20.8%), respectively. There were 2 patients with diarrhea, which occurred on the second day. Formula samples from 2 patients (100%) with diarrhea and 2 samples from 23 patients (8.7%) without diarrhea were contaminated with 10(4) cfu/mL or more, respectively. A significant difference (P = 0.04) was detected between the two groups. The other factors studied showed no significant association with the incidence of diarrhea. In conclusion, contaminated formula appears to play a significant role in the etiology of diarrhea in patients receiving enteral feeding.     

Dietary fibre and prebiotics in infant formulas

Prebiotics have the potential to promote immediate and long-term effects on the health and well-being of infants. They have been added to infant formulas in Japan for 20 years and have only recently been used in Europe. The objective is to change the intestinal microflora in order to mimic the bacteriological effect and, thus, the functional effects of human milk. There is, however, a potential risk of long-term effects of the use of these infant formulas. The consequences of using prebiotics in infants, during the first months of life, on the composition and development of the intestinal microflora, and on the resulting bacterial-bacterial and bacterial-host interactions are not known. Attempts have been made to improve infant and follow-on formulas by prebiotic supplementation, but intervention studies are needed to evaluate their immediate and long-term beneficial effects and demonstrate the absence of harmful consequences from their use.     

Quantitative determination of linoleic acid in infant formulas

The aim of this paper is to develop a gas chromatographic method for the quantitative determination of linoleic acid in adapted, preterm, follow-up and special infant formulas. For sample preparation, lipids were extracted with a Soxhlet extractor after acid hydrolysis, and methyl esters of fatty acids were prepared in a sealed vial with hydrochloric acid in methyl alcohol and analysed using a packed polar column (SP 2330). Triheptadecanoin was chosen as internal standard. The method yielded reliable and repeatable results for all the examined formulas.     

Pre-clinical and clinical evaluation of new infant formulas

Due to the importance of infant formulas as the primary source of nutrition for many infants, responsible infant formula manufacturers utilize a program of extensive premarket testing to evaluate the safety, reliability, and nutritional adequacy of such products. Based on the results of these studies, it is possible to document the usefulness of each formula in meeting infants' and parents' needs, and to provide physicians, nurses, dietitians, and regulatory agencies assurance of the appropriateness and safety of these products.     

Mineral and nutritional analysis of Polish infant formulas

The mineral composition and nutritional properties of 12 commercially available infant formula products widely distributed in the international market were investigated. Concentrations of the elements whose contents were reported by producers (Ca, Cu, Fe, Mg, Mn, P, Zn), and others with unknown levels (Al, B, Ba, Ni, and Sr), were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The protein and lactose contents in the formulas were investigated by titrations. The analysis results were generally close to the values declared by the producers. For the elements not reported by the producers, the Al and Ni concentrations were below element detection limits, but the B, Ba and Sr levels were up to 104, 117 and 221 μg/100 g, respectively. The composition of the milk products is discussed, taking into account requirements and daily permissible doses for infants and children, as well as considering the infant formulas as the source of minerals needed for good health and the growth of infants and toddlers.     

A comparison of the antigenicity of soya-bean-based infant formulas

1. The antigenicity of four soya-bean-based infant formulas (Prosobee powder, Prosobee liquid concentrate (Mead Johnson, Uxbridge, Middx), Wysoy (Wyeth, Maidenhead, Berks) and Formula S (Cow and Gate, Trowbridge, Wilts] was measured by enzyme-linked immunosorbent assays (ELISAs) specific for glycinin and beta-conglycinin. Results were compared with in vivo assessments of antigenicity using guinea-pigs, rabbits and calves. 2. The levels of antigenic glycinin and beta-conglycinin in Wysoy and Formula S were below the limits of detection of the ELISA. Both these proteins were detected in Prosobee powder and Prosobee liquid concentrate with the highest levels, especially for glycinin, being present in Prosobee powder. 3. Wysoy was sufficiently antigenic to evoke a soya-bean-specific serum antibody response in rabbits injected with this formula emulsified in complete Freunds adjuvant. A significantly greater response was obtained when rabbits were similarly injected with Prosobee powder. 4. The formulas varied in their ability to sensitize guinea-pigs for both anaphylaxis and antibody production when given orally, although the differences were not statistically significant. Prosobee powder appeared to be the most antigenic and Formula S the least, with Prosobee liquid concentrate and Wysoy being intermediate. 5. Similar variations in antigenicity were observed when Prosobee powder, Wysoy and Formula S were fed to soya-bean-sensitive calves. These formulas were all capable of provoking intestinal disturbances (seen as increased ileal flow-rate, decreased small intestinal transit time and decreased nitrogen absorption) but the most severe reactions were seen when Prosobee powder was fed and the least with Formula S. 6. Thus the four soya-bean-based infant formulas showed considerable differences in antigenicity. In vivo studies using guinea-pigs, rabbits and calves were in good agreement and broadly correlated with the immunochemical assessment of antigenicity. However, the in vitro and in vivo results did not correspond exactly and levels of glycinin and beta-conglycinin below the limit of detection by ELISA could evoke an immune response in the different animal species. We believe that these variations in antigenicity of different commercial products prepared from isolated soya-bean protein may be important when interpreting the results from studies of the development of allergy in infants given soya-bean-based formulas.     

Biopterin and neopterin in various milks and infant formulas

Biopterin and neopterin concentrations were measured by reverse-phase high pressure liquid chromatography in milks of man, cow, rabbit, cat, and rat and in commercial formulas widely used in North America. There was wide variation of concentration among species. Higher concentrations of biopterin were present in human milk (392.0 +/- 158.6 pmol/ml) than were present in all milk formulas analyzed (2.6-50.6 pmol/ml).