Dialyzability of iron, zinc, and copper of different types of infant formulas marketed in Spain

The bioavailability of trace elements in infant formulas is affected by different physiological and dietetic factors. In vitro methods based on element dialyzability have been proposed to estimate the bioavailability. Infant formulas of the same type but from different manufacturers can differ in the salt used for supplementation and in the contents of other components that can affect mineral bioavailability. The aim of our study is to estimate the dialyzability of iron, zinc, and copper of formulas marketed in Spain, in order to detect possible differences in formulas of the same type coming from different manufacturers. At the same time, the effects of the type of formula, the composition of the protein fraction, and the mineral content on the element dialyzability are also studied. Differences are found in the dialysis percentages of the elements studied in formulas of the same type but from different manufacturers. The formulas giving the highest dialysis percentages for the three considered elements are the hypoallergenic ones based on protein hydrolysates. No differences are observed in formulas having whey or casein as the main protein fraction. Significant correlations are obtained between the element contents and the dialyzability of the elements.     

Determination of relative bioavailability of zinc in a petit suisse cheese using weight gain and bone zinc content in rats as markers

The aim of the study was to determine the relative bioavailability of zinc gluconate stabilized with glycine in a Petit Suisse cheese from an infant dessert. Weight gain and bone zinc content were the nutritional responses evaluated for the diets of different zinc content: 2 ppm (basal) and 5, 10, and 30 ppm from zinc gluconate stabilized with glycine and zinc sulfate. Nonlinear regression analysis of the fitted curves for weight gain determined a relative zinc bioavailability of 100% for the Y _max ratio and 96% for Y _max/t _1/2 ratio for zinc gluconate stabilized with glycine (R ²=0.7996 for zinc sulfate and 0.8665 for zinc gluconate stabilized with glycine). The slope ratio analysis from linear regression of femur zinc determined a relative zinc bioavailability of 93% for zinc gluconate stabilized with glycine (R ²=0.8693 for zinc sulfate and 0.8307 for zinc gluconate stabilized with glycine). Zinc gluconate stabilized with glycine has similar bioavailability as zinc sulfate in a Petit Suisse cheese nutritional matrix, with the advantage that the stabilized compound does not modify the sensorial characteristics of the fortified cheese.     

The bioavailability of different zinc compounds used as human dietary supplements in rat prostate: a comparative study

The normal human prostate accumulates the highest levels of zinc (Zn) of any soft tissue in the body. The pool of zinc available to the body is known to significantly decrease with age. It is suggested that dietary Zn supplementation protects against oxidative damage and reduces the risk of cancer. Zinc sulfate and zinc gluconate were the most frequently mentioned in per os administration in studies on Zn supplementation. The major aim of the study was to compare the bioavailability of different Zn compounds (sulfate, gluconate and citrate) in the prostate after their daily administration to male rats at three different doses (3.0; 15.0; and 50.0 mg Zn/kg b.w.) for 30 days. The results show that bioavailability in the prostate differs significantly between individual zinc preparations. A significantly elevated Zn concentration in the dorso-lateral lobe of the prostate, compared to controls, was found in the rats supplemented with two compounds only: zinc gluconate and zinc citrate. However, after administration of zinc gluconate, this effect occurred even at the lowest dose. The lowest zinc bioavailability in the prostate was found in the rats administered zinc sulfate: no significant Zn increase was seen in particular zones of the prostate. To sum up, the use of zinc gluconate is worth considering as a possible means of zinc supplementation in men.     

In vitro dialyzability using meal approach as an index for zinc and iron absorption in humans

With a standardized protocol under simulated gastrointestinal conditions,⁶⁵Zn and⁵⁹Fe dialyzability was measured for 38 diets from 7 different published studies on human absorption. The compositions of these diets were available in the form of the amounts of food ingredients used for breakfast, lunch, and dinner. Considering each of these types as a separate meal, percent dialyzability was measured. The weighted average of breakfast, lunch, dinner, and snacks, if any, was taken to represent the entire day’s bioavailability. The correlation between in vitro percent dialyzability and reported human absorption was 0.92 for zinc and 0.96 for iron and both were statistically significant (p = 0.0001). The prediction equations for zinc and iron were obtained asy = -0.7718 + 1.1038x andy = 0.3197 + 0.9084x, respectively. This indicated that in vitro dialyzability using the meal approach can be used as an index with good discriminating power for different levels of human absorption.     

Heterodera glycines Cyst Components and Surface Disinfestants Affect H. glycines Hatching

We investigated the effects of Heterodera glycines cyst components and surface disinfestants on hatching of H. glycines eggs in vitro. Eggs were incubated in either H. glycines cyst wall fragments, cyst wall and egg rinsate, egg homogenate, or control solutions of soybean root diffusate, sterile distilled water, or zinc sulfate. Hatch in cyst wall and egg rinsate, and egg homogenate, was greater (α = 0.05) than hatch in sterile distilled water; however, it was not different from hatch in zinc sulfate according to Dunnett''s test. Hatch in cyst wall fragments was similar to hatch in sterile distilled water. To determine whether surface disinfestants affected hatch, eggs were treated first with chlorhexidine diacetate, mercuric chloride, sodium hypochlorite, or streptomycin sulfate and then incubated in H. glycines egg homogenate, soybean root diffusate, sterile distilled water, or zinc sulfate. Hatch of eggs treated with chlorhexidine diacetate, mercuric chloride, and streptomycin sulfate was reduced (α = 0.05), and hatch of eggs treated with sodium hypochlorite was increased (α = 0.05) relative to hatch of nontreated eggs in all incubation solutions except zinc sulfate according to Dunnett''s Test. Hatch in zinc sulfate was similar among all surface disinfestants except mercuric chloride, where hatch was reduced relative to hatch of nontreated and other surface disinfestant-treated eggs.     

The role of reduced iron powder in the fermentative production of tetanus toxin

When tetanus toxin is made by fermentation with Clostridium tetani, the traditional source of iron is an insoluble preparation called reduced iron powder. This material removes oxygen from the system by forming FeO₂ (rust). When inoculated in a newly developed medium lacking animal and dairy products and containing glucose, soy-peptone, and inorganic salts, growth and toxin production were poor without reduced iron powder. The optimum concentration of reduced iron powder for toxin production was found to be 0.5 g/l. Growth was further increased by higher concentrations, but toxin production decreased. Inorganic iron sources failed to replace reduced iron powder for growth or toxin formation. The iron source that came closest was ferrous ammonium sulfate. The organic iron sources ferric citrate and ferrous gluconate were more active than the inorganic compounds but could not replace reduced iron powder. Insoluble iron sources, such as iron wire, iron foil, and activated charcoal, were surprisingly active. Combinations of activated charcoal with soluble iron sources such as ferrous sulfate, ferric citrate, and ferrous gluconate showed increased activity, and the ferrous gluconate combination almost replaced reduced iron powder. It thus appears that the traditional iron source, reduced iron powder, plays a double role in supporting tetanus toxin formation, i.e., releasing soluble sources of iron and providing an insoluble surface.     

Effect of anions on the structure of glyceraldehyde-3-phosphate dehydrogenase from rat skeletal muscle

Glyceraldehyde-3-phosphate dehydrogenase from rat skeletal muscle undergoes reversible partial dissociation into 4.2–4.5 S fragments at +4°C and at protein concentrations as high as 8–9 mg/ml, depending upon the anion species present. The order of effectiveness of various anions in dissociating activity corresponds to their position in the Hofmeister series: bromide > nitrate > chloride > acetate > sulfate > phosphate=citrate. Quite similar is the order of activity of anions in their influence on the thermal stability of the dehydrogenase.     

Iron Dialyzability from Hospital Duplicate Meals: Daily Intake

Both total and dialyzable iron levels and corresponding dialyzability were determined in 108 duplicate meals during 36 consecutive days. Total mean iron fraction of 5.90 ± 4.97 mg was found in the meals. The iron supplied by the meals is directly and significantly (p < 0.05) correlated with macromicronutrient content (carbohydrates, fiber, and protein). The mean iron dialyzability (4.81 ± 3.25%) was low and not significantly different among the three primary meals (breakfast, lunch, and dinner). Significant interactions of several minerals on iron levels were found (p < 0.05). Iron dialyzability was only statistically influenced by zinc dialyzability in meals (p < 0.05). The dialyzed iron fraction present in meals was significantly correlated with protein and ascorbic acid levels (p < 0.01). The mean iron daily dietary intake was 17.7 ± 6.91 mg. The hospital meals provided enough iron. Foods of animal origin are primary sources of iron in diet.     

Glycation products in infant formulas: chemical,analytical and physiological aspects

Infant formulas are milk-based products, which are adapted to the composition of human milk. To ensure microbiological safety and long shelf life, infant formulas usually undergo rigid heat treatment. As a consequence of the special composition and the heat regimen, infant formulas are more prone to thermally induced degradation reactions than regular milk products. Degradation reactions observed during milk processing comprise lactosylation yielding the Amadori product lactulosyllysine, the formation of advanced glycation end products (AGEs), and protein-free sugar degradation products, as well as protein or lipid oxidation. Several methods have been developed to estimate the heat impact applied during the manufacturing of infant formulas, including indirect methods such as fluorescence analysis as well as the analysis of defined reaction products. Most studies confirm a higher degree of damage in infant formulas compared to regular milk products. Differences between various types of infant formulas, such as liquid, powdered or hypoallergenic formulas depend on the analyzed markers and brands. A considerable portion of protein degradation products in infant formulas can be avoided when process parameters and the quality of the ingredients are carefully controlled. The nutritional consequences of thermal degradation products in infant formulas are largely unknown.     

The Influence of Condition on Permeation of Ca(II) Ions from Solutions of Selected Calcium’s Salts Through Model Membrane

The permeation of calcium’s ions from calcium solutions of fumarate, gluconate, and citrate through model membrane from the donor chamber to the acceptor chamber has been examined. Process was traced depending on the concentration of the appropriate calcium’s salts (1, 2.5, and 5 mmol/l) and pH value of acceptor environment (1.3, 6.2, and 7.4) which imitated natural conditions appearing in the digestive tract. The amount of permeating Ca(II) ions (percent) and their Ca(II) availability AUC (0–6 h) has been determined. In dependence on the conditions, penetration was as follows: 30.3–95.2% of calcium ions from fumarate solution; 73.0–90.1% of Ca(II) from citrate solution; and 19.0–95.0% of Ca from gluconate solution. The investigation indicates that the amount of permeated Ca(II) ions and their availability are connected with the concentration of the calcium salt and pH of acceptor environment. Fumarate and citrate are available at pH value of acceptor environment 1.3 and 6.2 and gluconate at the pH value of 6.2 and 7.4. These substances are practically unavailable from the acceptor environment at pH value 1.3 for gluconate and 7.4 for fumarate. Results suggest that calcium citrate can be available for organism independently from pH value of acceptor environment.     

The Content of Elements in Infant Formulas and Drinks Against Mineral Requirements of Children

The present study aimed at analysing the content of fluorine (F), calcium (Ca), magnesium (Mg), iron (Fe) and zinc (Zn) in the drinks for children and infant formulas, a popular supplement or substitute for breast milk produced from cow milk on an industrial scale. Ca, Mg, Zn and Fe concentrations were determined using atomic absorption spectrophotometer, while F levels using a potentiometric method. F levels in the examined formula samples increased with the intended age range, until the intended age of 1 year, and then decreased. A lower content of Ca, Mg and Zn was observed in formulas intended for children <1 year of age and higher for older children. Fe content increased with the age range. A statistically significant higher content of Ca, Mg, Zn and Fe in samples intended for children with phenylketonuria in comparison to those intended for healthy children or children with food allergies was noted. The content of the analysed elements in juices and nectars showed the highest contents in products intended for infants (under 6 months of age). The lowest levels of elements tested were found in drinks for children over 6 months of age. In conclusion, the concentrations of the examined elements in infant formulas and juices for children were decidedly greater than the standards for the individual age groups. Although the absorption of these elements from artificial products is far lower than from breast milk, there is still the fear of consequences of excessive concentrations of these minerals.     

Comparison of chromosome damage induced by three zinc compounds using human leukocyte culture

The degree of chromosome damage induced by three compounds of zinc (zinc chloride, zinc sulfate, zinc acetate) was compared in human leucocytes in vitro. Three concentrations of each salt, 3.0×10⁻⁵ M, 3.0×10⁻⁴ M, and 1.5×10⁻³ M, were added to leukocyte cultures. The cells were harvested after 48 and 72 h and chromosome spreads were prepared following a colchicine-hypotonic-fixation-air drying-Giemsa staining schedule. The end point screened was chromosome aberrations. All three salts were lethal at the highest concentration. The degree of chromosome damage was directly proportional to the concentrations used for zinc sulfate and zinc acetate but not for zinc chloride.     

Effect of dietary nickel and iron on the trace element content of rat liver

The level and/or form of dietary iron, dietary nickel, and the interaction between them affected the trace element content of rat liver. Livers were from the offspring of dams fed diets containing 10–16 ng, or 20 μg, of nickel/g. Dietary iron was supplied as ferric chloride (30 μg/g) or ferric sulfate (30 μg, or 60 μg). In nickel-deprived rats fed 60 μg of iron/g of diet as ferric sulfate, at age 35 days, levels of iron and zinc were depressed in liver and the level of copper was elevated. At age 55 days, iron was still depressed, copper was still elevated, but zinc also was elevated. In rats fed 30 μg of iron/g of diet as ferric chloride, liver iron content was higher in nickel-deprived than in nickel-supplemented rats at 30, but not at 50, days of age. Also manganese and zinc were lower in nickel-deprived than in nickel-supplemented rats at age 35 days if their dams had been on experiment for an extended period of time (i.e., since age 21 days). Thus, the levels of copper, iron, manganese, and zinc in liver were affected by nickel deprivation, but the direction and extent of the affects depended upon the iron status of the rat.     

Bioavailability of zinc and its binding to casein in milks and formulas

Differences in zinc bioavailability among milk and formulas may be attributed to binding of zinc to various ligands. We determined the distribution of zinc and protein at different pHs and zinc and calcium concentrations. We used radiolabelled cow's milk, human milk, whey-predominant (WPF) and casein-predominant (CPF) infant formula. Lowering the pH changed zinc and protein distribution: zinc shifted from pellet (casein) to whey in cow's milk, from fat to whey in human milk and from fat and pellet to whey in formulas. Protein shifted from whey to pellet in human milk and from whey and pellet to fat in formulas. Increasing zinc and calcium concentrations shifted protein and zinc from pellet to whey for cow's milk and from whey and pellet to fat for the formulas. Protein distribution was not affected by calcium or zinc addition in human milk or CPF, while zinc shifted from whey to fat in human milk and from fat and pellet to whey in CPF. Zinc and calcium binding to isolated bovine or human casein increased with pH. At 500 mg/L of zinc, bovine casein bound 32.0 +/- 1.8 and human casein 10.0 +/- 0.9 mg zinc/g protein. At 500 mg/L of calcium, calcium was preferentially bound over zinc. Adding calcium and zinc resulted in 32.0 +/- 1.8 mg zinc/g bound to bovine casein and 17.0 +/- 0.8 mg zinc/g to human casein, while calcium binding was low. Suckling rat pups dosed with 65Zn labelled infant diets were killed and individual tissues were gamma counted. Lower zinc bioavailability was found for bovine milk at pH = 4.0 (%65Zn in liver = 18.7+1.4) when compared to WPF (22.8 +/- 1.6) or human milk (26.9 +/- 0.8). Lowering the pH further decreased zinc bioavailability from human milk, but not from cow's milk or WPF. Knowledge of the compounds binding minerals and trace elements in infant formulas is essential for optimizing zinc bioavailability.     

Zinc and iron bioavailability in a powder or in-bottle-sterilized infant formula estimated by in vitro and in suckling rats

Maillard reaction and lactose isomerization may be induced during the processing involved in the manufacture of infant formulas. The effects of dehydratation and sterilization in an infant formula on iron and zinc bioavailability were studied. A powder (PIF), previously reconstituted, and an in-bottle-sterilized liquid infant formula (LIF), from the same manufacturer, were evaluated using an in vitro method and in suckling rats. After in vitro digestion the dialyzed and non-dialyzed soluble, and insoluble fractions of iron and zinc were separated. Two-week-old rat pups were fed PIF or LIF in a drinking bottle for 7 days. Infant formula intake (I), body weight and the fecal and urinary excretions were monitored and the following parameters calculated: apparent absorption (A), retention (R), and the coefficients %A/I, %R/A and %R/I. Soluble iron (dialyzed) and zinc (non-dialyzed) were higher (p < 0.001) in LIF than PIF after in vitro digestion. Insoluble iron was similar in both infant formulas but insoluble zinc was lower (p < 0.05) in LIF than PIF. Food intake (p = 0.045) and body weight on day 4 (p < 0.05) and on day 7 (p < 0.001) were lower in LIF compared to PIF. A, R (p < 0.05 for both minerals), %A/I, and %R/I (p < 0.001 and p < 0.05 for iron and zinc, respectively) were significantly lower in rats fed LIF. Similarly, the %R/A of iron was lower (p < 0.001) in this group. Hematocrit and hemoglobin did not show significant differences. Iron and zinc levels in liver, spleen and erythrocytes were similar in both groups, but skin iron concentration was higher in LIF. Therefore, in contrast with the in vitro results, consumption of the in-bottle-sterilized formula determines lower iron and zinc bioavailability compared to the reconstituted powder infant formula.     

Effects of trace elements on the telomere lengths of hepatocytes L-02 and hepatoma cells SMMC-7721

The effects of selenium, zinc, iron, chromium, and lead on telomere lengths of human cells have not been investigated. This article adopted flow cytometry and fluorescence in situ hybridization to investigate the impact of different elements on cellular apoptosis and telomere lengths of human hepatocytes L-02 and hepatoma cells SMMC-7721. Results showed that these trace elements under the following dosages did not have remarkable effect on cellular apoptosis. However, sodium selenite at doses of 0.5 and 2.5 μmol/L significantly extended the telomere length of hepatocytes L-02; 0.5 μmol/L lead acetate remarkably shortened the telomere length of L-02 cells; 80 μmol/L zinc sulfate, 20 μmol/L ferric chloride, and 200 μmol/L chromic chloride only had slight impact on the telomere length, respectively. Regarding hepatoma cells SMMC-7721, sodium seleite at 0.5 and 2.5 μmol/L had little impact on the telomere length; 80 μmol/L zinc sulfate significantly accelerated the loss of telomere length, whereas 20 μmol/L ferric chloride, 200 μmol/L chromic chloride, and 0.5 μmol/L lead acetate remarkably extended the telomere lengths, respectively. The results revealed differential effects of each trace element on the life-span of human hepatocytes and hepatoma cell lines, which suggested further research on somatic hepatocytes and hepatoma in vivo.     

Limnological reconnaissance of waterbodies in central and southern Nepal

Ionic composition of waterbodies in central and southern Nepal sampled in spring 1985 differed from that normally found in freshwater. Distinguishing characteristics were: 1) predominance of bicarbonate among the anions — accounting for > 90% of the negative equivalents in two-thirds of the waterbodies, 2) the near absence of sulfates — accounting for < 1 % of the anions in half the samples so that chloride exceeded sulfate (as meq/L) in three-fourths of the waters tested and 3) calcium was the dominant cation, although in certain waters the relative proportion of either magnesium or the monovalent cations was much higher than the world average. Regional patterns in water chemistry were apparent and are largely explained by differences in local geology, inputs from artesian wells or extensive use by humans. Most ionic salinity values were <400 mg/L. Using conventional criteria to assess trophic state, most water-bodies were eutrophic or hypereutrophic when judged by total phosphorus and chlorophyll content but as a whole the lakes sampled were low in nitrogen. Nitrogen: phosphorus ratios (generally < 10) and a significant empirical relation for chlorophyll-nitrogen provide evidence that nitrogen limited algal biomass. Secchi transparency values indicate light regimes were affected by nonalgal materials. Contribution of the Missouri Agricultural Experiment Station Journal Series No. 10503. Contribution of the Missouri Agricultural Experiment Station Journal Series No. 10503.     

Normal growth rate in rats is recovered after a period of zinc deficiency by restoration of zinc supply by means of a zinc-fortified Petit Suisse cheese

Fortification of a Petit Suisse cheese with zinc sulfate and zinc gluconate stabilized with glycine was used as a tool to overcome zinc-deficiency effects on total-body growth and skeletal growth. Animals were divided in 4 groups of 10 rats: basal (B), control (C), depletion-repletion 1 (DR1), and depletion-repletion 2 (DR2). These four groups were fed with four diets: basal (2 ppm Zn), control (30 ppm Zn), DR1, and DR2; they received a basal diet for 14 d and a control diet for the other 14 d of the experiment, using zinc sulfate for DR1 and zinc gluconate stabilized with glycine for DR2. After 28 d of the experiment, total-body weight and weight gain of the control and DR1 and DR2 animals were not statistically different (p<0.05), Femur weight and femur zinc content of DR1 and DR2 did not achieve the values of control animals (p<0.05), but they were higher than that of basal animals. Our results show that restoration of dietary zinc levels by means of food fortification normalized weight gain, as an indicator of total-body growth, and presented a trend to normalize bone weight, as a marker of skeletal growth, in young rats and independently of the zinc source used.     

The effect of zinc on the oxidation of krebs cycle intermediates by rat liver and kidney homogenates

Zinc ions in small concentrations (2 × 10^?5M) inhibit rat liver and kidney succinoxidase systems by forming an inactive complex with the enzyme. Under conditions which favor oxidative phosphorylation (isotonic KCl homogenates, Mg ion, and muscle adenylate or adenosine triphosphate), inhibition by zinc occurs, but this inhibition is transitory. The rate of oxidation subsequently rises to a level even higher than shown by the control data. A later fall to a lower level of activity can be attributed to the zinc inhibition of other Krebs cycle intermediates, particularly the oxidation of α-ketoglutarate and citrate. The addition of a protein such as insulin has no protective action against zinc inhibition, and crystalline zinc insulin causes the same inhibition as does zinc sulfate. With the exception of succinoxidase, the oxidizing enzymes of rat kidney are more readily inhibited by zinc ions than are those of rat liver.Amorphous insulin, in itself, inhibits citrate oxidation by rat kidney homogenates.