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Determination of Aluminum and Zinc in Infant Formulas and Infant Foods
JOURNAL OF FOOD COMPOSITION AND ANALYSIS ARTICLE NO.
10, 36–42 (1997)
FC960513
Determination of Aluminum and Zinc in Infant Formulas and Infant Foods MARIA PLESSI,1 DAVIDE BERTELLI,
AND
AGAR MONZANI
Dipartimento di Scienze Farmaceutiche, Universita` di Modena, via Campi, 183, 41100 Modena, Italy Received April 5, 1996, and in revised form October 4, 1996 Seven different infant formulas and 18 different types of infant foods representative of infant diets in Italy were analyzed to gain further information about the composition of infant diets, with particular reference to Al and Zn intake. After a microwave mineralization pretreatment, Al concentrations in the digested solutions were determined by electrothermal atomic absorption spectrometry and Zn concentrations by flame atomic absorption spectrometry. Soy-based infant formulas have markedly higher Al values (7 and 7.8 mg/g) than milk-based formulas (3–3.5 mg/ g), while even higher values are found in formulas based on hydrolyzed protein (13 and 17 mg/ g). Values for Zn vary much more, and in only 1 sample was the Zn content (13 mg/g) below that stipulated under EEC norms. In infant foods the Al and Zn contents vary widely from sample to sample, depending on their different compositions. Of the beverages, those based on tea have the highest Al content. q 1997 Academic Press
The toxicity of aluminum for neuronal tissues is well documented (Edwardson et al., 1988). The skeleton may also become affected by the accumulation of aluminum (Kruck and McLachlan, 1988). Exposure of the general population to aluminum mainly originates from ingestion of food, drink, and pharmaceutical preparations, but the low intestinal absorption in healthy adults minimizes the problem. The toxic effects are serious in infants because the immature gastrointestinal tract of an infant may be more permeable to aluminum than that of an adult (Sedman et al., 1985). Infants at particular risk are those born prematurely or those with impaired renal function (Freundlich, 1985). Consequently, interest in the analysis and level of aluminum in foods, particularly infant food, has grown over the past few years, and the Joint FAO/WHO Expert Committee on Food Additives has fixed the provisional tolerable weekly intake (PTWI) at 7 mg/kg body weight (WHO/FAO, 1989). Serum zinc has been found to be reduced in relation to high blood-Al levels in dialysis patients (Stewart, 1989); furthermore the gastrointestinal absorption of aluminum occurs by competition for binding sites on the zinc-binding ligand (Wenk and Stemmer, 1983). Zinc is an essential element, and the recommended dietary allowance (RDA) of zinc for children is 5 mg (NRC, 1989); EEC Resolution 91/321 recommends that milk-based formulas and soy-based formulas contain, respectively, 0.5–1.5 and 0.75–2.4 mg of zinc/100 kcal (EEC Resolution, 1991), while limits on protein-hydrolyzed milk are not available. The purpose of the present study is to gain further information into the composition of the infant diet, with particular reference to aluminum and zinc content, while 1
To whom reprint requests should be addressed. 36
0889-1575/97 $25.00 Copyright q 1997 by Academic Press All rights of reproduction in any form reserved.
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ALUMINUM AND ZINC IN INFANT FORMULAS AND FOODS
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aluminum content in water of infant diet was previously considered (Plessi and Monzani, 1995a). MATERIALS AND METHODS
Equipment and Reagents Digestion was performed on a programmable Milestone 1200 microwave digestion system, equipped with the ACM-100 automatic capping module, using Teflon MV100 vessels with SV15 safety valve. All measurements were performed with a Perkin– Elmer 3030 atomic absorption spectrophotometer equipped with an HGA-600 graphite furnace and an AS-60 autosampler. Pyrolytic graphite-coated tubes with pyrolytic graphite platforms were used. All reagents used were of analytical grade. Ultrapure water was supplied by a MilliQ reagent water system (Millipore Corp.). Samples Seven different powdered infant formulas, including a formula for infants over 6 months of age (so-called follow-on formula), and 18 different types of infant foods representative of infant diet in Italy were purchased in retail outlets between September 1994 and September 1995. All infant foods were produced by industry for infants. Two or more packages of formula and infant food were purchased from different lot numbers. Contamination Control To avoid contamination from the containers, polypropylene volumetric flasks and recipients were used. They were scrupulously soaked in 2 M HNO3 , rinsed with ultrapure water, filled with 0.1 M EDTA, kept for at least 1 night, and again rinsed with ultrapure water. The Gilson removable tips and the autosampler cups were subjected to the same decontamination. All the analytical procedures were carried out under an environmental hood with a laminar flow bench to avoid dust contamination. The digestion vessels were cleaned by submitting 3 ml of 70% HNO3 to the same microwave program as were the samples; any contamination from the vessels was monitored by analyzing digestion blanks. Analytical Procedures Microwave sample digestion. Food sample analysis required a mineralization pretreatment; for this purpose, several decomposition procedures have been recommended, but best results are obtained by pressure microwave heating, which decreased the mineralization time and the contamination risk; sample matrices were digested by a previously optimized procedure (Plessi and Monzani, 1995b). From each sample two portions of {0.3 g were digested with 3 ml of 70% HNO3 in closed vessels with a three-step program: 25% power (300 W) for 2 min, 0% power for 2 min, and 50% power (600 W) for 5 min. After cooling, the contents of each vessel were transferred into a volumetric flask, diluted to 25 ml with ultrapure water, then further diluted and
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PLESSI, BERTELLI, AND MONZANI TABLE 1 INSTRUMENTAL CONDITIONS
AND
FURNACE PROGRAM
Note. Light source, hollow cathode lamp; lamp current, 25 mA; wavelength, 309.3 nm; spectral bandwidth, 0.7 nm; background corrector on; injection volume, 20 ml; and matrix modifier, 0.2% Mg(NO3)2 .
submitted to spectrophotometric analysis. Three samples and one blank were digested simultaneously. Aluminum determination. Concentrations of aluminum in the digested solutions were determined by electrothermal atomic absorption spectrometry. The instrumental conditions and the furnace program used are shown in Table 1. The calibration graph was obtained by standard solutions in 0.2% HNO3 ranging from 0 to 160 ng Al/ml and is linear to 120 ng/ml. Under these analytical conditions the calculated detection limit, based on the recommendations given by IUPAC, was 0.44 ng/ml. Zinc determination. Concentrations of zinc in the digested solutions were performed by flame atomic absorption spectrometry following established methods (Perkin– Elmer, 1982). Validation of methods. The accuracy and validity of the measurements were determined by analyzing National Institute of Standards and Technology standard reference materials: nonfat milk powder, SRM 1549, and total diet, SRM 1548. These materials were mineralized and analyzed as stated above for food samples; means { SD values (five independent analytical runs) obtained were Al 1.9 { 0.41 and Zn 46 { 2.6 mg/ g for nonfat milk powder and Al 34 { 2.23 and Zn 30 { 2.4 mg/g for total diet. Certified values { uncertainty range or ‘‘noncertified’’ values are Al 2 and Zn 46.1 { 2.2 mg/g for nonfat milk powder and Al 33 and Zn 30.8 { 1.1 mg/g for total diet. RESULTS AND DISCUSSION
The contents of aluminum and zinc in infant formulas and infant foods are shown in Table 2; the reported values are the means and SD of three replicated analyses for the two or more packages of each sample. Table 3 shows the estimated concentrations of aluminum and zinc in powdered infant formulas and drinks prepared with Al-free water, following the manufacturer’s instructions.
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ALUMINUM AND ZINC IN INFANT FORMULAS AND FOODS TABLE 2 ALUMINUM
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FOODS
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PLESSI, BERTELLI, AND MONZANI TABLE 3 ESTIMATED CONCENTRATIONS
IN
PREPARED FORMULAS
AND
DRINKSa
a The powdered formulas and dehydrated drinks were reconstituted according to the manufacturer’s instructions, with Al-free water.
As has already been reported (Baxter et al., 1989; Coni et al., 1993), the aluminum content of soy-based formulas is much higher than that of milk-based formulas, while that of protein-hydrolysate formulas is even higher. It is difficult to identify correctly the causes of different aluminum levels. The high aluminum levels in soy-based formulas could result from aluminum naturally present in soy-bean; in fact, the soymeal aluminum concentration was consistently higher (26 mg/g). The presence of the highest aluminum levels in protein-hydrolysate formulas could be due also to the complex processing that their preparation requires. When the aluminum values for the product reconstituted with Al-free water are compared, it is found that they are consistently higher than those of cow’s milk (0.018–0.056 mg/liter) (Decet, 1989) and of breast milk (0.03 mg/liter) (Weintraub, 1986) and that the highest of all are those of protein-hydrolysate formulas, which are used in cases of food intolerance. Assuming that infants ages 1–6 months take the amount of formula recommended by the manufacturers, we calculated the weekly intake of aluminum and compared it with the PTWI (7 mg/kg body weight). We found that aluminum intake is less for milk-based formula, more for soy-based formula, and even more for formula based on hydrolyzed protein. For example, in the case of a 6-month-old, the weekly ingestion
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ALUMINUM AND ZINC IN INFANT FORMULAS AND FOODS
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FIG. 1. Relationship between the Zn content of reconstituted infant formula samples and limits recommended by the EEC Resolution 91/321 for milk-based and soy-based formulas. Infant formulas (powder): 1, hydrolyzed protein formula; 2, hydrolyzed protein formula; 3, soy-based formula; 4, soy-based formula; 5, preterm milk-based formula; 6, adapted milk-based formula; and 7, follow-on milk-based formula.
of aluminum is 2.67 and 3.35 mg on milk-based formula, 5.43 and 6.59 mg on soybased formula, and 10.67 and 15.50 mg on protein-hydrolysate formula. However, these values are well below the PTWI of 25.2 and 24.5 mg Al/week for male and female babies, respectively, of this age. The zinc content in the different formulas varies between 110 and 13 mg/g and does not appear to be correlated with the respective aluminum content. In the reconstituted formulas the zinc content was within the limits recommended by the EEC resolution (Fig. 1), the sole exception being sample 4, where it was extremely low. The milkbased follow-on formula has the highest zinc content, but the EEC resolution does not set any upper limit for this category of foodstuff. A one-way analysis of variance was used to evaluate the Al content differences between the formula types (protein-hydrolysate, soy-based, and milk-based). The difference is statistically significant (P õ 0.01) for aluminum levels, but not for zinc levels. In infant foods, the aluminum and zinc contents vary considerably from sample to sample, depending on their different compositions. The greatest quantities of aluminum are found in soya meal (26 mg/g) and in freeze-dried sole and carrot (22.7 and 22 mg/ g, respectively). The greatest quantities of zinc are found in meat-based foods (180 and 43 mg/g), in apple sauce (53.8 mg/g), and in some foods of vegetable origin. Given the variability with which these foods form part of an infant’s diet, it is impossible to calculate their contribution to the dietary intake of aluminum and zinc from the data in this study.
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PLESSI, BERTELLI, AND MONZANI
Of the beverages, those based on tea have the highest aluminum values, which is in agreement with the findings reported in literature for both dry leaves and infusions (Koch et al., 1989). REFERENCES BAXTER, M. J., BURREL, J. A., CREWS, H. M., AND MASSEY, R. C. (1989). Aluminum in infant formulae and tea and leaching during cooking. In Aluminum in Food and the Environment (R. C. Massey and D. Taylor, Eds.), pp. 77–87. Royal Chem. Soc., London. CONI, E., BELLOMONTE, G., AND CAROLI, S. (1993). Aluminum content of infant formulas. J. Trace Elem. Electrolytes Health Dis. 7, 83–86. DECET, F. (1989). Determinazione dell’ alluminio nel latte. Ind. Aliment. 27, 589–592. EDWARDSON, J. A., OAKLEY, A. E., PULLEN, G. L., MCARTHUR, F. K., MORRIS, C. M., TAYLOR, G. A., AND CANDY, J. M. (1988). Aluminum and the pathogenesis of neurodegenerative disorders. In Aluminum in Food and the Environment (R. C. Massey and D. Taylor, Eds.), pp. 20–36. Royal Chem. Soc., London. EEC—EUROPEAN ECONOMIC COMMUNITY RESOLUTION 91/321 (1991). Off. J. Eur. Community n. L175, 4/7/1991. FREUNDLICH, M., ZILLERUELO, G., ABITBOL, C., AND STRAUSS, J. (1985). Infant formula as a cause of aluminum toxicity in neonatal uraemia. Lancet ii, 527–529. KOCH, K. R., POUGNET, M. A. B., AND DE VILLIERS, S. (1989). Determination of aluminum levels in tea and coffee by inductively coupled plasma optical emission spectrometry and graphite furnace atomic absorption spectrometry. Analyst 114, 911–913. KRUCK, T. P. A., AND MCLACHLAN, D. R. (1988). Mechanism of aluminum neurotoxicity—Relevance to human disease. In Metal Ions in Biological Systems (H. Sigel and A. Sigel, Eds.), Vol. 24, pp. 285–314. Dekker, New York/Basel. National Research Council, Food and Nutrition Board (NRC). (1989). Recommended Dietary Allowances, 10th ed. Natl. Acad. Sciences, Washington DC. PERKIN –ELMER (1982). Analytical Methods for Atomic Absorption Spectrophotometry. Perkin–Elmer Corp., Palo Alto, CA. PLESSI, M., AND MONZANI, A. (1995a). Aluminum determination in bottled mineral waters by electrothermal atomic absorption spectrometry. J. Food Comp. Anal. 8, 21–26. PLESSI, M., AND MONZANI, A. (1995b). Ottimizzazione delle condizioni analitiche nella determinazione mediante ETAAS dell’ alluminio in tracce negli alimenti. Atti 27 Cong. Nat. Chimica Alimenti, pp. 1027– 1031. SEDMAN, A. B., KLEIN, G. L., MERRITT, R. J., MILLER, K. O., WEBER, W., GILL, W. L., ANAND, H., AND ALFREY, C. (1985). Evidence of aluminum loading in infants receiving intravenous therapy. N. Engl. J. Med. 312, 1337. STEWART, W. K. (1989). Aluminium toxicity in individuals with chronic renal disease. In Aluminum in Food and the Environment (R. C. Massey and D. Taylor, Eds.), pp. 16–19. Royal Chem. Soc., London. WEINTRAUB, G. H., MEERKIN, M., AND ROSENBERG, R. (1986). High aluminum content of infant milk formulas. Arch. Dis. Child. 61, 914–916. WENK, G. L., AND STEMMER, K. L. (1983). Suboptimal dietary zinc intake increases aluminum accumulation into the rat brain. Brain Res. 288, 393–395. WORLD HEALTH ORGANIZATION (WHO/FAO). (1989). Technical Report Series 776. WHO, Geneva.
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10, 36–42 (1997)
FC960513
Determination of Aluminum and Zinc in Infant Formulas and Infant Foods MARIA PLESSI,1 DAVIDE BERTELLI,
AND
AGAR MONZANI
Dipartimento di Scienze Farmaceutiche, Universita` di Modena, via Campi, 183, 41100 Modena, Italy Received April 5, 1996, and in revised form October 4, 1996 Seven different infant formulas and 18 different types of infant foods representative of infant diets in Italy were analyzed to gain further information about the composition of infant diets, with particular reference to Al and Zn intake. After a microwave mineralization pretreatment, Al concentrations in the digested solutions were determined by electrothermal atomic absorption spectrometry and Zn concentrations by flame atomic absorption spectrometry. Soy-based infant formulas have markedly higher Al values (7 and 7.8 mg/g) than milk-based formulas (3–3.5 mg/ g), while even higher values are found in formulas based on hydrolyzed protein (13 and 17 mg/ g). Values for Zn vary much more, and in only 1 sample was the Zn content (13 mg/g) below that stipulated under EEC norms. In infant foods the Al and Zn contents vary widely from sample to sample, depending on their different compositions. Of the beverages, those based on tea have the highest Al content. q 1997 Academic Press
The toxicity of aluminum for neuronal tissues is well documented (Edwardson et al., 1988). The skeleton may also become affected by the accumulation of aluminum (Kruck and McLachlan, 1988). Exposure of the general population to aluminum mainly originates from ingestion of food, drink, and pharmaceutical preparations, but the low intestinal absorption in healthy adults minimizes the problem. The toxic effects are serious in infants because the immature gastrointestinal tract of an infant may be more permeable to aluminum than that of an adult (Sedman et al., 1985). Infants at particular risk are those born prematurely or those with impaired renal function (Freundlich, 1985). Consequently, interest in the analysis and level of aluminum in foods, particularly infant food, has grown over the past few years, and the Joint FAO/WHO Expert Committee on Food Additives has fixed the provisional tolerable weekly intake (PTWI) at 7 mg/kg body weight (WHO/FAO, 1989). Serum zinc has been found to be reduced in relation to high blood-Al levels in dialysis patients (Stewart, 1989); furthermore the gastrointestinal absorption of aluminum occurs by competition for binding sites on the zinc-binding ligand (Wenk and Stemmer, 1983). Zinc is an essential element, and the recommended dietary allowance (RDA) of zinc for children is 5 mg (NRC, 1989); EEC Resolution 91/321 recommends that milk-based formulas and soy-based formulas contain, respectively, 0.5–1.5 and 0.75–2.4 mg of zinc/100 kcal (EEC Resolution, 1991), while limits on protein-hydrolyzed milk are not available. The purpose of the present study is to gain further information into the composition of the infant diet, with particular reference to aluminum and zinc content, while 1
To whom reprint requests should be addressed. 36
0889-1575/97 $25.00 Copyright q 1997 by Academic Press All rights of reproduction in any form reserved.
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AP: JFCA
ALUMINUM AND ZINC IN INFANT FORMULAS AND FOODS
37
aluminum content in water of infant diet was previously considered (Plessi and Monzani, 1995a). MATERIALS AND METHODS
Equipment and Reagents Digestion was performed on a programmable Milestone 1200 microwave digestion system, equipped with the ACM-100 automatic capping module, using Teflon MV100 vessels with SV15 safety valve. All measurements were performed with a Perkin– Elmer 3030 atomic absorption spectrophotometer equipped with an HGA-600 graphite furnace and an AS-60 autosampler. Pyrolytic graphite-coated tubes with pyrolytic graphite platforms were used. All reagents used were of analytical grade. Ultrapure water was supplied by a MilliQ reagent water system (Millipore Corp.). Samples Seven different powdered infant formulas, including a formula for infants over 6 months of age (so-called follow-on formula), and 18 different types of infant foods representative of infant diet in Italy were purchased in retail outlets between September 1994 and September 1995. All infant foods were produced by industry for infants. Two or more packages of formula and infant food were purchased from different lot numbers. Contamination Control To avoid contamination from the containers, polypropylene volumetric flasks and recipients were used. They were scrupulously soaked in 2 M HNO3 , rinsed with ultrapure water, filled with 0.1 M EDTA, kept for at least 1 night, and again rinsed with ultrapure water. The Gilson removable tips and the autosampler cups were subjected to the same decontamination. All the analytical procedures were carried out under an environmental hood with a laminar flow bench to avoid dust contamination. The digestion vessels were cleaned by submitting 3 ml of 70% HNO3 to the same microwave program as were the samples; any contamination from the vessels was monitored by analyzing digestion blanks. Analytical Procedures Microwave sample digestion. Food sample analysis required a mineralization pretreatment; for this purpose, several decomposition procedures have been recommended, but best results are obtained by pressure microwave heating, which decreased the mineralization time and the contamination risk; sample matrices were digested by a previously optimized procedure (Plessi and Monzani, 1995b). From each sample two portions of {0.3 g were digested with 3 ml of 70% HNO3 in closed vessels with a three-step program: 25% power (300 W) for 2 min, 0% power for 2 min, and 50% power (600 W) for 5 min. After cooling, the contents of each vessel were transferred into a volumetric flask, diluted to 25 ml with ultrapure water, then further diluted and
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38
PLESSI, BERTELLI, AND MONZANI TABLE 1 INSTRUMENTAL CONDITIONS
AND
FURNACE PROGRAM
Note. Light source, hollow cathode lamp; lamp current, 25 mA; wavelength, 309.3 nm; spectral bandwidth, 0.7 nm; background corrector on; injection volume, 20 ml; and matrix modifier, 0.2% Mg(NO3)2 .
submitted to spectrophotometric analysis. Three samples and one blank were digested simultaneously. Aluminum determination. Concentrations of aluminum in the digested solutions were determined by electrothermal atomic absorption spectrometry. The instrumental conditions and the furnace program used are shown in Table 1. The calibration graph was obtained by standard solutions in 0.2% HNO3 ranging from 0 to 160 ng Al/ml and is linear to 120 ng/ml. Under these analytical conditions the calculated detection limit, based on the recommendations given by IUPAC, was 0.44 ng/ml. Zinc determination. Concentrations of zinc in the digested solutions were performed by flame atomic absorption spectrometry following established methods (Perkin– Elmer, 1982). Validation of methods. The accuracy and validity of the measurements were determined by analyzing National Institute of Standards and Technology standard reference materials: nonfat milk powder, SRM 1549, and total diet, SRM 1548. These materials were mineralized and analyzed as stated above for food samples; means { SD values (five independent analytical runs) obtained were Al 1.9 { 0.41 and Zn 46 { 2.6 mg/ g for nonfat milk powder and Al 34 { 2.23 and Zn 30 { 2.4 mg/g for total diet. Certified values { uncertainty range or ‘‘noncertified’’ values are Al 2 and Zn 46.1 { 2.2 mg/g for nonfat milk powder and Al 33 and Zn 30.8 { 1.1 mg/g for total diet. RESULTS AND DISCUSSION
The contents of aluminum and zinc in infant formulas and infant foods are shown in Table 2; the reported values are the means and SD of three replicated analyses for the two or more packages of each sample. Table 3 shows the estimated concentrations of aluminum and zinc in powdered infant formulas and drinks prepared with Al-free water, following the manufacturer’s instructions.
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ALUMINUM AND ZINC IN INFANT FORMULAS AND FOODS TABLE 2 ALUMINUM
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ZINC CONTENT
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FOODS
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PLESSI, BERTELLI, AND MONZANI TABLE 3 ESTIMATED CONCENTRATIONS
IN
PREPARED FORMULAS
AND
DRINKSa
a The powdered formulas and dehydrated drinks were reconstituted according to the manufacturer’s instructions, with Al-free water.
As has already been reported (Baxter et al., 1989; Coni et al., 1993), the aluminum content of soy-based formulas is much higher than that of milk-based formulas, while that of protein-hydrolysate formulas is even higher. It is difficult to identify correctly the causes of different aluminum levels. The high aluminum levels in soy-based formulas could result from aluminum naturally present in soy-bean; in fact, the soymeal aluminum concentration was consistently higher (26 mg/g). The presence of the highest aluminum levels in protein-hydrolysate formulas could be due also to the complex processing that their preparation requires. When the aluminum values for the product reconstituted with Al-free water are compared, it is found that they are consistently higher than those of cow’s milk (0.018–0.056 mg/liter) (Decet, 1989) and of breast milk (0.03 mg/liter) (Weintraub, 1986) and that the highest of all are those of protein-hydrolysate formulas, which are used in cases of food intolerance. Assuming that infants ages 1–6 months take the amount of formula recommended by the manufacturers, we calculated the weekly intake of aluminum and compared it with the PTWI (7 mg/kg body weight). We found that aluminum intake is less for milk-based formula, more for soy-based formula, and even more for formula based on hydrolyzed protein. For example, in the case of a 6-month-old, the weekly ingestion
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ALUMINUM AND ZINC IN INFANT FORMULAS AND FOODS
41
FIG. 1. Relationship between the Zn content of reconstituted infant formula samples and limits recommended by the EEC Resolution 91/321 for milk-based and soy-based formulas. Infant formulas (powder): 1, hydrolyzed protein formula; 2, hydrolyzed protein formula; 3, soy-based formula; 4, soy-based formula; 5, preterm milk-based formula; 6, adapted milk-based formula; and 7, follow-on milk-based formula.
of aluminum is 2.67 and 3.35 mg on milk-based formula, 5.43 and 6.59 mg on soybased formula, and 10.67 and 15.50 mg on protein-hydrolysate formula. However, these values are well below the PTWI of 25.2 and 24.5 mg Al/week for male and female babies, respectively, of this age. The zinc content in the different formulas varies between 110 and 13 mg/g and does not appear to be correlated with the respective aluminum content. In the reconstituted formulas the zinc content was within the limits recommended by the EEC resolution (Fig. 1), the sole exception being sample 4, where it was extremely low. The milkbased follow-on formula has the highest zinc content, but the EEC resolution does not set any upper limit for this category of foodstuff. A one-way analysis of variance was used to evaluate the Al content differences between the formula types (protein-hydrolysate, soy-based, and milk-based). The difference is statistically significant (P õ 0.01) for aluminum levels, but not for zinc levels. In infant foods, the aluminum and zinc contents vary considerably from sample to sample, depending on their different compositions. The greatest quantities of aluminum are found in soya meal (26 mg/g) and in freeze-dried sole and carrot (22.7 and 22 mg/ g, respectively). The greatest quantities of zinc are found in meat-based foods (180 and 43 mg/g), in apple sauce (53.8 mg/g), and in some foods of vegetable origin. Given the variability with which these foods form part of an infant’s diet, it is impossible to calculate their contribution to the dietary intake of aluminum and zinc from the data in this study.
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PLESSI, BERTELLI, AND MONZANI
Of the beverages, those based on tea have the highest aluminum values, which is in agreement with the findings reported in literature for both dry leaves and infusions (Koch et al., 1989). REFERENCES BAXTER, M. J., BURREL, J. A., CREWS, H. M., AND MASSEY, R. C. (1989). Aluminum in infant formulae and tea and leaching during cooking. In Aluminum in Food and the Environment (R. C. Massey and D. Taylor, Eds.), pp. 77–87. Royal Chem. Soc., London. CONI, E., BELLOMONTE, G., AND CAROLI, S. (1993). Aluminum content of infant formulas. J. Trace Elem. Electrolytes Health Dis. 7, 83–86. DECET, F. (1989). Determinazione dell’ alluminio nel latte. Ind. Aliment. 27, 589–592. EDWARDSON, J. A., OAKLEY, A. E., PULLEN, G. L., MCARTHUR, F. K., MORRIS, C. M., TAYLOR, G. A., AND CANDY, J. M. (1988). Aluminum and the pathogenesis of neurodegenerative disorders. In Aluminum in Food and the Environment (R. C. Massey and D. Taylor, Eds.), pp. 20–36. Royal Chem. Soc., London. EEC—EUROPEAN ECONOMIC COMMUNITY RESOLUTION 91/321 (1991). Off. J. Eur. Community n. L175, 4/7/1991. FREUNDLICH, M., ZILLERUELO, G., ABITBOL, C., AND STRAUSS, J. (1985). Infant formula as a cause of aluminum toxicity in neonatal uraemia. Lancet ii, 527–529. KOCH, K. R., POUGNET, M. A. B., AND DE VILLIERS, S. (1989). Determination of aluminum levels in tea and coffee by inductively coupled plasma optical emission spectrometry and graphite furnace atomic absorption spectrometry. Analyst 114, 911–913. KRUCK, T. P. A., AND MCLACHLAN, D. R. (1988). Mechanism of aluminum neurotoxicity—Relevance to human disease. In Metal Ions in Biological Systems (H. Sigel and A. Sigel, Eds.), Vol. 24, pp. 285–314. Dekker, New York/Basel. National Research Council, Food and Nutrition Board (NRC). (1989). Recommended Dietary Allowances, 10th ed. Natl. Acad. Sciences, Washington DC. PERKIN –ELMER (1982). Analytical Methods for Atomic Absorption Spectrophotometry. Perkin–Elmer Corp., Palo Alto, CA. PLESSI, M., AND MONZANI, A. (1995a). Aluminum determination in bottled mineral waters by electrothermal atomic absorption spectrometry. J. Food Comp. Anal. 8, 21–26. PLESSI, M., AND MONZANI, A. (1995b). Ottimizzazione delle condizioni analitiche nella determinazione mediante ETAAS dell’ alluminio in tracce negli alimenti. Atti 27 Cong. Nat. Chimica Alimenti, pp. 1027– 1031. SEDMAN, A. B., KLEIN, G. L., MERRITT, R. J., MILLER, K. O., WEBER, W., GILL, W. L., ANAND, H., AND ALFREY, C. (1985). Evidence of aluminum loading in infants receiving intravenous therapy. N. Engl. J. Med. 312, 1337. STEWART, W. K. (1989). Aluminium toxicity in individuals with chronic renal disease. In Aluminum in Food and the Environment (R. C. Massey and D. Taylor, Eds.), pp. 16–19. Royal Chem. Soc., London. WEINTRAUB, G. H., MEERKIN, M., AND ROSENBERG, R. (1986). High aluminum content of infant milk formulas. Arch. Dis. Child. 61, 914–916. WENK, G. L., AND STEMMER, K. L. (1983). Suboptimal dietary zinc intake increases aluminum accumulation into the rat brain. Brain Res. 288, 393–395. WORLD HEALTH ORGANIZATION (WHO/FAO). (1989). Technical Report Series 776. WHO, Geneva.
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AP: JFCA