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Minerals and trace elements in commercial infant food
Food and Chemical Toxicology 46 (2008) 3339–3342
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Minerals and trace elements in commercial infant food Renate Melø a, Kristin Gellein b, Lars Evjea, Tore Syversen a,* a b
Department of Neuroscience, Norwegian University of Science and Technology, NO 7489 Trondheim, Norway Department of Chemistry, Norwegian University of Science and Technology, NO 7491 Trondheim, Norway
a r t i c l e
i n f o
Article history: Received 7 December 2007 Accepted 11 August 2008
Keywords: Minerals Trace elements Infant Complementary food Infant formula
a b s t r a c t Adequate nutrition during infancy is essential for lifelong health and wellbeing. Breast-feeding is highly recommended for the first six month of life, but from then on complementary feeding is necessary. Industrially produced food is an important part of the diet for many infants and toddlers in developed countries. We have determined the concentration of major minerals and trace elements in 76 different products of infant formula, porridges, fruit purée and dinners by HR-ICP-MS. The products were collected from three suppliers on the Norwegian market (Nestlé, Tine and Nyco Pharma). A daily menu was also composed and the estimated daily intake was compared with current recommendations. All products were within the upper tolerable limit for the minerals of trace elements analysed and toxic elements were present at very low levels. A diet based solely on industrially prepared food products will provide a sufficient intake of minerals and trace elements. Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction Trace elements and minerals are essential for biological processes and play a vital role in normal growth and development. Infancy and early childhood are characterized by a very high growth rate and trace element requirements are more critical during this period (Brätter et al., 1998). The high growth rate and development of organ systems in childhood requires a balanced diet rich in nutrients. Minerals are involved in many important functions in the body, e.g. enzymatic reactions, bone mineralization, as well as protection of cells and lipids in biological membranes. Low intake or reduced bioavailability of minerals may lead to deficiencies, which causes impairment of body functions (Schlenker and Williams, 2003). In fact, infant feeding from birth up to the first years of life may influence an individual’s entire future life (Monte and Giugliani, 2004). Breast milk alone can be used to properly feed infants during the first six month of life, but from then on complementary feeding is necessary (Monte and Giugliani, 2004). Because industrially produced foods is an important part of the diet for many infants and toddlers it is very important that such food contain sufficient amounts of minerals. There have been several studies of infant diets in both developing and industrialized countries (Noble et al., 2001; Noble and Emmet, 2006; Bhutta, 2000; Kimmons et al., 2005; Asubiojo and Iskander, 1988). Complementary food is defined as all foods and fluids other than breast milk given to the infant. From the age of * Corresponding author. Tel.: +47 73 598848; fax: +47 73 596879. E-mail address: [email protected] (T. Syversen). 0278-6915/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.fct.2008.08.007
nine months, complementary food should provide 75–100% of the intake of Fe and Zn. These estimates emphasize the critical role that complementary food plays in providing adequate quantities of these trace minerals (Gibson and Hotz, 2000). Inadequate complementary food is a major cause of the high prevalence of malnutrition in the developing world (Michaelsen and Friis, 1998). The World Health Organization’s (WHO) have made recommendations as to the daily intake (RDI) of minerals for infants and toddlers (WHO/UNICEF, 1998). Some minerals may constitute a potential health risk when consumed above the tolerable upper intake levels (UL) over an extended period. Examples of this are iodine and iron poisoning. For other minerals, the negative effects are less obvious, e.g. gastrointestinal problems. For non-essential elements like aluminium and heavy metals (e.g. mercury, cadmium and lead) any exposure is undesirable, but acceptable levels in food have been determined by WHO as such trace elements are present in most food supplies. The aim of this study was to investigate any discrepancies between declared and analysed value, if any toxic elements could be found and consider the daily intake from diets composed according to manufacturer’s advice. The study included 76 different products of infant formula, porridges, fruit purée and dinners from the manufacturer Nestlé, Tine and Nycomed Pharma. The Nestlé products are available throughout Europe although composition may change due to production site. The Tine product range is available in Norway only while the Nycomed Pharma products are available in Scandinavia. The concentration of 18 major minerals and trace elements were determined by HR-ICP-MS (high resolution inductively coupled plasma mass spectrometry).
73.5 86.4 0.59 216 134 1.49 89.2 17.2 39.3 55.7 95.0 0.57 220 587 0.39 181 256 9.25 806 88.9 60.6 105.6 78.8 2.40 The products are grouped by recommended consumer age and given as an average of several products. Values are given for 100 g of products to facilitate comparison with product labels. Avg = arithmetic average. SD = standard deviation. n.d. = not detected, below the detection limit. lg = microgram. g = gram.
mg/100 g lg/100 g lg/100 g lg/100 g mg/100 g mg/100 g mg/100 g lg/100 g mg/100 g lg/100 g mg/100 g
Avg SD
180 136 0.40 2.08 77.3 2.78 210 16.8 14.0 58.4 21.7 0.28 277 738 0.29 0.93 244 11.1 820 93.8 38.6 101 22.1 2.14
Avg SD
334 158 0.65 – 39.9 1.04 154 19.8 12.4 46.3 27.4 0.36 397 584 0.32 n.d. 213 9.48 827 88.4 39.5 126 26.0 2.11
Avg SD
409 50.6 – 12.5 56.4 1.34 394 25.0 5.08 98.4 13.6 0.81 360 612.9 n.d 6.3 135 10.63 454 59.6 26.4 84.5 7.70 1.30
Avg SD
41.4 7.50 0.29 4.46 16.8 0.10 24.3 3.25 2.04 3.89 3.92 0.07 55.9 10.3 0.32 6.30 53.1 0.19 118 8.21 0.68 2.89 6.64 0.11
Avg SD
92.4 13.2 0.11 2.51 16.5 0.17 28.4 1.49 3.39 16.3 2.31 0.15 169 22.9 0.09 10.1 65.7 0.60 209 13.3 6.5 163 12.5 0.68
Avg SD
49.4 23.0 0.11 4.25 13.0 0.18 37.7 2.18 3.64 25.5 4.00 0.25 79.5 21.3 0.10 8.38 50.6 0.46 169 11.5 7.18 132 9.04 0.61
Avg SD
62.0 8.75 0.11 2.91 23.8 0.15 41.0 2.55 2.76 49.7 3.62 0.12 92.3 17.5 0.07 5.87 51.8 0.40 172 11.3 3.96 94.4 7.46 0.41
Avg SD
35.0 2.49 0.23 2.00 14.0 0.12 53.1 2.22 1.81 46.8 1.85 0.12 45.7 12.0 0.15 4.82 47.3 0.36 174 10.5 1.61 45.5 7.24 0.41
Avg SD
87.7 0.43 0.17 1.38 5.15 0.03 3.78 0.31 1.53 1.60 0.91 0.03 69.3 10.4 0.12 3.22 31.2 0.18 117 7.50 1.09 6.92 5.81 0.15
lg/100 g
Avg
SD
Avg
Porridge
4 months 4–8 months
Fruit purée Dinner
18 months 12 months
Dinner Dinner Dinner Dinner Infant formula Product
Table 1 Trace element and mineral content of infant food products
The concentrations of aluminium, arsenic, calcium, cadmium, cobalt, chromium, copper, iron, mercury, potassium, manganese, molybdenum, sodium, nickel, lead, and zinc in 74 infant food products and 2 infant formulas were determined by analysis on HR-ICPMS. Table 1 presents the average concentrations for most of these elements in infant formula, dinner, porridge and fruit puree. The products are divided into groups according to recommended age of the infant. Results are given as an average of several products (2–12). There is a wide range of dinners; containing beef, vegetables, lamb, turkey, pork, spaghetti etc. The porridges are also of different types, like wheat, wholegrain, müsli or corn. For the porridges a high and variable aluminium concentration was found. A possible explanation for this observation can be contamination as the dry material is packaged in plastic lined aluminium foil bags. Arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb) are toxic elements that may cause adverse effects in humans even at low levels (Nordberg and Cherian, 2005). None of the products contained arsenic, cadmium, mercury or lead in amounts that could represent a health hazard for the consumer. Dinners containing fish had the highest levels of mercury and arsenic, 1.10 lg/g As and 6 ng/g Hg. The highest cadmium concentration was 1.02 lg/g found in porridge. There were some discrepancies between declared and analysed values for these elements, but none was above tolerable upper intake level as given by WHO. A table have not been included as these metals were below detection the limit in the majority of samples. Table 2 shows the concentrations of nine trace elements and minerals in infant formulas, together with reported concentrations
8 months
3. Results
6 months
The accuracy of the method was verified by analysing the certified reference material Bovine Liver 1557b (NIST). The concentrations found were within 95– 105% of the certified values. To assess possible contamination during sample preparation, blank samples of ultrapure water were prepared using the same procedure as for the samples. All blank levels obtained were negligible.
4 months
2.3. Quality assurance
Age
HR-ICP-MS analyses were performed using a Thermo Finnigan model Element 2 instrument (Germany). The radio frequency power was set at 1250 W. The samples were introduced using a CETAC ASX 500 autosampler with a peristaltic pump (1 ml/ min). The instrument was equipped with a concentric Meinhart nebulizer connected to a Scott PFA spray chamber, platinum skimmer and interface cones and a demountable torch of quartz with a guard electrode. The argon gas flow rate and torch position was adjusted to give a stable signal with maximum intensity for the nuclides 7Li, 115In and 238U. The instrument was calibrated using 0.6 M HNO3 solutions of matrix matched multielement standards. Calibration curves using five different concentrations were made using these standards. To check for instrumental drift, one of these multielement standards and reference material (SW2, Spectrapure Standards) was analysed for every 10 samples.
– 75.7 0.000 0.00 849 1.13 40.4 0.13 0.05 9.21 – 0.53
2.2. Trace element analysis
n.d. 338 0.004 0.02 3300 5.13 456 34.2 0.06 108 n.d. 3.31
Porridge Porridge Porridge
8 months
A single sample of all products was obtained in Norway. The fruit purée and dinners were first homogenized using a blender (Multiquick, Braun) and duplicate samples of 1.0 g (wet weight) was weighed directly into microwave vessels. Porridges were homogenized by turning the aluminium bags upside down 50 times. Duplicate samples of about 0.3 g (dry weight) were weighed directly into microwave vessels. The infant formula samples were prepared by dissolving milk powder using ultrapure water (Elga) following the manufacturer’s description. Further, duplicate samples of 1 ml of the mixture were then digested in microwave vessels. All samples were added 4.0 ml concentrated HNO3 (Suprapur, Merck) and digested using a microwave oven (Multiwave 3000, Anton Paar). After digestion, samples were diluted with ultrapure water (92 ml, Ultra Analytic, Elga) directly in the microwave vessels. Duplicate samples (1.0 ml) were further diluted 1:10 in 14 ml tubes suitable for HR-ICP-MS analysis (Falcon, cat. no. 352059). HNO3 (0.4 ml, 14.4 M, Suprapure) was added to achieve a final acid concentration of 0.6 M HNO3.
6 months
2.1. Sample preparation for trace element analysis
12 months
2. Materials and methods
SD
R. Melø et al. / Food and Chemical Toxicology 46 (2008) 3339–3342
Al Ca Co Cr Cu Fe K Mg Mo Na Ni Zn
3340
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R. Melø et al. / Food and Chemical Toxicology 46 (2008) 3339–3342 Table 2 Analysed and declared values of minerals in infant formula from two manufacturers Element
Unit
Na Ca Fe Zn Mg K Cu
mg/g mg/g lg/g lg/g mg/g mg/g mg/g
Product nr 1
Product nr 2
Declared
Analysed
1.2 3.2 62 39 0.36 4.6 3.1
1.14 3.92 43 29 0.34 4.8 3.2
Declared
Analysed
5.1 56 35 0.4 5.0 3.0
1.01 2.85 59 37 0.34 4.3 4.0
Breast milk
Breast milk
Garg et al.
WHO
2.17 47
1.5
1.8 2.8 3 12 0.35 5.2 2.5
SD = standard deviation.
Table 3 Composition of a diet for children recommended for children aged six months (Nestlé, 2006) Meal
Product
Amount
1
Breast-milk substitute Fruit puree
200 ml
2
Porridge Fruit puree Breast-milk substitute
30 g 195 g 150 ml
3
Dinner Fruit puree Breast-milk substitute
195 g 195 g 150 ml
4
Porridge Fruit puree Breast-milk substitute
30 g 195 g 200 ml
Table 4 Comparison of total daily intake of minerals from the menu in Table 3 with recommended daily intake for children aged 6–12 months Mineral Ca Na K Mg Fe Zn Cu
mg mg mg mg mg mg lg
6 months
RDI (0–6 months)
RDI (7–12 months)
864 173 1831 151 11 5 252
525 280 800 60 11 4 200
525 350 700 75 11 5 300
Recommended daily intake (RDI) is given by WHO (WHO/UNICEF, 1998).
in human breast milk. The results are compared with the declared values from the producer. There are some minor discrepancies between declared and analysed values for some of the elements. However all concentrations are within min/max of recommended values. The concentrations found in the infant formula also agree quite well with concentrations in human breast milk (WHO/UNICEF, 1998; Garg et al., 1993). The exception is the level of iron in infant formula, which is much higher than in human breast milk. The composition of a daily menu for children aged six months as recommended from a producer of infant food is given in Table 3. Based on this menu we have analysed and calculated the daily intake of Ca, Cu, Fe, K, Mg, Na, and Zn. The results are presented in Table 4 and compared to the recommended daily intake as suggested by WHO (WHO/UNICEF, 1998). The composed menus are based solely on industrially prepared food. As can bee seen from Table 4, a diet based on industrially produced infant food will meet the infant’s daily requirement for the minerals analysed. This is also the case if the infant is fed breast milk instead of formula. 4. Discussion The bioavailability of iron is lower in infant formulas compared to breast milk (Lönnerdal, 1989). To compensate for this, commercial
infant formula preparations are usually fortified with iron and sometimes zinc (Domínguez et al., 2005). Iron fortification of complementary infant food is also widespread in industrialized countries. Because of rapid growth and high iron requirement during the first two years of life this may exceed the dietary intake among infants and toddlers (Hay et al., 2004). A study on the iron status of Norwegian children aged 6–24 months actually found a mild iron deficiency among otherwise healthy Norwegian infants (Hay et al., 2004). The problem of iron deficiency anaemia is however much higher in developing countries where iron-fortified food is less available than in industrialized countries. As a result, infant food in these countries is often based on plants and cereals, where elevated phytate content inhibits the uptake of iron and zinc. A WHO/UNICEF review of complementary feeding in developing countries also recognized that iron and zinc requirements may be difficult to meet from non-fortified complementary foods (WHO/UNICEF, 1998). Breast-feeding is recommended until six months of age. At this age introduction of complementary food is recommended to ensure an adequate intake of minerals (Monte and Giugliani, 2004). It should however be noted that trace element analysis of infant food only gives us the total content of trace elements, and does not consider differences in bioavailability (Domínguez et al., 2005). From the age of six months, it is probable that the child’s diet is gradually supplied or replaced in part with the ordinary family food. A dietary survey of healthy infants from 6–12 month may help in estimating the food intake as well as the dietary sources. However, food sources and cooking practises vary considerably between countries and even within the population in a given country. From Table 4 it is interesting to note that the suggested menu contains less sodium and more potassium than the recommended daily intake for the 6–12 months age group. Salt will enhance the flavour of food and flavour assessment is done by the child’s food provider. Thus, an adult person’s perception of food flavour is important for marketing of infant food. In many countries there is a concern over salt intake and the sodium chloride has been replaced by potassium chloride. This particular aspect of the results presented in Table 4 should be investigated further. Proper complementary feeding of infants is crucial for their optimal growth and development. This study shows that a diet based on commercially prepared food fulfils the infant’s need of minerals and trace elements. Further, it does not exceed the upper tolerable limit for any of the minerals or trace elements analysed. For the majority of products, toxic elements are present at very low levels. Conflict of interest statement The authors declare that there are no conflicts of interest statement. Funding source: The Norwegian University of Science and Technology. The work has been performed by a student. The samples were obtained free of charge from the manufacturer.
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R. Melø et al. / Food and Chemical Toxicology 46 (2008) 3339–3342
References Asubiojo, O.I., Iskander, F.Y., 1988. A trace element study of commercial infant milk and cereal formulas. J. Radioanal. Nucl. Chem. 125, 265–270. Bhutta, Z.A., 2000. Iron and zinc intakes from complementary foods: some issues from Pakistan. Pedriatrics 106, 1295–1297. Brätter, P., Blasco, I.N., Negretti de Brätter, V.E., Raab, A., 1998. Speciation as an analytical aid in trace element research in infant nutrition. Analyst 123, 821– 826. Domínguez, R., Peña, E., Bermejo, A., Cocho, J.A., 2005. Fe, Cu and Zn distribution in different components of commercial infant formulas. Eur. Food Res. Technol., 529–537. Garg, A.N., Weginwar, R.G., Chutke, N.L., 1993. A comparative study of minor and trace elements in human, animal and commercial milk samples by neutron activation analysis. J. Radioanal. Nucl. Chem. 172, 125–135. Gibson, R.S., Hotz, C., 2000. The adequacy of micronutrients in complementary foods. Pediatrics 106, 1298–1299. Hay, G., Sandstad, B., Whitelaw, A., Borch-Iohnsen, B., 2004. Iron status in a group of Norwegian children aged 6–24 months. Acta Pdiatr. 93, 592–598. Kimmons, J.E., Dewey, K.G., Haque, E., Chakraborty, J., Osendarp, S.J.M., Brown, K.H., 2005. Low nutrient intakes among infants in rural Bangladesh are attributable to low intake and micronutrient density of complementary foods. J. Nutr. 135, 444–451.
Lönnerdal, B., 1989. Trace element absorption in infants as a foundation to setting upper limits for trace elements in infant formulas. J. Nutr. 119, 1839–1845. Michaelsen, K.F., Friis, H., 1998. Complementary feeding: a global perspective. Nutrition 14, 763–766. Monte, C.M., Giugliani, E.R., 2004. Recommendations for the complementary feeding of the breastfed child. J. Pediatr. 80, S131–S141. Nestlé, 2006. Nestlé Barnemat. Source: Nestlé, Available from:
Contents lists available at ScienceDirect
Food and Chemical Toxicology journal homepage: www.elsevier.com/locate/foodchemtox
Minerals and trace elements in commercial infant food Renate Melø a, Kristin Gellein b, Lars Evjea, Tore Syversen a,* a b
Department of Neuroscience, Norwegian University of Science and Technology, NO 7489 Trondheim, Norway Department of Chemistry, Norwegian University of Science and Technology, NO 7491 Trondheim, Norway
a r t i c l e
i n f o
Article history: Received 7 December 2007 Accepted 11 August 2008
Keywords: Minerals Trace elements Infant Complementary food Infant formula
a b s t r a c t Adequate nutrition during infancy is essential for lifelong health and wellbeing. Breast-feeding is highly recommended for the first six month of life, but from then on complementary feeding is necessary. Industrially produced food is an important part of the diet for many infants and toddlers in developed countries. We have determined the concentration of major minerals and trace elements in 76 different products of infant formula, porridges, fruit purée and dinners by HR-ICP-MS. The products were collected from three suppliers on the Norwegian market (Nestlé, Tine and Nyco Pharma). A daily menu was also composed and the estimated daily intake was compared with current recommendations. All products were within the upper tolerable limit for the minerals of trace elements analysed and toxic elements were present at very low levels. A diet based solely on industrially prepared food products will provide a sufficient intake of minerals and trace elements. Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction Trace elements and minerals are essential for biological processes and play a vital role in normal growth and development. Infancy and early childhood are characterized by a very high growth rate and trace element requirements are more critical during this period (Brätter et al., 1998). The high growth rate and development of organ systems in childhood requires a balanced diet rich in nutrients. Minerals are involved in many important functions in the body, e.g. enzymatic reactions, bone mineralization, as well as protection of cells and lipids in biological membranes. Low intake or reduced bioavailability of minerals may lead to deficiencies, which causes impairment of body functions (Schlenker and Williams, 2003). In fact, infant feeding from birth up to the first years of life may influence an individual’s entire future life (Monte and Giugliani, 2004). Breast milk alone can be used to properly feed infants during the first six month of life, but from then on complementary feeding is necessary (Monte and Giugliani, 2004). Because industrially produced foods is an important part of the diet for many infants and toddlers it is very important that such food contain sufficient amounts of minerals. There have been several studies of infant diets in both developing and industrialized countries (Noble et al., 2001; Noble and Emmet, 2006; Bhutta, 2000; Kimmons et al., 2005; Asubiojo and Iskander, 1988). Complementary food is defined as all foods and fluids other than breast milk given to the infant. From the age of * Corresponding author. Tel.: +47 73 598848; fax: +47 73 596879. E-mail address: [email protected] (T. Syversen). 0278-6915/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.fct.2008.08.007
nine months, complementary food should provide 75–100% of the intake of Fe and Zn. These estimates emphasize the critical role that complementary food plays in providing adequate quantities of these trace minerals (Gibson and Hotz, 2000). Inadequate complementary food is a major cause of the high prevalence of malnutrition in the developing world (Michaelsen and Friis, 1998). The World Health Organization’s (WHO) have made recommendations as to the daily intake (RDI) of minerals for infants and toddlers (WHO/UNICEF, 1998). Some minerals may constitute a potential health risk when consumed above the tolerable upper intake levels (UL) over an extended period. Examples of this are iodine and iron poisoning. For other minerals, the negative effects are less obvious, e.g. gastrointestinal problems. For non-essential elements like aluminium and heavy metals (e.g. mercury, cadmium and lead) any exposure is undesirable, but acceptable levels in food have been determined by WHO as such trace elements are present in most food supplies. The aim of this study was to investigate any discrepancies between declared and analysed value, if any toxic elements could be found and consider the daily intake from diets composed according to manufacturer’s advice. The study included 76 different products of infant formula, porridges, fruit purée and dinners from the manufacturer Nestlé, Tine and Nycomed Pharma. The Nestlé products are available throughout Europe although composition may change due to production site. The Tine product range is available in Norway only while the Nycomed Pharma products are available in Scandinavia. The concentration of 18 major minerals and trace elements were determined by HR-ICP-MS (high resolution inductively coupled plasma mass spectrometry).
73.5 86.4 0.59 216 134 1.49 89.2 17.2 39.3 55.7 95.0 0.57 220 587 0.39 181 256 9.25 806 88.9 60.6 105.6 78.8 2.40 The products are grouped by recommended consumer age and given as an average of several products. Values are given for 100 g of products to facilitate comparison with product labels. Avg = arithmetic average. SD = standard deviation. n.d. = not detected, below the detection limit. lg = microgram. g = gram.
mg/100 g lg/100 g lg/100 g lg/100 g mg/100 g mg/100 g mg/100 g lg/100 g mg/100 g lg/100 g mg/100 g
Avg SD
180 136 0.40 2.08 77.3 2.78 210 16.8 14.0 58.4 21.7 0.28 277 738 0.29 0.93 244 11.1 820 93.8 38.6 101 22.1 2.14
Avg SD
334 158 0.65 – 39.9 1.04 154 19.8 12.4 46.3 27.4 0.36 397 584 0.32 n.d. 213 9.48 827 88.4 39.5 126 26.0 2.11
Avg SD
409 50.6 – 12.5 56.4 1.34 394 25.0 5.08 98.4 13.6 0.81 360 612.9 n.d 6.3 135 10.63 454 59.6 26.4 84.5 7.70 1.30
Avg SD
41.4 7.50 0.29 4.46 16.8 0.10 24.3 3.25 2.04 3.89 3.92 0.07 55.9 10.3 0.32 6.30 53.1 0.19 118 8.21 0.68 2.89 6.64 0.11
Avg SD
92.4 13.2 0.11 2.51 16.5 0.17 28.4 1.49 3.39 16.3 2.31 0.15 169 22.9 0.09 10.1 65.7 0.60 209 13.3 6.5 163 12.5 0.68
Avg SD
49.4 23.0 0.11 4.25 13.0 0.18 37.7 2.18 3.64 25.5 4.00 0.25 79.5 21.3 0.10 8.38 50.6 0.46 169 11.5 7.18 132 9.04 0.61
Avg SD
62.0 8.75 0.11 2.91 23.8 0.15 41.0 2.55 2.76 49.7 3.62 0.12 92.3 17.5 0.07 5.87 51.8 0.40 172 11.3 3.96 94.4 7.46 0.41
Avg SD
35.0 2.49 0.23 2.00 14.0 0.12 53.1 2.22 1.81 46.8 1.85 0.12 45.7 12.0 0.15 4.82 47.3 0.36 174 10.5 1.61 45.5 7.24 0.41
Avg SD
87.7 0.43 0.17 1.38 5.15 0.03 3.78 0.31 1.53 1.60 0.91 0.03 69.3 10.4 0.12 3.22 31.2 0.18 117 7.50 1.09 6.92 5.81 0.15
lg/100 g
Avg
SD
Avg
Porridge
4 months 4–8 months
Fruit purée Dinner
18 months 12 months
Dinner Dinner Dinner Dinner Infant formula Product
Table 1 Trace element and mineral content of infant food products
The concentrations of aluminium, arsenic, calcium, cadmium, cobalt, chromium, copper, iron, mercury, potassium, manganese, molybdenum, sodium, nickel, lead, and zinc in 74 infant food products and 2 infant formulas were determined by analysis on HR-ICPMS. Table 1 presents the average concentrations for most of these elements in infant formula, dinner, porridge and fruit puree. The products are divided into groups according to recommended age of the infant. Results are given as an average of several products (2–12). There is a wide range of dinners; containing beef, vegetables, lamb, turkey, pork, spaghetti etc. The porridges are also of different types, like wheat, wholegrain, müsli or corn. For the porridges a high and variable aluminium concentration was found. A possible explanation for this observation can be contamination as the dry material is packaged in plastic lined aluminium foil bags. Arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb) are toxic elements that may cause adverse effects in humans even at low levels (Nordberg and Cherian, 2005). None of the products contained arsenic, cadmium, mercury or lead in amounts that could represent a health hazard for the consumer. Dinners containing fish had the highest levels of mercury and arsenic, 1.10 lg/g As and 6 ng/g Hg. The highest cadmium concentration was 1.02 lg/g found in porridge. There were some discrepancies between declared and analysed values for these elements, but none was above tolerable upper intake level as given by WHO. A table have not been included as these metals were below detection the limit in the majority of samples. Table 2 shows the concentrations of nine trace elements and minerals in infant formulas, together with reported concentrations
8 months
3. Results
6 months
The accuracy of the method was verified by analysing the certified reference material Bovine Liver 1557b (NIST). The concentrations found were within 95– 105% of the certified values. To assess possible contamination during sample preparation, blank samples of ultrapure water were prepared using the same procedure as for the samples. All blank levels obtained were negligible.
4 months
2.3. Quality assurance
Age
HR-ICP-MS analyses were performed using a Thermo Finnigan model Element 2 instrument (Germany). The radio frequency power was set at 1250 W. The samples were introduced using a CETAC ASX 500 autosampler with a peristaltic pump (1 ml/ min). The instrument was equipped with a concentric Meinhart nebulizer connected to a Scott PFA spray chamber, platinum skimmer and interface cones and a demountable torch of quartz with a guard electrode. The argon gas flow rate and torch position was adjusted to give a stable signal with maximum intensity for the nuclides 7Li, 115In and 238U. The instrument was calibrated using 0.6 M HNO3 solutions of matrix matched multielement standards. Calibration curves using five different concentrations were made using these standards. To check for instrumental drift, one of these multielement standards and reference material (SW2, Spectrapure Standards) was analysed for every 10 samples.
– 75.7 0.000 0.00 849 1.13 40.4 0.13 0.05 9.21 – 0.53
2.2. Trace element analysis
n.d. 338 0.004 0.02 3300 5.13 456 34.2 0.06 108 n.d. 3.31
Porridge Porridge Porridge
8 months
A single sample of all products was obtained in Norway. The fruit purée and dinners were first homogenized using a blender (Multiquick, Braun) and duplicate samples of 1.0 g (wet weight) was weighed directly into microwave vessels. Porridges were homogenized by turning the aluminium bags upside down 50 times. Duplicate samples of about 0.3 g (dry weight) were weighed directly into microwave vessels. The infant formula samples were prepared by dissolving milk powder using ultrapure water (Elga) following the manufacturer’s description. Further, duplicate samples of 1 ml of the mixture were then digested in microwave vessels. All samples were added 4.0 ml concentrated HNO3 (Suprapur, Merck) and digested using a microwave oven (Multiwave 3000, Anton Paar). After digestion, samples were diluted with ultrapure water (92 ml, Ultra Analytic, Elga) directly in the microwave vessels. Duplicate samples (1.0 ml) were further diluted 1:10 in 14 ml tubes suitable for HR-ICP-MS analysis (Falcon, cat. no. 352059). HNO3 (0.4 ml, 14.4 M, Suprapure) was added to achieve a final acid concentration of 0.6 M HNO3.
6 months
2.1. Sample preparation for trace element analysis
12 months
2. Materials and methods
SD
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Al Ca Co Cr Cu Fe K Mg Mo Na Ni Zn
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R. Melø et al. / Food and Chemical Toxicology 46 (2008) 3339–3342 Table 2 Analysed and declared values of minerals in infant formula from two manufacturers Element
Unit
Na Ca Fe Zn Mg K Cu
mg/g mg/g lg/g lg/g mg/g mg/g mg/g
Product nr 1
Product nr 2
Declared
Analysed
1.2 3.2 62 39 0.36 4.6 3.1
1.14 3.92 43 29 0.34 4.8 3.2
Declared
Analysed
5.1 56 35 0.4 5.0 3.0
1.01 2.85 59 37 0.34 4.3 4.0
Breast milk
Breast milk
Garg et al.
WHO
2.17 47
1.5
1.8 2.8 3 12 0.35 5.2 2.5
SD = standard deviation.
Table 3 Composition of a diet for children recommended for children aged six months (Nestlé, 2006) Meal
Product
Amount
1
Breast-milk substitute Fruit puree
200 ml
2
Porridge Fruit puree Breast-milk substitute
30 g 195 g 150 ml
3
Dinner Fruit puree Breast-milk substitute
195 g 195 g 150 ml
4
Porridge Fruit puree Breast-milk substitute
30 g 195 g 200 ml
Table 4 Comparison of total daily intake of minerals from the menu in Table 3 with recommended daily intake for children aged 6–12 months Mineral Ca Na K Mg Fe Zn Cu
mg mg mg mg mg mg lg
6 months
RDI (0–6 months)
RDI (7–12 months)
864 173 1831 151 11 5 252
525 280 800 60 11 4 200
525 350 700 75 11 5 300
Recommended daily intake (RDI) is given by WHO (WHO/UNICEF, 1998).
in human breast milk. The results are compared with the declared values from the producer. There are some minor discrepancies between declared and analysed values for some of the elements. However all concentrations are within min/max of recommended values. The concentrations found in the infant formula also agree quite well with concentrations in human breast milk (WHO/UNICEF, 1998; Garg et al., 1993). The exception is the level of iron in infant formula, which is much higher than in human breast milk. The composition of a daily menu for children aged six months as recommended from a producer of infant food is given in Table 3. Based on this menu we have analysed and calculated the daily intake of Ca, Cu, Fe, K, Mg, Na, and Zn. The results are presented in Table 4 and compared to the recommended daily intake as suggested by WHO (WHO/UNICEF, 1998). The composed menus are based solely on industrially prepared food. As can bee seen from Table 4, a diet based on industrially produced infant food will meet the infant’s daily requirement for the minerals analysed. This is also the case if the infant is fed breast milk instead of formula. 4. Discussion The bioavailability of iron is lower in infant formulas compared to breast milk (Lönnerdal, 1989). To compensate for this, commercial
infant formula preparations are usually fortified with iron and sometimes zinc (Domínguez et al., 2005). Iron fortification of complementary infant food is also widespread in industrialized countries. Because of rapid growth and high iron requirement during the first two years of life this may exceed the dietary intake among infants and toddlers (Hay et al., 2004). A study on the iron status of Norwegian children aged 6–24 months actually found a mild iron deficiency among otherwise healthy Norwegian infants (Hay et al., 2004). The problem of iron deficiency anaemia is however much higher in developing countries where iron-fortified food is less available than in industrialized countries. As a result, infant food in these countries is often based on plants and cereals, where elevated phytate content inhibits the uptake of iron and zinc. A WHO/UNICEF review of complementary feeding in developing countries also recognized that iron and zinc requirements may be difficult to meet from non-fortified complementary foods (WHO/UNICEF, 1998). Breast-feeding is recommended until six months of age. At this age introduction of complementary food is recommended to ensure an adequate intake of minerals (Monte and Giugliani, 2004). It should however be noted that trace element analysis of infant food only gives us the total content of trace elements, and does not consider differences in bioavailability (Domínguez et al., 2005). From the age of six months, it is probable that the child’s diet is gradually supplied or replaced in part with the ordinary family food. A dietary survey of healthy infants from 6–12 month may help in estimating the food intake as well as the dietary sources. However, food sources and cooking practises vary considerably between countries and even within the population in a given country. From Table 4 it is interesting to note that the suggested menu contains less sodium and more potassium than the recommended daily intake for the 6–12 months age group. Salt will enhance the flavour of food and flavour assessment is done by the child’s food provider. Thus, an adult person’s perception of food flavour is important for marketing of infant food. In many countries there is a concern over salt intake and the sodium chloride has been replaced by potassium chloride. This particular aspect of the results presented in Table 4 should be investigated further. Proper complementary feeding of infants is crucial for their optimal growth and development. This study shows that a diet based on commercially prepared food fulfils the infant’s need of minerals and trace elements. Further, it does not exceed the upper tolerable limit for any of the minerals or trace elements analysed. For the majority of products, toxic elements are present at very low levels. Conflict of interest statement The authors declare that there are no conflicts of interest statement. Funding source: The Norwegian University of Science and Technology. The work has been performed by a student. The samples were obtained free of charge from the manufacturer.
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