Fe deficiency (ID) is the most common nutritional deficiency disorder in the world, affecting more than two billion people, mostly infants, children and women of childbearing age(Reference Stolzfus1).
In general, the symptoms of ID are considered to be due probably not to lowered Hb level, but to an insufficient supply of Fe to the tissues(Reference Hallberg2). The human brain develops up until about 20 years of age, and brain Fe content also increases concomitantly up to this age. It may be difficult to repair the negative effects of ID developed during this period(Reference Hallberg2). It may therefore be assumed that optimal Fe adequacy should prevail in an individual at least during the first 20 years of life(Reference Hallberg2). Several reviews(Reference Grantham-McGregor and Ani3, Reference Beard and Connor4) and recent reports(Reference Akman, Cebeci, Okur, Angin, Abali and Akman5, Reference Konofal, Lecendreux, Arnulf and Mouren6) show negative effects of ID related to mental symptoms in infants and children, but unrelated to anaemia; even in adolescents there exist concerns on this issue(Reference Bruner, Joffe, Duggan, Casella and Brandt7). Therefore, the outcome of current evidence strongly suggests that to assure optimal health and development, it is important to prevent and treat even mild ID of growing individuals, at least up to around 20 years of age, as well as during pregnancy(Reference Hallberg2).
Fortification of food with Fe, when an appropriate diet is not available, is considered the best sustainable way of preventing ID. The most difficult challenge to this end is to find the ideal combination of an Fe-fortified compound and its corresponding food vehicle(Reference Hurrell8).
There exist many reports on the successful addition of NaFeEDTA or Fe(ii) bisglycinate fortifiers in the form of an Fe chelate, which protects from combination with dietary inhibitors, mainly phytic acid(Reference Hurrell8). Furthermore, little evidence exists that Fe fortification of staple foods, such as corn flour, is a useful strategy to combat ID(Reference Hallberg9). Theoretically, it could be assumed that elemental Fe as a fortifier and corn flour as food vehicle would not be a really ideal combination. Concern exists about using this combination in phytate-rich diets, and diet in the poorer areas of Brazil is basically composed of rice, beans and vegetables.
However, it could be argued that reports on Fe absorption were verified with single meals, under special conditions, and that studies in which the effects of enhancers and inhibitors of Fe absorption were studied in whole meals showed results that were far less pronounced than those from single meals(Reference Cook, Dassenko and Lynch10, Reference Cook and Reddy11). Fortification of cereal flour with elemental Fe was successful in Chile(Reference Walter, Dallman, Pizarro, Vebozo, Peña, Bartholmey, Hertrampf, Olivares, Letelier and Arredondo12). Aside from these considerations, it should be emphasized that costs are very important in fortification measures, especially to convince political authorities in developing countries of the need for a continued Fe fortification programme.
The aim of the present study, therefore, was to investigate the effect of corn flour-derived products fortified with elemental Fe on ID and Fe-deficiency anaemia (IDA) prevalence in children and adolescents assisted by public educational centres in Londrina, Brazil.
Material and methods
The assessed population participated in public educational centres in Londrina, Parana State (southern Brazil), which assist families living under precarious socio-economic conditions. Their annual income is less than $US 2000·00 per capita; 85 % of the children’s parents have not more than 3–4 years of schooling. The evaluation study took place in nine peripheral city centres and was sponsored by the local city government; for 6 h each day, the centres provided recreation, pedagogic assistance, cultural activities and meals for children below 14 years of age. In most cases, meals provided at these centres are this population’s only access to food. It is important to mention that the population studied did not receive supplements from any government programme and had no involvement with any organization or entity with policy interest in the matter.
The Ethical Committee of the University of Londrina approved the study, and the children’s parents signed formal agreements to it.
All children and adolescents (362 subjects) from the nine peripheral city centres were recruited to participate in the study. Blood samples were collected by venepuncture from individuals who had fasted for 12 h. The following parameters were assessed: Hb, measured by an automated counter (Pentra 120 Retic; ABX-Horiba, Montpellier, France); percentage transferrin saturation (100 × serum Fe/total Fe-binding capacity), estimated by the Ferrozine method using an automatic chemistry analyser (Dimension AR; Dade-Behring, Deerfield, IL, USA); and serum ferritin, estimated by the microparticle enzyme immunoassay method using an automatic immunoassay analyser (AxSYM; Abbott, Irving, TX, USA). The children and adolescents were assessed at the beginning of the study (baseline) and after 6 months of treatment, and only data for the 162 individuals (eighty-six boys and seventy-six girls, age range 7–14 years) from whom blood samples were obtained at baseline and after 6 months are presented. IDA was so defined when Hb level lower than 12 g/dl and serum ferritin level lower than 20 μg/l were found, and ID when serum ferritin had fallen to less than 20 μg/l. The value used to express alteration in the other assessed parameter was transferrin saturation ≤16 %. Children and adolescents with clinically evident infection or inflammation, at the beginning and the end of the study, were excluded to avoid interference with the acute-phase reactant proteins serum ferritin and transferrin.
Fortification was accomplished by administering corn flour-derived sweet and salty products (biscuits, cakes and pies), fortified with elemental Fe powder in the form of H2-reduced Fe (<45 μm or 325 mesh). The corn flour-derived products had been previously evaluated and found to have an excellent acceptance. Each subject ingested daily 100 g of the corn flour-derived products, containing 76 g carbohydrates, 2 g fat, 8 g protein, 9·8 mg Fe and 0·35 mg folic acid.
Changes in blood parameters occurring during the study were estimated relative to baseline values, using the McNemar test for paired data. Differences (means and standard deviations, medians) between normal and altered blood parameters were calculated at the end of the study using the Mann–Whitney test. Differences showing P values of <0·05 found respectively prior to and following treatment were considered to be statistically significant.
Results
The prevalence of ID and IDA at the beginning of the study was 18·0 % and 14·9 %, respectively; a reduction to 5·6 % and 1·2 %, respectively, was observed after 6 months of Fe fortification (Fig. 1).
Fig. 1 Iron deficiency (ID) and iron-deficiency anaemia (IDA) prevalence in Brazilian children and adolescents at the beginning of the study (░) and following 6 months of treatment (␣) with corn flour-derived products fortified with powdered elemental iron in the form of hydrogen-reduced iron
Statistically significant changes from altered to normal values occurred more often than normal to altered values with transferrin saturation (14·2 % v. 6·8 %; P < 0·04) and ferritin (12·4 % v. 0 %; P < 0·001; Table 1).
Table 1 Prevalence of blood parameter changes in Brazilian children and adolescents during 6 months of treatment with corn flour-derived products fortified with powdered elemental iron in the form of hydrogen-reduced iron
No subject = no subject showed change.
*Statistically significant difference from altered first and normal second to normal first and altered second value assessments.
†McNemar’s test for paired data.
All blood parameters (mean and sd, median) showed statistically significant differences between altered and normal levels after 6 months (P < 0·001; Table 2). Altered transferrin saturation and serum ferritin increased from 10·9 (sd 3·8) % and 13·2 (sd 4·1) μg/l before fortification to 26·4 (sd 10·9) % and 25·5 (sd 10·8) μg/l, respectively, after fortification.
Table 2 Comparison of blood parameter values in Brazilian children and adolescents at the beginning of the study and following 6 months of treatment with corn flour-derived products fortified with powdered elemental iron in the form of hydrogen-reduced iron
†Mann–Whitney test to compare the difference between normal and altered values.
Discussion
In the present study, 14·9 % of the subjects had anaemia. It must be emphasized that a previous study at the same environmental outskirts’ educational centres showed initial anaemia prevalence of 41·9 % and, after 1 year of fortification with Fe(ii) bisglycinate, a final prevalence of 9·6 %(Reference Miglioranza, Matsuo, Caballero-Córdoba, Dichi, Cyrino, Oliveira, Martins, Polezer and Dichi13). Echoes of that long-term intervention study certainly still remained.
There was a high decrease in the number of subjects studied in the present study. The main reasons were the presence of infection or inflammation near the end of the study and dropout due mainly to socio-economic reasons. However, the number of subjects who dropped out was relatively proportional in all nine public educational centres.
Elemental Fe powders are the most common Fe fortifiers used worldwide, since they cause the least problems concerning colour, flavour and rancidity in food products and are in general less expensive. However, many concerns about their utilization remain(Reference Hurrell8, Reference Hurrell14). First, there is little evidence that they have a beneficial effect on Fe status. Second, powdered elemental Fe is water-insoluble and poorly soluble in dilute acids; thus, because it never dissolves completely in the gastric juice, it has a low and variable bioavailability, ranging from 5 % to 148 % relative to standard FeSO4. Third, powders with large particle size (>149 μm or 100 mesh) interfere negatively with Fe absorption.
There are five different types of elemental Fe powders used for food fortification: (i) electrolytically reduced; (ii) H2-reduced; (iii) CO-reduced; (iv) atomized (reduced); and (v) carbonyl-Fe. In a study of Fe absorption measured with 58Fe in ten non-anaemic female volunteers with fairly low Fe stores, Roe and Fairwheather-Tait(Reference Roe and Fairwheather-Tait15) verified that H2-reduced Fe powder compares favourably with the absorption of well-absorbed Fe (Fe(ii) ascorbate) and reinforced the current use of reduced Fe powder to fortify flour in the UK. García-Casal et al.(Reference García-Casal, Larysse, Pena-Rosas, Ramirez, Leets and Matus16) also found that H2-reduced Fe-fortified cereal had a significantly higher absorption rate than cereal without Fe fortification (9·27 and 3·38, respectively). Fe content of the corn flakes was 3·5 mg/30 mg, a content of H2-reduced Fe similar to that used in the present study (9·8 mg/100 g). On the other hand, Walter et al.(Reference Walter, Pizarro, Boy and Abrams17) found that H2-reduced Fe powder at 3 mg/100 g was ineffective as a fortifier in corn tortillas prepared with corn masa flour given to 5- to 7-year-old children.
However, an expert panel(Reference Hurrell, Bothwell and Cook18) reporting on the usefulness of elemental Fe powders for food fortification concluded that electrolytic Fe was the only Fe powder to be recommended. On the basis of the change in body Fe stores during a 35-week study in Thai women, Zimmermann et al.(Reference Zimmermann, Winichagoon, Gowachirapant, Hess, Harrington, Chavasit, Lynch and Hurrell19) verified that the relative efficacy of the electrolytic and H2-reduced Fe compared with FeSO4 (12 mg Fe/d) was 77 % and 49 %, respectively. Nevertheless, two other studies using electrolytic Fe did not find improvement of Fe status(Reference Andang’o, Osendarp, Ayah, West, Mwaniki, De Wolf, Kraaijenhagen, Kok and Verhoef20, Reference Nestel, Nalubola, Sivakaneshan, Wickramasinghe and Atukorala21).
Special concern prevails for the use of Fe-fortified cereals(Reference Hurrell8). There exist two major disadvantages in the use of cereal products as vehicles for Fe fortification: (i) they contain high levels of phytic acid, a potential inhibitor of Fe absorption; and (ii) they are extremely sensitive to fat oxidation during storage when highly bioavailable Fe compounds such as FeSO4 are employed(Reference Hurrell22). According to the International Nutritional Anemia Consultative Group(23), absorption of Fe is lower from maize than from other cereals. However, the type of cereal grain (rice, wheat, maize or oats) had shown little influence on Fe bioavailability in infant’s cereals(Reference Cook, Reddy, Burri, Juillerat and Hurrell24). Furthermore, the processing methods used to reduce the content of phytate from cereals seemed more useful than the choice of a particular cereal grain(Reference Cook, Reddy, Burri, Juillerat and Hurrell24). The complete degradation of phytic acid in maize and other infant cereals increased Fe absorption by up to ten times(Reference Hurrell14).
Another issue that needs to be considered is that short-term studies(Reference Hunt and Roughead25) and single meals(Reference Cook, Dassenko and Lynch10, Reference Cook and Reddy11) seem to overestimate differences in dietary Fe bioavailability. Lind et al.(Reference Lind, Lönnerdall, Persson, Stenlund, Tennefors and Hernell26) have not verified a greater effect on Hb or serum ferritin in a long-term study despite a 77 % reduction in the daily phytate intake from infant’s cereal.
The data of the present study show a decrease in ID and IDA from 18·0 % and 14·9 % to 5·6 % and 1·2 %, respectively, after 6 months. This favourable response can be partially explained by the milling and degerming methods used to transform the cereal grain into corn flour, which are responsible for decreasing phytic acid found in the germ part of the grain(Reference Cook, Reddy, Burri, Juillerat and Hurrell24). Moreover, the Brazilian regional diet offered at lunch in the educational centres consisted of rice, bean and 50 g of meat; this may have contributed to the observed favourable results, although the children were eating the educational centres’ diet for a long time before the beginning of the study.
Many studies have confirmed the enhancing effect of muscle tissue on Fe absorption(Reference Hurrell8, Reference Engelmann, Sandström and Michaelsen27, Reference Baech, Hansen, Bukhave, Jensen, Sorensen, Kristensen, Purslow, Skibsted and Sandström28), counteracting the inhibition of non-haem absorption by phytate(Reference Hallberg9). It was first shown 40 years ago that the addition of veal meat to a meal of black beans and maize doubled non-haem Fe absorption(Reference Hurrell29). Meat (20 g) has a non-haem Fe absorption factor from a typical wholegrain weaning meal of approximately 60 %(Reference Hallberg and Hulthén30). The enhancing effect of meat on Fe absorption is known as the ‘meat factor’ or ‘meat effect’, and may be related to the potential ability of sulfhydryl-containing amino acids or peptides to chelate non-haem Fe, thereby facilitating its intestinal absorption(Reference Baech, Hansen, Bukhave, Jensen, Sorensen, Kristensen, Purslow, Skibsted and Sandström28). In the present study, enhancing Fe absorption with ascorbic acid or its inhibition by tannins did not seem to play a role in the regional diet offered to the children.
Previous studies have reported the successful use of elemental electrolytic Fe to fortify wheat flour in Chile(Reference Walter, Dallman, Pizarro, Vebozo, Peña, Bartholmey, Hertrampf, Olivares, Letelier and Arredondo12); in contrast, increased ID from 39·3 % to 50·4 % was determined in 15- to 16-year-old Swedish girls(Reference Hulthén and Hallberg31) following withdrawal of carbonyl-Fe fortification from flour.
It is conceivable that Fe fortification treatment for periods longer than 6 months could normalize serum ferritin levels of the remaining nine children showing low serum ferritin levels at the end of the present study. Hallberg stated that the main effects on Fe status of fortification by the administration of Fe or by improvement of dietary bioavailability are to be expected after about one year(Reference Hallberg2).
Low cost is an important factor in the planning of public assistance programmes in underdeveloped and even in developed countries(Reference Walter, Dallman, Pizarro, Vebozo, Peña, Bartholmey, Hertrampf, Olivares, Letelier and Arredondo12). Although the utilization of corn flour as the vehicle and elemental Fe as the fortifier could be a reason for concern, this less expensive combined way of Fe fortification yielded a good response when part of a complete diet. Adequate processing methods of cereal flour fortified with sufficient doses of, and small size of the elemental Fe powder employed seem to be critically important for the good responses obtained in the present study.
To conclude, corn flour-derived products, fortified with reduced Fe administered during 6 months, significantly decreased the prevalence of ID and IDA in children and adolescents living in Londrina, Parana State, Brazil.
Acknowledgements
The material for the study was provided by Nutrimilho Ind. & Com. de Alimentos, Ltd (Maringá, Paraná, Brazil). None of the authors had any personal or financial conflict of interest. L.H.S.M. was responsible for recruiting the patients, the original concept of the study, the study design, interpretation of the results and the writing of the manuscript. I.D. was responsible for the interpretation of the results and the writing of the manuscript. T.M. was responsible for the statistical analysis. J.B.D. was responsible for interpretation of the results and the writing of the manuscript. J.W.B. was responsible for the haematological assessment. D.S.B. was responsible for the biochemical assessment. The resources employed in the investigation were obtained from the Universidade Estadual de Londrina, which maintains reagents and facilities for laboratory training of students, and those obtained through the Official Agreements between the University and the company Nutrimilho, which obtains rebate of income taxes for supporting the institution in developing research.
