Iron Nutrition in Schoolchildren of Western Mexico: The Effect of Iron Fortification

Abstract

In Mexico, food fortification is used as a strategy to combat micronutrient deficiencies. However, little is known about the effects of food fortification in vulnerable populations. This study was carried out in a population of school children believed to be at risk of various micronutrient deficiencies, including iron. The study aimed at determining iron status of children, and identifying and quantifying the sources of iron intake and the presence of relevant enhancers and inhibitors of iron absorption in the diet. The iron status and dietary iron intake was assessed of schoolchildren aged 3–14 years in western Mexico. Hemoglobin, serum ferritin, and transferrin saturation percentages were used to evaluate the iron status in a school-based sample of 762 children. Dietary data were collected from 607 children using semi-quantitative food frequency questionnaires. The overall prevalence of anemia and iron deficiency was 3.7% and 4%, respectively. Iron intake ranged from 1.9 to 3.3 times the recommended daily allowance, with fortified iron accounting for 72% of the total iron intake. Although iron fortification of staples such as maize flour in Mexico for more than a decade most likely contributed to reducing the prevalence of anemia and iron deficiency, the relatively large amounts of iron consumed could eventually lead to problems related to excessive iron intake in some children. Nutritional guidelines for iron fortification in Mexico should be defined and put into practice.

Keywords:

• anemia
• FFQ
• fortification
• iron deficiency
• RDA
• schoolchildren

ACKNOWLEDGMENTS

The authors want to thank the students and nurses who participated in collecting blood samples and the schoolchildren and their parents for their participation, as well as the schools' personnel for their assistance during the fieldwork.

Notes

¹Different superscripts (a, b, c) indicate statistically different means (p < 0.05); ANOVA and Bonferroni test were used.

²Mild anemia Hb < 110 g/l in chidren 3–5 years of age, Hb < 115 g/l in children 6–11 years of age, Hb < 120 g/l for chidren 12–13 years of age and girls of 14 years of age, Hb < 130 g/l for boys 14 years of age, moderate anemia Hb 80–99 g/l, severe anemia Hb < 80 g/l.

¹Different superscripts (a, b, c) indicate statistically different means (p < 0.05); ANOVA and Bonferroni tests were used.

²Statistically different proportions (p < 0.05); Pearson chi ² was used.

¹Different superscripts (a, b, c) indicate statistically different means (p < 0.05); ANOVA and Bonferroni tests were used.

²Ascorbic acid enhances non-heme iron absorption in a dose-dependent fashion. AA has a high impact on non-heme iron absorption if a meal contains > 50 mg of AA and enhancing effect is most apparent when consumption of muscle protein is low and in the presence of suboptimal iron status (Allen and Ahluwalia, 1997).

³Calcium inhibits both heme and non-heme iron absorption if consumed simultaneously; this effect appears to be dose-related up to 300 mg. Studies show that 300–600 mg of calcium inhibited iron absorption by 60%, after which only little additional inhibition can be detected (Hallberg et al., 1991; Hallberg, 1998).

¹RDA for ir/on in children aged 3 y is 7 mg (UL 40 mg); for those aged 4–8 y is 10 mg (UL 40), and for those aged 9–13 y is 8 mg (UL 40).

Instituto Nacional de Diagnostica y Referencia Epidemiologica (INDRE) (2001). Formato prevencion y control de bocio: Análisis de resultados de yodurias en menores en Colima, Mayo 2001.