Iron absorption prediction equations lack agreement and underestimate iron absorption

A Porcine-Derived Heme Iron Powder Restores Hemoglobin in Anemic Rats

BACKGROUND/OBJECTIVES

Iron-fortified foods reduce the incidence of iron deficiency anemia. However, the nutritional efficacy of heme iron fortificants is unclear.

METHODS

In this study, we determined the hemoglobin regeneration efficiency (HRE) of a porcine-derived heme iron powder (HIP), treating anemic rats (hemoglobin (Hb) 3-6 g/dL) with 14-day repletion diets fortified with four different concentrations (12, 24, 36, or 48 mg iron/kg diets) of HIP or a control diet ("no added iron"); n = 9-12/group.

RESULTS

Our results demonstrate an inverse association between HRE and increasing dietary iron from the HIP. The HRE ratios of diets containing the HIP powder at 12, 24, 36, or 48 mg iron/kg were 0.508, 0.268, 0.273, and 0.223, respectively. Based on the mean final Hb values at 14 d, the HRE ratio of the 12 mg iron/kg diet was significantly higher (p ≤ 0.05) compared to the other HIP diet groups; however, only the HIP provided in the 36 and 48 mg iron/kg diets restored hemoglobin to high enough levels (mean Hb > 6 g/dL) to correct anemia.

CONCLUSIONS

Our findings show that HIP at each of the concentrations tested increased Hb; moreover, when present at higher concentrations in the diet, the HIP is capable of restoring hemoglobin to resolve iron deficiency anemia.

The concentration of hemoglobin is associated with the dietary iron availability, food insecurity and the use of oral contraceptives among women in socially vulnerable areas of a capital city in northeastern Brazil

This study aimed to assess hemoglobin concentration and its association with oral contraceptive (OC) use, food insecurity (FI) and dietary iron availability (DIA) in adult women of reproductive age (20-44 years). This is a population-based cross-sectional study that analysed 505 women living in favelas and urban communities in a capital city in northeastern Brazil. Hemoglobin concentration was determined using capillary blood samples. FI and DIA were assessed using the Brazilian Food Insecurity Scale and the 24-h food recall, respectively. Association analysis was carried out using logistic regression. A directed acyclic graph (DAG) was designed to illustrate the causal paths between hemoglobin concentration and DIA. A significance level of 5 % was adopted. Low hemoglobin concentrations (11·2 g/dl: (1·79)) and a high prevalence of anaemia (64·0 %) were observed; 28·7 % used OC (28·7 %) and 76·4 % were in FI. An average energetic intake of 1495 kcal/d (482·0) and 0·46 mg/d (0·27) of DIA were also observed. In the DAG-guided multivariable analysis, it was observed that hemoglobin concentrations ≥ 12 mg/dl were directly associated with higher DIA (OR: 1·67; 95 % CI (1. 08, 2·59)) and OC use (OR: 1·67; 95 % CI (1·10, 2·55)) and inversely associated with mild FI (OR: 0·60; 95 % CI (0·37, 0·96)) or severe FI (OR: 0·37; 95 % CI: (0·18, 0·76)). Women taking OC and with a higher DIA were less likely to have low hemoglobin concentrations, while those in the context of FI were in the opposite situation.

Bioavailability of Australian pre-schooler iron intakes at specific eating occasions is low

PURPOSE

Poor bioavailability may contribute to iron deficiency among children in high-resource countries, but iron bioavailability of Australian pre-schooler diets is unknown. This study aimed to estimate the bioavailability of Australian pre-schooler iron intakes across the day and by eating occasions to identify optimal timing for intervention, by using five previously developed algorithms, and to estimate the proportion of children with intakes of absorbable iron below the requirements.

METHODS

Dietary data of children aged 2 to < 6 y (n = 812) from the 2011-12 National Nutrition and Physical Activity Survey were collected via two 24-h recalls. Usual food and nutrient intakes were estimated via Multiple Source Method. Phytate, polyphenol, and heme iron values were sourced from international databases or the literature. Five previously published algorithms were applied to observed dietary data to estimate iron bioavailability and calculate the prevalence of children with intakes of absorbable iron below requirements.

RESULTS

Pre-schooler daily iron bioavailability was low (2.7-10.5%) and corresponded to intakes of 0.18-0.75 mg/d of absorbable iron. The proportion of children with inadequate intakes of absorbable iron ranged between 32 and 98%. For all eating occasions, dinner offered iron of the greatest bioavailability (4.2-16.4%), while iron consumed at breakfast was of the lowest bioavailability (1.2-5.6%).

CONCLUSION

Future strategies are required to improve intakes of bioavailable iron for pre-schoolers to prevent the risk of deficiency. These strategies could include the encouragement of concomitant consumption of enhancers of iron absorption with iron-rich sources, particularly at breakfast.

Iron deficiency in astrocytes alters cellular status and impacts on oligodendrocyte differentiation

Iron deficiency (ID) has been shown to affect central nervous system (CNS) development and induce hypomyelination. Previous work from our laboratory in a gestational ID model showed that both oligodendrocyte (OLG) and astrocyte (AST) maturation was impaired. To explore the contribution of AST iron to the myelination process, we generated an in vitro ID model by silencing divalent metal transporter 1 (DMT1) in AST (siDMT1 AST) or treating AST with Fe3+ chelator deferoxamine (DFX; DFX AST). siDMT1 AST showed no changes in proliferation but remained immature. Co-cultures of oligodendrocyte precursors cells (OPC) with siDMT1 AST and OPC cultures incubated with siDMT1 AST-conditioned media (ACM) rendered a reduction in OPC maturation. These findings correlated with a decrease in the expression of AST-secreted factors IGF-1, NRG-1, and LIF, known to promote OPC differentiation. siDMT1 AST also displayed increased mitochondrial number and reduced mitochondrial size as compared to control cells. DFX AST also remained immature and DFX AST-conditioned media also hampered OPC maturation in culture, in keeping with a decrease in the expression of AST-secreted growth factors IGF-1, NRG-1, LIF, and CNTF. DFX AST mitochondrial morphology and number showed results similar to those observed in siDMT1 AST. In sum, our results show that ID, induced through two different methods, impacts AST maturation and mitochondrial functioning, which in turn hampers OPC differentiation.

Estimation of the availability of iron in the school meals of Municipal Centers for Early Childhood Education of a capital city in northeastern Brazil

The final stage of Fe deficiency is Fe deficiency anaemia, with repercussions for human health, especially in children under 5 years of age. Studies conducted in Brazilian public daycare centres show high prevalence of anaemia. The present study aims to evaluate the availability of Fe in the meals of the Municipal Centers of Early Childhood Education in Maceió. The experimental design comprises selection of algorithms, menu evaluation, calculation of the estimates, comparison between the estimates obtained and the recommendations, and analysis of correlation between meal constituents, and of the concordance between the absorbable Fe estimates. Four algorithms were selected and a monthly menu consisting of 22 d. The correlation analysis showed a moderate positive correlation to animal tissue (AT) v. non-heme iron (r = 0·42; P = 0·04), and negative to AT v. Ca (r = -0·54; P = 0·09) and Ca v. phytates (r = -0·46, P = 0·03). Estimates of absorbable Fe ranged from 0·23 to 0·44 mg/d. The amount of Fe available, unlike the total amount of Fe offered, does not meet the nutritional recommendations on most school days. The Bland-Altman analysis indicated that the Monsen and Balinfty and Rickard et al. showed greater agreement. The results confirm the need to adopt strategies to increase the availability of Fe in school meals.

Iron Nutrition of Pre-Schoolers in High-Income Countries: A Review

Pre-schoolers are vulnerable to iron deficiency, which, in high-resource countries, is mainly caused by suboptimal or poorly absorbable iron intakes. This review examines the prevalence of inadequate iron intakes and status, and the non-dietary factors associated with these, among children aged between 2 and 5 years within high-income countries. It then considers the quality of the pre-schooler diet in terms of dietary factors, dietary patterns, and iron intakes. Additionally, it discusses the assessment of iron bioavailability and examines the various methods used to estimate the amount of absorbable iron in pre-schooler diets. Knowledge of the adequacy of iron intakes and bioavailability of iron intakes, and dietary patterns associated with iron intakes can facilitate the design and implementation of effectively targeted community-based intervention studies to improve iron intakes and iron bioavailability to minimise the risk of iron deficiency.

Sociodemographic factors associated with low intake of bioavailable iron in preschoolers: National Health and Nutrition Survey 2012, Mexico

BACKGROUND

Children < 5 years of age are at risk of developing an iron deficiency due to a low intake of bioavailable iron (FeBio). Few studies have estimated dietary FeBio in children at a national level in relation to sociodemographic characteristics. This study aimed to estimate FeBio intake and its association with sociodemographic factors among Mexican children aged 12-59 months.

METHODS

A cross-sectional study was carried out. Information on serum ferritin and diet was obtained from a national survey and representative sample of 1012 Mexican children aged 12-59 months. We used a 24-h recall to estimate total iron, heme and non-heme iron, vitamin C, phytates, calcium, and meat intake. We calculated FeBio intake using an algorithm. Differences in FeBio intake were analyzed by area of residence (rural/urban), country region (north, center, south), and socioeconomic status (SES), using linear regression models by age subgroups (12-23 and 24-59 months) and total population, while adjusting for study design.

RESULTS

Total iron intake was 9.2 ± 6.7 mg/d. The estimated average of total FeBio fluctuated between 0.74-0.81 mg/d, with a bioavailability of 9.15-12.03% of total iron. Children aged 12-23 months residing in rural areas consumed less FeBio than those in urban areas (β = - 0.276) (p < 0.05). Children aged 24-59 months with high SES consumed more FeBio (β = 0.158 mg/d) than those of a low SES (p < 0.05).

CONCLUSIONS

FeBio is low in Mexican preschoolers. Being from a rural area and having low SES were negatively associated with FeBio intake. These results can benefit interventions seeking to improve iron status.

Biomarkers of Nutrition for Development (BOND)-Iron Review

This is the fifth in the series of reviews developed as part of the Biomarkers of Nutrition for Development (BOND) program. The BOND Iron Expert Panel (I-EP) reviewed the extant knowledge regarding iron biology, public health implications, and the relative usefulness of currently available biomarkers of iron status from deficiency to overload. Approaches to assessing intake, including bioavailability, are also covered. The report also covers technical and laboratory considerations for the use of available biomarkers of iron status, and concludes with a description of research priorities along with a brief discussion of new biomarkers with potential for use across the spectrum of activities related to the study of iron in human health.The I-EP concluded that current iron biomarkers are reliable for accurately assessing many aspects of iron nutrition. However, a clear distinction is made between the relative strengths of biomarkers to assess hematological consequences of iron deficiency versus other putative functional outcomes, particularly the relationship between maternal and fetal iron status during pregnancy, birth outcomes, and infant cognitive, motor and emotional development. The I-EP also highlighted the importance of considering the confounding effects of inflammation and infection on the interpretation of iron biomarker results, as well as the impact of life stage. Finally, alternative approaches to the evaluation of the risk for nutritional iron overload at the population level are presented, because the currently designated upper limits for the biomarker generally employed (serum ferritin) may not differentiate between true iron overload and the effects of subclinical inflammation.

Dietary Iron Bioavailability: Agreement between Estimation Methods and Association with Serum Ferritin Concentrations in Women of Childbearing Age

Predictive iron bioavailability (FeBio) methods aimed at evaluating the association between diet and body iron have been proposed, but few studies explored their validity and practical usefulness in epidemiological studies. In this cross-sectional study involving 127 women (18–42 years) with presumably steady-state body iron balance, correlations were checked among various FeBio estimates (probabilistic approach and meal-based and diet-based algorithms) and serum ferritin (SF) concentrations. Iron deficiency was defined as SF < 15 µg/L. Pearson correlation, Friedman test, and linear regression were employed. Iron intake and prevalence of iron deficiency were 10.9 mg/day and 12.6%. Algorithm estimates were strongly correlated (0.69≤ r ≥0.85; p < 0.001), although diet-based models (8.5–8.9%) diverged from meal-based models (11.6–12.8%; p < 0.001). Still, all algorithms underestimated the probabilistic approach (17.2%). No significant association was found between SF and FeBio from Monsen (1978), Reddy (2000), and Armah (2013) algorithms. Nevertheless, there was a 30–37% difference in SF concentrations between women stratified at extreme tertiles of FeBio from Hallberg and Hulthén (2000) and Collings’ (2013) models. The results demonstrate discordance of FeBio from probabilistic approach and algorithm methods while suggesting two models with best performances to rank individuals according to their bioavailable iron intakes.

Iron Metabolism in African American Women in the Second and Third Trimesters of High-Risk Pregnancies

OBJECTIVE

To examine iron metabolism during the second and third trimesters in African American women with high-risk pregnancies.

DESIGN

Longitudinal pilot study.

SETTING

Large, university-based, urban Midwestern U.S. medical center.

PARTICIPANTS

Convenience sample of 32 African American women with high-risk pregnancies seeking care at an urban maternal-fetal medicine clinic.

METHODS

Nonfasting venous blood was collected in the second and third trimesters to assess iron status, hepcidin, and systemic inflammation. Anthropometric and survey data were obtained via self-report. Descriptive statistics were calculated from these data, and changes in the clinical parameters between the second and third trimesters were evaluated via paired t tests. Associations among demographic, reproductive, anthropometric, inflammatory, and iron-related parameters were also assessed in each trimester.

RESULTS

The mean age of participants was 28.3 (± 6.8) years, and mean prepregnancy body mass index was 31.9 (± 10.7) kg/m2. In the longitudinal analysis, significant (p < .05) declines in serum iron, ferritin, transferrin saturation, and C-reactive protein were observed between the second and third trimesters. There was no statistically significant change in hepcidin between trimesters. When using a ferritin level cut-point of less than 15 ng/ml and soluble transferrin receptor level of greater than 28.1 nmol/L, 48% of the participants (14 of 29) were classified with iron deficiency in the third trimester.

CONCLUSION

In this pilot study, iron deficiency was prevalent among a small cohort of African American women with high-risk pregnancies. Hepcidin concentrations were greater than previously reported in healthy, pregnant, primarily White women, which suggests decreased iron bioavailability in this high-risk group.

Measurement of haem and total iron in fish, shrimp and prawn using ICP-MS: Implications for dietary iron intake calculations

Twenty-five species of fish, shrimp and prawn from local markets in Bangladesh were analysed for concentrations of total Fe, haem Fe and non-haem Fe by ICP-MS. Total Fe and non-haem Fe concentrations were measured in nitric acid-digested samples and haem Fe was extracted using acidified 80% acetone for 60 min. Total Fe concentrations ranged from 0.55-14.43 mg/100 g FW, and haem Fe% ranged from 18%-93% of total Fe. Repeat extractions with 80% acetone recovered additional haem Fe, suggesting that previous measurement by this technique may have underestimated haem Fe content. Calculation of Fe balance (summing Fe in acetone extracts and Fe in the residue after haem Fe extraction) was not significantly different from total Fe, indicating the two processes recovered the different forms of Fe with similar effectiveness.

Iron and vegetarian diets

Vegetarians who eat a varied and well balanced diet are not at any greater risk of iron deficiency anaemia than non-vegetarians. A diet rich in wholegrains, legumes, nuts, seeds, dried fruits, iron-fortified cereals and green leafy vegetables provides an adequate iron intake. Vitamin C and other organic acids enhance non-haem iron absorption, a process that is carefully regulated by the gut. People with low iron stores or higher physiological need for iron will tend to absorb more iron and excrete less. Research to date on iron absorption has not been designed to accurately measure absorption rates in typical Western vegetarians with low ferritin levels.

Estimation of dietary iron bioavailability from food iron intake and iron status

Currently there are no satisfactory methods for estimating dietary iron absorption (bioavailability) at a population level, but this is essential for deriving dietary reference values using the factorial approach. The aim of this work was to develop a novel approach for estimating dietary iron absorption using a population sample from a sub-section of the UK National Diet and Nutrition Survey (NDNS). Data were analyzed in 873 subjects from the 2000-2001 adult cohort of the NDNS, for whom both dietary intake data and hematological measures (hemoglobin and serum ferritin (SF) concentrations) were available. There were 495 men aged 19-64 y (mean age 42.7±12.1 y) and 378 pre-menopausal women (mean age 35.7±8.2 y). Individual dietary iron requirements were estimated using the Institute of Medicine calculations. A full probability approach was then applied to estimate the prevalence of dietary intakes that were insufficient to meet the needs of the men and women separately, based on their estimated daily iron intake and a series of absorption values ranging from 1-40%. The prevalence of SF concentrations below selected cut-off values (indicating that absorption was not high enough to maintain iron stores) was derived from individual SF concentrations. An estimate of dietary iron absorption required to maintain specified SF values was then calculated by matching the observed prevalence of insufficiency with the prevalence predicted for the series of absorption estimates. Mean daily dietary iron intakes were 13.5 mg for men and 9.8 mg for women. Mean calculated dietary absorption was 8% in men (50th percentile for SF 85 µg/L) and 17% in women (50th percentile for SF 38 µg/L). At a ferritin level of 45 µg/L estimated absorption was similar in men (14%) and women (13%). This new method can be used to calculate dietary iron absorption at a population level using data describing total iron intake and SF concentration.

Tissue iron deficiency and adiposity-related inflammation in disadvantaged preschoolers from NE Brazil

BACKGROUND/OBJECTIVES

Earlier we reported an association between iron deficiency and overweight in Brazilian preschoolers. Here, we investigate whether this is the result of adipose-related inflammation.

SUBJECTS/METHODS

Fasting serum C-reactive protein, α-1-acid glycoprotein (AGP), hepcidin, interleukin-6 (IL-6) and leptin, together with two iron biomarkers (serum ferritin and transferrin receptor (sTfR)), were measured in 364 disadvantaged preschoolers with a mean BMIZ (standardised Z-score for BMI) of 0.015, aged 3-6 years and attending day care in Salvador, Brazil. The role of genetic haemoglobin (Hb) disorders, intestinal parasites and dietary iron supply (calculated from serving sizes of 20 weekday menus) were also examined.

RESULTS

Forty-eight children (13%) were overweight (BMIZ >1). Prevalence of tissue iron deficiency (sTfR >113.3 nmol/l; 30.6 vs 12.5%; P=0.002) and chronic inflammation (AGP >25 μmol/l; 19 vs 10%; P=0.025) were higher in overweight than in normal-weight children. From multiple regression, BMIZ was a positive predictor of log serum sTfR, ferritin and leptin, but not of log hepcidin or IL-6. Instead, major positive predictors of log hepcidin were log IL-6, followed by an elevated AGP and sex (male), whereas for log IL-6 elevated AGP was the only significant predictor. Besides BMIZ, sex (female) was also a major positive predictor of leptin. Heterozygous variant of sickle cell Hb (n=20), but not helminths, was also a positive predictor of log sTfR. Median dietary iron supply (mg/day) was above the WHO Recommended Nutrient Intake assuming moderate bioavailability and appeared adequate.

CONCLUSIONS

The role of adiposity-related inflammation in tissue iron deficiency should be considered even when the prevalence of overweight is relatively low.

Bioavailability of iron, zinc, and provitamin A carotenoids in biofortified staple crops

International research efforts, including those funded by HarvestPlus, a Challenge Program of the Consultative Group on International Agricultural Research (CGIAR), are focusing on conventional plant breeding to biofortify staple crops such as maize, rice, cassava, beans, wheat, sweet potatoes, and pearl millet to increase the concentrations of micronutrients that are commonly deficient in specific population groups of developing countries. The bioavailability of micronutrients in unfortified staple crops in developing regions is typically low, which raises questions about the efficacy of these crops to improve population micronutrient status. This review of recent studies of biofortified crops aims to assess the micronutrient bioavailability of biofortified staple crops in order to derive lessons that may help direct plant breeding and to infer the potential efficacy of food-based nutrition interventions. Although reducing the amounts of antinutrients and the conduction of food processing generally increases the bioavailability of micronutrients, antinutrients still possess important benefits, and food processing results in micronutrient loss. In general, biofortified foods with relatively higher micronutrient density have higher total absorption rates than nonbiofortified varieties. Thus, evidence supports the focus on efforts to breed plants with increased micronutrient concentrations in order to decrease the influence of inhibitors and to offset losses from processing.

A complete diet-based algorithm for predicting nonheme iron absorption in adults

Many algorithms have been developed in the past few decades to estimate nonheme iron absorption from the diet based on single meal absorption studies. Yet single meal studies exaggerate the effect of diet and other factors on absorption. Here, we propose a new algorithm based on complete diets for estimating nonheme iron absorption. We used data from 4 complete diet studies each with 12-14 participants for a total of 53 individuals (19 men and 34 women) aged 19-38 y. In each study, each participant was observed during three 1-wk periods during which they consumed different diets. The diets were typical, high, or low in meat, tea, calcium, or vitamin C. The total sample size was 159 (53 × 3) observations. We used multiple linear regression to quantify the effect of different factors on iron absorption. Serum ferritin was the most important factor in explaining differences in nonheme iron absorption, whereas the effect of dietary factors was small. When our algorithm was validated with single meal and complete diet data, the respective R(2) values were 0.57 (P < 0.001) and 0.84 (P < 0.0001). The results also suggest that between-person variations explain a large proportion of the differences in nonheme iron absorption. The algorithm based on complete diets we propose is useful for predicting nonheme iron absorption from the diets of different populations.

Iron, meat and health

This article is a summary of the publication "Iron and Health" by the Scientific Advisory Committee on Nutrition (SACN) to the U.K. Government (2010), which reviews the dietary intake of iron and the impact of different dietary patterns on the nutritional and health status of the U.K. population. It concludes that several uncertainties make it difficult to determine dose-response relationships or to confidently characterize the risks associated with iron deficiency or excess. The publication makes several recommendations concerning iron intakes from food, including meat, and from supplements, as well as recommendations for further research.

An algorithm to assess intestinal iron availability for use in dietary surveys

In nutritional epidemiology, it is often assumed that nutrient absorption is proportional to nutrient intake. For several nutrients, including non-haem Fe, this assumption may not hold. Depending on the nutrients ingested with non-haem Fe, its availability for absorption varies greatly. Therefore, using Fe intake to examine associations between Fe and health can impact upon the validity of findings. Previous algorithms that adjust Fe intakes for dietary factors known to affect absorption have been found to underestimate Fe absorption and, in the present study, perform poorly on independent dietary data. We have designed a new algorithm to adjust Fe intakes for the effects of ascorbic acid, meat, fish and poultry, phytate, polyphenols and Ca, incorporating not only absorption data from test meals but also current understanding of Fe absorption. In so doing, we have created a robust and universal Fe algorithm with potential for use in large cohorts. The algorithm described aims not to predict Fe absorption but available Fe in the gut, a measure we believe to be of greater use in epidemiological research. Available Fe is Fe available for absorption from the gastrointestinal tract, taking into account enhancing or inhibiting effects of dietary modifiers. Our algorithm successfully estimated average Fe availability in test meal data used to construct the algorithm and, unlike other algorithms tested, also provided plausible predictions when applied to independent dietary data. Future research is needed to evaluate the extent to which this algorithm is useful in epidemiological research to relate Fe to health outcomes.

Education and improved iron intakes for treatment of mild iron-deficiency anemia in adolescent girls in southern Benin

BACKGROUND

To our knowledge, the impact of a nutrition education program combined with an increase in bioavailable dietary iron to treat iron-deficiency anemia has never been studied in adolescent girls.

OBJECTIVE

To evaluate the impact of an intensive dietary program for the treatment of iron-deficiency anemia in 34 intervention and 34 control boarding-school girls aged 12 to 17 years from Benin.

METHODS

A quasi-experimental design consisting of 4 weeks of nutrition education combined with an increase in the content and bioavailability of dietary iron for 22 weeks was implemented in the intervention school, but not in the control school. Data were obtained from both groups from a nutrition knowledge questionnaire, 24-hour dietary recalls, anthropometric measurements, measurement of iron status indices, and screening for malarial and intestinal parasitic infections.

RESULTS

Nutrition knowledge scores and mean intakes of nutrients, including dietary iron, absorbable iron, and vitamin C, were significantly higher in the intervention group (p < .05) than in the control group after 26 weeks. Mean hemoglobin and serum ferritin values were also significantly higher in the intervention group than in the control group (122 vs. 112 g/L [p = .0002] and 32 vs. 19 microg/L [p = .04], respectively), whereas the prevalence of anemia (32% vs. 85% [p = .005] and iron-deficiency anemia (26% vs. 56% [p = .04]) was significantly lower in the intervention group than in the control group. No significant differences between the groups were observed in intestinal parasitic infections or malaria status postintervention.

CONCLUSIONS

A multidietary strategy aiming to improve available dietary iron can reduce iron-deficiency anemia in adolescent girls.

Simulation model of the impact of biofortification on the absorption of adequate amounts of zinc and iron among Mexican women and preschool children

BACKGROUND

Biofortification is an agricultural process that attempts to increase the iron and zinc content of staple food crops. Improving the absorption of zinc and iron could contribute to reducing the high rates of deficiency of these micronutrients in developing-country settings.

OBJECTIVE

To simulate the effects of biofortification of staple food crops (maize, wheat, rice, and beans) on the absorption of zinc and iron among women and children in Mexico.

METHODS

We analyzed dietary data from the 1999 Mexican National Nutrition Survey. On the basis of the intake of the four staple food crops and the increase in zinc and iron content that could be achieved by conventional breeding in the short term, the prevalence of inadequacy in the amounts of absorbed zinc and iron was determined. The mean increase in the amounts of absorbed zinc and iron was compared according to rural and urban residence and according to region of the country.

RESULTS

In rural areas, simulated biofortification of maize resulted in a reduction in the prevalence of absorption of inadequate amounts of zinc of 47% in children and 56% in women but had no effect on the prevalence of absorption of inadequate amounts of iron. The increase in zinc absorption was greater in rural populations and in the Central and Southern regions (p < .05).

CONCLUSIONS

Biofortification of maize could significantly improve zinc absorption among children and women in Mexico living in areas most vulnerable to zinc deficiency. Studies of the biological impact of biofortified maize on zinc status are warranted.