Current methods for estimating dietary iron bioavailability do not work in China

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.

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.

Association between Household Food Security and Anemia among Pregnant Women in Rural Area in Indonesia

BACKGROUND: The increase of high anemia prevalence among pregnant women in Indonesia can reflect the raise of anemia potential in pregnancy. Food insecurity might influence the ability of households to meet the nutritional needs of pregnant women. AIM: This research aimed to find out the relationship between household food security status and anemia in pregnant women in Bektiharjo Village, Semanding District, Tuban Regency. METHODS: This was a cross-sectional study involving 50 pregnant women who lived in a typical rural area in Indonesia, namely Bektiharjo Village Semanding Sub-District Tuban District. The United States Household Food Security Survey Module questionnaire was used as the instrument for household food security status, while the level of hemoglobin was measured by the Easy Touch GCHb digital device. The Pearson Correlation test was used as a statistical test for this study. RESULTS: most respondents were of healthy reproductive age (76%). The prevalence of anemia was 32% affecting mostly women aged 20–35. Forty-six percent of households were experiencing food insecurity. There was a significant relationship between household food security status with anemia among pregnant women (p = 0.019; OR = −0.331). CONCLUSIONS: Pregnant women with food-insecure household status are more at risk of experiencing anemia, especially iron-deficiency anemia. Increasing consumption of affordable foods that contain non-heme iron and iron enhancers is recommended for pregnant women living in food-insecure households.

Can Bureaucrats Really Be Paid Like Ceos? Substitution Between Incentives and Resources Among School Administrators in China

Unlike performance incentives for private sector managers, little is known about performance incentives for managers in public sector bureaucracies. Through a randomized trial in rural China, we study performance incentives rewarding school administrators for reducing student anemia-as well as complementarity between incentives and orthogonally assigned discretionary resources. Large (but not small) incentives and unrestricted grants both reduced anemia, but incentives were more cost-effective. Although unrestricted grants and small incentives do not interact, grants fully crowd-out the effect of larger incentives. Our findings suggest that performance incentives can be effective in bureaucratic environments, but they are not complementary to discretionary resources.

Dynamic Anemia Status from Infancy to Preschool-Age: Evidence from Rural China

Anemia is a serious nutritional deficiency among infants and toddlers in rural China. However, it is unclear how the anemia status changes among China's rural children as they age. This study investigates the prevalence of anemia as children grow from infancy to preschool-age, as well as the dynamic anemia status of children over time. We conducted longitudinal surveys of 1170 children in the Qinba Mountain Area of China in 2013, 2015 and 2017. The results show that 51% of children were anemic in infancy (6-12 months), 24% in toddlerhood (22-30 months) and 19% at preschool-age (49-65 months). An even larger share of children (67%) suffered from anemia at some point over the course of study. The data also show that although only 4% of children were persistently anemic from infancy to preschool-age, 8% of children saw their anemia status deteriorate. We further found that children may be at greater risk for developing anemia, or for having persistent anemia, during the period between toddlerhood and preschool-age. Combined with the finding that children with improving anemia status showed higher cognition than persistently anemic children, there is an urgent need for effective nutritional interventions to combat anemia as children grow, especially between toddlerhood and preschool age.

High iron intake is associated with poor cognition among Chinese old adults and varied by weight status-a 15-y longitudinal study in 4852 adults

Background

High body iron status has been shown to be associated with adverse health outcomes. However, the relation between high body iron status, body mass index (BMI), and cognition is still understudied.

Objective

This study aimed to examine the association between iron intake and cognitive function in Chinese adults and tested the interaction effect of iron intake and BMI on cognition.

Design

Longitudinal study data from a nationwide sample (n = 4852; age ≥55 y) from the China Health and Nutrition Survey during 1991-2006 were used. Of the participants, 3302 had completed cognitive screening tests in ≥2 surveys. Cognitive function was assessed in 1997, 2000, 2004, and 2006. Dietary iron intake was obtained from a 3-d food record during home visits in 1991, 1993, 1997, 2000, 2004, and 2006. Multivariable mixed linear regression and logistic regression were used.

Results

The cumulative mean ± SD iron intake in 1997 of tested subjects was 23.7 ± 11.3 mg/d (25.4 mg/d in men and 22.2 mg/d in women). High iron intake was associated with poor cognition. In fully adjusted models, across the quartiles of iron intake the regression coefficients (95% CIs) were 0, -0.39 (-0.77, -0.01), -0.55 (-0.95, -0.15), and -0.90 (-1.33, -0.47), respectively. Comparing extreme quartiles of iron intake (high), the OR (95% CI) for poor cognitive function was 1.30 (1.04, 1.64). There was a significant interaction between iron intake and BMI. The association between high iron intake and poor cognition was stronger among those with a high BMI than those with a low BMI. Among those with a BMI (kg/m2) >24, across quartiles of iron intake the ORs (95% CIs) for poor cognitive function were 1.00, 1.27 (0.91, 1.78), 1.41 (0.97, 2.04), and 2.04 (1.38, 3.01), respectively.

Conclusion

Higher iron intake is associated with poor cognition in Chinese adults, especially among those with a high BMI.

Associations of dietary, lifestyle, and sociodemographic factors with iron status in Chinese adults: a cross-sectional study in the China Health and Nutrition Survey

BACKGROUND

Although a high prevalence of anemia and related disease burden have been documented in China, limited evidence is available on the current population-level iron status and risk factors for iron imbalance.

OBJECTIVE

We explored the associations of dietary, lifestyle, and sociodemographic factors with iron status in Chinese adults.

DESIGN

Our study population consisted of 7672 adults aged 18-65 y from the 2009 China Health and Nutrition Survey. Diet was assessed with the use of 3 consecutive 24-h dietary recalls. Serum ferritin, serum transferrin receptor, and hemoglobin concentrations were measured.

RESULTS

The geometric means ± SDs for ferritin concentrations were 135.9 ± 2.7 ng/mL in men and 42.7 ± 3.1 ng/mL in women. After adjustment for potential risk factors, including high-sensitivity C-reactive protein concentration, the association between age and ferritin concentration was inverse in men (P-trend < 0.001) and positive in women (P-trend < 0.001). We observed a positive association between body mass index (in kg/m²) and ferritin concentration in both men and women (both P-trends < 0.001). Dietary phytate intake was inversely associated with ferritin concentration in men (P-trend = 0.002) but not in women. Red meat consumption was positively associated with ferritin concentration both in men (P-trend = 0.002) and in older women (P-trend = 0.009). Lower intakes of grains and higher intakes of pork and poultry were associated with higher ferritin concentrations (all P-trends ≤ 0.05) in men but not in women. We observed variations in ferritin concentrations across different geographic regions (both P ≤ 0.01).

CONCLUSIONS

Serum ferritin concentrations varied across different sociodemographic, lifestyle, and dietary factors in this Chinese population. A higher intake of red meat was associated with higher ferritin concentrations in men and older women.

Association between predominantly plant-based diets and iron status in Chinese adults: a cross-sectional analysis

Current evidence of the relationship between diets and Fe status is mostly derived from studies in developed countries with Western diets, which may not be translatable to Chinese with a predominantly plant-based diet. We extracted data that were nationally sampled from the 2009 wave of China Health and Nutrition Survey; dietary information was collected using 24-h recalls combined with a food inventory for 3 consecutive days. Blood samples were collected to quantify Fe status, and log-ferritin, transferrin receptor and Hb were used as Fe status indicators. In total, 2905 (1360 males and 1545 females) adults aged 18–50 years were included for multiple linear regression and stratified analyses. The rates of Fe deficiency and Fe-deficiency anaemia were 1·6 and 0·7 % for males and 28·4 and 10·7 % for females, respectively. As red meat and haem Fe consumption differed about fifteen to twenty times throughout the five groups, divided by quintiles of animal protein intake per 4·2 MJ/d, only Fe status as indicated by log-ferritin (P=0·019) and transferrin receptor (P=0·024) concentrations in males was shown to be higher as intakes of animal foods increased. Log-ferritin was positively associated with intakes of red meat (B=0·3 %, P=0·01) and haem Fe (B=12·3 %, P=0·010) in males and with intake of non-haem Fe in females (B=2·2 %, P=0·024). We conclude that diet has a very limited association with Fe status in Chinese adults consuming a traditional Chinese diet, and a predominantly plant-based diet may not be necessarily responsible for poor Fe status.

Reducing Anemia Prevalence in Afghanistan: Socioeconomic Correlates and the Particular Role of Agricultural Assets

This research aims to examine the socio-economic correlates of anemia in women, and potential sources of iron in household diets in Afghanistan. It also examines whether ownership of agricultural (particularly livestock) assets and their use in food production has a role in alleviating anaemia, especially where local markets may be inadequate. We analyse data from the 2010/11 Afghanistan Multiple Indicator Cluster Survey, estimating a logistic regression to examine how anemia status of women is associated with socio-economic covariates. A key result found is that sheep ownership has a protective effect in reducing anemia (prevalence odds ratio of sheep ownership on anemia of 0.83, 95% confidence interval (CI): 0.73-0.94) after controlling for wealth and other covariates. This association is found to be robust to alternative model specifications. Given the central role of red meat in heme iron provision and absorption of non-heme iron, we hypothesise that sheep ownership promotes mutton consumption from own-production in a setting where market-sourced provision of nutritious food is a challenge. We then use the 2011/12 National Risk and Vulnerability Assessment household data to understand the Afghan diet from the perspective of dietary iron provision, and to understand interactions between own-production, market sourcing and mutton consumption. Sheep ownership is found to increase the likelihood that a household consumed mutton (odds ratio of 1.27, 95% CI: 1.15-1.42), the number of days in the week that mutton was consumed (prevalence rate ratio of 1.24. 95% CI: 1.12-1.37) and the quantity of mutton consumed (7 grams/person/week). In the subsample of mutton consumers, households sourcing mutton mostly from own production consumed mutton 1.5 days more frequently on average than households relying on market purchase, resulting in 100 grams per person per week higher mutton intake. Thus this analysis lends support to the notion that the linkage between sheep ownership and anemia risk is at least partly due to consumption arising from own-production in the presence of market incompleteness.

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.

Total Iron Bioavailability from the US Diet Is Lower Than the Current Estimate

BACKGROUND

Total (heme and nonheme) iron bioavailability from the US diet has been estimated to be 18% based on a single human absorption study. New data, however, suggest that it may be time to revisit this estimate.

OBJECTIVE

We estimated total iron bioavailability from the US diet with the use of our recently reported algorithm that estimates nonheme iron absorption and a conservative value for heme iron absorption.

METHODS

We used dietary intake and biomarker information from the NHANES 2001-2002, MyPyramid Equivalents Database, and Food and Nutrient Database for Dietary Studies. The survey package in R software was used to estimate means and CIs, taking into account the strata, primary sampling units, and appropriate survey weight. We implemented 2 different approaches to estimate total iron absorption. In the first approach, we included all survey participants but adjusted the geometric mean of nonheme iron absorption to 15 μg ferritin/L serum to mimic values of individuals with no iron stores; in the second approach, absorption was estimated for only nonanemic subjects with no iron stores. A total sample size of 6631 was used based on availability of dietary and iron status biomarker data and C-reactive protein concentration ≤ 6 mg/L.

RESULTS

The geometric mean (95% CI) of unadjusted nonheme iron absorption for all subjects was 3.7% (3.6%, 3.8%), higher in female subjects [5.6% (5.4%, 5.7%)] than male subjects [2.6% (2.5%, 2.7%)] (P < 0.0001). Nonheme iron absorption was lower in non-Hispanic whites [3.5% (3.4%, 3.6%)] than Mexican Americans [4.5% (4.2%, 4.8%)] and non-Hispanic blacks [4.4% (4.1%, 4.7%)]. Estimated total iron absorption was 15.5% or 15.1%, depending on which approach was used to carry out the calculations.

CONCLUSION

This study provides useful data for evaluating the current value of iron bioavailability from the US diet.

Micronutrient deficiencies and developmental delays among infants: evidence from a cross-sectional survey in rural China

OBJECTIVES

Research increasingly indicates the importance of the nutritional programming that occurs in the first 2-3 years of life. Quality nutrition during this brief window has been shown to have large and significant effects on health and development throughout childhood and even into adulthood. Despite the widespread understanding of this critical window, and the long-term consequences of leaving nutritional deficiencies unaddressed, little is known about the status of infant nutrition in rural China, or about the relationship between infant nutrition and cognitive development in rural China.

DESIGN, SETTING AND PARTICIPANTS

In April 2013 and October 2013, we conducted a survey of 1808 infants aged 6-12 months living in 351 villages across 174 townships in nationally designated poverty counties in rural areas of southern Shaanxi Province, China.

MAIN OUTCOME MEASURES

Infants were administered a finger prick blood test for haemoglobin and assessed according to the Bayley Scales of Infant Development. They were also measured for length and weight. Caregivers were administered a survey of demographic characteristics and feeding practices.

RESULTS

We found that 48.8% of sample infants were anaemic, 3.7% were stunted, 1.2% were underweight and 1.6% were wasted. Approximately 20.0% of the sample infants were significantly delayed in their cognitive development, while just over 32.3% of the sample infants were significantly delayed in their psychomotor development. After controlling for potential confounders, infants with lower haemoglobin counts were significantly more likely to be delayed in both their cognitive (p<0.01) and psychomotor development (p<0.01).

CONCLUSIONS

The anaemia rates that we identify in this study classify anaemia as a 'severe' public health problem according to the WHO. In contrast, there is virtually no linear growth failure among this population. We find that low haemoglobin levels among our sample population are associated with significant cognitive and psychomotor delays that could eventually affect children's schooling performance and labour force outcomes.

TRIAL REGISTRATION NUMBER

ISRCTN44149146.

Implications of iron deficiency/anemia on the classification of diabetes using HbA1c

Background/Objectives:

Nonglycemic factors like iron deficiency (ID) or anemia may interfere with classification of diabetes and prediabetes using hemoglobin A1c (HbA1c). However, few population-based studies of diabetes in areas with endemic ID/anemia have been conducted. We aimed to determine how mutually exclusive categories of ID alone, anemia alone and iron-deficiency anemia (IDA) were each associated with prediabetes and diabetes prevalence using fasting blood glucose (FBG) versus HbA1c in a population-based study of adults with endemic ID/anemia.

Subjects/Methods:

We used data from the China Health and Nutrition Survey, a longitudinal, population-based study across 228 communities within nine provinces of China. This analysis included 7308 adults seen in the 2009 survey aged 18–75 years. We used descriptive and covariate-adjusted models to examine relative risk of prediabetes and diabetes using FBG alone, HbA1c alone, HbA1c and FBG, or neither (normoglycemia) by anemia alone, ID alone, IDA or normal iron/hemoglobin.

Results:

Approximately 65% of individuals with diabetes in our sample were concordantly classified with diabetes using both FBG and HbA1c, while 35% had a discordant diabetes classification: they were classified using either FBG or HbA1c, but not both. Fewer participants with ID alone versus normal iron/hemoglobin were classified with diabetes using HbA1c only. From covariate-adjusted, multinomial regression analyses, the adjusted prevalence of prediabetes using HbA1c only was 22% for men with anemia alone, but 13% for men with normal iron/hemoglobin. In contrast, the predicted prevalence of prediabetes using HbA1c only was 8% for women with ID alone, compared with 13% for women with normal iron/hemoglobin.

Conclusions:

These findings suggest potential misclassification of diabetes using HbA1c in areas of endemic ID/anemia. Estimating diabetes prevalence using HbA1c may result in under-diagnosis in women with ID and over-diagnosis in men with anemia.

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.

Red meat and poultry intakes and risk of total and cause-specific mortality: results from cohort studies of Chinese adults in Shanghai

Most previous studies of meat intake and total or cause-specific mortality were conducted in North America, whereas studies in other areas have been limited and reported inconsistent results. This study investigated the association of red meat or poultry intake with risk of total and cause-specific mortality, including cancer and cardiovascular disease (CVD), in two large population-based prospective cohort studies of 134,290 Chinese adult women and men in Shanghai. Meat intakes were assessed through validated food frequency questionnaires administered in person at baseline. Vital status and dates and causes of deaths were ascertained through annual linkage to the Shanghai Vital Statistics Registry and Shanghai Cancer Registry databases and home visits every 2-3 years. Cox regression was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the risk of death associated with quintiles of meat intake. During 803,265 person-years of follow up for women and 334,281 person-years of follow up for men, a total of 4,210 deaths in women and 2,733 deaths in men accrued. The median intakes of red meat were 43 g/day among women and 54 g/day among men, and pork constituted at least 95% of total meat intake for both women and men. Red meat intake was associated with increased total mortality among men, but not among women; the HR (95% CI) comparing the highest with the lowest quintiles were 1.18 (1.02-1.35) and 0.92 (0.82-1.03), respectively. This sex difference was statistically significant (P = 0.01). Red meat intake was associated with increased risk of ischemic heart disease mortality (HR = 1.41, 95% CI = 1.05-1.89) and with decreased risk of hemorrhagic stroke mortality (HR = 0.62, 95% CI = 0.45-0.87). There were suggestive inverse associations of poultry intake with risk of total and all-CVD mortality among men, but not among women. Further investigations are needed to elucidate the sex-specific associations between red meat intake and mortality.

Are Child Eating Patterns Being Transformed Globally?

OBJECTIVE

To examine the extent to which child dietary patterns and trends are changing globally.

RESEARCH METHODS AND PROCEDURES

Diets of children 2 to 19 years of age were studied with nationally representative data from Russia and the United States, nationwide data from China, and regional data from metropolitan Cebu, Philippines. Twenty-four-hour dietary recalls were examined at several points in time to examine trends in calories consumed away from home, snacking behavior, and soft drink and modern fast food consumption. Urban-rural trends were compared.

RESULTS

U.S. and Cebu youth consume more than one-third of their daily calories and a higher proportion of snack calories from foods prepared away from home. In contrast, away from home food consumption is minimal in Chinese and Russian children. U.S. and Cebu youth consume about one-fifth of their total daily energy from snacks, but snacks provide a much lower proportion of energy in Russia ( approximately 16%) and China (where snacks provide only approximately 1% of energy). Fast food plays a much more dominant role in the American diet ( approximately 20% of energy vs. 2% to 7% in the other countries), but as yet does not contribute substantially to children's diets in the other countries. Urban-rural differences were found to be important, but narrowing over time, for China and Cebu, whereas they are widening for Russia.

DISCUSSION

This research suggests that globalization of the fast food and other modern food sectors is beginning to affect child eating patterns in several countries undergoing nutrition transition. However, the contribution of fast food and soft drinks to the diet of children remains relatively small in China, Russia, and Cebu, Philippines, relative to the United States.

Dietary iron intake and risk of endometrial cancer: a population-based case-control study in Shanghai, China

Dietary red meat and animal fat have been linked to endometrial cancer (EC) risk, but the impact of bioavailable iron in animal-derived foods has been less well studied. Our objective was to investigate the effects of iron and fats on the risk of EC in a large, population-based, case-control study. The Shanghai Endometrial Cancer Study enrolled 1,204 EC cases and 1,212 controls who completed in-person interviews, including a food frequency questionnaire. Animal-derived iron and fat intakes were calculated from dietary intakes and food composition tables. Logistic regression models were used to evaluate independent and joint effects of iron and fat on EC risk. Animal-derived iron intake was positively associated with EC risk [adjusted OR = 1.9; 95% CI = 1.4-2.7, P(trend) < 0.01, highest vs. lowest quartile], predominantly after menopause (OR = 2.2; 95%CI = 1.4-3.4, P(trend) < 0.01) and in women with BMI >or= 25 kg/m(2)(OR = 3.2; 95% CI = 1.4-7.5 in postmenopausal obese women, P(trend) < 0.01). Animal-derived fat was also associated with postmenopausal EC risk (OR = 1.7; 95% CI = 1.2-2.5, P(trend) < 0.01). Multiplicative interactions between animal-derived iron and BMI or animal-derived fat intake were not observed. Animal-derived iron intake is associated with increased risk of EC after menopause and among obese women. Avoidance of animal-derived (heme) iron may reduce the risk of EC in these women.

Overweight children have higher circulating hepcidin concentrations and lower iron status but have dietary iron intakes and bioavailability comparable with normal weight children

BACKGROUND

Obesity increases the risk for iron deficiency, but the underlying mechanism is unclear. It is possible that overweight individuals may have lower dietary iron intake and/or bioavailability. Alternatively, obesity-related inflammation may increase hepcidin concentrations and reduce iron availability. Circulating hepcidin levels have not been compared in normal weight vs overweight individuals.

OBJECTIVE

The objective of this study was to compare iron status, dietary iron intake and bioavailability, as well as circulating levels of hepcidin, leptin and interleukin-6 (IL-6), in overweight vs normal weight children.

DESIGN

In 6-14-year-old normal and overweight children (n=121), we measured dietary iron intake, estimated iron bioavailability and determined body mass index s.d. scores (BMI-SDS). In all children (n=121), we measured fasting serum ferritin, soluble transferrin receptor (sTfR), C-reactive protein (CRP) and leptin; in a subsample, we measured IL-6 (n=68) and serum hepcidin (n=30).

RESULTS

There were no significant differences in dietary iron intake or bioavailability comparing normal and overweight children. The prevalence of iron-deficient erythropoiesis (an increased sTfR concentration) was significantly higher in the overweight than in the normal weight children (20 vs 6%, P=0.022, with sTfR concentrations of 4.40+/-0.77 and 3.94+/-0.88 mg l(-1), respectively, P=0.010). Serum hepcidin levels were significantly higher in the overweight children (P=0.001). BMI-SDS significantly correlated with sTfR (P=0.009), serum hepcidin (P=0.005) and the three measures of subclinical inflammation, namely CRP (P<0.001), IL-6 (P<0.001) and leptin (P<0.001). In a multiple regression model, serum hepcidin was correlated with BMI-SDS (P=0.020) and body iron (P=0.029), but not with the inflammatory markers.

CONCLUSION

Our findings indicate that there is reduced iron availability for erythropoiesis in overweight children and that this is unlikely due to low dietary iron supply but rather due to hepcidin-mediated reduced iron absorption and/or increased iron sequestration.

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.

Bioavailable dietary iron is associated with hemoglobin concentration in Mexican preschool children

The objective of this study was to estimate the amount of bioavailable iron (FeBIO) in the diet of Mexican children aged 12-59 mo through the application of algorithms that use dietary variables and analyze the association between estimated FeBIO and hemoglobin (Hb) concentration. Data were analyzed for 919 children aged 12-59 mo old who participated in a national probabilistic survey on nutrition, in which a 24-h dietary recall was applied and Hb concentration was determined through the use of portable photometers. Dietary intakes were determined for total iron, heme and nonheme iron, vitamin C, phytates, and meat (red meat, poultry, and fish). Using these dietary variables and distinct scenarios on body iron reserves, we used algorithms to estimate the amount of FeBIO in the diet. Linear regression models were adjusted to evaluate the association between FeBIO and Hb. The mean iron intake was 6.2 +/- 4.4 mg/d and the mean estimated FeBIO ranged between 0.14 and 0.37 mg/d depending on different assumptions about iron reserves, representing 2.7-6.1% of total iron intake. The Hb concentration, adjusted for altitude and presence of diarrhea, was positively associated with FeBIO in children 12-23 mo old (P < 0.05) but not in children 24-59 mo old. The estimated FeBIO is low in relation to physiological requirements and is compatible with existing high iron deficiency prevalence rates in Mexico. Although Hb is not a specific indicator of iron status, it was significantly associated with FeBIO.

Effect of vitamin A supplementation on immune function of well-nourished children suffering from vitamin A deficiency in China

OBJECTIVE

To clearly clarify the protective effect of vitamin A supplementation on immune function of well-nourished children suffering from vitamin A deficiency.

METHODS

Three hundred sixty-two children in two kindergartens in Wuhan China were enrolled. Detailed dietary assessment and anthropometry were undertaken to facilitate the exclusion of malnourished children. Seventy vitamin A-deficient children with informed consent were randomly divided into the vitamin A-deficient-supplemented group and vitamin A-deficient placebo group, 35 vitamin A-sufficient children (age- and sex-matched with the vitamin A-deficient-supplemented group children) were selected as vitamin A-sufficient placebo group. The baseline and follow-up level of selected immune parameters of the 105 children in three intervention groups were compared.

RESULTS

The total proportion of severe and marginal vitamin A-deficient children was 10.9 and 21.96%, respectively. At baseline, the serum complement C3 and sIgA level of vitamin A-sufficient children was significantly higher than that of vitamin A-deficient children (P < 0.05). However, the serum lysozyme level of vitamin A-sufficient children was inversely lower. After intervention, vitamin A-deficient-supplemented children increased serum vitamin A, complement C3 and sIgA level, but their serum lysozyme level inversely decreased.

CONCLUSIONS

Vitamin A deficiency was still a serious health problem in children in China cities. Vitamin A supplementation was efficacious in ameliorating serum vitamin A status and partially impaired immune function of well-nourished children suffering from vitamin A deficiency.

Statistical model for predicting non-heme iron bioavailability from vegetarian meals

Availability of non-heme iron has been extensively discussed when meals comprise heme as well as non-heme iron, but seldom so for exclusively vegetarian meals. The present study aimed to develop a statistical model for predicting non-heme iron availability from a composite vegetarian meal. Radioisotopic measurements of in vitro iron dialyzability of 208 out of 274 meals representing vegetarian diets from Asia, Africa, Europe and Latin America and the meal contents of iron, zinc, copper, ascorbic acid, beta-carotene, riboflavin, thiamin, folic acid, tannic acid, fiber and degraded phytate forms (IP6-IP1) were used for development of the model. A multiple regression model weighted for calorie contents was developed for the percentage iron dialyzability with the possible predictors as meal contents along with plausible interaction terms. The model was validated with in vitro iron dialyzability of 66 meals and in vivo iron absorption in five ileostomized adults. Application of the model was demonstrated using data on the daily dietary intake of 215 young adults whose hemoglobin levels were estimated twice in 3 weeks. Weighted multiple regression model was: ln(% Fe dialyzability)=1.340-0.259xln(IP2 [mg])+0.188xln(IP3 [mg])-0.278xln(IP5 [mg])+0.0912xln(ascorbic acid [mg])+0.06693xln(tannins [mg])+0.09552xln(beta-carotene [microg])+0.137xln(hemicellulose [g]) (P<0.01, R2=0.51). Good agreement was seen between observed and predicted dialyzability (r=0.90) and human absorption (r=0.89). The model would be useful to estimate bioavailable iron intakes of vegetarian populations and to identify at-risk individuals.

Iron absorption prediction equations lack agreement and underestimate iron absorption

A number of algorithms have been developed to predict the bioavailability of iron from mixed meals and diets, but their direct validity in predicting change in iron status remains questionable. Throughout the course of conducting a large feeding trial in 10 convents in Manila, we collected weighed food intake data (n = 317) and directly compared the performance of these prediction equations to each other and to the change in serum ferritin (SF). Dietary weighed food intakes were measured on d 3 every 2 wk for each woman and iron status determined at baseline, 4.5 mo, and 9 mo. The Monsen and Balintfy equation predicted higher median absorption efficiency (7.3%) than did the equations of Hallberg and Hulthen (6.1%) and Reddy et al. (5.8%). In contrast, the predictions that used the equations of Bhargava et al. (3.8%), Tseng et al. (2.9%), and Du et al. (2.6%) were significantly lower. The iron absorption efficiencies calculated using the Monsen and Balintfy equation correlated with those using the Hallberg and Hulthen equation (r = 0.91, P < 0.001). This slope did not differ from unity, whereas all other equations underestimated iron absorption efficiency relative to Monsen and Balintfy's equation. The median efficiency of absorption, based on change in SF in 114 subjects, was 17.2%, suggesting that these equations underestimate iron absorption. The inhibitory and enhancing factors in the published prediction equations were quantitatively either too large or perhaps too small to correctly predict apparent iron bioavailability over a 9-mo period. The causes of the lack of agreement between change in iron status estimated by SF change and absorption predicted by algorithms are open to discussion and will need to be resolved.

The role of diet- and host-related factors in nutrient bioavailability and thus in nutrient-based dietary requirement estimates

To convert physiological requirements into dietary requirements, adjustments are needed for some nutrients that take into account certain diet- and host-related factors specific to a country or region. Nutrients whose requirements should be adjusted in this way include calcium, magnesium, iron, zinc, protein, folate, vitamin A, and carotenoids. The diet-related factors that must be considered depend on the nature of the habitual diet and may include the chemical form of the nutrient and the nature of the dietary matrix, interactions between nutrients and/or organic components, and food preparation and processing practices within the country or region. The host-related factors can be further subdivided into intestinal and systemic factors. Reductions in the secretion of hydrochloric acid, gastric acid, and/or intrinsic factor, together with alterations in the permeability of the intestinal mucosa, are all examples of intestinal factors that can markedly influence the absorption of certain nutrients, but that are often ignored when setting dietary requirements. Systemic factors that should also be considered include nutrient status of the host, age, sex, ethnicity, genotype, and physiological state (e.g., pregnancy or lactation), and chronic and acute infectious disease states. Algorithms can estimate the bioavailability of iron, zinc, protein, folate, vitamin A, and carotenoids, although their accuracy is limited by the complex interactions among the absorption modifiers in the whole diet. For calcium and magnesium, the amount available for absorption is still estimated from their major food sources in the habitual diet. Currently, there are often large differences in the adjustments employed to convert physiological requirements to dietary requirements, even among countries consuming diets of similar patterns.

Dietary animal-derived iron and fat intake and breast cancer risk in the Shanghai Breast Cancer Study

BACKGROUND

Dietary fats and other constituents have been studied extensively in relation to breast cancer risk. Iron, an essential micronutrient with pro-oxidant properties, has received little attention, and specific fats may augment its toxicity. We investigated the effects of iron and fats from various food sources on the risk of breast cancer.

METHODS

Participants in a population-based case-control study, 3,452 breast cancer cases, and 3,474 age-frequency-matched controls, completed in-person interviews, including a detailed food-frequency questionnaire. Plant- and animal-derived iron and fat intakes were derived from dietary intake data and food composition tables. Unconditional logistic regression models were used to study the independent and interactive effects of different forms of iron and fats on breast cancer risk.

RESULTS

Animal-derived (largely heme) iron intake was positively associated with breast cancer risk (P (trend) < 0.01; OR = 1.49 in the highest vs. lowest quartile, 95% confidence interval [CI] 1.25-1.78) after adjustment for known risk factors, antioxidant vitamin and isoflavone intake, and vitamin supplement use. The effect of animal-derived iron was similar in pre- and postmenopausal women. Intake of animal-derived fats was also associated with increased risk (adjusted OR = 1.34, 95% CI 1.14-1.58), particularly after menopause. A significant interaction between iron and fat from animal sources was observed (P < 0.01).

CONCLUSIONS

A high intake of animal-derived (heme) iron may be associated with an increased risk of primary breast cancer in Chinese women, and saturated and mono-unsaturated fats that are also derived from animal sources may augment this effect. Combined reductions in animal-derived iron and fat consumption have the potential to reduce breast cancer risk.

Physiologic mechanisms can predict hematologic responses to iron supplements in growing children: a computer simulation model

BACKGROUND

Iron deficiency is the most common preventable nutrition problem in developing countries. Several randomized clinical trials (RCTs) have been conducted to determine the effectiveness of various iron dosing schemes in multiple settings.

OBJECTIVE

The objective was to determine whether enough is known about iron metabolism to predict hemoglobin and serum ferritin (SF) concentrations with a computer model and whether the model could be used as a substitute for new RCTs.

DESIGN

Guided by the physiology of iron absorption and regulation, we used data from RCTs that tested iron Sprinkles to develop a computer model. Of 2 RCTs in Ghana, we used 1 to compute the amount of iron absorbed from a given dose in anemic and nonanemic children and the other to compute the resulting change in hemoglobin concentrations. We used this model to predict hemoglobin and SF concentrations in a new RCT in China and compared model-predicted values with actual values by using summary statistics (means and medians) and quantile-quantile plots.

RESULTS

The model-predicted hemoglobin means were within +/-2 g/L, and SF medians were within +/-3 microg/L of the corresponding means and medians of the actual values. On quantile-quantile plots, the predicted hemoglobin quantiles were within +/-5 g/L, and SF quantiles were within +/-10 microg/L of the corresponding quantiles of the actual values.

CONCLUSION

Our model of iron metabolism can accurately predict hemoglobin and SF concentrations after iron supplementation with Sprinkles in children; the model can thus obviate the need for repeating RCTs in multiple settings.

Iron deficiency due to consumption of a habitual diet low in bioavailable iron: a longitudinal cohort study in Moroccan children

BACKGROUND

In many developing countries, cereal and legume-based diets contain low amounts of bioavailable iron, which may increase the risk of iron deficiency.

OBJECTIVE

The objective was to measure change in iron status in Moroccan children who consumed their habitual diet containing low amounts of bioavailable iron.

DESIGN

The design was a prospective, longitudinal, free-living cohort study in iron-replete, nonanemic 6-10-y-old children (n = 126). Hemoglobin, serum ferritin, and transferrin receptor were measured at baseline. The children then consumed their habitual cereal and legume-based diet for 15 mo, when their iron status was retested. We used weighed food records and direct food analysis to calculate dietary iron intake and iron bioavailability. On the basis of the change in hemoglobin and body iron stores calculated from the serum transferrin receptor-to-ferritin ratio, iron balance and iron absorption were estimated over the 15-mo period.

RESULTS

Mean daily iron intake was 10.8 mg/d, 97% of which was nonheme iron. Estimated nonheme-iron bioavailability from algorithms was 1.0-4.3% adjusted for low body iron stores. Over 15 mo, the mean change in total body iron was -142 mg, and mean iron absorption was estimated to be 0.22 mg/d, or 2% of dietary iron. Mean hemoglobin concentration decreased 12 g/L. At 15 mo, 75% of the cohort had deficits in tissue iron, and one-third had mild iron deficiency anemia.

CONCLUSION

Low iron bioavailability from legume and cereal-based diets is a cause of iron deficiency anemia in children in rural Africa.

The Diet Quality Index-International (DQI-I) provides an effective tool for cross-national comparison of diet quality as illustrated by China and the United States

A composite measure of diet has been preferred to an index of a single nutrient or food in the area of dietary assessment. However, the lack of such a tool for cross-national comparisons has restricted the ability to compare diet quality between countries using an overall measure of diet. In this study, we created a tool called the Diet Quality Index-International (DQI-I) for global monitoring and exploration of diet quality across countries. The major categories of the index components are variety, adequacy, moderation and overall balance. Using the tool, this research presents a cross-national comparison of diet quality between China and the United States, incorporating comparable national in-depth diet data. The mean of the DQI-I score was slightly higher in China than in the United States. By major categories of the DQI-I, dietary variety was better achieved in the U.S. diet; moderation and overall balance of intakes were better accomplished in China. The DQI-I was successful in capturing variability in intakes of food and nutrients in both countries. Some distinct patterns of poor quality diet in each country were also identified. As demonstrated in this study, the DQI-I provides an effective means of cross-national comparative work for global understanding of diet quality. Furthermore, the dietary problem areas identified by the DQI-I may be useful in guiding the development of programs to improve public health.

Dietary intakes and socioeconomic factors are associated with the hemoglobin concentration of Bangladeshi women

Iron deficiency anemia affects a large number of women in developing countries, especially during child-bearing years. The hemoglobin concentration is useful for identifying iron deficiency anemia. The main objectives of this study were, first, to extend algorithms for calculating bioavailable iron from mixed diets, taking into account the enhancers and inhibitors of iron absorption under alternative assumptions on body iron stores. Second, a comprehensive longitudinal model was developed for the proximate determinants of hemoglobin concentration that included the subjects' dietary intakes, nutritional status, morbidity and socioeconomic factors and the unobserved between-subject differences. The model for hemoglobin concentration was estimated using three repeated observations on 514 free living women in Bangladesh. Socioeconomic factors affecting the iron intake from meat, fish and poultry and from all animal sources were also modeled. The main results were that bioavailable iron, women's height and mid upper arm circumference and intake of iron tablets were significant predictors of hemoglobin concentration. Increases in household incomes were associated with higher intake of iron from meat, fish and poultry and from all animal sources. The algorithms for estimating bioavailable iron showed the importance of assumptions regarding body iron stores and underscored the need to develop suitable algorithms for subjects in developing countries.