Methods to assess iron and iodine status. Br J Nutr. 2008;99 Suppl 3:S2-S9. [PMID: 18598585 DOI: 10.1017/s000711450800679x]

Fostering healthy aging through selective nutrition: A long-term comparison of two dietary patterns and their holistic impact on mineral status in middle-aged individuals-A randomized controlled intervention trial in Germany

Aging is associated with a decline in physiological functions and an increased risk of age-related diseases, emphasizing the importance of identifying dietary strategies for healthy aging. Minerals play a crucial role in maintaining optimal health during aging, making them relevant targets for investigation. Therefore, we aimed to analyze the effect of different dietary pattern on mineral status in the elderly. We included 502 individuals aged 50-80 years in a 36-month randomized controlled trial (RCT) (NutriAct study). This article focuses on the results within the two-year intervention period. NutriAct is not a mineral-modulating-targeted intervention study, rather examining nutrition in the context of healthy aging in general. However, mineral status might be affected in an incidental manner. Participants were assigned to either NutriAct dietary pattern (proportionate intake of total energy consumption (%E) of 35-45 %E carbohydrates, 35-40 %E fats, and 15-25 %E protein) or the German Nutrition Society (DGE) dietary pattern (proportionate intake of total energy consumption (%E) of 55 %E carbohydrates, 30 %E fats, and 15 %E protein), differing in the composition of macronutrients. Data from 368 participants regarding dietary intake (energy, calcium, magnesium, iron, and zinc) and serum mineral concentrations of calcium, magnesium, iron, copper, zinc, selenium, iodine, and manganese, free zinc, and selenoprotein P were analyzed at baseline, as well as after 12 and 24 months to gain comprehensive insight into the characteristics of the mineral status. Additionally, inflammatory status - sensitive to changes in mineral status - was assessed by measurement of C-reactive protein and interleukin-6. At baseline, inadequate dietary mineral intake and low serum concentrations of zinc and selenium were observed in both dietary patterns. Throughout two years, serum zinc concentrations decreased, while an increase of serum selenium, manganese and magnesium concentrations was observable, likely influenced by both dietary interventions. No significant changes were observed for serum calcium, iron, copper, or iodine concentrations. In conclusion, long-term dietary interventions can influence serum mineral concentrations in a middle-aged population. Our findings provide valuable insights into the associations between dietary habits, mineral status, and disease, contributing to dietary strategies for healthy aging.

Risks of Iodine Excess

Iodine is a micronutrient that is required for thyroid hormone synthesis. The iodide cycle in thyroid hormone synthesis consists of a series of transport, oxidation, organification, and binding/coupling steps in thyroid follicular cells. Common sources of iodine include the consumption of an iodine-rich diet or iodine fortified foods, the administration of amiodarone, iodine-containing supplements, or iodinated contrast media, and other miscellaneous sources. Methods to assess population iodine status include the measurement of urinary iodine concentrations, blood thyroglobulin levels, prevalence of elevated neonatal TSH levels, and thyroid volume. Although excessive iodine intake or exposure is generally well tolerated, an acute iodine load may result in thyroid dysfunction (hypothyroidism or hyperthyroidism) in certain susceptible individuals due to the failure to escape from the Wolff-Chaikoff effect and to the Jod-Basedow phenomenon, respectively. In this review, we discuss the associations between excessive iodine intake or exposure, with particular focus on iodinated contrast media as a common source of excess iodine in healthcare settings, and risks of incident thyroid dysfunction. We also summarize the risks of iodine excess in vulnerable populations and review current guidelines regarding the screening and monitoring of iodinated contrast-induced thyroid dysfunction. Finally, we discuss the long-term potential nonthyroidal health risks associated with iodine excess and suggest the need for more data to define safe upper limits for iodine intake, particularly in high-risk populations.

Postprandial Micronutrient Variability and Bioavailability: An Interventional Meal Study in Young vs. Old Participants

This study explores age- and time-dependent variations in postprandial micronutrient absorption after a micronutrient-rich intervention meal within the Biomiel (bioavailability of micronutrients in elderly) study. Comprising 43 healthy participants, the study compares young (n = 21; mean age 26.90 years) and old (n = 22; mean age 66.77 years) men and women, analyzing baseline concentrations and six-hour postprandial dynamics of iron (Fe), copper (Cu), zinc (Zn), selenium (Se), iodine (I), free zinc (fZn), vitamin C, retinol, lycopene, β-carotene, α-tocopherol, and γ-tocopherol, along with 25(OH) vitamin D (quantified only at baseline). Methodologically, quantifications in serum or plasma were performed at baseline and also at 90, 180, 270, and 360 min postprandially. Results reveal higher baseline serum Zn and plasma lycopene concentrations in the young group, whereas Cu, Se, Cu/Zn ratio, 25(OH) vitamin D, α-tocopherol, and γ-tocopherol were higher in old participants. Postprandial variability of Zn, vitamin C, and lycopene showed a strong time-dependency. Age-related differences in postprandial metabolism were observed for Se, Cu, and I. Nevertheless, most of the variance was explained by individuality. Despite some limitations, this study provides insights into postprandial micronutrient metabolism (in serum/plasma), emphasizing the need for further research for a comprehensive understanding of this complex field. Our discoveries offer valuable insights for designing targeted interventions to address and mitigate micronutrient deficiencies in older adults, fostering optimal health and well-being across the lifespan.

The use of breast milk iodine concentration in the first week of lactation as a biomarker of iodine status in breast-feeding women

Breast milk iodine concentration (BMIC) is a promising indicator of iodine status in lactating women. However, there are limited data on its usefulness to reflect maternal iodine deficiency. Therefore, the aim of our study was to assess iodine concentration in breast milk and urine samples in exclusively breast-feeding women. Eligible pregnant women undergoing routine antenatal care in a large hospital in Shaanxi Province, China, were followed up from the third trimester of pregnancy until the first week of lactation. Urine samples (20 ml) were collected during pregnancy and lactation. Iodine concentration in samples was measured based on Sandell-Kolthoff reaction. Breast milk samples (5 ml) were provided during lactation. A receiver operating curve (ROC) was constructed to determine the diagnostic performance of BMIC. An iodine-specific FFQ was completed twice during pregnancy and lactation. A total of 200 women completed the study. The overall median BMIC was 89 μg/l, indicating iodine sufficiency (i.e. BMIC reference range between 60 and 465 μg/l). Women reported similar median urinary iodine concentration (UIC) during pregnancy and lactation (112 and 113 μg/l, respectively), but their iodine status differed - mild-to-moderate iodine deficiency during pregnancy and iodine sufficiency during lactation. The ROC for BMIC using UIC as a reference standard was 0·755 (95 % CI: 0·644, 0·866). In conclusion, this study demonstrated that women were iodine sufficient in the first week of lactation as assessed by UIC, which was consistent with BMIC. These findings suggested that BMIC is a useful biomarker to assess iodine status in lactating women.

Maternal Iron and Vitamin D Status during the Second Trimester Is Associated with Third Trimester Depression Symptoms among Pregnant Participants in the APrON Cohort

BACKGROUND

The maternal status of multiple micronutrients during pregnancy and postpartum and their potential associations with maternal health outcomes are largely undescribed.

OBJECTIVES

This study aimed to examine associations between maternal iron and vitamin D status, individually and in combination, on depression symptoms in pregnant individuals.

METHODS

The Alberta Pregnancy Outcomes and Nutrition cohort study included pregnant participants and their children from Calgary and Edmonton, Canada. Iron biomarkers (serum ferritin [SF], soluble transferrin receptor, and hepcidin) were measured via immunoassays and vitamin D [25-hydroxyvitamin D3 (25(OH)D3) and 3-epi-25-hydoxyvitamin D3 (3-epi-25(OH)D3)] metabolites were quantifed using liquid chromatography with tandem mass spectroscopy. Four categories of maternal iron and vitamin D status during the second trimester were conceptualized using concentrations of SF and total 25-hydoxyvitamin D [25(OH)D], respectively. Maternal Edinburgh Postnatal Depression Scale (EPDS) scores during the third trimester (n = 1920) and 3 mo postpartum (n = 1822) were obtained.

RESULTS

Concentrations of maternal 25(OH)D3, 3-epi-25(OH)D3, and the ratio of both metabolites were significantly higher during the second trimester compared with their status at 3 mo postpartum. Higher second trimester maternal concentrations of SF (β: -0.8; 95% confidence interval [CI]: -1.5, -0.01), hepcidin (β: -0.5; 95% CI: -0.9, -0.2), and 25(OH)D3 (β: -0.01; 95% CI: -0.02, -0.004) predicted lower maternal EPDS scores during the third trimester. Pregnant individuals with a low iron (SF <15 μg/L) and replete vitamin D (25(OH)D ≥75 nmol/L) (β: 1.1; 95% CI: 0.03, 2.1) or low iron (SF <15 μg/L) and vitamin D (25(OH)D <75 nmol/L) (β: 2.2; 95% CI: 0.3, 4.2) status during midpregnancy had higher third trimester EPDS scores compared with those that were replete in both micronutrients.

CONCLUSIONS

A higher midpregnancy maternal iron and vitamin D status, independently or in combination, predicted fewer maternal depression symptoms in the third trimester. Concentrations of maternal 25(OH)D3 and 3-epi-25(OH)D3 may be lower in the postpartum period compared with midpregnancy.

Urinary iodine excretion and optimal time point for sampling when estimating 24-h urinary iodine

Iodine deficiency may cause thyroid dysfunction. The iodine intake in a population is measured by urinary iodine concentration (UIC) in spot samples or 24-h urinary iodine excretion (24UIE). 24UIE is considered the gold standard and may be estimated using an equation including UIC, urinary creatinine concentration, sex and age (e24UIE). The aims of this study were to evaluate the preferable timing of UIC when using this equation and assess the variability of UIE. Sixty healthy non-smoking women (n 31) and men (n 29) were included in Gothenburg, Sweden. Twelve urine samples were collected at six fixed times on two separate days. Variability was calculated for UIC, 24UIE, e24UIE, iodine excretion per hour (iHr) and UIC adjusted for creatinine and specific gravity. Median 24UIE was 156 µg/24 h and the median UIC (all spot samples) was 104 µg/l. UIC (P < 0·001), 24UIE (P = 0·001) and e24UIE (P < 0·001) were significantly higher in men. e24UIE was relatively similar to 24UIE. However, when e24UIE was calculated from UIC in the first void, it was about 15 % lower than 24UIE (P < 0·001). iHr was lowest in the morning and highest in the afternoon. Median iHr was higher in men (7·4 v. 5·3 µg/h, P < 0·001). The variability of UIE was higher within individuals than between individuals. This study suggests that most time points for estimation of individual 24UIE are appropriate, but they should preferably not be collected in the first void.

Assessment of Joint Impact of Iodine, Selenium, and Zinc Status on Women's Third-Trimester Plasma Thyroid Hormone Concentrations

BACKGROUND

Iodine is essential for synthesizing thyroid hormones, but other micronutrients are also required for optimal thyroid function. However, there is a lack of data on combined micronutrient status in relation to thyroid hormones in pregnancy.

OBJECTIVES

We aimed to assess the joint associations of iodine, selenium, and zinc status with plasma concentrations of thyroid hormones and thyroid-stimulating hormone (TSH) in pregnancy.

METHODS

We included 531 pregnant women (aged 22-40 y) participating in a Swedish birth cohort who provided blood and spot urine samples in gestational weeks 27-33 (mean: 29). Associations of urinary iodine concentration (UIC), plasma selenium concentration, and plasma zinc concentration (measured by inductively coupled plasma mass spectrometry) with plasma hormone concentrations [total and free thyroxine (tT4, fT4), total and free triiodothyronine (tT3, fT3), and TSH] were explored with Bayesian kernel machine regression (BKMR; n = 516; outliers excluded) and multivariable-adjusted linear regression (n = 531; splined for nonlinear associations).

RESULTS

Median (IQR) micronutrient concentrations were 112 μg/L (80-156 μg/L) for UIC, 67 μg/L (58-76 μg/L) for plasma selenium, and 973 μg/L (842-1127 μg/L) for plasma zinc; the former 2 median values were below recommended concentrations (150 μg/L and 70 μg/L, respectively). Mean ± SD TSH concentration was 1.7 ± 0.87 mIU/L, with 98% < 4 mIU/L. BKMR showed a positive trend of joint micronutrient concentrations in relation to TSH. Plasma zinc was most influential for all hormones but tT3, for which plasma selenium was most influential. In adjusted linear regression models, zinc was positively associated with tT4, tT3, and TSH, and <1200 μg/L also with fT4 and fT3. Selenium was inversely associated with fT3, and <85 μg/L with tT3.

CONCLUSIONS

Pregnant women's plasma TSH concentrations in the early third trimester increased with increasing joint status of iodine, selenium, and zinc. Zinc and selenium were more influential than iodine for the hormone concentrations. Multiple micronutrients need consideration in future studies of thyroid hormone status.

Iodine intake in healthy Japanese aged from 6 to 70 years residing in the same district

Iodine is an essential component of thyroid hormones and a dietary micronutrient for humans, and adequate iodine intake is necessary to maintain thyroid function. A population's iodine intake and nutritional status are assessed based on urinary iodine excretion. There are few studies on iodine nutritional status for all age groups residing in the same area in Japan. Between 2010 and 2017, a total of 769 healthy subjects aged 6.4-73 years in three sites in Yokohama City, were enrolled in the survey. The urinary iodine concentration (UIC), iodine to creatinine (Cr) ratio (UI/Cr) and estimated 24-h urinary iodine excretion (UIE) in single spot urine samples were measured, and habitual dietary iodine intake was assessed by food frequency questionnaires. The estimated 24-h UIE was calculated using individual predicted 24-h creatinine excretion by the validated equations developed for healthy Japanese children and adults which vary by age, gender and anthropometry. The median UIC for all participants was 219 μg/L, suggesting adequate iodine intake for this population. There was an increasing trend in median UI/Cr and estimated 24-h UIE by age. A significant correlation between UIC and UI/Cr (r = 0.6378), UIC and estimated 24-h UIE (r = 0.6804), and UI/Cr and estimated 24-h UIE (r = 0.5756) were observed. These estimates can be feasible, convenient and alternative methods to 24-h urine collection in order to assess iodine status in some populations such as ethnically or racially homogeneous and well-nourished people. Additional studies are required to validate these findings.

Improving Iodine Status in Lactating Women: What Works?

PURPOSE OF REVIEW

Iodine deficiency is a global concern, and in recent years, there has been a significant improvement in the number of countries identified as being iodine-sufficient. This review considers the best strategies to ensure iodine sufficiency among breastfeeding women and their infants.

RECENT FINDINGS

Fortification strategies to improve iodine intake have been adequate for school-age children (SAC); however, often, iodine deficiency remains for breastfeeding women and their infants. Daily supplementation with iodine is not an ideal strategy to overcome deficiency. Countries defined as iodine-sufficient, but where pregnant and breastfeeding women have inadequate intake, should consider increasing salt iodine concentration, such that the median urinary iodine concentration of SAC can be up to 299 µg/L. This will ensure adequate intake for mothers and infants, without SAC being at risk thyroid dysfunction. Consensus is required for thresholds for iodine adequacy for breastfeeding women and infants.

Low Urinary Iodine Concentration Is Associated with Increased Risk for Elevated Plasma Glucose in Females: An Analysis of NHANES 2011-12

Iodine intake in the US has declined in recent years. Iodine insufficiency increases the risk for inadequate thyroid hormone production and there is growing evidence that sub-clinical hypothyroidism may be disruptive to metabolic health, including insulin resistance (IR). We investigated the association between urinary iodine concentrations (UIC), a measurement of iodine status, and IR in adults. Data from 1286 US adults (≥20 years) in the NHANES 2011-2012 were analyzed. Two subgroups (low = UIC < 100 µg/L and normal = UIC ≥ 100 µg/L) were compared for markers of IR, including fasting plasma glucose (FPG) and insulin, homeostatic model assessment of insulin resistance (HOMA-IR), and glycated hemoglobin (HbA1C). Chi-square test, both linear and logistic regression models were used. In males, there were no significant associations between UIC and markers of IR; however, females with normal UIC had greater risks for elevated HOMA-IR (AOR = 0.56, 95% CI= 0.32-0.99) and HbA1C (AOR = 0.56, 95% CI = 0.34-0.90), while females with low UIC had a greater risk for FPG ≥ 5.6 mmol/L (AOR = 1.73, 95% CI = 1.09-2.72). Results only partially support our hypothesis that UIC is associated with the odds of IR in adults. The finding of an increased risk for elevated FPG, a marker of prediabetes, in female adults with low iodine status requires further investigation.

Prevalence of thyroid dysfunction in postpartum women with suboptimal iodine and selenium and adequate iron status

OBJECTIVE

Postpartum women experience thyroid dysfunction at twice the prevalence of the general population. Adequate biosynthesis of thyroid hormones depends on three trace elements: iodine, selenium and iron. This study aimed to investigate thyroid dysfunction within a cohort of women at six months postpartum in relation to iodine, selenium and iron status.

DESIGN

This cross-sectional study was part of an observational longitudinal cohort Mother and Infant Nutrition Investigation; data obtained at six months postpartum are reported.

SUBJECTS

Mother-infant pairs (n = 87) were recruited at three months postpartum and followed up at six months postpartum (n = 78).

MEASUREMENTS

Thyroid hormones (free triiodothyronine, free thyroxine, thyroid-stimulating hormone) and thyroid peroxidase antibodies were measured. Urinary iodine concentration, breast milk iodine concentration, serum thyroglobulin, plasma selenium, serum ferritin and serum soluble transferrin receptors were determined. Nonparametric data were expressed as median (25th, 75th percentile).

RESULTS

Thyroid dysfunction was found in 18% of women, and 4% of women had iron deficiency. Median urinary iodine concentration was 85 (43, 134) µg/L, median breast milk iodine concentration was 59 (39, 109) µg/L, and median serum thyroglobulin at 11.4 (8.6, 18.6) µg/L, indicating iodine deficiency. Median plasma selenium concentration was 105.8 (95.6, 115.3) µg/L. Women with marginally lower plasma selenium concentration were 1.12% times more likely to have abnormal TSH concentrations (p = .001).

CONCLUSIONS

There was a high prevalence of thyroid dysfunction. Plasma selenium concentration was the only significant predictor of the likelihood that women had thyroid dysfunction within this cohort, who were iodine deficient and mostly had adequate iron status. Strategies are required to improve both iodine and selenium status to better support maternal thyroid function.

HPLC Analysis of the Urinary Iodine Concentration in Pregnant Women

Iodine is an essential component for fetal neurodevelopment and maternal thyroid function. Urine iodine is the most widely used indicator of iodine status. In this study, a novel validated ion-pair HPLC-UV method was developed to measure iodine concentration in clinical samples. A sodium thiosulfate solution was added to the urine sample to convert the total free iodine to iodide. Chromatographic separation was achieved in a Pursuit XRs C8 column. The mobile phase consisted of acetonitrile and a water phase containing 18-crown-6-ether, octylamine and sodium dihydrogen phosphate. Validation parameters, such as accuracy, precision, limits of detection and quantification, linearity and stability, were determined. Urinary samples from pregnant women were used to complete the validation and confirm the method's applicability. In the studied population of 93 pregnant women, the median UIC was lower in the group without iodine supplementation (117 µg/L, confidence interval (%CI): 95; 138) than in the supplement group (133 µg/L, %CI: 109; 157). In conclusion, the newly established ion-pair HPLC-UV method was adequately precise, accurate and fulfilled validation the criteria for analyzing compounds in biological fluids. The method is less complicated and expensive than other frequently used assays and permits the identification of the iodine-deficient subjects.

Autism spectrum disorder: Trace elements imbalances and the pathogenesis and severity of autistic symptoms

The identification of biomarkers as diagnostic tools and predictors of response to treatment of neurological developmental disorders (NDD) such as schizophrenia (SZ), attention deficit hyperactivity disorder (ADHD), or autism spectrum disorder (ASD), still remains an important challenge for clinical medicine. Metallomic profiles of ASD patients cover, besides essential elements such as cobalt, chromium, copper, iron, manganese, molybdenum, zinc, selenium, also toxic metals burden of: aluminum, arsenic, mercury, lead, beryllium, nickel, cadmium. Performed studies indicate that children with ASD present a reduced ability of eliminating toxic metals, which leads to these metals' accumulation and aggravation of autistic symptoms. Extensive metallomic studies allow a better understanding of the importance of trace elements as environmental factors in the pathogenesis of ASD. Even though a mineral imbalance is a fact in ASD, we are still expecting relevant tests and the elaboration of reference levels of trace elements as potential biomarkers useful in diagnosis, prevention, and treatment of ASD.

Reflection of Dietary Iodine in the 24 h Urinary Iodine Concentration, Serum Iodine and Thyroglobulin as Biomarkers of Iodine Status: A Pilot Study

BACKGROUND

The iodine status of the US population is considered adequate, but subpopulations remain at risk for iodine deficiency and a biomarker of individual iodine status has yet to be determined. The purpose of this study was to determine whether a 3 day titration diet, providing known quantities of iodized salt, is reflected in 24 h urinary iodine concentration (UIC), serum iodine, and thyroglobulin (Tg).

METHODS

A total of 10 participants (31.3 ± 4.0 years, 76.1 ± 6.3 kg) completed three, 3 day iodine titration diets (minimal iodine, US RDA, (United States Recommended Daily Allowance), and 3× RDA). The 24 h UIC, serum iodine, and Tg were measured following each diet. The 24 h UIC and an iodine-specific food frequency questionnaire (FFQ) were completed at baseline.

RESULTS

UIC increased an average of 19.3 μg/L for every gram of iodized salt consumed and was different from minimal to RDA (p = 0.001) and RDA to 3× RDA diets (p = 0.04). Serum iodine was different from RDA to 3× RDA (p = 0.006) whereas Tg was not responsive to diet. Baseline UIC was associated with iodine intake from milk (r = 0.688, p = 0.028) and fish/seafood (r = 0.646, p = 0.043).

CONCLUSION

These results suggest that 24 h UIC and serum iodine may be reflective of individual iodine status and may serve as biomarkers of iodine status.

Neonatal heel prick screening TSH concentration in the Netherlands as indicator of iodine status

Background

Neonatal Thyroid Stimulating Hormone (nTSH) is proposed as indicator of iodine deficiency in a population. Population’s iodine sufficiency is indicated by a proportion of the newborns less than 3% having nTSH above 5 mIU/L. The aim of this study was to explore the Dutch neonatal heel prick screening TSH data to assess iodine status in the Netherlands and identify determinants and potential confounders of this assessment.

Methods

All newborns born in the Netherlands between 2007 and 2015 with a heel prick collection at day 3-7 were included (n = 1,435,600), except preterm neonates and baby’s with a low birth weight. Total T4 was measured for all children, nTSH was measured in the ~ 20% children with lowest total T4.

Results

The proportion with nTSH > 5mIU/L fluctuated between 0.6-1.3% in 2007-2015. nTSH was significantly associated with laboratory performing the nTSH assay and age of heel prick sampling. The overall increasing trend in proportion nTSH >1mIU/L was confounded by the laboratories with different and changed assays.

Conclusions

The low proportion neonates with high nTSH suggests a sufficient iodine status in the Netherlands. Whether the increased proportion nTSH>1mIU/L over the years is an early indicator of deterioration of the iodine status remains unclear, due to differences and changes in analytical assays. nTSH might be a valuable and inexpensive way to get crude insight in the (trend in) iodine status, but more research is needed on the validity and potential conditions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12937-021-00722-4.

Consumption of multiple micronutrients or small-quantity lipid-based nutrient supplements containing iodine at the recommended dose during pregnancy, compared with iron and folic acid, does not affect women's urinary iodine concentration in rural Malawi: a secondary outcome analysis of the iLiNS DYAD trial

OBJECTIVES

Inadequate iodine intake during pregnancy increases the risk of neonatal morbidity and mortality. We aimed to evaluate whether prenatal supplements containing iodine affect urinary iodine concentrations (UIC) of pregnant women in Malawi.

DESIGN

A randomised controlled trial. Pregnant women (n 1391) were assigned to consume 60 mg/d Fe and 400 µg/d folic acid (IFA) or 18 vitamins and minerals including 250 µg/d iodine (MMN) or 20 g/d small-quantity lipid-based nutrient supplements (SQ-LNS) with similar nutrient contents as MMN group, plus macronutrients (LNS) until childbirth. In a sub-study (n 317), we evaluated group geometric mean urinary iodine concentration (UIC) (µg/L) at 36 weeks of gestation controlling for baseline UIC and compared median (baseline) and geometric mean (36 weeks) UIC with WHO cut-offs: UIC < 150, 150-249, 250-499 and ≥500 reflecting insufficient, adequate, above requirements and excessive iodine intakes, respectively.

SETTING

Mangochi District, Malawi.

PARTICIPANTS

Women ≤20 weeks pregnant.

RESULTS

Groups had comparable background characteristics. At baseline, overall median (Q1, Q3) UIC (319 (167, 559)) suggested iodine intakes above requirements. At 36 weeks, the geometric mean (95 % CI) UIC of the IFA (197 (171, 226)), MMN (212 (185, 243)) and LNS (220 (192, 253)) groups did not differ (P = 0·53) and reflected adequate intakes.

CONCLUSIONS

In this setting, provision of supplements containing iodine at the recommended dose to pregnant women with relatively high iodine intakes at baseline, presumably from iodised salt, has no impact on the women's UIC. Regular monitoring of the iodine status of pregnant women in such settings is advisable. Clinicaltrials.gov identifier: NCT01239693.

Biomarkers and Fatty Fish Intake: A Randomized Controlled Trial in Norwegian Preschool Children

BACKGROUND

Biomarkers such as omega-3 (n-3) PUFAs, urinary iodine concentration (UIC), 1-methylhistidine (1-MH), and trimethylamine N-oxide (TMAO) have been associated with fish intake in observational studies, but data from children in randomized controlled trials are limited.

OBJECTIVES

The objective of this exploratory analysis was to investigate the effects of fatty fish intake compared with meat intake on various biomarkers in preschool children.

METHODS

We randomly allocated (1:1) 232 children, aged 4 to 6 y, from 13 kindergartens. The children received lunch meals of either fatty fish (herring/mackerel) or meat (chicken/lamb/beef) 3 times a week for 16 wk. We analyzed 86 biomarkers in plasma (n = 207), serum (n = 195), RBCs (n = 211), urine (n = 200), and hair samples (n = 210). We measured the effects of the intervention on the normalized biomarker concentrations in linear mixed-effect regression models taking the clustering within the kindergartens into account. The results are presented as standardized effect sizes.

RESULTS

We found significant effects of the intervention on the following biomarkers: RBC EPA (20:5n-3), 0.61 (95% CI: 0.36, 0.86); DHA (22:6n-3), 0.43 (95% CI: 0.21, 0.66); total n-3 PUFAs, 0.41 (95% CI: 0.20, 0.64); n-3/n-6 ratio, 0.48 (95% CI: 0.24, 0.71); adrenic acid (22:4n-6, -0.65 (95% CI: -0.91, -0.40), arachidonic acid (20:4n-6), -0.54 (95% CI: -0.79, -0.28); total n-6 PUFAs, -0.31 (95% CI: -0.56, -0.06); UIC, 0.32 (95% CI: 0.052, 0.59); hair mercury, 0.83 (95% CI: 0.05, 1.05); and plasma 1-MH, -0.35 (95% CI: -0.61, -0.094).

CONCLUSIONS

Of the 86 biomarkers, the strongest effect of fatty fish intake was on n-3 PUFAs, UIC, hair mercury, and plasma 1-MH. We observed no or limited effects on biomarkers related to micronutrient status, inflammation, or essential amino acid, choline oxidation, and tryptophan pathways.The trial was registered at clinicaltrials.gov (NCT02331667).

Abnormal iron status is independently associated with reduced oscillometric lung function in schoolchildren

BACKGROUND

Associations between anemia and allergic diseases have been reported, but the relationship of iron deficiency with airway dysfunction in children remains unclear. We aimed to investigate the relationship between abnormal iron parameters and lung function in schoolchildren.

METHODS

Four hundred and forty-five children (10-12 years-old) from 11 elementary schools in were enrolled. The relationships of different iron parameters (hemoglobin, serum iron, transferrin saturation, and serum ferritin) with lung function evaluated by impulse oscillometry (airways resistance at 5 Hz [Rrs5], 10 Hz [Rrs10], and the difference of Rrs5 and Rrs20 Hz [Rrs5-20]), and with exhaled nitric oxide (FeNO) were evaluated after adjustment for confounders including height, sex, and body mass index z-score, and for additional covariates that could affect airway function.

RESULTS

Total airway dysfunction represented by Rrs5 was reduced in participants with low serum iron level (aβ: -0.13, 95% CI: -0.23 to -0.03, p = 0.040) after adjustment for key confounders, but did not correlate with other iron profiles. Reduced oscillometric lung function recorded as Rrs5-20 was related with low serum iron and high serum ferritin, but the results were inconsistent after multiple comparisons. Associations were not observed with serum hemoglobin.

CONCLUSIONS

Decreased serum iron level was related with airway dysfunction represented as oscillomteric Rrs5. Our results suggest a relationship of reduced lung function with abnormal iron status in children.

Rapid and efficient autoclave digestion for the extraction of iodine-129 from urine samples

A new method was developed to extract ¹²⁹I from urine samples and measure it using accelerator mass spectrometry (AMS). The samples were pre-treated in an autoclave with hydrogen peroxide and were then acidified with nitric acid, followed by the precipitation of iodine as silver iodide (AgI) for measurement by AMS. This new procedure is substantially faster than previous methods for the extraction of iodine from urine and results in less chemical waste. The efficiency and reproducibility of this method were evaluated by using ¹²⁵I as a yield tracer, eventually giving a recovery above 99%. To achieve this, several iterations of the method were required. The method was then successfully applied to measure ¹²⁹I/¹²⁷I isotopic ratios and ¹²⁹I concentrations in 25 human urine samples. The AMS results for ¹²⁹I in urine ranged 3.3 × 10⁶ atoms/L to 884 × 10⁶ atoms/L and the isotope ratio (¹²⁹I/¹²⁷I) in human urine ranged from 7.38 × 10^-12 to 3.97 × 10^-10 with a median of 1.29 × 10^-10. This new method will be useful for investigations into the sources of iodine in the human diet and their relative importance for iodine sufficiency.

Impact of iron fortification on anaemia and iron deficiency among pre-school children living in Rural Ghana

Anaemia in young sub-Saharan African children may be due to the double burden of malaria and iron deficiency. Primary analysis of a double-blind, cluster randomized trial of iron containing micronutrient powder supplementation in Ghanaian children aged 6 to 35 months found no difference in malaria risk between intervention and placebo groups. Here, we performed a secondary analysis of the trial data to assess the impact of long-term prophylactic iron fortificant on the risk of iron deficiency and anaemia in trial subjects. This population-based randomized-cluster trial involved 1958 children aged between 6 to 35 months, identified at home and able to eat semi-solid foods. The intervention group (n = 967) received a daily dose containing 12.5 mg elemental iron (as ferrous fumarate), vitamin A (400 μg), ascorbic acid (30 mg) and zinc (5 mg). The placebo group (n = 991) received a similar micronutrient powder but without iron. Micronutrient powder was provided daily to both groups for 5 months. At baseline and endline, health assessment questionnaires were administered and blood samples collected for analysis. The two groups had similar baseline anthropometry, anaemia, iron status, demographic characteristics, and dietary intakes (p > 0.05). Of the 1904 (97.2%) children who remained at the end of the intervention, the intervention group had significantly higher haemoglobin (p = 0.0001) and serum ferritin (p = 0.0002) levels than the placebo group. Soluble transferrin receptor levels were more saturated among children from the iron group compared to non-iron group (p = 0.012). Anaemia status in the iron group improved compared to the placebo group (p = 0.03). Continued long-term routine use of micronutrient powder containing prophylactic iron reduced anaemia, iron deficiency and iron deficiency anaemia among pre-school children living in rural Ghana's malaria endemic area.

Iodine status during pregnancy and at 6 weeks, 6, 12 and 18 months post-partum

Iodine deficiency during pregnancy and in the post-partum period may lead to impaired child development. Our aim is to describe iodine status longitudinally in women from pregnancy until 18 months post-partum. Furthermore, we explore whether iodine status is associated with dietary intake, iodine-containing supplement use and breastfeeding status from pregnancy until 18 months post-partum. We also assess the correlation between maternal iodine status 18 months post-partum and child iodine status at 18 months of age. Iodine status was measured by urinary iodine concentration (UIC) during pregnancy (n = 1,004), 6 weeks post-partum (n = 915), 6 months post-partum (n = 849), 12 months post-partum (n = 733) and 18 months post-partum (n = 714). The toddlers' UIC was assessed at 18 months of age (n = 416). Demographic variables and dietary data (food frequency questionnaire) were collected during pregnancy, and dietary data and breastfeeding practices were collected at all time points post-partum. We found that iodine status was insufficient in both pregnant and post-partum women. The UIC was at its lowermost 6 weeks post-partum and gradually improved with increasing time post-partum. Intake of milk and use of iodine-containing supplements significantly increased the odds of having a UIC above 100 μg/L. Neither the mothers' UIC, vegetarian practice, nor exclusion of milk and dairy products were associated with the toddlers UIC 18 months post-partum. Women who exclude milk and dairy products from their diets and/or do not use iodine-containing supplements may be at risk of iodine deficiency. The women possibly also have an increased risk of thyroid dysfunction and for conceiving children with nonoptimal developmental status.

Accurate Noninvasive Assessment of Myocardial Iron Load in Advanced Heart Failure Patients

Background

Heart failure patients presenting with iron deficiency can benefit from systemic iron supplementation; however, there is the potential for iron overload to occur, which can seriously damage the heart. Therefore, myocardial iron (M-Iron) content should be precisely balanced, especially in already failing hearts. Unfortunately, the assessment of M-Iron via repeated heart biopsies or magnetic resonance imaging is unrealistic, and alternative serum markers must be found. This study is aimed at assessing M-Iron in patients with advanced heart failure (HF) and its association with a range of serum markers of iron metabolism.

Methods

Left ventricle (LV) myocardial biopsies and serum samples were collected from 33 consecutive HF patients (25 males) with LV dysfunction (LV ejection fraction 22 (11) %; NT-proBNP 5464 (3308) pg/ml) during heart transplantation. Myocardial ferritin (M-FR) and soluble transferrin receptor (M-sTfR1) were assessed by ELISA, and M-Iron was determined by Instrumental Neutron Activation Analysis in LV biopsies. Nonfailing hearts (n = 11) were used as control/reference tissue. Concentrations of serum iron-related proteins (FR and sTfR1) were assessed.

Results

LV M-Iron load was reduced in all HF patients and negatively associated with M-FR (r = -0.37, p = 0.05). Of the serum markers, sTfR1/logFR correlated with (r = -0.42; p = 0.04) and predicted (in a step-wise analysis, R ² = 0.18; p = 0.04) LV M-Iron. LV M-Iron load (μg/g) can be calculated using the following formula: 210.24-22.869 × sTfR1/logFR.

Conclusions

The sTfR1/logFR ratio can be used to predict LV M-Iron levels. Therefore, serum FR and sTfR1 levels could be used to indirectly assess LV M-Iron, thereby increasing the safety of iron repletion therapy in HF patients.

Iodine status of pregnant women with obesity from inner city populations in the United Kingdom

BACKGROUND/OBJECTIVES

Iodine is essential for foetal neurodevelopment and growth. Requirements increase in pregnancy to support increased thyroid hormone synthesis for maternal and foetal requirements, and for foetal transfer. Iodine deficiency in pregnancy is widely reported, and obesity has been associated with sub-optimal thyroid function. We evaluated iodine status and its relation with birthweight in a secondary analysis of pregnant women with obesity from multi-ethnic inner-city settings who participated in the UK Pregnancies Better Eating and Activity trial (UPBEAT).

SUBJECTS/METHODS

Iodine and creatinine concentrations were evaluated in spot urine samples in the second (15⁺⁰-18⁺⁶ weeks, n = 954) trimester of pregnancy. We assessed iodine status as urinary iodine concentration (UIC) and urinary iodine-to-creatinine ratio (UI/Cr) and applied WHO/UNICEF/IGN population threshold of median UIC > 150 µg/L for iodine sufficiency. Relationships between iodine status and birthweight were determined using linear and logistic regression with appropriate adjustment, including for maternal BMI and gestational age.

RESULTS

Median (IQR) UIC and UI/Cr in the second trimester of pregnancy were 147 µg/L (99-257) and 97 µg/g (59-165), respectively. An UI/Cr <150 μg/g was observed in 70% of women. Compared to women with UI/Cr >150 µg/g, there was a trend for women with UI/Cr <150 µg/g to deliver infants with a lower birthweight (β = -60.0 g; 95% CI -120.9 to -1.01, P = 0.05).

CONCLUSIONS

Iodine status of pregnant women with obesity from this cohort of UK women was suboptimal. Lower iodine status was associated with lower birthweight.

Iodine status of consumers of milk-alternative drinks v. cows' milk: data from the UK National Diet and Nutrition Survey

Milk is the main source of iodine in the UK; however, the consumption and popularity of plant-based milk-alternative drinks are increasing. Consumers may be at risk of iodine deficiency as, unless fortified, milk alternatives have a low iodine concentration. We therefore aimed to compare the iodine intake and status of milk-alternative consumers with that of cows' milk consumers. We used data from the UK National Diet and Nutrition Survey from years 7 to 9 (2014-2017; before a few manufacturers fortified their milk-alternative drinks with iodine). Data from 4-d food diaries were used to identify consumers of milk-alternative drinks and cows' milk, along with the estimation of their iodine intake (µg/d) (available for n 3976 adults and children ≥1·5 years). Iodine status was based on urinary iodine concentration (UIC, µg/l) from spot-urine samples (available for n 2845 adults and children ≥4 years). Milk-alternative drinks were consumed by 4·6 % (n 185; n 88 consumed these drinks exclusively). Iodine intake was significantly lower in exclusive consumers of milk alternatives than cows' milk consumers (94 v. 129 µg/d; P < 0·001). Exclusive consumers of milk alternatives also had a lower median UIC than cows' milk consumers (79 v. 132 µg/l; P < 0·001) and were classified as iodine deficient by the WHO criterion (median UIC < 100 µg/l), whereas cows' milk consumers were iodine sufficient. These data show that consumers of unfortified milk-alternative drinks are at risk of iodine deficiency. As a greater number of people consume milk-alternative drinks, it is important that these products are fortified appropriately to provide a similar iodine content to that of cows' milk.

No effect of 6-month supplementation with 300 mg/d docosahexaenoic acid on executive functions among healthy school-aged children: a randomized, double-blind, placebo-controlled trial

PURPOSE

Docosahexaenoic acid (DHA) plays an essential role in brain, and its status is dependent on dietary intakes. School-aged children in rural China, who consume diets low in omega-3 polyunsaturated fatty acids, may benefit from DHA supplementation. Therefore, this trial was performed to examine the effect of 6-month DHA supplementation on executive functions (EFs) among healthy school-aged children in rural China.

METHODS

A randomized, double-blind, placebo-controlled trial was conducted among 106 primary school children aged 7-12 years in rural China. Participants were randomized to receive either 300 mg/d DHA or placebo for 6 months. EFs including working memory and cognitive flexibility were evaluated at baseline, at 3 months and at 6 months, using Digit Span Backwards and Wisconsin card sorting test, respectively. Socio-demographic data were collected at baseline, and erythrocyte membrane fatty acids and serum neurotransmitters were measured at baseline and after 6-month intervention.

RESULTS

Ninety-four children (88.7%) completed the study according to the protocol. Changes in erythrocyte membrane fatty acids indicated good compliance of the participants. There was no significant intervention effect on serum neurotransmitters. In two-factor ANCOVA, both groups showed a significant improvement in the Digit Span Backwards and the Wisconsin card sorting test from baseline to endpoint. However, no significant intervention effect was found on any EF scores. Linear regression analysis suggested no significant association between changes in erythrocyte DHA level with changes in any EF scores.

CONCLUSIONS

Supplementation with 300 mg/d DHA for 6 months had no benefit on EFs including working memory and cognitive flexibility among healthy school-aged children. This trial was registered at clinicaltrials.gov as NCT02308930 on December 5, 2014.

Mother and Infant Nutrition Investigation in New Zealand (MINI Project): Protocol for an Observational Longitudinal Cohort Study

Background

Thyroid dysfunction is associated with cognitive impairment, mood disturbance, and postnatal depression. Sufficient thyroid hormone synthesis requires adequate intake of iodine, selenium, and iron. Iodine deficiency was historically a problem for New Zealand, and initiatives were introduced to overcome the problem: (1) mandatory fortification of all bread (except organic) with iodized salt (2009) and (2) provision of subsidized iodine supplements for pregnant and breastfeeding women (2010). Subsequent to these initiatives, most adults and children have adequate iodine status; however, status among breastfeeding women and their infants remains unclear. This paper outlines the methodology of the Mother and Infant Nutrition Investigation (MINI) study: an observational longitudinal cohort study of breastfeeding women and their infants.

Objective

This study will determine (1) women’s iodine intake and status among supplement users and nonusers; (2) women’s intake and status of iodine, selenium, and iron relating to thyroid function; (3) associations between women’s selenium status, thyroid function, and postnatal depression; (4) infants’ iodine and selenium status relating to first year neurodevelopment.

Methods

Breastfeeding women aged over 16 years with a healthy term singleton infant were recruited from Manawatu, New Zealand. Participants attended study visits 3, 6, and 12 months postpartum. Maternal questionnaires investigated supplement use before and after birth, iodine knowledge, and demographic information. Dietary assessment and urine, blood, and breast milk samples were taken to measure iodine, selenium, and iron intake/status. The Edinburgh Postnatal Depression Scale was used repeatedly to screen for postnatal depression. Thyroid hormones (free triiodothyronine, free thyroxine, thyroid stimulating hormone, thyroglobulin, antithyroglobulin antibodies, and antithyroid peroxidase) were measured in blood samples, and thyroid gland volume was measured by ultrasound at 6 months postpartum. Infant iodine and selenium concentrations were determined in urine. The Ages and Stages Questionnaire was used to assess infant development at 4, 8, and 12 months.

Results

Data collection was completed. Biological samples analysis, excluding nail clippings, is complete. Data analysis and presentation of the results will be available after 2020.

Conclusions

This study will provide data on the current iodine status of breastfeeding women. It will also provide a greater understanding of the three essential minerals required for optimal thyroid function among breastfeeding women. The prospective longitudinal design allows opportunities to examine women’s mental health and infant neurodevelopment throughout the first year, a crucial time for both mothers and their infants.

Trial Registration

Australian New Zealand Clinical Trials Registry ACTRN12615001028594; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=369324

International Registered Report Identifier (IRRID)

DERR1-10.2196/18560

Systematic review and meta-analysis of the effects of iodine supplementation on thyroid function and child neurodevelopment in mildly-to-moderately iodine-deficient pregnant women

BACKGROUND

Mild-to-moderate iodine deficiency, particularly in pregnancy, is prevalent; this is of concern because observational studies have shown negative associations with child neurodevelopment. Although neither the benefits nor the safety of iodine supplementation in pregnancy in areas of mild-to-moderate deficiency are well researched, such supplementation is increasingly being recommended by health authorities in a number of countries.

OBJECTIVES

By reviewing the most recent published data on the effects of iodine supplementation in mildly-to-moderately deficient pregnant women on maternal and infant thyroid function and child cognition, we aimed to determine whether the evidence was sufficient to support recommendations in these areas.

METHODS

A systematic review of randomized controlled trials (RCTs), non-RCT interventions, and observational studies was conducted. To identify relevant articles, we searched the PubMed and Embase databases. We defined mild-to-moderate iodine deficiency as a baseline median urinary iodine concentration (UIC) of 50-149 µg/L. Eligible studies were included in meta-analyses.

RESULTS

In total, 37 publications were included-10 RCTs, 4 non-RCT interventions, and 23 observational studies. Most studies showed no effect of iodine supplementation on maternal or infant thyroid-stimulating hormone and free thyroxine. Most RCTs found that supplementation reduced maternal thyroglobulin and in 3 RCTs, it prevented or diminished the increase in maternal thyroid volume during pregnancy. Three RCTs addressed child neurodevelopment; only 1 was adequately powered. Meta-analyses of 2 RCTs showed no effect on child cognitive [mean difference (MD): -0.18; 95% CI: -1.22, 0.87], language (MD: 1.28; 95% CI: -0.28, 2.83), or motor scores (MD: 0.28; 95% CI: -1.10, 1.66).

CONCLUSIONS

There is insufficient good-quality evidence to support current recommendations for iodine supplementation in pregnancy in areas of mild-to-moderate deficiency. Well-designed RCTs, with child cognitive outcomes, are needed in pregnant women who are moderately deficient (median UIC < 100 µg/L). Maternal intrathyroidal iodine stores should be considered in future trials by including appropriate measures of preconceptional iodine intake.This review was registered at www.crd.york.ac.uk/prospero as CRD42018100277.

Erythrocyte transfusions increased the risk of elevated serum ferritin in very low birthweight infants and were associated with altered longitudinal growth

Aim

There has been a lack of population‐based longitudinal data on serum ferritin in very low birthweight (VLBW) infants during hospitalisation. Our aim was to fill this gap in the knowledge and investigate risk factors for elevated serum ferritin and associations between erythrocyte transfusions and longitudinal growth.

Methods

We retrospectively reviewed longitudinal data on 126 VLBW infants treated at Umeå University Hospital, Sweden, between 2010 and 2013.

Results

The infants' mean gestational age and birthweight were 26.9 weeks and 899 g. Most (91%) received erythrocyte transfusions, and the majority had multiple erythrocyte transfusions. There was a significant correlation between serum ferritin and the volume of transfusions. Almost two‐thirds had at least one serum ferritin measurement of more than 350 µg/L, indicating iron overload. In those with complete anthropometric data (n = 78), there was no significant effect of serum ferritin concentrations in relation to longitudinal growth, but there was a positive association between the erythrocyte transfusion dose and longitudinal growth in VLBW infants born before 25 weeks.

Conclusion

This is the first population‐based study to investigate longitudinal data on serum ferritin in VLBW infants during hospitalisation. The unexpected positive finding in the subgroup born at less than 25 weeks needs further research with a larger cohort.

Association of Family Income and Risk of Food Insecurity With Iron Status in Young Children

IMPORTANCE

Iron deficiency (ID) has the greatest prevalence in early childhood and has been associated with poor developmental outcomes. Previous research examining associations of income and food insecurity (FI) with ID is inconsistent.

OBJECTIVE

To examine the association of family income and family risk of FI with iron status in healthy young children attending primary care.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study included 1245 children aged 12 to 29 months who attended scheduled primary care supervision visits from 2008 to 2018 in Toronto, Canada, and the surrounding area.

EXPOSURES

Family income and risk of FI were collected from parent-reported questionnaires. Children whose parents provided an affirmative response to the 1-item FI screen on the Nutrition Screening Tool for Every Toddler or at least 1 item on the 2-item Hunger Vital Sign FI screening tool were categorized as having family risk of FI.

MAIN OUTCOMES AND MEASURES

Iron deficiency (serum ferritin level <12 ng/mL) and ID anemia (IDA; serum ferritin level <12 ng/mL and hemoglobin level <11.0 g/dL). All models were adjusted for age, sex, birth weight, body mass index z score, C-reactive protein level, maternal education, breastfeeding duration, bottle use, cow's milk intake, and formula feeding in the first year.

RESULTS

Of 1245 children (595 [47.8%] girls; median [interquartile range] age, 18.1 [13.3-24.0] months), 131 (10.5%) were from households with a family income of less than CAD $40 000 ($29 534), 77 (6.2%) were from families at risk of FI, 185 (14.9%) had ID, and 58 (5.3%) had IDA. The odds of children with a family income of less than CAD $40 000 having ID and IDA were 3 times higher than those of children in the highest family income group (ID: odds ratio [OR], 3.08; 95% CI, 1.66-5.72; P < .001; IDA: OR, 3.28; 95% CI, 1.22-8.87; P = .02). Being in a family at risk of FI, compared with all other children, was not associated with ID or IDA (ID: OR, 0.43; 95% CI, 0.18-1.02; P = .06; IDA: OR, 0.16; 95% CI, 0.02-1.23; P = .08).

CONCLUSIONS AND RELEVANCE

In this study, low family income was associated with increased risk of ID and IDA in young children. Risk of FI was not a risk factor for ID or IDA. These findings suggest that targeting income security may be more effective than targeting access to food to reduce health inequities in the prevention of iron deficiency.

The Central Role of Iron in Human Nutrition: From Folk to Contemporary Medicine

Iron is a fundamental element in human history, from the dawn of civilization to contemporary days. The ancients used the metal to shape tools, to forge weapons, and even as a dietary supplement. This last indication has been handed down until today, when martial therapy is considered fundamental to correct deficiency states of anemia. The improvement of the martial status is mainly targeted with dietary supplements that often couple diverse co-factors, but other methods are available, such as parenteral preparations, dietary interventions, or real-world approaches. The oral absorption of this metal occurs in the duodenum and is highly dependent upon its oxidation state, with many absorption influencers possibly interfering with the intestinal uptake. Bone marrow and spleen represent the initial and ultimate step of iron metabolism, respectively, and the most part of body iron circulates bound to specific proteins and mainly serves to synthesize hemoglobin for new red blood cells. Whatever the martial status is, today’s knowledge about iron biochemistry allows us to embrace exceedingly personalized interventions, which however owe their success to the mythical and historical events that always accompanied this metal.

Hemoglobin and hepcidin have good validity and utility for diagnosing iron deficiency anemia among pregnant women

BACKGROUND/OBJECTIVES

Screening and diagnosis of iron deficiency anemia (IDA) is cumbersome as it may require testing for hemoglobin, ferritin, and an inflammatory biomarker. The aim of this study was to compare the diagnostic capacity of hematologic biomarkers to detect IDA among pregnant women in Tanzania.

SUBJECTS/METHODS

We pooled data from an iron supplementation trial of 1500 iron-replete pregnant woman and a prospective cohort of 600 iron-deficient pregnant women. Receiver operating characteristic curves (ROC) for hematologic biomarkers were used to assess the sensitivity, specificity, and area under the curve (AUC) for iron deficiency (ID) and iron deficiency anemia (IDA), crude, or corrected for inflammation. Regression models assessed the relationship of baseline biomarker categories (gestational age <27 weeks) and IDA at delivery.

RESULTS

Hemoglobin had the largest AUC for crude ID (0.96), while hepcidin had the largest AUC for corrected ID (0.80). The optimal hepcidin cutoff for the diagnosis of corrected IDA based on maximal sensitivity and specificity was ≤1.6 µg/L. An hepcidin cutoff of <4.3 µg/L had a sensitivity of 95% for regression-corrected ID. Among iron-replete women who did not receive iron, the association of baseline hemoglobin >110 g/L with IDA at delivery (RR = 0.73; 95% CI: 0.47, 1.13) was attenuated. Baseline hepcidin >1.6 µg/L was associated with reduced risk of anemia at delivery by 49% (95% CI: 27%, 45%).

CONCLUSIONS

Ascertaining hemoglobin and hepcidin levels may improve the targeting of iron supplementation programs in resource-limited countries, though hepcidin's high costs may limit its use.

Factors Associated with Urinary Iodine Concentration among Women of Reproductive Age, 20-49 Years Old, in Tanzania: A Population-Based Cross-Sectional Study

BACKGROUND

Universal salt iodization (USI) is the most feasible and cost-effective, and equitable, approach to prevent iodine deficiency. Severe maternal iodine deficiency during pregnancy is associated with serious adverse gestational and birth outcomes.

OBJECTIVES

The aim was to assess iodine status and identify independent factors associated with urinary iodine concentration (UIC) among women of reproductive age in Tanzania.

METHODS

This was a weighted, population-based, cross-sectional study in 2985 women of reproductive age (20-49 y) in Tanzania who participated in the Demographic and Health Surveys in 2015-2016 (DHS 2015-2016) and had measured UIC. Multivariable generalized linear regression was used to identify potential factors that were associated with UIC.

RESULTS

The median UICs among women consuming inadequately iodized salt (93.6 μg/L; 25th and 75th percentiles: 43.1, 197.9 μg/L) and women in the lowest socioeconomic status (92.3 μg/L; 45.6, 194.4 μg/L) were below the WHO-recommended ranges (≥150 μg/L for pregnant women and ≥100 μg/L for nonpregnant women). The results of multivariable models indicated that pregnant women had 1.21 μg/L lower UIC than nonpregnant women (β = -1.21; 95% CI: -3.42, -0.12), breastfeeding women had 1.02 μg/L lower UIC than nonbreastfeeding women (β = -1.02; 95% CI: -2.25, -0.27), and women with no education had a 1.88 μg/L lower UIC compared with those with secondary/highest education (β = -1.88; 95% CI: -4.58, -0.36). Women consuming inadequately iodized salt had 6.55 μg/L lower UIC than those consuming adequately iodized salt (β = -6.55; 95% CI: -9.24, -4.33). The median UIC varied substantially across geographic zones, ranging from 83.2 μg/L (45.9, 165.3) in the Western region to 347.8 μg/L (185.0, 479.8) in the Eastern region.

CONCLUSIONS

Our findings indicated a great heterogeneity in median UIC across regions of Tanzania among women of reproductive age. Poverty, consuming inadequately iodized salt, and lack of education appeared to be the driving factors for lower UIC in Tanzania.

Can Improved Legume Varieties Optimize Iron Status in Low- and Middle-Income Countries? A Systematic Review

Iron and zinc deficiencies are some of the most widespread micronutrient deficiencies in low- and middle-income countries (LMIC). Dietary diversification, food fortification, nutrition education, and supplementation can be used to control micronutrient deficiencies. Legumes are important staple foods in most households in LMIC. Legumes are highly nutritious (good sources of essential minerals, fiber, and low glycemic index) and offer potential benefits in addressing nutrition insecurity in LMIC. Several efforts have been made to increase micronutrient intake by use of improved legumes. Improved legumes have a higher nutrient bioavailability, lower phytate, or reduced hard-to-cook (HTC) defect. We hypothesize that consumption of improved legumes leads to optimization of zinc and iron status and associated health outcomes. Therefore, the objective of this review is to examine the evidence on the efficacy of interventions using improved legumes. Nine relevant studies are included in the review. Consumption of improved legumes resulted in a ≥1.5-fold increase in iron intake. Several studies noted modest improvements in biomarkers of iron status [hemoglobin (Hb), serum ferritin (SF), and transferrin receptor] associated with consumption of improved legumes. Currently, no efficacy studies assessing the relation between consumption of improved legumes and zinc status are available in the literature. Evidence shows that, in addition to repletion of biomarkers of iron status, consumption of improved legumes is associated with both clinical and functional outcomes. The prevalence of iron deficiency (ID) decreases with consumption of improved legumes, with increases of ≤3.0 g/L in Hb concentrations. Improvement in cognition and brain function in women has been reported as well. However, further research is necessary in more at-risk groups and also to show if the reported improvements in status markers translate to improved health outcomes. Evidence from the included studies shows potential from consumption of improved legumes suggesting them to be a sustainable solution to improve iron status.

Cross-sectional analysis of trace element status in thyroid disease

BACKGROUND

The synthesis of thyroid hormone depends on a set of trace elements, most importantly selenium and iodine. The dietary supply with certain micronutrients is limited in many areas of the world, including central Europe and large parts of Asia and Africa. Moreover, both thyroid disease risk and therapy effects are modulated by trace element supply and status.

OBJECTIVE

Assessment of trace element status in thyroid patients in a European metropolis.

MATERIAL AND METHODS

Adult patients visiting a medical praxis in Berlin, Germany, were enrolled into a cross-sectional analysis, and serum samples were obtained from thyroid patients (n = 323) with different conditions including goitre, hypothyroidism, malignancy or autoimmune thyroid disease. Trace elements (iodine, selenium, copper and zinc) were assessed by ICP-MS/MS or total reflection X-ray analysis, along with two protein biomarkers of selenium status (selenoprotein P, glutathione peroxidase), and compared to the clinical phenotype.

RESULTS

The patients displayed relatively low serum zinc and selenium concentrations as compared to a set (n = 200) of healthy subjects (zinc; 1025+/-233 vs. 1068+/-230 μg/L, p < 0.01, selenium; 76.9+/18.8 vs. 85.1+/-17.4 μg/L, p < 0.0001). A high fraction of patients (37.5%) was classified as selenium-deficient (serum selenium concentrations <70 μg/L), in particular the patients with thyroid malignancy (59%). Serum copper was not different between the groups, and total serum iodine concentrations were unrelated to thyroid disease. Explorative statistical analyses yielded no significant interactions between the trace elements and disease parameters, except for free thyroxine inversely correlating to the copper/selenium ratio.

CONCLUSIONS

In adult thyroid patients, there is no relation of circulating copper, iodine, selenium or zinc concentrations to thyroid hormone. However, a large fraction of German thyroid patients displays a considerable selenium deficit, known to constitute a disease risk potentially impairing convalescence and aggravating autoimmune disease processes. It appears advisable to testing thyroid patients for selenium deficiency, and once diagnosed, an increased supply via dietary counselling or active supplementation should be considered.

The Reliability of Iodine Concentration in Diaper-Retrieved Infant Urine Using Urine Collection Pads, and in Their Mothers' Breastmilk

Mild to moderate iodine deficiency is common among women of childbearing age. Data on iodine status in infants are sparse, partly due to the challenges in collecting urine. Urinary iodine concentration (UIC) is considered a good marker for recent dietary iodine intake and status in populations. The aim of this study was to investigate the reliability of iodine concentration measured in two spot-samples from the same day of diaper-retrieved infant urine and in their mothers' breastmilk. We collected urine and breastmilk from a sample of 27 infants and 25 mothers participating in a cross-sectional study at two public healthcare clinics in Norway. The reliability of iodine concentration was assessed by calculating the intraclass correlation coefficients (ICC) and the coefficient of variation (CV). The ICC for infants' urine was 0.64 (95% confidence interval (CI) 0.36-0.82), while the ICC for breastmilk was 0.83 (95% CI 0.65-0.92) Similarly, the intraindividual CV for UIC was 0.25 and 0.14 for breastmilk iodine concentration (BIC). Compared to standard methods of collecting urine for measuring iodine concentration, the diaper-pad collection method does not substantially affect the reliability of the measurements.

Similarities and differences of dietary and other determinants of iodine status in pregnant women from three European birth cohorts

PURPOSE

As a component of thyroid hormones, adequate iodine intake is essential during pregnancy for fetal neurodevelopment. Across Europe, iodine deficiency is common in pregnancy, but data are lacking on the predictors of iodine status at this life stage. We, therefore, aimed to explore determinants of iodine status during pregnancy in three European populations of differing iodine status.

METHODS

Data were from 6566 pregnant women from three prospective population-based birth cohorts from the United Kingdom (ALSPAC, n = 2852), Spain (INMA, n = 1460), and The Netherlands (Generation R, n = 2254). Urinary iodine-to-creatinine ratio (UI/Creat, µg/g) was measured in spot-urine samples in pregnancy (≤ 18-weeks gestation). Maternal dietary intake, categorised by food groups (g/day), was estimated from food-frequency questionnaires (FFQs). Multivariable regression models used dietary variables (energy-adjusted) and maternal characteristics as predictors of iodine status.

RESULTS

Median UI/Creat in pregnant women of ALSPAC, INMA, and Generation R was 121, 151, and 210 µg/g, respectively. Maternal age was positively associated with UI/Creat in all cohorts (P < 0.001), while UI/Creat varied by ethnicity only in Generation R (P < 0.05). Of the dietary predictors, intake of milk and dairy products (per 100 g/day) was positively associated with UI/Creat in all cohorts [ALSPAC (B = 3.73, P < 0.0001); INMA (B = 6.92, P = 0.002); Generation R (B = 2.34, P = 0.001)]. Cohort-specific dietary determinants positively associated with UI/Creat included fish and shellfish in ALSPAC and INMA, and eggs and cereal/cereal products in Generation R.

CONCLUSIONS

The cohort-specific dietary determinants probably reflect not only dietary habits but iodine-fortification policies; hence, public-health interventions to improve iodine intake in pregnancy need to be country-specific.

Oral Supplementation with Sucrosomial Ferric Pyrophosphate Plus L-Ascorbic Acid to Ameliorate the Martial Status: A Randomized Controlled Trial

Altered martial indices before orthopedic surgery are associated with higher rates of complications and greatly affect the patient’s functional ability. Oral supplements can optimize the preoperative martial status, with clinical efficacy and the patient’s tolerability being highly dependent on the pharmaceutical formula. Patients undergoing elective hip/knee arthroplasty were randomized to be supplemented with a 30-day oral therapy of sucrosomial ferric pyrophosphate plus L-ascorbic acid. The tolerability was 2.7% among treated patients. Adjustments for confounding factors, such as iron absorption influencers, showed a relevant response limited to older patients (≥ 65 years old), whose uncharacterized Hb loss was averted upon treatment with iron formula. Older patients with no support lost −2.8 ± 5.1%, while the intervention group gained +0.7 ± 4.6% of circulating hemoglobin from baseline (p = 0.019). Gastrointestinal diseases, medications, and possible dietary factors could affect the efficacy of iron supplements. Future opportunities may consider to couple ferric pyrophosphate with other nutrients, to pay attention in avoiding absorption disruptors, or to implement interventions to obtain an earlier martial status optimization at the population level.

Comparison of 24-h Diet Records, 24-h Urine, and Duplicate Diets for Estimating Dietary Intakes of Potassium, Sodium, and Iodine in Children

Accurately estimating nutrient intake can be challenging, yet it is important for informing policy. This cross-sectional validation study compared the use of three methods for estimating the intake of sodium, potassium, and iodine in children aged 9–11 years in New Zealand. Over the same 24 hour period, participants collected duplicate diets (n = 37), weighed food records (n = 84), and 24 hour urine samples (n = 82). Important differences were found between dietary estimates of sodium, potassium, and iodine using the three methods of dietary assessment, suggesting that different methods of assessment have specific limitations for the measurement of these nutrients in children. Bland Altman plots show relatively wide limits of agreement for all measures and nutrients. These results support the World Health Organization’s (WHOs) recommendations to use urinary assessment to measure population sodium and iodine intake, while dietary assessment appears to be more accurate for estimating potassium intake. Compared to reference values, our results suggest that the children in this study consume inadequate iodine, inadequate potassium, and excess dietary sodium. Public health measures to reduce sodium intake, increase intake of fruit and vegetables, and iodine-rich foods are warranted in New Zealand.

Changes of trace element status during aging: results of the EPIC-Potsdam cohort study

Purpose

We aimed to evaluate age-dependent changes of six trace elements (TE) [manganese (Mn), iron (Fe), zinc (Zn), copper (Cu), iodine (I), and selenium (Se)] over a 20-year period.

Methods

TE concentrations were determined using repeated serum samples taken at baseline and after 20 years of follow-up from 219 healthy participants of the EPIC-Potsdam study, using inductively coupled plasma tandem mass spectrometry. For each TE, absolute and relative differences were calculated between the two time points, as well as the proportion of individuals within normal reference ranges. Interdependence between age-related TE differences was investigated using principal component analysis (PCA). Relationships between selected factors (lifestyle, sociodemographic, anthropometric factors, and hypertension) and corresponding TE longitudinal variability were examined using multivariable linear regression models.

Results

Median age of our study sample was 58.32 years (4.42) at baseline and 40% were females. Median Mn, Zn, Se concentrations and Se to Cu ratio significantly decreased during aging while median Fe, Cu, I concentrations and Cu to Zn ratio significantly increased. A substantial percentage of the participants, at both time points, had Zn concentrations below the reference range. The first PCA-extracted factor reflected the correlated decline in both Mn and Zn over time while the second factor reflected the observed (on average) increase in both Cu and I over time. Overall, none of the investigated factors were strong determinants of TE longitudinal variability, except possibly dietary supplement use, and alcohol use for Fe.

Conclusions

In conclusion, in this population-based study of healthy elderly, decrease in Mn, Zn, and Se concentrations and increase in Fe, Cu, and I concentrations were observed over 20 years of follow-up. Further research is required to investigate dietary determinants and markers of TE status as well as the relationships between TE profiles and the risk of age-related diseases.

Electronic supplementary material

The online version of this article (10.1007/s00394-019-02143-w) contains supplementary material, which is available to authorized users.

Contribution of iodized salt to total iodine and total salt intake in Germany

BACKGROUND

Salt reduction campaigns without a parallel increase of iodine fortification will lead to a worsened iodine status in countries with a relevant salt iodization. A decline in iodine supply bears the risk of higher prevalences of goiter, thyroid nodules, and cognitive delay in children. Against this background, we analyzed the contribution of iodized salt to total iodine and salt intake in Germany and compared the results with data from Switzerland.

METHODS

Analyses were performed with data of the representative German Health-Interview and Examination-Survey for Adults (DEGS1, 2008-2011) using spot urine measurements of creatinine, iodine, and sodium (n = 6738). Median daily iodine and salt intakes were calculated by estimating 24-h iodine and sodium excretions from urinary analyte/creatinine ratios. Linear regressions were used to deduce iodine intake that originates from iodine containing foods (i.e., salt-independent iodine). From this, ingested iodine originating from salt and the proportion of iodized salt to total salt intake were calculated. Data from Switzerland were obtained from the literature.

RESULTS

In Germany, only 42% (52.2 µg/d) of the predicted median total iodine intake (126.2 µg/d), i.e., 12% less than in Switzerland, were found to originate from salt, whereas 73.7 µg/d came from iodine containing foods. 28% (2.6 g/d) of the median salt intake (9.3 g/d) of the German population was calculated to represent iodized salt against 43% in Switzerland.

CONCLUSIONS

Along with an almost identical inherent iodine intake in Germany and Switzerland, the average total iodine intake, the contribution of iodized salt to total iodine intake, and the proportion of iodized salt to total salt are higher in Switzerland than in Germany. Despite this, iodine fortification of table salt has recently been increased in Switzerland from 20 to 25 mg/kg to ensure iodine sufficiency in the population, whereas in Germany fortification still remains at a mean level of 20 mg/kg implying a growing risk of increasing iodine deficiency rates if general salt intake drops.

Assessment of Iodine Status among Pregnant Women and Neonates Using Neonatal Thyrotropin (TSH) in Mainland China after the Introduction of New Revised Universal Salt Iodisation (USI) in 2012: A Re-Emergence of Iodine Deficiency?

Iodine deficiency during pregnancy can cause iodine deficiency disorders (IDD). However, it is unclear about iodine and thyroid status of Chinese pregnant women and neonates after the implementation of the revised universal salt iodisation (USI) level in 2012. Therefore, the aim of the cross-sectional study was to determine iodine nutrition and thyroid status among pregnant women and their neonates in China after the implementation of USI. Medical records of pregnant women and neonates in Northern Jiangsu People's Hospital between January 2016 and December 2017 were reviewed and included. We included 3060 mother-and-newborn pairs in the study. Mean age of participants was 28.2 ± 4.1 years. TSH, FT3, and FT4 of participants were within normal reference range. The overall mean neonatal TSH, birth weight, and prevalence of low birth weight (LBW) were 4.86 ± 2.06 mIU/L, 3358 ± 455 g, and 3.2%, respectively. The prevalence of neonatal TSH values >5 mIU/L was 29.3%, suggesting iodine deficiency in the region. In conclusion, our results indicated iodine deficiency in the region, according to the neonatal TSH cutoff recommended by WHO/UNICEF/IGD. More efforts are urgently required to improve iodine status of pregnant women in the region in order to prevent a re-emergence of iodine deficiency.

Agreement between markers of population iodine status in classifying iodine status of populations: a systematic review

BACKGROUND

Population iodine deficiency is indicated by >3% of the population with newborn thyroid-stimulating hormone (TSH) concentration >5 mIU/L, median urinary iodine concentration (MUIC) <100 µg/L, or >5% prevalence of goiter in school-age children. However, the agreement between these population markers has not been systematically investigated.

OBJECTIVE

To assess the agreement between TSH, MUIC, and goiter as markers of population iodine status.

METHODS

We performed a systematic search for studies published on PubMed, Scopus, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Embase, and PsycINFO up to 29 October, 2018. Studies assessing iodine status in the population using the TSH marker and either MUIC or goiter prevalence in school-age children were included. The agreement between markers in classifying iodine status of the population was assessed. The sensitivity and specificity of the TSH marker was determined against MUIC and goiter prevalence as the reference markers.

RESULTS

Of 17,435 records identified by the search strategy, 57 eligible studies were included in the review. The agreement between markers in classifying the iodine status of populations into the same category was 65% for TSH and MUIC, and 83% for TSH and goiter prevalence. The TSH marker had a sensitivity of 0.75 and specificity of 0.53 when compared with MUIC, and 0.86 and 0.50 when compared with goiter prevalence.

CONCLUSIONS

The TSH marker has a better agreement with goiter prevalence than MUIC when classifying the iodine status of populations. Re-evaluation of the current criteria for classifying the iodine status of populations using the TSH marker is warranted. This systematic review was registered at PROSPERO (http://www.crd.york.ac.uk/prospero/) as CRD42018091247.

Micronutrients, iodine status and concentrations of thyroid hormones: a systematic review

Context

The metabolism of thyroid hormones, which are essential for normal development, involves many proteins and enzymes. It requires iodine as a key component but is also influenced by several other micronutrients, including selenium, zinc, iron, and vitamin A.

Objective

This systematic review was designed to investigate the effect of micronutrient status and supplementation on iodine status and thyroid hormone concentrations.

Data Sources

Using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines, electronic databases were searched from their inception to April 2016.

Study Selection

Human studies published in English and reporting data on micronutrient status and iodine status and/or thyroid hormone concentrations were included. Studies that examined the effect of micronutrient supplementation on iodine status and/or thyroid hormone concentrations were also included.

Data Extraction

A predesigned and piloted data extraction form was used to compile data from individual studies.

Results

A total of 57 studies were included: 20 intervention studies and 37 observational studies. Although observational evidence suggests that concentrations of selenium, zinc, and iron are positively associated with iodine status, data from randomized controlled trials fail to confirm this relationship.

Conclusions

Further studies are needed to provide greater understanding of the role of micronutrient status in iodine nutrition and thyroid function to ascertain the public health implications for populations worldwide.

Weighing the risks of high intakes of selected micronutrients compared with the risks of deficiencies

Several intervention strategies are available to reduce micronutrient deficiencies, but uncoordinated implementation of multiple interventions may result in excessive intakes. We reviewed relevant data collection instruments and available information on excessive intakes for selected micronutrients and considered possible approaches for weighing competing risks of intake above tolerable upper intake levels (ULs) versus insufficient intakes at the population level. In general, population-based surveys in low- and middle-income countries suggest that dietary intakes greater than the UL are uncommon, but simulations indicate that fortification and supplementation programs could lead to high intakes under certain scenarios. The risk of excessive intakes can be reduced by considering baseline information on dietary intakes and voluntary supplement use and continuously monitoring program coverage. We describe a framework for comparing risks of micronutrient deficiency and excess, recognizing that critical information for judging these risks is often unavailable. We recommend (1) assessing total dietary intakes and nutritional status; (2) incorporating rapid screening tools for routine monitoring and surveillance; (3) addressing critical research needs, including evaluations of the current ULs, improving biomarkers of excess, and developing methods for predicting and comparing risks and benefits; and (4) ensuring that relevant information is used in decision-making processes.

Fluoride Exposure Induces Inhibition of Sodium/Iodide Symporter (NIS) Contributing to Impaired Iodine Absorption and Iodine Deficiency: Molecular Mechanisms of Inhibition and Implications for Public Health

The sodium iodide symporter (NIS) is the plasma membrane glycoprotein that mediates active iodide transport in the thyroid and other tissues, such as the salivary, gastric mucosa, rectal mucosa, bronchial mucosa, placenta and mammary glands. In the thyroid, NIS mediates the uptake and accumulation of iodine and its activity is crucial for the development of the central nervous system and disease prevention. Since the discovery of NIS in 1996, research has further shown that NIS functionality and iodine transport is dependent on the activity of the sodium potassium activated adenosine 5'-triphosphatase pump (Na+, K+-ATPase). In this article, I review the molecular mechanisms by which F inhibits NIS expression and functionality which in turn contributes to impaired iodide absorption, diminished iodide-concentrating ability and iodine deficiency disorders. I discuss how NIS expression and activity is inhibited by thyroglobulin (Tg), tumour necrosis factor alpha (TNF-α), transforming growth factor beta 1 (TGF-β1), interleukin 6 (IL-6) and Interleukin 1 beta (IL-1β), interferon-γ (IFN-γ), insulin like growth factor 1 (IGF-1) and phosphoinositide 3-kinase (PI3K) and how fluoride upregulates expression and activity of these biomarkers. I further describe the crucial role of prolactin and megalin in regulation of NIS expression and iodine homeostasis and the effect of fluoride in down regulating prolactin and megalin expression. Among many other issues, I discuss the potential conflict between public health policies such as water fluoridation and its contribution to iodine deficiency, neurodevelopmental and pathological disorders. Further studies are warranted to examine these associations.

Investigating the Essentiality and Requirements of Iron from the Ancient to the Present

This review discusses the development of studies that evaluated the essentiality and requirements of iron from the ancient to the present. The therapeutic effects of iron compounds were recognized by the ancient Greeks and Romans. The earliest recognition of the essentiality of iron was stated by Paracelsus, a distinguished physician alchemist, in the sixteenth century. Iron was included in the earliest nutritional standard prepared for the Royal Army by E. A. Parkes, the first professor of hygiene. The League of Nations Health Organisation determined average iron requirements based on literature review. In the first US Recommended Dietary Allowances (RDA), the RDA of iron was determined from the results of iron balance studies. In the current Dietary Reference Intakes, iron requirements were determined based on the factorial method with the aid of Monte Carlo simulation for combining basal and menstrual iron losses. Population data analysis is a recently developed alternative that does not use the pre-estimated iron absorption rate and requires the prevalence of inadequacy instead. Population data analysis uses the convolution integral for combining basal and menstrual iron losses to ensure the required accuracy. This review also provides new estimates of hair and nail iron losses.

Prevalence and risk factors of preconception anemia: A community based cross sectional study of rural women of reproductive age in northeastern Tanzania

BACKGROUND

Anemia is a major public health problem that adversely affects pregnancy outcomes. The prevalence of anemia among pregnant women before conception is not well known in Tanzania. The aim of this study was to determine the prevalence, types, and risk factors of preconception anemia in women of reproductive age from a rural Tanzanian setting.

METHODS

Trained field workers visited households to identify all female residents aged 18-40 years and invited them to the nearby health facility for screening and enrolment into this study. Baseline samples were collected to measure hemoglobin levels, serum ferritin, vitamin B12, folate, C-reactive protein, alanine amino-transferase, the presence of malaria, HIV, and soil transmitted helminth infections. Anthropometric and socio-economic data were recorded alongside with clinical information of participants. Logistic regression analysis was used to determine the adjusted odds ratios (AOR) for the factors associated with preconception anemia.

FINDINGS

Of 1248 women enrolled before conception, 36.7% (95% confidence interval (CI) 34.1-39.4) had anemia (hemoglobin <12 g/dL) and 37.6% (95% CI 34.9-40.4) had iron deficiency. For more than half of the anemic cases, iron deficiency was also diagnosed (58.8%, 95% CI 54.2-63.3). Anemia was independently associated with increased age (AOR 1.05, 95% CI 1.03-1.07), malaria infection at enrolment (AOR 2.21, 95% CI 1.37-3.58), inflammation (AOR 1.77, 95% CI 1.21-2.60) and iron deficiency (AOR 4.68, 95% CI 3.55-6.17). The odds of anemia were reduced among women with increased mid-upper arm circumference (AOR 0.90, 95% CI 0.84-0.96).

CONCLUSION

Anemia among women of reproductive age before conception was prevalent in this rural setting. Increased age, iron deficiency, malaria infection and inflammation were significant risk factors associated with preconception anemia, whereas increased mid-upper arm circumference was protective against anemia. Interventions to ensure adequate iron levels as well as malaria control before conception are needed to prevent anemia before and during pregnancy and improve birth outcomes in this setting.

TRIAL REGISTRATION

NCT02191683.