Iodine levels in Edible Salt Sold in Malawi, Kenya and Zambia

Kenji, Glaston M.; Nyirenda, KK; Kabwe, GC

doi:10.4314/ajfand.v3i2.19138

Cited by 5 publications

(6 citation statements)

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“…This finding complements previous studies that question the monitoring of the salt iodisation campaign in Malawi. Kenji et al (2003) 63 reported I concentrations in supermarket-bought iodised salt well above the recommended range with a mean of 101.6 mg kg −1 and in open market vendors a mean of 68.1 mg kg −1 and as low as 17.6 mg kg −1 . The Malawi Micronutrient Survey (2001) 64 found that only 36% of households were using salt at greater than the recommended concentration of I, whilst the Malawi Demographic and Health Survey 65 reported successful coverage of 62% of households.…”

Section: Discussionmentioning

confidence: 98%

Iodine source apportionment in the Malawian diet

Watts

Joy

Young

et al. 2015

Sci Rep

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The aim of this study was to characterise nutritional-I status in Malawi. Dietary-I intakes were assessed using new datasets of crop, fish, salt and water-I concentrations, while I status was assessed for 60 women living on each of calcareous and non-calcareous soils as defined by urinary iodine concentration (UIC). Iodine concentration in staple foods was low, with median concentrations of 0.01 mg kg−1 in maize grain, 0.008 mg kg−1 in roots and tubers, but 0.155 mg kg−1 in leafy vegetables. Freshwater fish is a good source of dietary-I with a median concentration of 0.51 mg kg−1. Mean Malawian dietary-Iodine intake from food, excluding salt, was just 7.8 μg d−1 compared to an adult requirement of 150 μg d−1. Despite low dietary-I intake from food, median UICs were 203 μg L−1 with only 12% defined as I deficient whilst 21% exhibited excessive I intake. Iodised salt is likely to be the main source of dietary I intake in Malawi; thus, I nutrition mainly depends on the usage and concentration of I in iodised salt. Drinking water could be a significant source of I in some areas, providing up to 108 μg d−1 based on consumption of 2 L d−1.

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Section: Discussionmentioning

confidence: 98%

Iodine source apportionment in the Malawian diet

Watts

Joy

Young

et al. 2015

Sci Rep

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“…In fact, given our finding that the women's UIC at enrolment was within the WHO cut-off range for 'above requirements', consumption of salt with excess iodine concentration may have been common. At least two other previous reports (16,17) showed that the iodine content of salt sold in some outlets in Malawi was too high. Persistent intakes of iodine higher than needed may impair thyroid function by inhibiting the synthesis and release of thyroid hormones (52) .…”

Section: Discussionmentioning

confidence: 95%

“…We evaluated the efficacy of the SQ-LNS among pregnant women in a semi-urban setting in Ghana (13) and a predominantly rural site in Malawi (14) . In both countries, micronutrient deficiencies are common and there is a national salt iodisation programme, but both countries face various challenges in the implementation of the programme, including the presence of small-scale salt producers with little or no capacity to iodise the salt they produce, poor packaging and handling of iodised salt resulting in excess loss of added iodine (15)(16)(17) and resource constraints hampering monitoring and quality assurance (18) .…”

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confidence: 99%

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

Adu‐Afarwuah

Maleta

Ashorn

et al. 2020

Public Health Nutr.

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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.

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“…The aim of the study was to investigate the role of iodine intake in modulating BP. The two iodine dosages (high and low) were in extreme ranges within the Kenyan mandatory salt iodization level (50–84 mg/kg) (Kenji et al., 2003). A total of 174 mother–child pair randomized into two independent treatment sequences were followed for 6 weeks, constituting two treatment periods of 3 weeks each with no washout between each treatment period.…”

Section: Motivating Case Studymentioning

confidence: 99%

Pairwise fitting of piecewise mixed models for the joint modeling of multivariate longitudinal outcomes, in a randomized crossover trial

Mwangi,

Molenberghs,

Njagi

et al. 2024

Biometrical J

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Many statistical models have been proposed in the literature for the analysis of longitudinal data. One may propose to model two or more correlated longitudinal processes simultaneously, with a goal of understanding their association over time. Joint modeling is then required to carefully study the association structure among the outcomes as well as drawing joint inferences about the different outcomes. In this study, we sought to model the associations among six nutrition outcomes while circumventing the computational challenge posed by their clustered and high‐dimensional nature. We analyzed data from a 2 2 randomized crossover trial conducted in Kenya, to compare the effect of high‐dose and low‐dose iodine in household salt on systolic blood pressure (SBP) and diastolic blood pressure (DBP) in women of reproductive age and their household matching pair of school‐aged children. Two additional outcomes, namely, urinary iodine concentration (UIC) in women and children were measured repeatedly to monitor the amount of iodine excreted through urine. We extended the model proposed by Mwangi et al. (2021, Communications in Statistics: Case Studies, Data Analysis and Applications, 7(3), 413–431) allowing flexible piecewise joint models for six outcomes to depend on separate random effects, which are themselves correlated. This entailed fitting 15 bivariate general linear mixed models and deriving inference for the joint model using pseudo‐likelihood theory. We analyzed the outcomes separately and jointly using piecewise linear mixed‐effects (PLME) model and further validated the results using current state‐of‐the‐art Jones and Kenward methodology (JKME model) used for analyzing randomized crossover trials. The results indicate that high‐dose iodine in salt significantly reduced blood pressure (BP) compared to low‐dose iodine in salt. Estimates for the random effects and residual error components showed that SBP and DBP had strong positive correlation, with effect of the random slope indicating that significantly related outcomes are strongly associated in their evolution. There was a moderately strong inverse relationship between evolutions of UIC and BP both in women and children. These findings confirmed the original hypothesis that high‐dose iodine salt has significant lowering effect on BP. We further sought to evaluate the performance of our proposed PLME model against the widely used JKME model, within the multivariate joint modeling framework through a simulation study mimicking a crossover design. From our findings, the multivariate joint PLME model performed exceptionally well both in estimation of random‐effects matrix (G) and Hessian matrix (H), allowing satisfactory model convergence during estimation. It allowed a more complex fit to the data with both random intercepts and slopes effects compared to the multivariate joint JKME model that allowed for random intercepts only. When a hierarchical viewpoint is adopted, in the sense that outcomes are specified conditionally upon random effects, the variance–covariance matrix of the random effects must be positive definite. In some cases, additional random effects could explain much variability in the data, thus improving precision in estimation of the estimands (effect size) parameters. The key highlight in this evaluation shows that multivariate joint JKME model is a powerful tool especially while fitting mixed models with random intercepts only, in crossover design settings. Addition of random slopes may lead to model complexities in most cases, resulting in unsatisfactory model convergence during estimation. To circumvent convergence pitfalls, extention of JKME model to PLME model allows a more flexible fit to the data (generated from crossover design settings), especially in the multivariate joint modeling framework.

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Iodine levels in Edible Salt Sold in Malawi, Kenya and Zambia

Cited by 5 publications

References 0 publications

Iodine source apportionment in the Malawian diet

Iodine source apportionment in the Malawian diet

Pairwise fitting of piecewise mixed models for the joint modeling of multivariate longitudinal outcomes, in a randomized crossover trial

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