A Meta-Analysis of the Effect of Iodine Excess on the Intellectual Development of Children in Areas with High Iodine Levels in their Drinking Water

Fan, Li; Wan, Siyuan; Zhang, Li; Li, Baoxiang; He, Yu; Shen, Hongmei; Liu, Lixiang

doi:10.1007/s12011-021-02801-3

Cited by 11 publications

(11 citation statements)

References 20 publications

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“…Research on the effects of excessive iodine on the IQ of children have been conducted in Asian regions where iodine concentrations in drinking water are very high [ 16 ]. Despite some inconsistent results, in general, these studies point to the presence of decreased intelligence levels among children residing in high-iodine areas, namely, when compared with their lower-iodine counterparts [ 16 , 17 , 18 ].…”

Section: Discussionmentioning

confidence: 99%

“…Where several studies have focused on the role of iodine deficiency on children’s cognitive function, namely in European countries [ 14 , 15 ], the role of iodine excess on cognition has received relatively less attention. Studies with the latter focus have been conducted in Asian countries, areas with high concentrations of iodine in drinking water [ 16 , 17 , 18 , 19 , 20 , 21 ]. Although there are some inconsistent results, a recent meta-analysis of such studies reported significantly lower intelligence levels among the children residing in high-iodine areas when compared to the controls [ 16 ].…”

Section: Introductionmentioning

confidence: 99%

“…Studies with the latter focus have been conducted in Asian countries, areas with high concentrations of iodine in drinking water [ 16 , 17 , 18 , 19 , 20 , 21 ]. Although there are some inconsistent results, a recent meta-analysis of such studies reported significantly lower intelligence levels among the children residing in high-iodine areas when compared to the controls [ 16 ]. However, the role of excessive iodine on child cognition among generally healthy populations from regions where the levels of iodine are less extreme remains unclear.…”

Section: Introductionmentioning

confidence: 99%

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Association between Elevated Iodine Intake and IQ among School Children in Portugal

et al. 2022

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The goal of this work was to examine whether elevated iodine intake was associated with adverse effects on IQ among school-age children in Portugal. In a representative sample of children from the north of the country, IQ percentiles by age (assessed with Raven’s Colored Progressive Matrices) were dichotomized to <50 (“below-average” IQs) and ≥50. Morning urine iodine concentrations, corrected for creatinine, were dichotomized to <250 µg/g and ≥250 µg/g, according to the European Commission/Scientific Committee on Food’s tolerable upper level of daily iodine intake for young children. Data were examined with Chi-square tests, logistic regression, and GLM univariate analysis. The sample (N = 1965) was classified as generally iodine-adequate (median urinary iodine concentration = 129 µg/L; median iodine-to-creatinine ratio = 126 µg/g) according to the WHO’s criteria. A greater proportion of children in the ≥250 µg/g group had below-average IQs, compared to children with less than 250 µg/g (p = 0.037), despite a sizable (though non-significant) proportion of children in the less-than-250 µg/g group also presenting below-average IQs, at the bottom of the iodine distribution (<50 µg/g). The proportion of below-average IQs increased with increasingly elevated iodine concentrations (p = 0.047). The association remained significant after the adjustment for confounders, with the elevated iodine group showing increased odds of having below-average IQs when compared with the non-elevated iodine group (OR 1.55; 95% CI 1.11–2.17; p = 0.011). Consistently, the former group presented a lower mean IQ than the latter (p = 0.006). High iodine intake was associated with lower IQs even in a population classified as iodine-adequate. These results bear on child cognition and on initiatives involving iodine supplementation.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Association between Elevated Iodine Intake and IQ among School Children in Portugal

et al. 2022

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“…Of the 601 children who completed IQ testing, 366 had complete data on maternal urinary fluoride (MUF), maternal urinary iodine concentration (MUIC), urinary creatinine (CRE), and covariates (See Figure 1 ); 235 were excluded for missing (i) creatinine data at all three trimesters ( n = 175), (ii) a valid MUF measure available at all three trimesters ( n = 9), (iii) MUIC CRE < 600 μg/g data at trimesters 1 and 2 ( n = 40), and (4) covariate data ( n = 11). Women with MUIC CRE values greater than or equal to 600 μg/g ( n = 37) were excluded from the analyses because excess iodine levels have been linked to diminished intelligence [ 35 ], and we were specifically interested in comparing women with “low” levels of iodine with those with “adequate” levels of iodine, rather than “excess” levels of iodine. We considered MUIC CRE values greater than or equal to 600 μg/g to be “higher than adequate” as opposed to the WHO cut-off of 500 μg/L for unadjusted MUIC [ 36 ], given that we used MUIC values corrected for creatinine, and MUIC CRE values increase from trimester 1 to 2 [ 37 ].…”

Section: Methodsmentioning

confidence: 99%

“…trients 2022, 14, x FOR PEER REVIEW [35], and we were specifically interested in comparing women with "low" levels o with those with "adequate" levels of iodine, rather than "excess" levels of iodine. sidered MUICCRE values greater than or equal to 600 µg/g to be "higher than adeq opposed to the WHO cut-off of 500 µg/L for unadjusted MUIC [36], given that w MUIC values corrected for creatinine, and MUICCRE values increase from trimest [37].…”

Section: Participantsmentioning

confidence: 99%

Iodine Status Modifies the Association between Fluoride Exposure in Pregnancy and Preschool Boys’ Intelligence

et al. 2022

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In animal studies, the combination of in utero fluoride exposure and low iodine has greater negative effects on offspring learning and memory than either alone, but this has not been studied in children. We evaluated whether the maternal urinary iodine concentration (MUIC) modifies the association between maternal urinary fluoride (MUF) and boys’ and girls’ intelligence. We used data from 366 mother–child dyads in the Maternal–Infant Research on Environmental Chemicals Study. We corrected trimester-specific MUF and MUIC for creatinine, and averaged them to yield our exposure variables (MUFCRE, mg/g; MUICCRE, µg/g). We assessed children’s full-scale intelligence (FSIQ) at 3 to 4 years. Using multiple linear regression, we estimated a three-way interaction between MUFCRE, MUICCRE, and child sex on FSIQ, controlling for covariates. The MUICCRE by MUFCRE interaction was significant for boys (p = 0.042), but not girls (p = 0.190). For boys whose mothers had low iodine, a 0.5 mg/g increase in MUFCRE was associated with a 4.65-point lower FSIQ score (95% CI: −7.67, −1.62). For boys whose mothers had adequate iodine, a 0.5 mg/g increase in MUFCRE was associated with a 2.95-point lower FSIQ score (95% CI: −4.77, −1.13). These results suggest adequate iodine intake during pregnancy may minimize fluoride’s neurotoxicity in boys.

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Synthesis, Characterization, and Catalytic Performance of Modified Keggin‐type Calix[6]arene‐like Polyoxometalates

et al. 2023

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Two modified Calix[6]arene-like polyoxometalates of the Keggin type with similar structures were synthesized under hydrothermal conditions by H 3 PMo 12 O 40 . H 3 PW 12 O 40 , 4H-1,2,4triazol-3-amine (3-atrz) and copper ions were used as precursors, respectively, bridging organic ligand and transition metals. The result of single-crystal X-ray diffraction and elemental analysis showed that the structural formulas of the two crystalline compounds were: [2(C 6 H 12 N 12 Cu 3 PW 12 O 40 )] (3-atrz-Cu-PW 12 ), and [2(C 6 H 12 N 12 Cu 3 PMo 12 O 40 )] ⋅ 0.5H 2 O (3-atrz-Cu-PMo 12 ). They were composed of two classic Keggin-type polyoxometalate anions and six [Cu(C 2 H 4 N 4 )] + coordination polymers similar to Calix[6]arene. The catalytic studies repre-sented that the two heterogeneous catalysts catalyzed the oxidation of iodide ions in hydrogen peroxide. The catalytic reaction of 3-atrz-Cu-PW 12 only took 30 min and 15 s to complete the reaction. The rate of iodine generation was 6.86 × 10 À 7 mol L À 1 s À 1 . The 3-atrz-Cu-PMo 12 catalytic reaction needed only 1 min and 51 s, in which the rate of iodine generation was 1.126 × 10 À 5 mol L À 1 s À 1 . The catalytic reaction rate of 3-atrz-Cu-PMo 12 was 16.35 times higher than 3-atrz-Cu-PW 12 . Both catalysts were reused nine times, and the conversion rate was still 99.96 %, showing excellent catalytic activity and repeatability.

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A Meta-Analysis of the Effect of Iodine Excess on the Intellectual Development of Children in Areas with High Iodine Levels in their Drinking Water

Cited by 11 publications

References 20 publications

Association between Elevated Iodine Intake and IQ among School Children in Portugal

Association between Elevated Iodine Intake and IQ among School Children in Portugal

Iodine Status Modifies the Association between Fluoride Exposure in Pregnancy and Preschool Boys’ Intelligence

Synthesis, Characterization, and Catalytic Performance of Modified Keggin‐type Calix[6]arene‐like Polyoxometalates

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