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Doggui R, McCormick BJ, Caulfield LE, Schulze KJ, Murray-Kolb LE. Adequacy of Iodine Status and Associations with Gut Health: A Prospective Cohort Study among Infants in 8 Low- and Middle-Income Countries. J Nutr 2023; 153:828-838. [PMID: 36797135 DOI: 10.1016/j.tjnut.2022.11.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 10/25/2022] [Accepted: 11/15/2022] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Environmental enteric dysfunction increases the likelihood of micronutrient deficiencies among infants, but few studies have assessed the potential impact of gut health on urinary iodine concentration (UIC) among this vulnerable group. OBJECTIVES We describe the trends of iodine status among infants from 6 to 24 mo old and examine the associations between intestinal permeability, inflammation, and UIC from 6 to 15 mo of age. METHODS Data from 1557 children enrolled in this birth cohort study conducted in 8 sites were included in these analyses. UIC was measured at 6, 15, and 24 mo of age by using the Sandell-Kolthoff technique. Gut inflammation and permeability were assessed using the concentrations of fecal neopterin (NEO), myeloperoxidase (MPO) and alpha-1-antitrypsin (AAT), and lactulose-mannitol ratio (LM). A multinomial regression analysis was used to assess the classified UIC (deficiency or excess). Linear mixed regression was used to test the effect of interactions among biomarkers on logUIC. RESULTS All studied populations had adequate (≥100 μg/L) to excess (≥371 μg/L) median UIC at 6 mo. Between 6 and 24 mo, 5 sites displayed a significant decline in the infant's median UIC. However, median UIC remained within the optimal range. An increase of NEO and MPO concentrations by +1 unit in ln scale reduced the risk of low UIC by 0.87 (95% CI: 0.78-0.97) and 0.86 (95% CI: 0.77-0.95), respectively. AAT moderated the association between NEO and UIC (P < 0.0001). The shape of this association appears to be asymmetric and in a reverse J-shape, with a higher UIC observed at both lower NEO and AAT concentrations. CONCLUSIONS Excess UIC was frequent at 6 mo and tended to normalize at 24 mo. Aspects of gut inflammation and increased permeability appear to reduce the prevalence of low UIC in children aged 6 to 15 mo. Programs addressing iodine-related health should consider the role of gut permeability in vulnerable individuals.
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Affiliation(s)
- Radhouene Doggui
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA, USA.
| | | | - Laura E Caulfield
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Kerry J Schulze
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Laura E Murray-Kolb
- Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA, USA; Department of Nutrition Science, Purdue University, West Lafayette, IN, USA
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Lee YJ, Cho SW, Lim YH, Kim BN, Kim JI, Hong YC, Park YJ, Shin CH, Lee YA. Relationship of iodine excess with thyroid function in 6-year-old children living in an iodine-replete area. Front Endocrinol (Lausanne) 2023; 14:1099824. [PMID: 36860373 PMCID: PMC9968830 DOI: 10.3389/fendo.2023.1099824] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 02/01/2023] [Indexed: 02/15/2023] Open
Abstract
BACKGROUND Adequate iodine intake is essential for growing children, as both deficient and excessive iodine status can result in thyroid dysfunction. We investigated the iodine status and its association with thyroid function in 6-year-old children from South Korea. METHODS A total of 439 children aged 6 (231 boys and 208 girls) were investigated from the Environment and Development of Children cohort study. The thyroid function test included free thyroxine (FT4), total triiodothyronine (T3), and thyroid-stimulating hormone (TSH). Urine iodine status was evaluated using urine iodine concentration (UIC) in morning spot urine and categorized into iodine deficient (< 100 μg/L), adequate (100-199 μg/L), more than adequate (200-299 μg/L), mild excessive (300-999 μg/L), and severe excessive (≥ 1000 μg/L) groups. The estimated 24-hour urinary iodine excretion (24h-UIE) was also calculated. RESULTS The median TSH level was 2.3 μIU/mL, with subclinical hypothyroidism detected in 4.3% of patients without sex differences. The median UIC was 606.2 μg/L, with higher levels in boys (684 μg/L vs. 545 μg/L, p = 0.021) than girls. Iodine status was categorized as deficient (n = 19, 4.3%), adequate (n = 42, 9.6%), more than adequate (n = 54, 12.3%), mild excessive (n = 170, 38.7%), or severe excessive (n = 154, 35.1%). After adjusting for age, sex, birth weight, gestational age, body mass index z-score, and family history, both the mild and severe excess groups showed lower FT4 (β = - 0.04, p = 0.032 for mild excess; β = - 0.04, p = 0.042 for severe excess) and T3 levels (β = - 8.12, p = 0.009 for mild excess; β = - 9.08, p = 0.004 for severe excess) compared to the adequate group. Log-transformed estimated 24h-UIE showed a positive association with log-transformed TSH levels (β = 0.04, p = 0.046). CONCLUSION Excess iodine was prevalent (73.8%) in 6-year-old Korean children. Excess iodine was associated with a decrease in FT4 or T3 levels and an increase in TSH levels. The longitudinal effects of iodine excess on later thyroid function and health outcomes require further investigation.
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Affiliation(s)
- Yun Jeong Lee
- Department of Pediatrics, Seoul National University Children’s Hospital, Seoul, Republic of Korea
- Department of Pediatrics, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Sun Wook Cho
- Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea
- Department of Internal Medicine, Seoul National University Hospital College of Medicine, Seoul, Republic of Korea
| | - Youn-Hee Lim
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
- Institute of Environmental Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea
- Environmental Health Center, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Bung-Nyun Kim
- Division of Children and Adolescent Psychiatry, Department of Psychiatry, Seoul National University Hospital, Seoul, Republic of Korea
| | - Johanna Inhyang Kim
- Department of Psychiatry, Hanyang University Medical Center, Seoul, Republic of Korea
| | - Yun-Chul Hong
- Institute of Environmental Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea
- Environmental Health Center, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Young Joo Park
- Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea
- Department of Internal Medicine, Seoul National University Hospital College of Medicine, Seoul, Republic of Korea
| | - Choong Ho Shin
- Department of Pediatrics, Seoul National University Children’s Hospital, Seoul, Republic of Korea
- Department of Pediatrics, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Young Ah Lee
- Department of Pediatrics, Seoul National University Children’s Hospital, Seoul, Republic of Korea
- Department of Pediatrics, Seoul National University College of Medicine, Seoul, Republic of Korea
- *Correspondence: Young Ah Lee,
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Ye Y, Wang Y, Li S, Guo J, Ding L, Liu M. Association of Hypothyroidism and the Risk of Cognitive Dysfunction: A Meta-Analysis. J Clin Med 2022; 11:jcm11226726. [PMID: 36431204 PMCID: PMC9694203 DOI: 10.3390/jcm11226726] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 11/02/2022] [Accepted: 11/09/2022] [Indexed: 11/16/2022] Open
Abstract
Objectives: The purpose of this meta-analysis was to assess whether there is an association between hypothyroidism and the risk of cognitive dysfunction. Methods: PubMed, Cochrane Library, and Embase were searched for relevant studies published from database inception to 4 May 2022, using medical subject headings (MeSHs) and keywords. Results: Eight studies involving 1,092,025 individuals were included, published between 2010 and 2021. The pooled analysis showed that there was no association between hypothyroidism and cognitive dysfunction (OR = 1.13, 95% CI = 0.84−1.51, p = 0.426), including both all-cause dementia (OR = 1.04, 95% CI = 0.76−1.43, p = 0.809) and cognitive impairment (OR = 1.50, 95% CI = 0.68−3.35, p = 0.318). Neither overt hypothyroidism (OR = 1.19, 95% CI = 0.70−2.02, p = 0.525) nor subclinical hypothyroidism (OR = 1.04, 95% CI = 0.73−1.48, p = 0.833) was associated with cognitive dysfunction. Neither prospective cohort (OR = 1.08, 95% CI = 0.77−1.51, p = 0.673) nor cross-sectional studies (OR = 1.23, 95% CI = 0.63−2.42, p = 0.545) had any effect on the association. Interestingly, the risk of cognitive dysfunction was significantly increased in the group not adjusted for vascular comorbidity (OR = 1.47, 95% CI = 1.07−2.01, p = 0.017), while it was reduced in the adjusted group (OR =0.82, 95% CI = 0.79−0.85, p < 0.001). Conclusions: This meta-analysis shows that hypothyroidism was associated with a reduced risk of cognitive dysfunction after adjustment for vascular-disease comorbidities. More prospective observational studies are needed in the future to investigate the relationship between hypothyroidism and cognitive dysfunction.
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Affiliation(s)
| | | | | | | | - Li Ding
- Correspondence: (L.D.); (M.L.)
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Abstract
Iodine is a micronutrient needed for the production of thyroid hormones, which regulate metabolism, growth, and development. Iodine deficiency or excess may alter the thyroid hormone synthesis. The potential effects on infant development depend on the degree, timing, and duration of exposure. The iodine requirement is particularly high during infancy because of elevated thyroid hormone turnover. Breastfed infants rely on iodine provided by human milk, but the iodine concentration in breast milk is determined by the maternal iodine intake. Diets in many countries cannot provide sufficient iodine, and deficiency is prevented by iodine fortification of salt. However, the coverage of iodized salt varies between countries. Epidemiological data suggest large differences in the iodine intake in lactating women, infants, and toddlers worldwide, ranging from deficient to excessive intake. In this review, we provide an overview of the current knowledge and recent advances in the understanding of iodine nutrition and its association with thyroid function in lactating women, infants, and toddlers. We discuss risk factors for iodine malnutrition and the impact of targeted intervention strategies on these vulnerable population groups. We highlight the importance of appropriate definitions of optimal iodine nutrition and the need for more data assessing the risk of mild iodine deficiency for thyroid disorders during the first 2 years in life.
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Affiliation(s)
- Maria Andersson
- Nutrition Research Unit, University Children’s Hospital Zurich, CH-8032 Zürich, Switzerland
| | - Christian P Braegger
- Nutrition Research Unit, University Children’s Hospital Zurich, CH-8032 Zürich, Switzerland
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Wu K, Zhou Y, Ke S, Huang J, Gao X, Li B, Lin X, Liu X, Liu X, Ma L, Wang L, Wu L, Wu L, Xie C, Xu J, Wang Y, Liu L. Lifestyle is associated with thyroid function in subclinical hypothyroidism: a cross-sectional study. BMC Endocr Disord 2021; 21:112. [PMID: 34049544 PMCID: PMC8161919 DOI: 10.1186/s12902-021-00772-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 05/17/2021] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Few studies have focused on the association between lifestyle and subclinical hypothyroidism (SCH). The purpose of this study was to investigate the association between lifestyle and thyroid function in SCH. METHODS This study was a part of a community-based and cross-sectional study, the Epidemiological Survey of Thyroid Diseases in Fujian Province, China. A total of 159 participants with SCH (81 males and 78 females) and 159 euthyroid (87 males and 72 females) participants without any missing data were included in the analysis. General information and lifestyle information including sleep, exercise, diet and smoking habits of the participants was collected by questionnaire and Pittsburgh sleep quality index scale (PSQI) was collected. Thyroid stimulating hormone (TSH), free thyroxine (FT4), thyroid peroxidase antibody (TPOAb), thyroid globulin antibody (TgAb) and urine iodine concentration (UIC) were tested. Thyroid homeostasis parameter thyroid' s secretory capacity (SPINA-GT), Jostel's TSH index (TSHI), thyrotroph T4 sensitivity index (TTSI) were calculated. Logistic regression and multiple linear regression were performed to assess associations. RESULTS Compared with euthyroid subjects, patients with SCH were more likely to have poor overall sleep quality (15.1 vs.25.8 %, P = 0.018) and l less likely to stay up late on weekdays (54.7 vs. 23.9 % P < 0.001). In SCH group, exercise was the influencing factor of TSH (β= -0.224, P = 0.004), thyroid secretory capacity (β = 0.244, P = 0.006) and thyrotropin resistance (β = 0.206, P = 0.009). Iodine excess was the influencing factor of thyroid secretory capacity (β = 0.209, P = 0.001) and pituitary thyroid stimulating function (β = 0.167, P = 0.034). Smoking was the influencing factor of pituitary thyroid stimulating function (β = 0.161, P = 0.040). Staying up late on weekends was the influencing factor of thyroid secretory capacity (β = 0.151, P = 0.047). After adjusting for possible confounders, logistic regression showed that those with poor overall sleep quality assessed by PSQI and iodine excess had an increased risk of SCH (OR 2.159, 95 %CI 1.186-3.928, P = 0.012 and OR 2.119, 95 %CI 1.008-4.456, P = 0.048, respectively). CONCLUSIONS Lifestyle including sleep, smoking, diet and exercise was closely related to thyroid function especially thyroid homeostasis in SCH.
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Affiliation(s)
- Kejun Wu
- Department of Endocrinology and Metabolism, Fujian Medical University Union Hospital, 29 Xinquan Road, Fujian, 350001, Fuzhou, China
| | - Yu Zhou
- Department of Endocrinology and Metabolism, Fujian Medical University Union Hospital, 29 Xinquan Road, Fujian, 350001, Fuzhou, China
- Department of Clinical Pharmacy and Pharmacy Administration, School of Pharmacy, Fujian Medical University, 350122, Fuzhou, Fujian, China
| | - Sujie Ke
- Department of Endocrinology and Metabolism, Fujian Medical University Union Hospital, 29 Xinquan Road, Fujian, 350001, Fuzhou, China
| | - Jingze Huang
- Department of Endocrinology and Metabolism, Fujian Medical University Union Hospital, 29 Xinquan Road, Fujian, 350001, Fuzhou, China
| | - Xuelin Gao
- Department of Endocrinology and Metabolism, Fujian Medical University Union Hospital, 29 Xinquan Road, Fujian, 350001, Fuzhou, China
| | - Beibei Li
- Department of Endocrinology and Metabolism, Fujian Medical University Union Hospital, 29 Xinquan Road, Fujian, 350001, Fuzhou, China
| | - Xiaoying Lin
- Department of Endocrinology and Metabolism, Fujian Medical University Union Hospital, 29 Xinquan Road, Fujian, 350001, Fuzhou, China
| | - Xiaohong Liu
- Department of Endocrinology and Metabolism, Fujian Medical University Union Hospital, 29 Xinquan Road, Fujian, 350001, Fuzhou, China
| | - Xiaoying Liu
- Department of Endocrinology and Metabolism, Fujian Medical University Union Hospital, 29 Xinquan Road, Fujian, 350001, Fuzhou, China
| | - Li Ma
- Department of Endocrinology and Metabolism, Fujian Medical University Union Hospital, 29 Xinquan Road, Fujian, 350001, Fuzhou, China
| | - Linxi Wang
- Department of Endocrinology and Metabolism, Fujian Medical University Union Hospital, 29 Xinquan Road, Fujian, 350001, Fuzhou, China
| | - Li Wu
- Department of Endocrinology and Metabolism, Fujian Medical University Union Hospital, 29 Xinquan Road, Fujian, 350001, Fuzhou, China
| | - Lijuan Wu
- Department of Endocrinology and Metabolism, Fujian Medical University Union Hospital, 29 Xinquan Road, Fujian, 350001, Fuzhou, China
| | - Chengwen Xie
- Department of Endocrinology and Metabolism, Fujian Medical University Union Hospital, 29 Xinquan Road, Fujian, 350001, Fuzhou, China
| | - Junjun Xu
- Department of Endocrinology and Metabolism, Fujian Medical University Union Hospital, 29 Xinquan Road, Fujian, 350001, Fuzhou, China
| | - Yanping Wang
- Department of Endocrinology and Metabolism, Fujian Medical University Union Hospital, 29 Xinquan Road, Fujian, 350001, Fuzhou, China.
| | - Libin Liu
- Department of Endocrinology and Metabolism, Fujian Medical University Union Hospital, 29 Xinquan Road, Fujian, 350001, Fuzhou, China.
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Nazeri P, Tahmasebinejad Z, Pearce EN, Zarezadeh Z, Tajeddini T, Mirmiran P, Azizi F. Does maternal iodine supplementation during the lactation have a positive impact on neurodevelopment of children? Three-year follow up of a randomized controlled trial. Eur J Nutr 2021; 60:4083-4091. [PMID: 33974129 DOI: 10.1007/s00394-021-02574-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 04/27/2021] [Indexed: 11/24/2022]
Abstract
PURPOSE The aim of this study was to examine, for the first time, the neurodevelopmental outcomes in children whose mothers received different doses of iodine supplements during lactation. METHODS We conducted a follow-up study on children whose mothers participated in a randomized clinical trial to receive placebo, 150 µg/day or 300 µg/day of iodine until 12 months postpartum. Child neurocognitive development was assessed at 36 months of age using the Bayley Scales of Infant and Toddler Development Third Edition. Linear mixed-model analysis was preformed to assess iodine supplement dose effects on child cognitive, language, and motor functions. RESULTS A total of 122 children provided neurodevelopmental data as follows: 300 µg/d iodine group: 45; 150 µg/d iodine group: 35; and placebo group: 42. Cognitive scores were higher in children whose mothers received 150 µg iodine/d compared to children whose mothers received placebo [102.8 (SD 13.2) vs. 99.2 (SD 10.5); β = 4.43, P = 0.032]. However, supplementation with 150 µg iodine/d had no effect on language or motor development. No significant differences were observed in cognitive, language, or motor functions between children whose mothers received 300 µg iodine/d and those whose mothers received 150 µg iodine/d or placebo. CONCLUSION Maternal iodine supplementation with 150 µg/d during lactation may have a beneficial effect on child cognitive development; however, we found no evidence of either improved or delayed neurodevelopmental outcomes in children whose mothers received iodine supplements at doses higher than recommended. Further randomized controlled trials with larger sample sizes are needed to confirm these results. CLINICAL TRIAL REGISTRY IRCT201303164794N8; registration date: 2013-05-20.
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Affiliation(s)
- Pantea Nazeri
- Family Health Institute, Breastfeeding Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Zhale Tahmasebinejad
- Nutrition and Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, P.O. Box: 19395-4763, Tehran, Iran
| | - Elizabeth N Pearce
- Section of Endocrinology, Diabetes and Nutrition, Boston University School of Medicine, Boston, USA
| | - Zinat Zarezadeh
- Family Health Institute, Breastfeeding Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Tahere Tajeddini
- Family Health Institute, Breastfeeding Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Parvin Mirmiran
- Nutrition and Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, P.O. Box: 19395-4763, Tehran, Iran. .,Department of Clinical Nutrition and Dietetics, Faculty of Nutrition Sciences and Food Technology, National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, P.O. Box: 19395-4763, Tehran, Iran.
| | - Fereidoun Azizi
- Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, P.O. Box: 19395-4763, Tehran, Iran.
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7
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Petersen E, Thorisdottir B, Thorsdottir I, Gunnlaugsson G, Arohonka P, Erlund I, Gunnarsdottir I. Iodine status of breastfed infants and their mothers' breast milk iodine concentration. MATERNAL AND CHILD NUTRITION 2020; 16:e12993. [PMID: 32162412 PMCID: PMC7296790 DOI: 10.1111/mcn.12993] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 02/24/2020] [Accepted: 02/26/2020] [Indexed: 12/26/2022]
Abstract
Iodine is an essential nutrient for growth and development during infancy. Data on iodine status of exclusively (EBF) and partially breastfed (PBF) infants as well as breast milk iodine concentration (BMIC) are scarce. We aimed to assess (a) infant iodine nutrition at the age of 5.5 months by measuring urinary iodine concentration (UIC) in EBF (n = 32) and PBF (n = 28) infants and (b) mothers' breast milk iodine concentration (n = 57). Sixty mother–infant pairs from three primary health care centres in Reykjavik and vicinities provided urine and breast milk samples for iodine analysis and information on mothers' habitual diet. The mother–infant pairs were participants of the IceAge2 study, which focuses on factors contributing to infant growth and development, including body composition and breast‐milk energy content. The median (25th–75th percentiles) UIC was 152 (79–239) μg/L, with no significant difference between EBF and PBF infants. The estimated median iodine intake ranged from 52 to 86 μg/day, based on urinary data (assuming an average urine volume of 300–500 ml/day and UIC from the present study). The median (25th–75th percentiles) BMIC was 84 (48–114) μg/L. It is difficult to conclude whether iodine status is adequate in the present study, as no ranges for median UIC reflecting optimal iodine nutrition exist for infants. However, the results add important information to the relatively sparse literature on UIC, BMIC, and iodine intake of breastfed infants.
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Affiliation(s)
- Erna Petersen
- Department of Clinical Nutrition, Landspitali University Hospital, Reykjavik, Iceland.,Unit for Nutrition Research, Faculty of Food Science and Nutrition, Landspitali University Hospital, University of Iceland, Reykjavik, Iceland
| | - Birna Thorisdottir
- Unit for Nutrition Research, Faculty of Food Science and Nutrition, Landspitali University Hospital, University of Iceland, Reykjavik, Iceland
| | - Inga Thorsdottir
- School of Health Sciences, University of Iceland, Reykjavik, Iceland
| | - Geir Gunnlaugsson
- Faculty of Sociology, Anthropology and Folkloristics, School of Social Sciences, University of Iceland, Reykjavik, Iceland
| | - Petra Arohonka
- Forensic Toxicology Unit, Biochemistry Laboratory, Finnish Institute for Health and Welfare (THL), Helsinki, Finland
| | - Iris Erlund
- Forensic Toxicology Unit, Biochemistry Laboratory, Finnish Institute for Health and Welfare (THL), Helsinki, Finland
| | - Ingibjörg Gunnarsdottir
- Department of Clinical Nutrition, Landspitali University Hospital, Reykjavik, Iceland.,Unit for Nutrition Research, Faculty of Food Science and Nutrition, Landspitali University Hospital, University of Iceland, Reykjavik, Iceland
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8
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Chen W, Zhang Y, Hao Y, Wang W, Tan L, Bian J, Pearce EN, Zimmermann MB, Shen J, Zhang W. Adverse effects on thyroid of Chinese children exposed to long-term iodine excess: optimal and safe Tolerable Upper Intake Levels of iodine for 7- to 14-y-old children. Am J Clin Nutr 2019; 107:780-788. [PMID: 29722836 DOI: 10.1093/ajcn/nqy011] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Accepted: 01/10/2018] [Indexed: 11/13/2022] Open
Abstract
Background The adverse effects of iodine excess on the thyroid in children are not well understood, and the Tolerable Upper Intake Level for iodine in children is unclear. Objective The aims of this study were to assess the effects of chronic long-term iodine excess on thyroid function in children and to explore the safe Tolerable Upper Intake Level of iodine in Chinese children. Design A multistage cross-sectional study was conducted in 2224 children from areas with adequate to excessive iodine content in drinking water. Repeated samples of 24-h urine and spot urine samples were collected to estimate habitual daily iodine intakes of children. The thyroid volume in children was measured and blood samples were collected to determine thyroid function. Results The habitual iodine intake of children was 298 μg/d (range: 186-437 μg/d). The total goiter rate was 9.7%, 232 (11.2%) children had hyperthyrotropinemia, and 232 (11.2%) children had thyroglobulin (Tg) concentrations >40 μg/L. The prevalence of hyperthyrotropinemia was >10% in children at iodine intakes of 200-300 μg/d. Tg concentrations increased with increased iodine intake (β = 0.5; 95% CI: 0.4, 0.6), and the prevalence of Tg >40 μg/L was >3% in all iodine-intake groups. Multivariate logistic regression analysis indicated that the risk of total goiter significantly increased at iodine intakes ≥250-299 μg/d in 7- to 10-y-old children (OR: 8.8; 95% CI: 2.3, 34.0) and at iodine intakes ≥300-399 μg/d in 11- to 14-y-old children (OR: 5.2; 95% CI: 1.5, 18.3). However, there were no consistent differences in the risk of hyperthyrotropinemia and Tg >40 μg/L in children between different iodine-intake groups. Conclusions Thyroid volume and goiter appear to be more sensitive indicators of thyroid stress than thyrotropin and Tg in children with long-term excess iodine intakes. We recommend 250 and 300 μg/d as safe Tolerable Upper Intake Levels of iodine for children aged 7-10 y and 11-14 y, respectively. This trial was registered at www.clinicaltrials.gov as NCT02915536.
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Affiliation(s)
- Wen Chen
- Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China
| | - Yixin Zhang
- Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China
| | - Yunmeng Hao
- Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China
| | - Wei Wang
- Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China
| | - Long Tan
- Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China
| | - Jiancao Bian
- The Shandong Institute for Endemic Disease Control and Research, Shandong, China
| | - Elizabeth N Pearce
- Section of Endocrinology, Diabetes, and Nutrition, Boston University School of Medicine, Boston, MA
| | - Michael B Zimmermann
- Human Nutrition Laboratory, Swiss Federal Institute of Technology, Zurich, Switzerland
| | - Jun Shen
- Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China
| | - Wanqi Zhang
- Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China.,Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
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9
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Tamang MK, Gelal B, Tamang B, Lamsal M, Brodie D, Baral N. Excess urinary iodine concentration and thyroid dysfunction among school age children of eastern Nepal: a matter of concern. BMC Res Notes 2019; 12:294. [PMID: 31133065 PMCID: PMC6537302 DOI: 10.1186/s13104-019-4332-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 05/22/2019] [Indexed: 11/17/2022] Open
Abstract
Objectives Deficiency as well as excess dietary iodine is associated with several thyroid disorders including Grave’s disease and goitre. Previously, cross sectional studies conducted among school children in Nepal showed high prevalence of iodine deficiency. In contrast, recently, few studies have revealed emerging trends of excess urinary iodine concentration in children. This paper, reports excess urinary iodine excretion and thyroid dysfunction among school age children from eastern Nepal. Results It was a community based cross sectional study in which we measured urinary iodine excretion levels among school age children at baseline and after educational program. The educational program consisted of audio-visual and pamphlets on thyroid health. We also screened them for thyroid function status by physical examination and measuring serum thyroid hormones. Our results show that 34.4% of the children had excess urinary iodine concentration above the WHO recommended levels. Overall, 3.2% of the children were identified to have thyroid dysfunction. Urinary iodine concentration was significantly different between types of salt used and between salt iodine content categories.
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Affiliation(s)
- Man Kumar Tamang
- Rotary Club of Dharan Ghopa, B. P. Koirala Institute of Health Sciences, Dharan, Nepal.
| | - Basanta Gelal
- Department of Biochemistry, B. P. Koirala Institute of Health Sciences, Dharan, Nepal
| | - Binaya Tamang
- Department of Biochemistry, B. P. Koirala Institute of Health Sciences, Dharan, Nepal
| | - Madhab Lamsal
- Department of Biochemistry, B. P. Koirala Institute of Health Sciences, Dharan, Nepal
| | | | - Nirmal Baral
- Department of Biochemistry, B. P. Koirala Institute of Health Sciences, Dharan, Nepal
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10
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Farebrother J, Zimmermann MB, Andersson M. Excess iodine intake: sources, assessment, and effects on thyroid function. Ann N Y Acad Sci 2019; 1446:44-65. [PMID: 30891786 DOI: 10.1111/nyas.14041] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 01/30/2019] [Accepted: 02/02/2019] [Indexed: 12/15/2022]
Abstract
Iodine is essential for thyroid hormone synthesis. High iodine intakes are well tolerated by most healthy individuals, but in some people, excess iodine intakes may precipitate hyperthyroidism, hypothyroidism, goiter, and/or thyroid autoimmunity. Individuals with preexisting thyroid disease or those previously exposed to iodine deficiency may be more susceptible to thyroid disorders due to an increase in iodine intake, in some cases at intakes only slightly above physiological needs. Thyroid dysfunction due to excess iodine intake is usually mild and transient, but iodine-induced hyperthyroidism can be life-threatening in some individuals. At the population level, excess iodine intakes may arise from consumption of overiodized salt, drinking water, animal milk rich in iodine, certain seaweeds, iodine-containing dietary supplements, and from a combination of these sources. The median urinary iodine concentration (UIC) of a population reflects the total iodine intake from all sources and can accurately identify populations with excessive iodine intakes. Our review describes the association between excess iodine intake and thyroid function. We outline potential sources of excess iodine intake and the physiological responses and consequences of excess iodine intakes. We provide guidance on choice of biomarkers to assess iodine intake, with an emphasis on the UIC and thyroglobulin.
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Affiliation(s)
- Jessica Farebrother
- Human Nutrition Laboratory, Institute of Food, Nutrition, and Health, ETH Zurich, Zurich, Switzerland.,Department of Women and Children's Health, King's College London, London, UK
| | - Michael B Zimmermann
- Human Nutrition Laboratory, Institute of Food, Nutrition, and Health, ETH Zurich, Zurich, Switzerland.,Iodine Global Network, Ottawa, Ontario, Canada
| | - Maria Andersson
- Human Nutrition Laboratory, Institute of Food, Nutrition, and Health, ETH Zurich, Zurich, Switzerland.,Iodine Global Network, Ottawa, Ontario, Canada.,Division of Gastroenterology and Nutrition, University Children's Hospital Zurich, Zurich, Switzerland
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11
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Farebrother J, Zimmermann MB, Assey V, Castro MC, Cherkaoui M, Fingerhut R, Jia Q, Jukic T, Makokha A, San Luis TO, Wegmüller R, Andersson M. Thyroglobulin Is Markedly Elevated in 6- to 24-Month-Old Infants at Both Low and High Iodine Intakes and Suggests a Narrow Optimal Iodine Intake Range. Thyroid 2019; 29:268-277. [PMID: 30648484 DOI: 10.1089/thy.2018.0321] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
BACKGROUND In areas with incomplete salt iodization coverage, infants and children aged 6-24 months weaning from breast milk and receiving complementary foods are at risk of iodine deficiency. However, few data exist on the risk of excessive iodine intake in this age group. Thyroglobulin (Tg) is a sensitive marker of iodine intake in school-age children and adults and may be used to estimate the optimal iodine intake range in infancy. The aim of this study was to assess the association of low and high iodine intakes with Tg and thyroid function in weaning infants. METHODS This multicenter cross-sectional study recruited infants aged 6-24 months (n = 1543; Mage = 12.2 ± 4.6 months) receiving breast milk with complementary foods, from seven countries in areas with previously documented deficient, sufficient, or excessive iodine intake in schoolchildren or pregnant women. Urinary iodine concentration (UIC) and Tg, total thyroxine, and thyrotropin were measured using dried blood spot testing. RESULTS Median UIC ranged from 48 μg/L (interquartile range 31-79 μg/L) to 552 μg/L (interquartile range 272-987 μg/L) across the study sites. Median Tg using dried blood spot testing was high (>50 μg/L) at estimated habitual iodine intakes <50 μg/day and >230 μg/day. Prevalence of overt thyroid disorders was low (<3%). Yet, subclinical hyperthyroidism was observed in the countries with the lowest iodine intake. CONCLUSIONS Tg is a sensitive biomarker of iodine intake in 6- to 24-month-old infants and follows a U-shaped relationship with iodine intake, suggesting a relatively narrow optimal intake range. Infants with low iodine intake may be at increased risk of subclinical thyroid dysfunction. In population monitoring of iodine deficiency or excess, assessment of iodine status using UIC and Tg may be valuable in this young age group.
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Affiliation(s)
- Jessica Farebrother
- 1 Human Nutrition Laboratory, Institute of Food, Nutrition and Health, ETH Zurich, Switzerland
| | - Michael B Zimmermann
- 1 Human Nutrition Laboratory, Institute of Food, Nutrition and Health, ETH Zurich, Switzerland
- 2 Iodine Global Network, Ottawa, Ottawa, Canada
| | - Vincent Assey
- 2 Iodine Global Network, Ottawa, Ottawa, Canada
- 3 Nutrition Services Section, Preventive Services Department; Ministry of Health, Community Development, Gender, Elderly, and Children, Dar es Salaam, Tanzania
| | | | - Mohamed Cherkaoui
- 5 Faculté des Sciences Semlalia, Université Caddi Ayyed, Marrakech, Morocco
| | - Ralph Fingerhut
- 6 Swiss Newborn Screening Laboratory and Children's Research Center; University Children's Hospital Zurich, Zurich, Switzerland
| | - Qingzhen Jia
- 7 Shanxi Institute for Prevention and Treatment of Endemic Disease, Linfen, P.R. China
| | - Tomislav Jukic
- 8 Department of Nuclear Medicine and Oncology, Sestre Milosrdnice University Hospital Center and School of Medicine, University of Zagreb, Zagreb, Croatia
- 9 Faculty of Medicine Osijek, University Josip Juraj Strossmayer Osijek, Osijek, Croatia
| | - Anselimo Makokha
- 10 Department of Food Science, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
| | - Theofilo O San Luis
- 2 Iodine Global Network, Ottawa, Ottawa, Canada
- 11 St Luke's Medical Center, Quezon City, Manila, The Philippines
| | - Rita Wegmüller
- 12 Medical Research Council The Gambia, Keneba, The Gambia
| | - Maria Andersson
- 1 Human Nutrition Laboratory, Institute of Food, Nutrition and Health, ETH Zurich, Switzerland
- 2 Iodine Global Network, Ottawa, Ottawa, Canada
- 13 Division of Gastroenterology and Nutrition; University Children's Hospital Zurich, Zurich, Switzerland
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12
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Nazeri P, Tahmasebinejad Z, Mehrabi Y, Hedayati M, Mirmiran P, Azizi F. Lactating Mothers and Infants Residing in an Area with an Effective Salt Iodization Program Have No Need for Iodine Supplements: Results from a Double-Blind, Placebo-Controlled, Randomized Controlled Trial. Thyroid 2018; 28:1547-1558. [PMID: 30272528 DOI: 10.1089/thy.2018.0153] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
BACKGROUND The necessity of iodine supplementation in lactating mothers residing in countries with sustained salt iodization programs for iodine sufficiency of breast-fed infants remains unclear. The aims of this study were to investigate the effect of iodine supplementation on iodine status and growth parameters of lactating mothers and breast-fed infants and to compare these data with that of formula-feeding mothers and their infants during the first year of infancy. METHODS In this multicenter, double-blinded, randomized clinical trial conducted in four healthcare centers in Tehran (Iran), healthy lactating mothers and their term newborns aged 3-5 days were randomly assigned to treatment groups: placebo, 150 μg/day iodine, or 300 μg/day iodine. They were followed up for 12 months. Formula-fed infants aged 30-45 days and their mothers were randomly selected from the same centers. The primary outcomes were maternal and infant urinary iodine concentrations (UICs), breast-milk iodine concentrations (BMICs), and infant growth parameters, measured at 1, 2, 4, 6, 9, and 12 months during routine health visits. The formula-fed group was assessed at 2, 4, 6, 9, and 12 months of age. Analysis was by per protocol principle using mixed-effects models. RESULTS Mother-newborn pairs (n = 180) in treatment groups and partially/exclusively formula-feeding mother-infant pairs (n = 60) participated between October 2014 and January 2016. Median baseline UICs in the treatment groups were 84 μg/L (interquartile range [IQR] 41-143 μg/L) in mothers and 208 μg/L (IQR 91-310 μg/L) in their infants. The values in the formula-fed group were 76 μg/L (IQR 40-144 μg/L) in mothers and 121 μg/L (IQR 66-243 μg/L) in infants. The 300 μg/day iodine group showed significantly higher UICs and BMICs than did the other treatment groups; infant UICs in the 150 μg/day iodine, placebo, and formula-fed groups were similar. Infants in all groups showed iodine sufficiency (median UIC ≥100 μg/L) throughout the study period. Anthropometric measurements were similar between the treatment and formula-fed groups over the study period, except at the last follow-up visit at 12 months. CONCLUSION Supplementation of breast-feeding mothers with either 300 or 150 μg/day iodine improved their iodine status. However, the iodine status of infants in all groups studied indicated iodine sufficiency during the first year of infancy, demonstrating that in countries with effective salt iodization program, iodine supplementation for lactating mothers is unnecessary.
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Affiliation(s)
- Pantea Nazeri
- 1 Family Health Institute, Breastfeeding Research Center, Tehran University of Medical Sciences , Tehran, Iran
- 2 Nutrition and Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences , Tehran, Iran
| | - Zhale Tahmasebinejad
- 2 Nutrition and Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences , Tehran, Iran
| | - Yadollah Mehrabi
- 3 Department of Epidemiology, School of Public Health, Shahid Beheshti University of Medical Sciences , Tehran, Iran
| | - Mehdi Hedayati
- 4 Cellular and Molecular Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences , Tehran, Iran
| | - Parvin Mirmiran
- 2 Nutrition and Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences , Tehran, Iran
| | - Fereidoun Azizi
- 5 Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences , Tehran, Iran
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13
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Farebrother J, Zimmermann MB, Abdallah F, Assey V, Fingerhut R, Gichohi-Wainaina WN, Hussein I, Makokha A, Sagno K, Untoro J, Watts M, Andersson M. Effect of Excess Iodine Intake from Iodized Salt and/or Groundwater Iodine on Thyroid Function in Nonpregnant and Pregnant Women, Infants, and Children: A Multicenter Study in East Africa. Thyroid 2018; 28:1198-1210. [PMID: 30019625 DOI: 10.1089/thy.2018.0234] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Acute excess iodine intake can damage the thyroid, but the effects of chronic excess iodine intake are uncertain. Few data exist for pregnant and lactating women and infants exposed to excessive iodine intake. METHODS This was a multicenter cross-sectional study. At study sites in rural Kenya and urban Tanzania previously reporting iodine excess in children, urinary iodine concentration (UIC), thyrotropin, total thyroxine, and thyroglobulin (Tg) were measured in school-age children (SAC), women of reproductive age, pregnant (PW) and lactating women, and breast-feeding and weaning infants. In a national study in Djibouti, UIC was measured in SAC and PW. At all sites, daily iodine intake was estimated based on UIC, and iodine concentration was measured in household salt and drinking water. RESULTS The total sample size was 4636: 1390, 2048, and 1198 subjects from Kenya, Tanzania, and Djibouti, respectively. In Kenya and Tanzania: (i) median UIC was well above thresholds for adequate iodine nutrition in all groups and exceeded the threshold for excess iodine intake in SAC; (ii) iodine concentrations >40 mg of iodine/kg were found in approximately 55% of household salt samples; (iii) iodine concentrations ≥10 μg/L were detected in 9% of drinking water samples; (iv) Tg was elevated in all population groups, but the prevalence of thyroid disorders was negligible, except that 5-12% of women of reproductive age had subclinical hyperthyroidism and 10-15% of PW were hypothyroxinemic. In Djibouti: (i) the median UIC was 335 μg/L (interquartile range [IQR] = 216-493 μg/L) in SAC and 265 μg/L (IQR = 168-449 μg/L) in PW; (ii) only 1.6% of Djibouti salt samples (n = 1200) were adequately iodized (>15 mg/kg); (iii) the median iodine concentration in drinking water was 92 μg/L (IQR = 37-158 μg/L; n = 77). In all countries, UIC was not significantly correlated with salt or water iodine concentrations. CONCLUSIONS Although iodine intake was excessive and Tg concentrations were elevated, there was little impact on thyroid function. Chronic excess iodine intake thus appears to be well tolerated by women, infants, and children. However, such high iodine intake is unnecessary and should be avoided. Careful evaluation of contributions from both iodized salt and groundwater iodine is recommended before any review of iodization policy is considered.
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Affiliation(s)
- Jessica Farebrother
- 1 Human Nutrition Laboratory, Institute of Food, Nutrition, and Health , ETH Zurich, Zurich, Switzerland
| | - Michael B Zimmermann
- 1 Human Nutrition Laboratory, Institute of Food, Nutrition, and Health , ETH Zurich, Zurich, Switzerland
- 2 Iodine Global Network , Ottawa, Canada
| | - Fatma Abdallah
- 3 Tanzania Food and Nutrition Centre , Dar es Salaam, Tanzania
| | - Vincent Assey
- 4 Nutrition Services Section, Preventive Services Department, Ministry of Health , Community Development, Gender, Elderly, and Children, Dar es Salaam, Tanzania
- 5 Regional Coordinator East and Southern Africa, Iodine Global Network , Ottawa, Canada
| | - Ralph Fingerhut
- 6 University Children's Hospital Zurich , Swiss Newborn Screening Laboratory and Children's Research Center, Zurich, Switzerland
| | - Wanjiku N Gichohi-Wainaina
- 7 International Crops Research Institute for Semi-Arid Tropics (ICRISAT) , Lilongwe, Malawi
- 8 Department of Food Science, Jomo Kenyatta University of Agriculture and Technology , Nairobi, Kenya
| | - Izzeldin Hussein
- 9 Regional Coordinator Middle East and North Africa, Iodine Global Network , Ottawa, Canada
| | - Anselimo Makokha
- 8 Department of Food Science, Jomo Kenyatta University of Agriculture and Technology , Nairobi, Kenya
| | - Kalil Sagno
- 10 Djibouti Country Office, United Nations Children's Fund , Djibouti, Djibouti
| | - Juliawati Untoro
- 11 Eastern and Southern Africa Regional Office, United Nations Children's Fund , Nairobi, Kenya
| | - Michael Watts
- 12 Inorganic Geochemistry, Centre for Environmental Geochemistry, British Geological Survey , Nottingham, United Kingdom
| | - Maria Andersson
- 1 Human Nutrition Laboratory, Institute of Food, Nutrition, and Health , ETH Zurich, Zurich, Switzerland
- 2 Iodine Global Network , Ottawa, Canada
- 13 Division of Gastroenterology and Nutrition, University Children's Hospital Zurich , Zurich, Switzerland
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14
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Dold S, Zimmermann MB, Jukic T, Kusic Z, Jia Q, Sang Z, Quirino A, San Luis TOL, Fingerhut R, Kupka R, Timmer A, Garrett GS, Andersson M. Universal Salt Iodization Provides Sufficient Dietary Iodine to Achieve Adequate Iodine Nutrition during the First 1000 Days: A Cross-Sectional Multicenter Study. J Nutr 2018; 148:587-598. [PMID: 29659964 DOI: 10.1093/jn/nxy015] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 01/16/2018] [Indexed: 12/14/2022] Open
Abstract
Background Dietary iodine requirements are high during pregnancy, lactation, and infancy, making women and infants vulnerable to iodine deficiency. Universal salt iodization (USI) has been remarkably successful for preventing iodine deficiency in the general population, but it is uncertain if USI provides adequate iodine intakes during the first 1000 d. Objective We set out to assess if USI provides sufficient dietary iodine to meet the iodine requirements and achieve adequate iodine nutrition in all vulnerable population groups. Methods We conducted an international, cross-sectional, multicenter study in 3 study sites with mandatory USI legislation. We enrolled 5860 participants from 6 population groups (school-age children, nonpregnant nonlactating women of reproductive age, pregnant women, lactating women, 0-6-mo-old infants, and 7-24-mo-old infants) and assessed iodine status [urinary iodine concentration (UIC)] and thyroid function in Linfen, China (n = 2408), Tuguegarao, the Philippines (n = 2512), and Zagreb, Croatia (n = 940). We analyzed the iodine concentration in household salt, breast milk, drinking water, and cow's milk. Results The salt iodine concentration was low (<15 mg/kg) in 2.7%, 33.6%, and 3.1%, adequate (15-40 mg/kg) in 96.3%, 48.4%, and 96.4%, and high (>40 mg/kg) in 1.0%, 18.0%, and 0.5% of household salt samples in Linfen (n = 402), Tuguegarao (n = 1003), and Zagreb (n = 195), respectively. The median UIC showed adequate iodine nutrition in all population groups, except for excessive iodine intake in school-age children in the Philippines and borderline low intake in pregnant women in Croatia. Conclusions Salt iodization at ∼25 mg/kg that covers a high proportion of the total amount of salt consumed supplies sufficient dietary iodine to ensure adequate iodine nutrition in all population groups, although intakes may be borderline low during pregnancy. Large variations in salt iodine concentrations increase the risk for both low and high iodine intakes. Strict monitoring of the national salt iodization program is therefore essential for optimal iodine nutrition. This trial was registered at clinicaltrials.gov as NCT02196337.
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Affiliation(s)
- Susanne Dold
- Human Nutrition Laboratory, Institute of Food Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Michael B Zimmermann
- Human Nutrition Laboratory, Institute of Food Nutrition and Health, ETH Zurich, Zurich, Switzerland.,Iodine Global Network, Ottawa, Ontario, Canada
| | - Tomislav Jukic
- Department of Nuclear Medicine and Oncology, Sestre Milosrdnice University Hospital Centre and School of Medicine, University of Zagreb, Zagreb, Croatia.,Faculty of Medicine Osijek, University Josip Juraj Strossmayer Osijek, Osijek, Croatia
| | - Zvonko Kusic
- Department of Nuclear Medicine and Oncology, Sestre Milosrdnice University Hospital Centre and School of Medicine, University of Zagreb, Zagreb, Croatia.,Croatian Academy of Sciences and Arts, Zagreb, Croatia
| | - Qingzhen Jia
- Shanxi Institute for Prevention and Treatment of Endemic Disease, Linfen, China
| | - Zhongna Sang
- Institute of Endocrinology, Tianjin Medical University, Tianjin, China
| | - Antonio Quirino
- Technological Institute of the Philippines, Manila, Philippines
| | | | - Ralph Fingerhut
- Swiss Newborn Screening Laboratory, Division of Metabolism and Children's Research Centre (CRC), University Children's Hospital Zurich, Zurich, Switzerland
| | | | - Arnold Timmer
- Global Alliance for Improved Nutrition (GAIN), Geneva, Switzerland
| | - Greg S Garrett
- Global Alliance for Improved Nutrition (GAIN), Geneva, Switzerland
| | - Maria Andersson
- Human Nutrition Laboratory, Institute of Food Nutrition and Health, ETH Zurich, Zurich, Switzerland.,Iodine Global Network, Ottawa, Ontario, Canada
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15
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Nazeri P, Kabir A, Dalili H, Mirmiran P, Azizi F. Breast-Milk Iodine Concentrations and Iodine Levels of Infants According to the Iodine Status of the Country of Residence: A Systematic Review and Meta-Analysis. Thyroid 2018; 28:124-138. [PMID: 29334343 DOI: 10.1089/thy.2017.0403] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Iodine, an essential micronutrient, plays a critical role in normal growth and development, especially during the first two years of life. This systematic review and meta-analysis is among the first to evaluate breast-milk iodine concentrations and infant iodine status in countries characterized by iodine sufficiency or deficiency. METHODS PubMed, Web of Science, Cochrane Library, Google Scholar, and other relevant databases, as well as reference lists of previous reviews, were searched for relevant studies published between 1986 and 2016. Mean or median breast-milk and infant urinary iodine concentrations, along with other relevant data, were extracted from eligible studies. Each study was assessed for quality and risk of bias. RESULTS Of the 496 identified studies, 57 met the criteria for inclusion in the meta-analysis. The mean (confidence interval [CI]) iodine concentrations in maternal colostrum were 152.0 μg/L [CI 106.2-198.7 μg/L] and 57.8 μg/L [CI 41.4-74.1 μg/L] in iodine-sufficient and -deficient countries, respectively, indicating a significant difference between the two iodine statuses. By contrast, the corresponding values in mature milk did not differ significantly between mothers in iodine-sufficient and -deficient countries (71.5 μg/L [CI 51.0-92.0 μg/L] and 28.0 μg/L [CI -13.8 to 69.9 μg/L], respectively]. The weighted urinary iodine levels [CIs] of breast-fed infants in iodine-sufficient countries were significantly higher than those in iodine-deficient countries (164.5 μg/L [CI 116.4-212.7 μg/L] vs. 70.4 μg/L [CI 46.2-94.6 μg/L]). Similarly, a significant difference was observed in the pooled estimates of urinary iodine levels [CIs] among formula-fed infants in iodine-sufficient versus iodine-deficient countries (310.3 μg/L [CI 287.4-342.1 μg/L] vs. 38.3 μg/L [CI 23.4-53.2 μg/L]). CONCLUSION The meta-analysis reveals that in iodine-sufficient countries, the mean iodine concentrations in colostrum and mature breast milk corresponded to iodine sufficiency among infants. The results are thus compatible with the international recommendation that lactating women and infants younger than two years of age who reside in iodine-sufficient countries do not require iodine supplementation.
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Affiliation(s)
- Pantea Nazeri
- 1 Family Health Institute, Breastfeeding Research Center, Tehran University of Medical Sciences , Tehran, Iran
- 2 Nutrition and Endocrine Research Center, Shahid Beheshti University of Medical Sciences , Tehran, Iran
| | - Ali Kabir
- 3 Minimally Invasive Surgery Research Center, Iran University of Medical Sciences , Tehran, Iran
| | - Hosein Dalili
- 1 Family Health Institute, Breastfeeding Research Center, Tehran University of Medical Sciences , Tehran, Iran
| | - Parvin Mirmiran
- 2 Nutrition and Endocrine Research Center, Shahid Beheshti University of Medical Sciences , Tehran, Iran
| | - Fereidoun Azizi
- 4 Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences , Tehran, Iran
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16
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Ross GR, Fabersani E, Russo M, Gómez A, Japaze H, González SN, Gauffin Cano P. Effect of Excess Iodide Intake on Salivary Glands in a Swiss Albino Mice Model. BIOMED RESEARCH INTERNATIONAL 2017; 2017:6302869. [PMID: 29250546 PMCID: PMC5698784 DOI: 10.1155/2017/6302869] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 08/16/2017] [Accepted: 10/15/2017] [Indexed: 12/11/2022]
Abstract
Iodine is an important micronutrient required for nutrition. Excess iodine has adverse effects on thyroid, but there is not enough information regarding its effect on salivary glands. In addition to food and iodized salt, skin disinfectants and maternal nutritional supplements contain iodide, so its intake could be excessive during pregnancy, lactation, and infancy. The aim of this work was to evaluate the effect of excess iodide ingestion on salivary glands during mating, gestation, lactation, and postweaning period in mouse. During assay, mice were allocated into groups: control and treatment groups (received distilled water with NaI 1 mg/mL). Water intake, glandular weight, and histology were analyzed. Treatment groups showed an increase in glandular weight and a significantly (p < 0.05) higher water intake than control groups. Lymphocyte infiltration was observed in animals of treatment groups, while there was no infiltration in glandular sections of control groups. Results demonstrated that a negative relationship could exist between iodide excess and salivary glands. This work is novel evidence that high levels of iodide intake could induce mononuclear infiltration in salivary glands. These results should be considered, especially in pregnant/lactating women, to whom a higher iodine intake is usually recommended.
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Affiliation(s)
- Gloria Romina Ross
- Instituto de Biotecnología Farmacéutica y Alimentaria (INBIOFAL-CONICET), Tucumán, Argentina
- Facultad de Ciencias de la Salud, Universidad del Norte Santo Tomás de Aquino (UNSTA), Tucumán, Argentina
| | - Emanuel Fabersani
- Facultad de Agronomía y Zootecnia, Universidad Nacional de Tucumán, Tucumán, Argentina
| | - Matías Russo
- Centro de Referencia para Lactobacilos (CERELA-CONICET), Tucumán, Argentina
| | - Alba Gómez
- Facultad de Medicina, Universidad Nacional de Tucumán, Tucumán, Argentina
| | - Hugo Japaze
- Facultad de Medicina, Universidad Nacional de Tucumán, Tucumán, Argentina
| | - Silvia Nelina González
- Instituto de Biotecnología Farmacéutica y Alimentaria (INBIOFAL-CONICET), Tucumán, Argentina
| | - Paola Gauffin Cano
- Facultad de Ciencias de la Salud, Universidad del Norte Santo Tomás de Aquino (UNSTA), Tucumán, Argentina
- Centro de Referencia para Lactobacilos (CERELA-CONICET), Tucumán, Argentina
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17
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Serrano-Nascimento C, Salgueiro RB, Vitzel KF, Pantaleão T, Corrêa da Costa VM, Nunes MT. Iodine excess exposure during pregnancy and lactation impairs maternal thyroid function in rats. Endocr Connect 2017; 6:510-521. [PMID: 28814477 PMCID: PMC5597975 DOI: 10.1530/ec-17-0106] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 08/16/2017] [Indexed: 12/21/2022]
Abstract
Adequate maternal iodine consumption during pregnancy and lactation guarantees normal thyroid hormones (TH) production, which is crucial to the development of the fetus. Indeed, iodine deficiency is clearly related to maternal hypothyroidism and deleterious effects in the fetal development. Conversely, the effects of iodine excess (IE) consumption on maternal thyroid function are still controversial. Therefore, this study aimed to investigate the impact of IE exposure during pregnancy and lactation periods on maternal hypothalamus-pituitary-thyroid axis. IE-exposed dams presented reduced serum TH concentration and increased serum thyrotropin (TSH) levels. Moreover, maternal IE exposure increased the hypothalamic expression of Trh and the pituitary expression of Trhr, Dio2, Tsha and Tshb mRNA, while reduced the Gh mRNA content. Additionally, IE-exposed dams presented thyroid morphological alterations, increased thyroid oxidative stress and decreased expression of thyroid genes/proteins involved in TH synthesis, secretion and metabolism. Furthermore, Dio1 mRNA expression and D1 activity were reduced in the liver and the kidney of IE-treated animals. Finally, the mRNA expression of Slc5a5 and Slc26a4 were reduced in the mammary gland of IE-exposed rats. The latter results are in accordance with the reduction of prolactin expression and serum levels in IE-treated dams. In summary, our study indicates that the exposure to IE during pregnancy and lactation induces primary hypothyroidism in rat dams and impairs iodide transfer to the milk.
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Affiliation(s)
- Caroline Serrano-Nascimento
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Rafael Barrera Salgueiro
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Kaio Fernando Vitzel
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Thiago Pantaleão
- Carlos Chagas Filho Biophysics InstituteFederal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Maria Tereza Nunes
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
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18
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Katagiri R, Yuan X, Kobayashi S, Sasaki S. Effect of excess iodine intake on thyroid diseases in different populations: A systematic review and meta-analyses including observational studies. PLoS One 2017; 12:e0173722. [PMID: 28282437 PMCID: PMC5345857 DOI: 10.1371/journal.pone.0173722] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 02/24/2017] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Although several reports concerning the association of iodine excess and thyroid disease have appeared, no systematic review of the association between iodine excess intake and thyroid diseases, especially hyperthyroidism and hypothyroidism, has yet been reported. METHOD We conducted a systematic search of Ovid MEDLINE, PubMed, Cochrane Central Register of Controlled Trials databases, Ichushi-Web and CiNii database for intervention trials and observational studies. Search terms were constructed from related words for excess AND iodine intake or excretion AND thyroid hormones or diseases AND study designs. After considering the qualitative heterogeneity among studies, a meta-analysis was conducted and odds ratios and 95% confidence intervals (CI) were estimated in random-effects models. A protocol was registered with PROSPERO (No. CRD42015028081). RESULTS 50 articles were included, including three intervention trials, six case-control studies, six follow-up studies and 35 cross-sectional studies. Three cross-sectional studies in adults included in meta-analysis. Odds ratio of overt and subclinical hypothyroidism between excess and adequate populations were 2.78 (CI:1.47 to 5.27) and 2.03 (CI:1.58 to 2.62) in adults, respectively. Source of excess iodine status was mainly iodized salt or water in included studies. CONCLUSION Although universal salt iodization has improved goiter rates, chronic exposure to excess iodine from water or poorly monitored salt are risk factors for hypothyroidism in free-living populations. Monitoring of both iodine concentration in salt as well as the iodine concentration in local drinking water are essential to preventing thyroid diseases. Hypothyroidism should be also carefully monitored in areas with excess iodine. Because of the low quality and limited number of included studies, further evidence and review are required.
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Affiliation(s)
- Ryoko Katagiri
- Department of Social and Preventive Epidemiology, Graduate School of Medicine, the University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Xiaoyi Yuan
- Department of Social and Preventive Epidemiology, School of Public Health, the University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Satomi Kobayashi
- Department of Social and Preventive Epidemiology, School of Public Health, the University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Satoshi Sasaki
- Department of Social and Preventive Epidemiology, Graduate School of Medicine, the University of Tokyo, Bunkyo-ku, Tokyo, Japan
- Department of Social and Preventive Epidemiology, School of Public Health, the University of Tokyo, Bunkyo-ku, Tokyo, Japan
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Nazeri P, Mirmiran P, Tahmasebinejad Z, Hedayati M, Delshad H, Azizi F. The Effects of Iodine Fortified Milk on the Iodine Status of Lactating Mothers and Infants in an Area with a Successful Salt Iodization Program: A Randomized Controlled Trial. Nutrients 2017; 9:nu9020180. [PMID: 28241419 PMCID: PMC5331611 DOI: 10.3390/nu9020180] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 02/06/2017] [Accepted: 02/17/2017] [Indexed: 11/20/2022] Open
Abstract
Iodine deficiency during the first two years of life may cause irreversible brain damage and mental retardation. The aim of the present study was to investigate, for the first time, the effect of iodine fortified milk on the iodine status of lactating mothers and their infants. In this multicenter randomized controlled trial, 84 lactating mother-infant pairs from health care centers were randomly selected. After meeting the inclusion criteria, lactating mothers were randomly assigned to two groups: the iodine fortified milk group and the control group (n = 42 each). Maternal and infant urine and breast milk samples were collected at 3–5 (baseline), 7, 10, 14 days, and 1 month postpartum, for a measurement of the iodine concentration. A total of 84 lactating mothers, with a mean age of 28.2 ± 4.5 years, and 84 infants, with a mean age of 4.2 ± 0.7 days, were included in the study. Compared to mothers of the control group, mothers receiving iodine fortified milk had higher urinary (p < 0.001) and breast milk (p < 0.001) iodine concentrations. Urinary iodine levels in infants revealed no significant differences between the two groups. The findings of this study indicate that supplementation with daily iodine fortified milk provides iodine nutrition adequacy among lactating mothers. However, it had no effect on the iodine status of infants, who were previously iodine sufficient.
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Affiliation(s)
- Pantea Nazeri
- Nutrition and Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, 19395-4763 Tehran, Iran.
| | - Parvin Mirmiran
- Nutrition and Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, 19395-4763 Tehran, Iran.
- Department of Nutrition and Clinical Dietetics, Faculty of Nutrition Sciences and Food Technology, National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, 19395-4741 Tehran, Iran.
| | - Zhale Tahmasebinejad
- Nutrition and Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, 19395-4763 Tehran, Iran.
| | - Mehdi Hedayati
- Cellular and Molecular Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, 19395-4763 Tehran, Iran.
| | - Hossein Delshad
- Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, 19395-4763 Tehran, Iran.
| | - Fereidoun Azizi
- Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, 19395-4763 Tehran, Iran.
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20
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Chen W, Li X, Wu Y, Bian J, Shen J, Jiang W, Tan L, Wang X, Wang W, Pearce EN, Zimmermann MB, Carriquiry AL, Zhang W. Associations between iodine intake, thyroid volume, and goiter rate in school-aged Chinese children from areas with high iodine drinking water concentrations. Am J Clin Nutr 2017; 105:228-233. [PMID: 27927635 DOI: 10.3945/ajcn.116.139725] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 11/02/2016] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Excessive iodine intake may have adverse effects on the thyroid, particularly in children, but the safe upper iodine intake concentration in children is unclear. OBJECTIVE We assessed the adverse effects of high iodine intake from iodine-rich drinking water on thyroid size in children by examining associations between thyroid volume (Tvol), total goiter rate (TGR), and iodine intake. DESIGN In a multistage cross-sectional survey, we collected two 24-h urine samples on 2 nonconsecutive days and determined 24-h urinary iodine excretion, then calculated habitual daily iodine intake. Ultrasonographic Tvol was measured, and TGR was calculated based on international and Chinese reference ranges for Tvol in children. RESULTS This study included 2089 children from Shandong province, where the median (IQR) drinking water iodine concentration was 183 μg/L (69-406 μg/L). The median (IQR) 24-h urinary iodine concentrations for the 2 collections were 381 μg/L (203-649 μg/L) and 398 μg/L (202-687 μg/L), respectively. The median (IQR) habitual daily iodine intake of children was 298 μg/d (186-437 μg/d). Tvols were slightly higher in boys than in girls (P = 0.035). The overall TGR was 9.7% and did not differ by sex. The TGR was ∼5% for children aged 7-10 and 11-14 y at iodine intakes of 200-249 and 250-299 μg/d, respectively. With the use of logistic regression and 2-step linear regression, a nonlinear association was observed between Tvol, TGR, and iodine intake, with a threshold intake of 150 μg/d. CONCLUSIONS Tvol begins to increase in children when iodine intake is ≥150 μg/d, and the TGR exceeds 5% when daily iodine intake is ≥250 μg/d for children aged 7-10 y and ≥300 μg/d for children aged 11-14 y. Our findings suggest that 150-249 and 150-299 μg/d seem to be safe upper iodine intake ranges for children aged 7-10 and 11-14 y, respectively. This trial was registered at clinicaltrials.gov as NCT02915536.
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Affiliation(s)
- Wen Chen
- Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China
| | - Xiang Li
- Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China
| | - Yalan Wu
- Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China
| | - Jianchao Bian
- Shandong Institute for Endemic Disease Control and Research, Jinan, China
| | - Jun Shen
- Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China
| | - Wen Jiang
- Shandong Institute for Endemic Disease Control and Research, Jinan, China
| | - Long Tan
- Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China
| | - Xiaoming Wang
- Shandong Institute for Endemic Disease Control and Research, Jinan, China
| | - Wei Wang
- Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China
| | - Elizabeth N Pearce
- Section of Endocrinology, Diabetes, and Nutrition, Boston University School of Medicine, Boston, MA
| | - Michael B Zimmermann
- Human Nutrition Laboratory, Swiss Federal Institute of Technology (ETH), Zürich, Switzerland; and
| | | | - Wanqi Zhang
- Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China;
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21
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Osei J, Andersson M, Reijden OVD, Dold S, Smuts CM, Baumgartner J. Breast-Milk Iodine Concentrations, Iodine Status, and Thyroid Function of Breastfed Infants Aged 2-4 Months and Their Mothers Residing in a South African Township. J Clin Res Pediatr Endocrinol 2016; 8:381-391. [PMID: 27217155 PMCID: PMC5197995 DOI: 10.4274/jcrpe.2720] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 05/22/2016] [Indexed: 12/19/2022] Open
Abstract
OBJECTIVE Lactating women and their infants are susceptible to iodine deficiency and iodine excess. In South Africa, no data exist on the iodine status and thyroid function of these vulnerable groups. METHODS In a cross-sectional study, urinary iodine concentrations (UIC), thyroid function, and breast-milk iodine concentrations (BMIC) were assessed in 100 lactating women from a South African township and their 2-4-month-old breastfed infants. Potential predictors of UIC, thyroid function, and BMIC, including household salt iodine concentrations (SIC) and maternal sodium excretion, were also investigated. RESULTS The median (25th-75th percentile) UIC was 373 (202-627) μg/L in infants and 118 (67-179) μg/L in mothers. Median household SIC was 44 (27-63) ppm. Household SIC and maternal urinary sodium excretion predicted UIC of lactating mothers. Median BMIC was 179 (126-269) μg/L. Age of infants, SIC, and maternal UIC predicted BMIC. In turn, infant age and BMIC predicted UIC of infants. Forty-two percent of SIC values were within the South African recommended salt iodine fortification level at production of 35-65 ppm, whilst 21% of SIC were >65 ppm. Thyroid-stimulating hormone, total thyroxine, and thyroglobulin concentrations in the dried whole blood spot specimens from the infants were 1.3 (0.8-1.9) mU/L, 128±33 mmol/L, and 77.1 (56.3-105.7) μg/L, respectively, and did not correlate with infant UIC or BMIC. CONCLUSION Our results suggest that the salt fortification program in South Africa provides adequate iodine to lactating women and indirectly to their infants via breast milk. However, monitoring of salt iodine content of the mandatory salt iodization program in South Africa is important to avoid over-iodization of salt.
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Affiliation(s)
- Jennifer Osei
- North-West University, Centre of Excellence for Nutrition, Potchefstroom, South Africa, Phone: +27 18 299 40 11 E-mail:
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Aakre I, Strand TA, Bjøro T, Norheim I, Barikmo I, Ares S, Alcorta MD, Henjum S. Thyroid Function among Breastfed Children with Chronically Excessive Iodine Intakes. Nutrients 2016; 8:E398. [PMID: 27367720 PMCID: PMC4963874 DOI: 10.3390/nu8070398] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 06/16/2016] [Accepted: 06/23/2016] [Indexed: 12/30/2022] Open
Abstract
Iodine excess may impair thyroid function and trigger adverse health consequences for children. This study aims to describe iodine status among breastfed infants with high iodine exposure in the Saharawi refugee camps Algeria, and further assess thyroid function and iodine status among the children three years later. In 2010, a cross-sectional study among 111 breastfed children aged 0-6 months was performed (baseline study). In 2013, a second cross-sectional study (follow-up study) was conducted among 289 children; 213 newly selected and 76 children retrieved from baseline. Urinary iodine concentration (UIC) and breast milk iodine concentration (BMIC) were measured at baseline. UIC, thyroid hormones and serum thyroglobulin (Tg) were measured at follow-up. At baseline and follow-up, 88% and 72% had excessive iodine intakes (UIC ≥ 300 µg/L), respectively. At follow-up, 24% had a thyroid hormone disturbance and/or elevated serum Tg, including 9% with subclinical hypothyroidism (SCH), 4% with elevated fT3 and 14% with elevated Tg. Children with SCH had poorer linear growth and were more likely to be underweight than the children without SCH. Excessive iodine intakes and thyroid disturbances were common among children below four years of age in our study. Further, SCH seemed to be associated with poor growth and weight.
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Affiliation(s)
- Inger Aakre
- Department of Nursing and Health Promotion, Faculty of Health Sciences, Oslo and Akershus University College, 0130 Oslo, Norway.
- Department of Global Public Health and Primary Care, Faculty of Medicine and Dentistry, University of Bergen, 5018 Bergen, Norway.
| | - Tor A Strand
- Department of Global Public Health and Primary Care, Faculty of Medicine and Dentistry, University of Bergen, 5018 Bergen, Norway.
- Research Department, Innlandet Hospital Trust, 2609 Lillehammer, Norway.
| | - Trine Bjøro
- Department of Medical Biochemistry, Oslo University Hospital, 0379 Oslo, Norway.
- Institute of Clinical Medicine, University of Oslo, 0379 Oslo, Norway.
| | - Ingrid Norheim
- Department of Endocrinology, Morbid Obesity and Preventive Medicine, Oslo University Hospital, 0424 Oslo, Norway.
| | - Ingrid Barikmo
- Department of Nursing and Health Promotion, Faculty of Health Sciences, Oslo and Akershus University College, 0130 Oslo, Norway.
| | - Susana Ares
- Neonatology Unit, University Hospital La Paz, University of Madrid, 28046 Madrid, Spain.
| | - Marta Duque Alcorta
- Neonatology Unit, University Hospital La Paz, University of Madrid, 28046 Madrid, Spain.
| | - Sigrun Henjum
- Department of Nursing and Health Promotion, Faculty of Health Sciences, Oslo and Akershus University College, 0130 Oslo, Norway.
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Henjum S, Kjellevold M, Ulak M, Chandyo RK, Shrestha PS, Frøyland L, Strydom EE, Dhansay MA, Strand TA. Iodine Concentration in Breastmilk and Urine among Lactating Women of Bhaktapur, Nepal. Nutrients 2016; 8:E255. [PMID: 27136582 PMCID: PMC4882668 DOI: 10.3390/nu8050255] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 04/15/2016] [Accepted: 04/21/2016] [Indexed: 11/24/2022] Open
Abstract
Adequate iodine concentration in breastmilk (BMIC) is essential for optimal neonatal thyroid hormone synthesis and neurological development in breastfed infants. For many decades, iodine deficiency has been a public health problem in Nepal. However, recently, excessive iodine intakes among Nepali infants have been reported. This study aimed to measure BMIC and urinary iodine concentration (UIC) among lactating women in a peri-urban area of Nepal. Iodine concentration was measured in spot urine (n = 485) and breastmilk samples (n = 291) of 500 randomly selected lactating women. The median (p25, p75) BMIC and median UIC were 250 (130, 370) µg/L and 230 (135-377) µg/L, respectively. Around 82% had BMIC > 100 µg/L, 61% had BMIC > 200 µg/L and 81% had UIC > 100 µg/L, 37% had >300 µg/L and 20% had >500 µg/L. In multiple linear regression models, time since birth (β 3.0, 95% CI (0.2, 5.0)) and UIC (β 1.0, 95% CI (0.1, 2.0)) were associated with BMIC, explaining 26% of the variance. A large proportion of the women had adequate BMIC and UIC; however, a subset had high iodine concentrations. These findings emphasize the importance of carefully monitoring iodine intake to minimize the risk of iodine excess and subsequently preventing transient iodine-induced hypothyroidism in breastfed infants.
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Affiliation(s)
- Sigrun Henjum
- Oslo and Akershus University College of Applied Sciences, P.O. Box 4, St. Olavs plass, Oslo 0130, Norway.
| | - Marian Kjellevold
- National Institute of Nutrition and Seafood Research (NIFES), Bergen 5817, Norway.
| | - Manjeswori Ulak
- Department of Child Health, Institute of Medicine, Tribhuvan University ,Maharajgunj, P.O. Box 1524, Kathmandu 44600, Nepal.
| | - Ram K Chandyo
- Centre for International Health, University of Bergen, P.O. Box 7800, Bergen 5020, Norway.
| | - Prakash S Shrestha
- Department of Child Health, Institute of Medicine, Tribhuvan University ,Maharajgunj, P.O. Box 1524, Kathmandu 44600, Nepal.
| | - Livar Frøyland
- National Institute of Nutrition and Seafood Research (NIFES), Bergen 5817, Norway.
| | - Emmerentia E Strydom
- Burden of Disease Research Unit, South African Medical Research Council, P.O. Box 19070, Tygerberg 7505, South Africa.
| | - Muhammad A Dhansay
- Burden of Disease Research Unit, South African Medical Research Council, P.O. Box 19070, Tygerberg 7505, South Africa.
- Division of Human Nutrition and Department of Paediatrics and Child Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Francie van Zijl Drive, Tygerberg Hospital, Tygerberg 7505, South Africa.
| | - Tor A Strand
- Department of Research, Innlandet Hospital Trust, Lillehammer 2629, Norway.
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