Iodine deficiency in the UK: an overlooked cause of impaired neurodevelopment?

This review describes historical iodine deficiency in the UK, gives current information on dietary sources of iodine and summarises recent evidence of iodine deficiency and its association with child neurodevelopment. Iodine is required for the production of thyroid hormones that are needed for brain development, particularly during pregnancy. Iodine deficiency is a leading cause of preventable brain damage worldwide and is associated with impaired cognitive function. Despite a global focus on the elimination of iodine deficiency, iodine is a largely overlooked nutrient in the UK, a situation we have endeavoured to address through a series of studies. Although the UK has been considered iodine-sufficient for many years, there is now concern that iodine deficiency may be prevalent, particularly in pregnant women and women of childbearing age; indeed we found mild-to-moderate iodine deficiency in pregnant women in Surrey. As the major dietary source of iodine in the UK is milk and dairy produce, it is relevant to note that we have found the iodine concentration of organic milk to be over 40% lower than that of conventional milk. In contrast to many countries, iodised table salt is unlikely to contribute to UK iodine intake as we have shown that its availability is low in grocery stores. This situation is of concern as the level of UK iodine deficiency is such that it is associated with adverse effects on offspring neurological development; we demonstrated a higher risk of low IQ and poorer reading-accuracy scores in UK children born to mothers who were iodine-deficient during pregnancy. Given our findings and those of others, iodine status in the UK population should be monitored, particularly in vulnerable subgroups such as pregnant women and children.

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Iodine Deficiency in Latvia: Current Status and Need for National Recommendations

Proceedings of the Latvian Academy of Sciences Section B Natural Exact and Applied Sciences ◽

10.1515/prolas-2017-0071 ◽

2017 ◽

Vol 71 (6) ◽

pp. 401-407

Author(s):

Ilze Konrāde ◽

Ieva Kalere ◽

Ieva Strēle ◽

Marina Makrecka-Kūka ◽

Vija Veisa ◽

...

Keyword(s):

Pregnant Women ◽

Iodine Deficiency ◽

Urinary Iodine ◽

Iodine Concentration ◽

Iodine Intake ◽

Medical Decision ◽

Current Status ◽

Urinary Iodine Concentration ◽

Childbearing Age ◽

Cross Sectional

Abstract In the absence of a mandatory salt iodisation programme, two nationwide cross-sectional cluster surveys revealed persisting iodine deficiency among Latvian schoolchildren during the spring season and a noteworthy iodine deficiency in pregnant women in Latvia; these deficiencies warrant intervention. The consequences of mild-to-moderate iodine deficiency during pregnancy and lactation can adversely affect foetal brain development. Data from a Latvian population survey revealed the consumption of approximately 100 μg of iodine per day through foods and iodised salt. Therefore, strategies to increase the consumption of iodine-containing products should be implemented, particularly for children. In addition, to meet the increased iodine requirement during pregnancy, pregnant women should take daily supplements containing 150 μg iodine from the earliest time possible. All women of childbearing age should be advised to increase their dietary iodine intake by using iodised table salt and iodine-rich products: seafood, milk and milk products. For women with pre-existing thyroid pathologies, the medical decision should be considered on a case-by-case basis. Urinary iodine concentration monitoring among schoolchildren and pregnant women and neonatal thyrotropin registry analysis every five years would be an appropriate strategy for maintaining iodine intake within the interval that prevents iodine deficiency disorders.

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

British Journal Of Nutrition ◽

10.1017/s0007114520003876 ◽

2020 ◽

pp. 1-9

Author(s):

M. Dineva ◽

M. P. Rayman ◽

S. C. Bath

Keyword(s):

At Risk ◽

Iodine Deficiency ◽

Urinary Iodine ◽

Iodine Concentration ◽

Iodine Intake ◽

Urinary Iodine Concentration ◽

Nutrition Survey ◽

Iodine Status ◽

Adults And Children ◽

The Uk

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

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Iodine deficiency in pregnant women living in the South East of the UK: the influence of diet and nutritional supplements on iodine status

British Journal Of Nutrition ◽

10.1017/s0007114513004030 ◽

2014 ◽

Vol 111 (9) ◽

pp. 1622-1631 ◽

Cited By ~ 60

Author(s):

Sarah C. Bath ◽

Alan Walter ◽

Andrew Taylor ◽

John Wright ◽

Margaret P. Rayman

Keyword(s):

Pregnant Women ◽

Iodine Deficiency ◽

Urinary Iodine ◽

World Health ◽

The South ◽

Childbearing Age ◽

Iodine Status ◽

Supplement Use ◽

Iodine Excretion ◽

The Uk

Iodine is a key component of the thyroid hormones which are crucial for brain development. Adequate intake of iodine in pregnancy is important as in utero deficiency may have lifelong consequences for the offspring. Data on the iodine status of UK pregnant women are sparse, and there are no such data for pregnant women in the South East of the UK. A total of 100 pregnant women were recruited to a cross-sectional study carried out at the Royal Surrey County Hospital, Guildford, at their first-trimester visit for an ultrasound scan. The participants provided a spot-urine sample (for the measurement of urinary iodine concentration (UIC) and creatinine concentration) and 24 h iodine excretion was estimated from the urinary iodine:creatinine ratio. Women completed a general questionnaire and a FFQ. The median UIC (85·3 μg/l) indicated that the group was iodine deficient by World Health Organisation criteria. The median values of the iodine:creatinine ratio (122·9 μg/g) and of the estimated 24 h iodine excretion (151·2 μg/d) were also suggestive of iodine deficiency. UIC was significantly higher in women taking an iodine-containing prenatal supplement (n 42) than in those not taking such a supplement (P< 0·001). In the adjusted analyses, milk intake, maternal age and iodine-containing prenatal supplement use were positively associated with the estimated 24 h urinary iodine excretion. Our finding of iodine deficiency in these women gives cause for concern. We suggest that women of childbearing age and pregnant women should be given advice on how to improve their iodine status through dietary means. A national survey of iodine status in UK pregnant women is required.

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Prevalence of iodine deficiency among pregnant women in Gwembe and Sinazongwe districts of Southern Province, Zambia: a cross-sectional study

BMC Nutrition ◽

10.1186/s40795-020-00397-w ◽

2020 ◽

Vol 6 (1) ◽

Author(s):

Trevor Kaile ◽

Bornwell Sikateyo ◽

Masauso M. Phiri ◽

Charles Michelo

Keyword(s):

Pregnant Women ◽

Iodine Deficiency ◽

Iodine Concentration ◽

Cross Sectional Study ◽

Iodine Intake ◽

Health Concern ◽

Cross Sectional ◽

Southern Province ◽

Food And Nutrition ◽

Urine Iodine

Abstract Background Maternal iodine deficiency is one of the common causes of morbidity and mortality during pregnancy. Maternal iodine deficiency during pregnancy is associated with a number of adverse outcomes such as abortion, stillbirth, congenital anomalies, perinatal mortality and irreversible mental retardation. A study conducted in Zambia among pregnant women in 2013 on the prevalence of iodine deficiency showed that iodine deficiency was not a public health concern. The previous study used Urine Iodine concentration (UIC) as a marker of iodine deficiency among the pregnant women. Our study was conducted to assess the prevalence of iodine deficiency among pregnant women in Gwembe and Sinazongwe districts of Southern Province, Zambia, using urine iodine concentration and goitre presence by manual palpation. Methods We carried out a community based, cross sectional study in rural areas of Gwembe and Sinazongwe districts between April 2016 to March 2018. Data were collected from 412 pregnant women by a multistage cluster sampling technique. The presence of a goitre was examined by manual palpation and urinary iodine concentration was determined by the Ultra Violet Method using PerkinElmer Labda UV Spectrometer equipment made in Jena Germany (Model 107,745). As part of the existing baseline data, we used results of a 2013 countrywide study (n = 489) for household salt iodine content which showed a greater than 40 ppm at 76.2%, between 15 and 40 ppm at 19.21% and less than 15 ppm at 4.59%. Statistical analysis was done using Stata version 14.0. The outputs of analysis are presented as median and Interquartile range (IQR) as the urine data were not normally distributed. Further, the categorical and independent variables were presented as proportions (percentages) to describe the distribution and trends in the target sample population. Results The median Urine Iodine concentration (UIC) of the pregnant women was 150 μg/L (Interquartile Range (IQR): 100–200 μg/L). Based on the UIC, There were 49% pregnant women who had inadequate iodine intake with urine iodine concentration of less than 150 μg/L, 34.0% had UIC of 150–249 μg/L indicating adequate iodine intake, 13.0% with UIC of 250–499 μg/L indicating more than adequate iodine intake, and 5.0% with UIC of above 500 μg/L indicating excessive iodine intake. To determine whether the women had access to iodized salt, we used baseline data from 2013 Zambia national survey for iodine concentration in household salt samples as being an average of 40 ppm, which also showed that 95.41% households consumed adequately iodized salt (≥15 ppm). The prevalence of goitre in our study was very low at 0.02% among the pregnant women of all ages who participated in the study (18–49 years). Conclusion Iodine deficiency was still not a public health concern among the pregnant women of Gwembe and Sinazongwe districts of Southern Province in Zambia. Goitre prevalence has remained very low in this study area. The UIC and goitre observations were consistent with the Zambia National Food and Nutrition Commission findings in 2013 report. However, our study showed more pregnant women with insufficient than adequate iodine status indicating the risk of developing IDD is still high in this region. It also reinforces the argument that strengthening of the existing salt iodization program is needed in order to make a homogenous iodated salt available to the communities. The National Food and Nutrition Commission of Zambia needs to find innovative ways of sensitizing people about the adverse effects of IDDs and how these could be prevented. It is recommended that iodine supplementation be introduced as part of the package of Antenatal clinic care for all pregnant women.

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Indicators of Iodine Status in Pregnancy and Postpartum in a Group of Pregnant Women from Perimarine Area of Romania

ARS Medica Tomitana ◽

10.2478/arsm-2020-0013 ◽

2020 ◽

Vol 26 (2) ◽

pp. 63-69

Author(s):

Scrinic Olesea ◽

Delia Corina Elena ◽

Toma Geanina Mirela ◽

Circo Eduard

Keyword(s):

Pregnant Women ◽

Iodine Deficiency ◽

Urinary Iodine ◽

Iodine Concentration ◽

Iodine Intake ◽

Iodized Salt ◽

Urinary Iodine Concentration ◽

Urinary Creatinine ◽

Iodine Status ◽

In Pregnancy

Abstract Objective: Assessment of iodine nutritional status in pregnant women in the perimarine area of Romania, a region without iodine deficiency. Adequate iodine intake is the main source for normal thyroid function, ensuring the need for maternal thyroid hormones during pregnancy, but also for the development and growth of children in the fetal and postpartum period. Material and method: Prospective study performed on 74 pregnant women in the first 2 trimesters of pregnancy, originating from the perimarin area. The following indicators of iodine status were analyzed: urinary iodine concentration (UIC), the ratio between urinary iodine concentration and urinary creatinine (UIC/UCr), the prevalence of maternal goiter and the value of neonatal TSH (thyroid stimulating hormone). Results: The mean gestational age was 11 weeks. The ways of iodine intake are: iodized salt - 59.4%, iodized salt and iodine supplements- 23%, only iodine supplements -10.8% and 6.8% consume only non-iodized salt. The median of UIC was 133.03 mcg/l considered insufficient iodine intake (normal in pregnancy UIC >150 mcg/l), but the adjustment of UIC to urinary creatinine reveals a median of 152.83 mcg/g, a value that reflects an adequate iodine intake. The prevalence of goiter was 25.6% characteristic for a moderate iodine deficiency. The prevalence of neonatal TSH >5 mIU/L was registered in 18.8% characteristic of mild iodine deficiency. Conclusions: Monitoring of the iodine nutritional status is recommended for the prevention of disorders due to iodine deficiency under the conditions of universal salt iodization. Perimarine areas considered sufficient in iodine may show variations in iodine status in subpopulations under certain physiological conditions, such as pregnancy. An indicator of iodine status of the population is UIC, but the UIC/UCr ratio may be a more optimal indicator for pregnant women, to avoid possible overestimated results of iodine deficiency in pregnancy.

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Iodine deficiency among Belgian pregnant women not fully corrected by iodine-containing multivitamins: a national cross-sectional survey

British Journal Of Nutrition ◽

10.1017/s0007114512004473 ◽

2012 ◽

Vol 109 (12) ◽

pp. 2276-2284 ◽

Cited By ~ 32

Author(s):

Stefanie Vandevijvere ◽

Sihame Amsalkhir ◽

Ahmed Bensouda Mourri ◽

Herman Van Oyen ◽

Rodrigo Moreno-Reyes

Keyword(s):

Pregnant Women ◽

Iodine Deficiency ◽

Urinary Iodine ◽

Iodine Intake ◽

Urinary Iodine Concentration ◽

Childbearing Age ◽

Third Trimester ◽

Cross Sectional Survey ◽

Cross Sectional ◽

Iodine Status

Low iodine intake during pregnancy may cause thyroid dysfunction in pregnant women and their newborn. In the present study, iodine status among a nation-wide representative sample of Belgian pregnant women in the first and third trimester of pregnancy was determined, and determinants of iodine status were assessed 1 year after the introduction of bread fortified with iodised salt. The women were selected according to a multistage proportionate-to-size sampling design. Urine samples were collected and a general questionnaire was completed face to face with the study nurse. The median urinary iodine concentration (UIC) among pregnant women (n1311) was 124·1 μg/l and 122·6 μg/g creatinine when corrected for urinary creatinine. The median UIC in the first trimester (118·3 μg/l) was significantly lower than that in the third trimester (131·0 μg/l) but significantly higher than among non-pregnant women (84·8 μg/l). Iodine-containing supplement intake was reported by 60·8 % of the women and 57·4 % of the women took this supplement daily. The risk of iodine deficiency was significantly higher in younger women, in women not taking iodine-containing supplements, with low consumption of milk and dairy drinks and during autumn. Women with a higher BMI had a higher risk of iodine deficiency but the risk was lower in women who reported alcohol consumption. The median UIC during pregnancy indicates iodine deficiency in Belgium and some women are at a higher risk of deficiency. The current low iodine intake in women of childbearing age precludes the correction of iodine deficiency in pregnant women supplemented with multivitamins containing 150 μg iodine as recommended.

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A systematic review of iodine deficiency among women in the UK

Public Health Nutrition ◽

10.1017/s1368980018003506 ◽

2018 ◽

Vol 22 (06) ◽

pp. 1138-1147 ◽

Cited By ~ 1

Author(s):

Huiqing Jiang ◽

Hilary J Powers ◽

Giulia S Rossetto

Keyword(s):

Systematic Review ◽

Pregnant Women ◽

Iodine Deficiency ◽

Large Scale ◽

Urinary Iodine ◽

Women Of Childbearing Age ◽

Childbearing Age ◽

Female Population ◽

Iodine Status ◽

The Uk

AbstractObjectiveThe present study reviewed the literature on iodine status among women of childbearing age and pregnant women in the UK. Particular attention was given to study quality and methods used to assess iodine status.DesignA systematic review was conducted to examine the literature and critically evaluate study design.SettingStudies were identified in PubMed, Web of Science, Scopus and Ovid MEDLINE databases, as well as from secondary references.ParticipantsWomen of childbearing age or pregnant, living in the UK.ResultsFifty-seven articles were identified and twelve articles were selected, including a total of 5283 women. Nine studies conducted urinary iodine assessments, three studies conducted dietary assessments only, and seven studies classified their target population as iodine deficient according to WHO criteria.ConclusionsNo single study from the selected articles could produce nationally representative results regarding the prevalence of iodine deficiency among the female population in the UK. Consideration of the evidence as a whole suggests that women of childbearing age and pregnant women in the UK are generally iodine insufficient. Further large-scale research is required for more accurate and reliable evidence on iodine status in the UK.

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Symposium on ‘Geographical and geological influences on nutrition’ Iodine deficiency in industrialised countries

Proceedings of The Nutrition Society ◽

10.1017/s0029665109991819 ◽

2009 ◽

Vol 69 (1) ◽

pp. 133-143 ◽

Cited By ~ 51

Author(s):

Michael B. Zimmermann

Keyword(s):

Pregnant Women ◽

Iodine Deficiency ◽

Dairy Industry ◽

Iodine Intake ◽

Salt Consumption ◽

Iodine Supplementation ◽

The Usa ◽

The Republic ◽

The Uk ◽

Industrialised Countries

Iodine deficiency is not only a problem in developing regions; it also affects many industrialised countries. Globally, two billion individuals have an insufficient iodine intake, and approximately 50% of continental Europe remains mildly iodine deficient. Iodine intakes in other industrialised countries, including the USA and Australia, have fallen in recent years. Iodine deficiency has reappeared in Australia, as a result of declining iodine residues in milk products because of decreased iodophor use by the dairy industry. In the USA, although the general population is iodine sufficient, it is uncertain whether iodine intakes are adequate in pregnancy, which has led to calls for iodine supplementation. The few available data suggest that pregnant women in the Republic of Ireland and the UK are now mildly iodine deficient, possibly as a result of reduced use of iodophors by the dairy industry, as observed in Australia. Representative data on iodine status in children and pregnant women in the UK are urgently needed to inform health policy. In most industrialised countries the best strategy to control iodine deficiency is carefully-monitored salt iodisation. However, because approximately 90% of salt consumption in industrialised countries is from purchased processed foods, the iodisation of household salt only will not supply adequate iodine. Thus, in order to successfully control iodine deficiency in industrialised countries it is critical that the food industry use iodised salt. The current push to reduce salt consumption to prevent chronic diseases and the policy of salt iodisation to eliminate iodine deficiency do not conflict; iodisation methods can fortify salt to provide recommended iodine intakes even ifper capitasalt intakes are reduced to <5 g/d.

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Evaluation of median urinary iodine concentration cut-off for defining iodine deficiency in pregnant women after a long term USI in China

Nutrition & Metabolism ◽

10.1186/s12986-019-0381-4 ◽

2019 ◽

Vol 16 (1) ◽

Cited By ~ 4

Author(s):

Huidi Zhang ◽

Meng Wu ◽

Lichen Yang ◽

Jinghuan Wu ◽

Yichun Hu ◽

...

Keyword(s):

Pregnant Women ◽

Thyroid Function ◽

Iodine Deficiency ◽

Urinary Iodine ◽

Iodine Concentration ◽

Iodine Intake ◽

Urinary Iodine Concentration ◽

Normal Thyroid ◽

Normal Thyroid Function

Abstract Background The WHO/UNICEF/ICCIDD define iodine deficiency during pregnancy as median urinary iodine concentration (MUIC) ≤ 150 μg/L. China implemented universal salt iodization (USI) in 1995, and recent surveillance showed nationwide elimination of iodine deficiency disorders (IDD). Data from 2014 showed that the MUIC in 19,500 pregnant women was 154.6 μg/L and 145 μg/L in 9000 pregnant women in 2015. However, symptoms of iodine deficiency were absent. Our study sought to evaluate whether MUIC below 150 μg/L affects thyroid function of Chinese pregnant women and their newborns in Chinese context. Methods We screened 103 women with normal thyroid function and MUIC lower than 150 μg/L during week 6 of pregnancy at Peking Union Medical College Hospital. Patient demographics and dietary salt intake were recorded. Subjects were followed at 12, 24, and 32 gestational weeks. At each visit, a 3-day dietary record, drinking water samples, and edible salt samples were collected and analyzed for total dietary iodine intake. Additionally, 24-h urine iodine and creatinine were measured. Blood tests assessed thyroid function in both mothers and newborns. Results Of 103 pregnant women enrolled, 79 completed all follow-up visits. Most subjects maintained normal thyroid function throughout pregnancy. However, 19 had thyroid dysfunction based on thyroid stimulating hormone and free thyroxine levels. The median serum iodine was 71 μg/L (95% CI: 44, 109). The median thyroglobulin was < 13 μg/L. values above this level indicate iodine deficiency in pregnant women. The median dietary iodine intake during pregnancy, derived from the 3-day record and measures of water and salt, was 231.17 μg/d. Assuming 90% urinary iodine excretion (UIE), 200.11 μg/d UIE means the 222.34 μg iodine loss per day, suggesting that subjects had a positive iodine balance throughout pregnancy. All neonatal blood samples showed TSH levels lower than 10 mIU/L, indicating normal thyroid function. No significant difference was found among gestational weeks for urinary iodine, and the MUIC in subjects who completed 3 follow-up visits was 107.41 μg/L. Conclusion Twenty years after implementing USI, expectant Chinese mothers with MUIC of 107.4 μg/L, less than the WHO’s 150 μg/L benchmark, maintained thyroid function in both themselves and their newborn babies.

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