Iodine knowledge is positively associated with dietary iodine intake among women of childbearing age in the UK and Ireland

Iodine status and knowledge among pregnant and lactating women in Large City in Northern China after nearly 30 years of the universal salt iodization

BACKGROUND

With the implementation of the universal salt iodization, the iodine nutrition for children and adults has been appropriate, but pregnant women are still at risk of iodine deficiency. It is of great public health significance to explore the iodine status and knowledge, and influence factors and the appropriate health education methods among pregnant and lactating women.

METHODS

From January 2022 to December 2023, at least 50 pregnant women and 50 lactating women were randomly selected from the resident population annually in 16 districts of Tianjin, North China. A total of 1671 pregnant women and 1658 lactating women were recruited. All participants' households salt and random urine samples were collected. A questionnaire was conducted to collect data on iodine related knowledge and behaviors as well as needs of health education from all participants. Logistic regression models were constructed to analyze the factors affecting the iodine related knowledge level. We used the Rasch model and the quadrantal graph to analyze the participants' knowledge level on different iodine-related questions and their needs for health education.

RESULTS

The median urine iodine concentration (UIC) of pregnant and lactating women in Tianjin were 152.40 μg/L and 124.60 μg/L. In some districts, the median UIC of pregnant and lactating women below the appropriate range. The iodized salt coverage rate of pregnant and lactating women in Tianjin was 76.12% and 77.40%, respectively. In pregnant and lactating women who did not actively supplement with iodine, the median UIC in those who consumed non-iodized salt were significantly lower than that in those who consumed iodized salt (139.26 μg/L and 154.40 μg/L, P = 0.044; 94.60 μg/L and 123.80 μg/L, P < 0.001). Compared with the low knowledge score group, pregnant women in the high knowledge score group had a higher proportion of iodized salt consumption (71.25% and 78.05%, P = 0.003), and pregnant and lactating women in the high knowledge score group had a higher proportion of actively supplement iodine (44.61% and 55.34%, P < 0.001; 39.26% and 49.78%, P < 0.001). Health education may be the main factor affecting the iodine related knowledge scores for pregnant and lactating women, with adjusted odds ratios (OR) and 95% confidence intervals (CI) of 2.89 (2.30, 3.62) and 2.46 (1.97, 3.07), respectively. Pregnant and lactating women are most expected to acquire knowledge through healthcare professionals (72.11%) and wechat/website (74.91%), respectively.

CONCLUSIONS

Pregnant and lactating women in some areas of Tianjin are at risk of iodine deficiency. Iodized salt consumption is an important way to ensure iodine nutrition of the population, and the lack of iodine related knowledge is an important factor affecting the consumption of iodized salt. Health education in different ways can be carried out for different people to improve the acceptance and efficiency of health education.

Low Iodine Nutrition Knowledge in Chinese Breastfeeding Women despite Adequate Iodine Status

There has been a scarcity of evidence about iodine nutrition knowledge among women during pregnancy and lactation. The aim of this study was to determine women's iodine knowledge and the relationship between knowledge and iodine status during pregnancy and lactation. Women were recruited from a hospital in the western part of China in the third trimester of pregnancy and followed until the end of the first week of lactation. The women's iodine status was measured by their urinary iodine concentration (UIC) and an iodine-specific, validated food frequency questionnaire (FFQ). Iodine nutrition knowledge was assessed using an iodine nutrition knowledge questionnaire. A total of 200 women (mean age of 29.0 ± 4.2 years) completed the whole study. The majority of the women did not consume enough iodine during both pregnancy and lactation (231.89 vs. 237.26 µg/day). The overall mean iodine knowledge scores in our sample of women during pregnancy and lactation were 4.77 and 4.87, indicating low iodine knowledge. The use of iodized salt and a higher education level were significantly associated with an increased iodine knowledge score. In conclusion, this study reported poor iodine nutrition knowledge in women, highlighting a public health concern. Therefore, the iodine knowledge of women should be improved, possibly via maternal health campaigns to avoid the consequences of iodine deficiency disorders in newborns.

Adoption of a Short-Term (4-Week) Vegan Diet as Part of 'Veganuary' Significantly Reduces Saturated Fatty Acid (SFA), Cholesterol, B12, and Iodine Intake in Omnivorous Individuals-An Observational Study

Global veganism campaigns like 'Veganuary' have gained popularity. We conducted an observational study to assess the impact of a 4-week vegan diet during 'Veganuary' on nutrient intake, status, knowledge, and motivations for veganism. Data were collected before and after 'Veganuary', using Food Frequency Questionnaires (FFQs) to estimate dietary intake. Micronutrient knowledge and motivation were assessed through questionnaires. A total of 154 UK adults aged 18-60 years (2019: n81; 2020: n73) participated. Groups were vegetarians and omnivores committed to a 4-week vegan diet during 'Veganuary'. Control groups were vegans and omnivores who did not transition. Short-term vegan diets significantly decreased intake of iodine, B12, cholesterol, and saturated fatty acids (SFAs) in omnivores. Micronutrient knowledge was low, and motivation for veganism varied. Short-term vegan diets reduce macro- and micronutrient intake in omnivores. Veganuary participants could benefit from nutritional guidance or supplementation. Attention is required for UK micronutrient intake and knowledge. Motivations for vegan pledges may influence diets, warranting further research.

Factors associated with recent iodine intake level among household food handlers in Southwest Ethiopia: a cross-sectional study

BACKGROUND

Iodine deficiency is a global public health threat, affecting an estimated two billion people. The median urinary iodine concentration is more reliable in determining recent iodine intakes and the risks of iodine deficiency. Therefore, this study was aimed to identify the factors associated with recent iodine intake level using median urinary iodine concentration as an indicator among household food handlers in southwest Ethiopia.

METHODS

A community-based survey was conducted with selected households using a pretested interviewer-administered questionnaire in southwest Ethiopia. A 20-gram sample of table salt and a 5 ml causal urine samples were also collected and analyzed using rapid test kit and a Sandell-Kolthoff reaction, respectively. A salt iodine concentration above 15 ppm was classified as adequately iodized and a median urinary iodine concentration between 100 and 200µgl^- 1 was considered as adequate iodine intake. A bivariable and multivariable logistic regression model was fitted. Crude and adjusted odds ratios with their 95% confidence levels were reported. Associations with a p-value ≤ 0.05 were used to declare statistical significance.

RESULTS

A total of 478 women were included, with a mean age of 33.2 (± 8.4 years). Only 268 (56.1%) of the households had adequately iodized salt (> 15 ppm). The median urinary iodine concentration (interquartile range) was 87.5 µg l^- 1 (45.6-107.6). In a fitted multivariable logistic regression model (p-value = 0.911), illiterate women (AOR = 4.61; 95% CI: 2.17, 9.81), poorly iodized salt in the household (AOR = 25.0; 95% CI: 13-48), salt purchased from open market (AOR = 1.93; 95% CI: 1.0, 3.73) and women who do not read the label during purchasing the salt (AOR = 3.07; 95% CI: 1.31, 7.17) were important predictors of the risk of Iodine deficiency.

CONCLUSION

Despite public health efforts to improve iodine intake, its deficiency is still a major public health problem among southwest Ethiopian women.

Geographic and urban-rural disparities in dietary energy and macronutrient composition among women of childbearing age: findings from the China health and nutrition survey,1991-2015

BACKGROUND

Understanding nutritional status among women of childbearing age (WCA) is of increasing concern, as nutrient intakes may affect the health of WCA and well-being of their offspring. This study aimed to investigate secular trends of dietary energy and macronutrients intakes and access longitudinally the urban-rural and geographic disparities among Chinese WCA.

METHODS

A total of 10,219 participants were involved in three rounds of the Chinese Health and Nutrition Survey (CHNS:1991, 2004, and 2015). Average macronutrients intakes were compared against the Chinese Dietary Reference Intakes Standard (DRIs) to better assess adequacy. Mixed effect models were used to estimate the secular trends of dietary intake.

RESULTS

A total of 10,219 participants were involved. Dietary fat, the percentage of energy (%E) from fat, and the proportion with more than 30% of energy from fat and less than 50% from carbohydrates increased notably over time (p < 0.001). In 2015, urban western WCA had the most dietary fat (89.5 g/d), %E from fat (41.4%), with the highest proportion of energy from fat (81.7%) and carbohydrate (72.1%) out the range of DRIs. From 1991 to 2015, the average urban-rural differences in dietary fat decreased from 15.7 g/d to 3.2 g/d among eastern WCA. However, it increased to 16.4 g/d and 6.3 g/d among central and western WCA, respectively.

CONCLUSION

WCA was experiencing a rapid transformation to a high-fat diet. Temporal variation with obvious urban-rural and geographic disparities in dietary. energy and macronutrient composition persistently existed among Chinese WCA.These findings have implications of future public strategies to strengthen the nutrition propaganda and education of balanced diet for WCA to help them to improve their nutritional status, especially for those living in western China.

Iodine fortification of plant-based dairy and fish alternatives: the effect of substitution on iodine intake based on a market survey in the UK

Milk, dairy products, and fish are the main sources of iodine in the UK. Plant-based products are increasingly popular, especially with young women, which may affect iodine intake as they are naturally low in iodine; this is concerning as iodine is required for fetal brain development. We, aimed to (i) assess the iodine fortification of products sold as alternatives to milk, yoghurt, cheese and fish through a cross-sectional survey of UK retail outlets in 2020, and (ii) model the impact of substitution with such products on iodine intake, using portion-based scenarios. We identified 300 products, including plant-based alternatives to: (i) milk (n 146); (ii) yoghurt (n 76); (iii) cheese (n 67) and (iv) fish (n 11). After excluding organic products (n 48), which cannot be fortified, only 28 % (n 29) of milk alternatives and 6 % (n 4) of yoghurt alternatives were fortified with iodine, compared with 88 % (n 92) and 73 % (n 51), respectively, with Ca. No cheese alternative was fortified with iodine, but 55 % were fortified with Ca. None of the fish alternatives were iodine fortified. Substitution of three portions of dairy product (milk/yoghurt/cheese) per day with unfortified alternatives would reduce the iodine provided by 97·9 % (124 v. 2·6 µg) and substantially reduce the contribution to the adult intake recommendation (150 µg/d; 83 v. 1·8 %). Our study highlights that the majority of plant-based alternatives are not iodine fortified and that the use of unfortified alternatives put consumers at risk of iodine deficiency.

Invited review: Iodine level in dairy products-A feed-to-fork overview

The theme of iodine in the dairy sector is of particular interest due to the involvement and the interconnection of several stakeholders along the dairy food chain. Iodine plays a fundamental role in animal nutrition and physiology, and in cattle it is an essential micronutrient during lactation and for fetal development and the calf's growth. Its correct use in food supplementation is crucial to guarantee the animal's recommended daily requirement to avoid excess intake and long-term toxicity. Milk iodine is fundamental for public health, being one of the major sources of iodine in Mediterranean and Western diets. Public authorities and the scientific community have made great efforts to address how and to what extent different drivers may affect milk iodine concentration. The scientific literature concurs that the amount of iodine administered through animal feed and mineral supplements is the most important factor affecting its concentration in milk of most common dairy species. Additionally, farming practices related to milking (e.g., use of iodized teat sanitizers), herd management (e.g., pasture vs. confinement), and other environmental factors (e.g., seasonality) have been identified as sources of variation of milk iodine concentration. Overall, the aim of this review is to provide a multilevel overview on the mechanisms that contribute to the iodine concentration of milk and dairy products.

Assessment of Dietary Intake of Iodine and Risk of Iodine Deficiency in Children with Classical Galactosaemia on Dietary Treatment

Iodine is an essential mineral required for the synthesis of thyroid hormones. Iodine plays a critical role in growth and neurocognitive development. Classical galactosaemia is a disorder resulting from an inborn error in galactose metabolism. Its current management consists of life-long lactose and galactose dietary restriction. This study estimated dietary intakes of iodine in infants and children with classical galactosaemia in the Republic of Ireland. The diets of 43 participants (aged 7 months-18 years) with classical galactosaemia were assessed for iodine intake using an iodine-specific food frequency questionnaire. Intakes were compared to the European Food Safety Authority (EFSA) dietary recommendations for iodine intake. The potential role of iodine fortification of dairy alternative products was also examined. There were no significant differences observed between sex, ethnicity and parental education and meeting dietary iodine recommendations. Differences, however, were seen between age groups, causing the p value to approach statistical significance (p = 0.06). Infants consuming infant formula were likely to meet iodine recommendations. However, over half (53%) of children aged 1-18 years had average intakes below the recommendations for age. For these children, consumption of iodine-fortified dairy alternative milk was the leading source of iodine in the diets, followed by fish/shellfish and eggs. An assessment of iodine intake should be undertaken during dietetic reviews for those with classical galactosaemia. Mandatory iodine fortification of all dairy alternative products would result in 92% of the total population cohort meeting iodine recommendations based on their current consumption.

Knowledge and awareness about and use of iodised salt among students in Germany and Greece

BACKGROUND

Iodine is an essential trace element, which is important for human metabolism, growth and mental development. Iodine deficiency may still occur in Europe and the use of iodised salt is an effective measure to enhance iodine intake. Knowledge and awareness about the importance of iodine in nutrition and health can have a positive impact on the use of iodised salt. Therefore, the aim of this study was to assess the knowledge about and use of iodised salt among university students in two European countries.

METHOD

Data from two countries (Germany and Greece) were extracted from a multi-centre cross-sectional survey, conducted among non-nutrition science/non-medical students from October 2018 to April 2019.

RESULTS

Among the 359 participants in Germany (35% females, median age: 22 years) and the 403 participants in Greece (51% females, median age: 21 years), 41% and 37%, respectively, reported use of iodised salt at home. Users and non-users did not differ by age, gender and Body Mass Index or general interest in nutrition in both cohorts. However, those who had a better knowledge about iodine and (iodised) salt or had previously attended nutrition classes were more likely to report iodised salt usage.

CONCLUSION

The results suggest that strengthening the imparting of nutritional information and additional education of young adults are needed and may improve knowledge about and usage of iodised salt.

A review of current knowledge about the importance of iodine among women of child-bearing age and healthcare professionals

Iodine is required for thyroid hormone synthesis and fetal neurogenesis. Recent population studies in the United Kingdom (UK) have found iodine deficiency among schoolgirls, women of child-bearing age and pregnant women. This review explores knowledge and awareness of iodine among women of child-bearing age and healthcare professionals (HCPs) in the UK, set within a global context. We aimed to identify gaps in iodine knowledge in the current UK setting of iodine deficiency without iodine fortification and where iodine is not included in antenatal guidelines. The search terms ‘iodine knowledge’ and ‘iodine awareness’ were used to identify relevant papers. Iodine knowledge is poor among women of child-bearing age in the UK according to four studies using questionnaires and qualitative methods. They were unsure of dietary sources of iodine and were not consistently provided with relevant information from HCPs during clinical care. Midwives have been recognised as the main providers of dietary information during pregnancy and, although they recognised the importance of their role in providing nutrition advice, they did not feel equipped to do so and lacked confidence in addressing nutritional concerns. Globally, there was a similar lack of knowledge, however, this was somewhat improved by the inclusion of iodine in antenatal care guidelines. Midwives’ knowledge of iodine was poor, as was knowledge among women of child-bearing age. Improved HCP knowledge and effective communication of information to pregnant women and women planning to conceive may help to improve iodine status which is of particular concern in pregnancy.

Vegans and vegetarians living in Nottingham (UK) continue to be at risk of iodine deficiency

Iodine is essential for thyroid hormone synthesis. Individuals adhering to vegan and vegetarian diets have been found to be vulnerable to iodine deficiency. Yet, iodine has not been monitored in these groups across time. This study aims to investigate iodine status, intake and knowledge in vegans, vegetarians and omnivores and determine changes between 2016-2017 and 2019. Dietary intake (µg/d) was estimated by 3-d food diaries and iodine FFQ. Urinary iodine concentration, analysed by inductively coupled plasma mass spectrometry, assessed iodine status according to WHO criteria. Iodine knowledge was scored by an adapted questionnaire. IBM SPSS was used for statistical analysis. Ninety-six adults (18-60 years) were recruited in October 2016-2017 (vegans: 12; vegetarians: 5; omnivores: 43) and June 2019 (vegans: 7; vegetarians: 10;omnivores: 19). Median dietary iodine was below the Reference Nutrient Intake for all groups. Vegans and vegetarians had the lowest iodine intake. Vegans had significantly lower iodine intake than omnivores (2016-2017, P = 0 032; 2019, P = 0 001). Omnivores had the highest iodine status (2016-2017, 79 4 µg/l; 2019, 72 4 µg/l) and vegans the lowest (2016-2017, 31 2 µg/l; 2019, 12 2 µg/l). Iodine knowledge was poor but did not differ between dietary groups (2016-2017, P = 0 219; 2019, P = 0 532). Vegans and vegetarians continue to be at risk of iodine deficiency. Further, iodine intake in the UK is poor independent of dietary choice. Iodine education is needed along with research into improving iodine nutrition at national level.

OUP accepted manuscript

Context

Adequate iodine intake is essential throughout life. Key dietary sources are iodized salt and animal products, but dietary patterns in Europe are changing, for example toward lower salt intake and a more plant-based diet.

Objective

To review iodine intake (not status) in European populations (adults, children, and pregnant women) to identify at-risk groups and dietary sources.

Data sources

PubMed, Embase, and Cochrane databases, as well as European national nutrition surveys were searched for data on had iodine intake (from dietary assessment) and sources of iodine, collected after 2006.

Data selection

In total, 57 studies were included, comprising 22 national surveys and 35 sub-national studies. Iodine intake data were available from national surveys of children aged <10 years (n = 11), 11–17 years (n = 12), and adults (n = 15), but data from pregnancy were only available from sub-national studies.

Results

Iodine intake data are lacking—only 17 of 45 (38%) European countries had iodine-intake data from national surveys. Iodine intake reported from national surveys was below recommendations for: (1) children aged <10 years in 2 surveys (18%), (2) boys and girls aged 11–17 years in 6 (50%) and 8 (68%) surveys, respectively, and (3) adult men and women in 7 (47%) and 12 (80%) surveys, respectively. In pregnant women, intake was below recommendations except where women were taking iodine-containing supplements. Just 32% of national surveys (n = 7) included iodized salt when estimating iodine intake. Milk, dairy products, fish, and eggs were important contributors to intake in many countries, suggesting limited sources in plant-based diets.

Conclusion

Results are limited by the challenges of dietary assessment for measuring iodine intake. Future national surveys should include iodine intake. Policy makers should consider dietary sources alongside any iodized salt policies when considering methods for improving population iodine intake.

Systematic Review Registration

PROSPERO 2017 CRD42017075422.

Consumer Acceptance and Market Potential of Iodine-Biofortified Fruit and Vegetables in Germany

Biofortification of food crops with iodine is a novel approach to preventing iodine deficiency in humans. The present study analyses the consumer target groups and the market potential of iodine-biofortified fruit and vegetables in Germany. For this purpose, an online survey of 1016 German fruit and vegetable consumers was conducted to investigate the acceptance of different product categories as well as relevant criteria for the market launch. The results show that iodine-biofortified fruit and vegetables are particularly attractive to consumers who purchase at farmers’ markets, organic food shops, and farm stores. Out of this group, 39% of consumers rate such iodine-rich foods as very appealing. They attach importance to food that naturally contains iodine and prefer produce from integrated domestic cultivation. With their focus on sustainability and naturalness, this group of consumers clearly differs from typical users of dietary supplements, who are primarily concerned with health benefits. However, overall about 85% of respondents would prefer biofortified fruits and vegetables to supplements to improve their iodine supply. The greatest market potential for iodine-biofortified fruit and vegetables is to be expected in supermarkets, as this is the preferred food shopping location for most consumers. A total of 28% of those who buy here rate the biofortified foods presented as very appealing. Nevertheless, a successful market launch requires that the benefits of the new products are communicated according to the potential consumer group needs.

Use of Iodine Supplements by Breastfeeding Mothers Is Associated with Better Maternal and Infant Iodine Status

Adequate iodine status during conception, pregnancy and lactation is essential for supporting infant neurodevelopment. Iodine status in adults and children was improved after two New Zealand government initiatives, but the status of breastfeeding women is unknown. This study aimed to investigate the iodine intake and status of lactating mother-infant pairs at 3 months postpartum and to assess maternal iodine knowledge and practice. Iodine intake was estimated by a weighed 4-day diet diary (4DDD). Maternal urinary iodine concentrations (UIC) in spot urine, breast milk iodine concentrations (BMIC) and infant UIC were measured. Questions about iodine-specific knowledge and practice were asked. In 87 breastfeeding mother-infant pairs, maternal iodine intake was 151 (99, 285) μg/day, and 58% had an intake below the estimated average requirement (EAR) of 190 μg/day. Maternal median UIC (MUIC) was 82 (46, 157) μg/L indicating iodine deficiency (i.e., < 100 μg/L). Women who used iodine-containing supplements had a significantly higher MUIC (111 vs 68 μg/L, P = 0.023) and BMIC (84 vs 62 μg/L, P < 0.001) than non-users. Infants fed by women using iodine-containing supplements had a higher MUIC (150 vs 86 μg/L, P = 0.036) than those of non-users. A total of 66% (57/87) of women had no or low iodine knowledge. The iodine knowledge score was a statistically significant predictor of consuming iodine-containing supplements [(beta = 1.321, P = 0.008)]. Despite a decade of initiatives to increase iodine intakes in New Zealand, iodine knowledge was low; iodine intake and status of these lactating women were suboptimal, but women who used iodine-containing supplement were more likely to achieve adequate status.Study Registration Number (Australia and New Zealand Clinical Trials Registry): ACTRN12615001028594.

Associations between maternal urinary iodine assessment, dietary iodine intakes and neurodevelopmental outcomes in the child: a systematic review

OBJECTIVE

Mild to moderate iodine deficiency during pregnancy has been associated with adverse neurodevelopmental outcomes in offspring. Few research studies to date combine assessment of urinary iodine (UIC and/or ICr), biomarkers that best reflect dietary intake, with reported dietary intake of iodine rich foods in their assessment of iodine deficiency. Thus, a systematic review was conducted to incorporate both these important measures.

DESIGN

Using PRISMA guidelines, a comprehensive search was conducted in three electronic databases (EMBASE®, MedLine® and Web of Science®) from January 1970-March 2021. Quality assessment was undertaken using the Newcastle Ottawa Scale. Eligible studies included reported assessment of iodine status through urinary iodine (UIC and/or ICr) and/or dietary intake measures in pregnancy alongside neurodevelopmental outcomes measured in the children. Data extracted included study author, design, sample size, country, gestational age, child age at testing, cognitive tests, urinary iodine assessment (UIC in μg/L and/or ICr in μg/g), dietary iodine intake assessment and results of associations for the assessed cognitive outcomes.

RESULTS

Twelve studies were included with nine reporting women as mild-moderately iodine deficient based on World Health Organization (WHO) cut-offs for urinary iodine measurements < 150 μg/l, as the median UIC value in pregnant women. Only four of the nine studies reported a negative association with child cognitive outcomes based on deficient urinary iodine measurements. Five studies reported urinary iodine measurements and dietary intakes with four of these studies reporting a negative association of lower urinary iodine measurements and dietary iodine intakes with adverse offspring neurodevelopment. Milk was identified as the main dietary source of iodine in these studies.

CONCLUSION

The majority of studies classified pregnant women to be mild-moderately iodine deficient based on urinary iodine assessment (UIC and/or ICr) and/or dietary intakes, with subsequent offspring neurodevelopment implications identified. Although a considerable number of studies did not report an adverse association with neurodevelopmental outcomes, these findings are still supportive of ensuring adequate dietary iodine intakes and urinary iodine monitoring throughout pregnancy due to the important role iodine plays within foetal neurodevelopment. This review suggests that dietary intake data may indicate a stronger association with cognitive outcomes than urinary iodine measurements alone. The strength of this review distinguishes results based on cognitive outcome per urinary iodine assessment strategy (UIC and/or ICr) with dietary data. Future work is needed respecting the usefulness of urinary iodine assessment (UIC and/or ICr) as an indicator of deficiency whilst also taking account of dietary intakes.

Knowledge, attitude and behaviour of university students regarding salt and iodine: a multicentre cross-sectional study in six countries in Europe and Asia

Background

Strategies to reduce salt intake are encouraged to be implemented in parallel with those that aim to ensure iodine adequacy at the population level. The aim of the present study was to assess and compare knowledge, attitudes and behaviours related to salt and iodine among students in Europe and Asia.

Methods

A multicentre cross-sectional study was conducted with 2459 university students in total (42.7% males, median age 21 years) from four countries in Europe and two countries in Asia. Data were collected with the use of a self-administered questionnaire, and univariate and multivariate statistical analyses were performed to explore any association between variables.

Results

Only 6.5% of all participants knew the correct salt recommendations. Nearly a quarter of them (24.4%) found salt recommendations confusing and/or contradictory. There were significant differences between European and Asian participants, with those from Europe being better informed about salt recommendations, but significantly less knowledgeable about iodine. The reported frequency of use of salt and salt-containing sauces either at the table or for cooking, as well as knowledge about ways to reduce salt intake among those who indicated to make conscious efforts to do so, differed significantly between countries. Significant differences between countries were also observed with respect to the type of salt used, with about one third of all participants (34%) not being aware of the kind of salt they used.

Conclusion

The results of this survey highlight serious salt- and iodine-related knowledge gaps among university students in Europe and Asia. Raising awareness and conducting information campaigns is needed to promote changes in behaviour that would result in a reduction of salt intake and conscious use of iodised salt at the individual level.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13690-021-00593-5.

Factors Associated with Thyroid Disorders and Iodine Adequacy in Pregnant Saudi Women

Little is known about iodine adequacy and gestational thyroid disorders (GTDs) in Saudi Arabia. This study measured the rates of GTDs and iodine adequacy in 810 healthy Saudi women. Concentrations of serum thyroid hormones and 24-h urine iodine (24-h UIC), and GTDs were diagnosed according to the American Thyroid Association guidelines. Dietary and socioeconomic data to determine factors associated with GTDs and iodine insufficiency were collected. GTDs were detected in 265 women (32.7%) as follows: subclinical (SCH; 20.2%) and overt (OH; 5.8%) hypothyroidism, isolated hypothyroxinemia (ISH; 4.7%) and hyperthyroidism (2%). The SCH (109.2 μg/L; IQR: 77.2-149.7), OH (95.3 μg/L; IQR: 74.3-130.5) and ISH (107.3 μg/L; IQR: 65.5-133.1) groups had median 24-h UIC below the WHO recommended limit, whereas the euthyroid (191.4 μg/L; IQR: 170.03-219.8) and hyperthyroid (159.5 μg/L; IQR: 152.9-238.3) groups were iodine sufficient. Numbers of pregnancies, less education, not consuming iodized salt and not using iodine supplements increased risk of hypothyroidism and ISH. Contrariwise, interval ≥ 3 years from last pregnancy and higher 24-h UIC decreased odds of hypothyroidism and ISH. Moreover, dairy products and egg consumption were markedly lower in all GTD groups. Dairy products and seafood consumption correlated independently with 24-h UIC of the study participants, whereas consuming yogurt, eggs, redfish and shellfish protected against GTDs. In conclusion, GTDs appear to be prevalent in pregnant Saudi women and the hypothyroid and hypothyroxinemia groups had iodine insufficiency. However, consuming iodized salt, iodine supplements, dairy products, seafoods and eggs may protect against GTDs.

Effect of nutrition education on iodine deficiency disorders and iodized salt intake in south west Ethiopian women: a cluster randomized controlled trial

BACKGROUND

Although iodine nutrition status is improving globally, the progress is not uniform throughout the world due to several factors. Among these, poor knowledge, negative attitude and improper practice of iodized salt are the main risk factors for poor iodine nutrition in Ethiopia. This study was aimed to assess the effect of nutrition education intervention on knowledge, attitude and practice (KAP) of iodine deficiency and iodized salt utilization.

METHODS

A cluster randomized controlled trial was carried out among 652 women of reproductive age group in southwest Ethiopia. A total of 24 clusters were selected and randomized in to an intervention and control villages. Women in the intervention village received iodine nutrition related education for 6 months; while those in the control village did not receive any education. Baseline and endline data were collected from both groups. Generalized Estimating Equations (GEE) was used to determine the effect of intervention.

RESULTS

A total of 647 (99.2%) participants were successfully involved in the study. In the intervention group the median attendance was 10 out of 12 sessions. Women in the intervention group had shown statistically significant change in knowledge, attitude and practice scores as compared to control one. In multivariable GEE linear model, after adjusting for other background characteristics, the mean difference (95% CI) scores were 8.81 (8.46, 9.16) for knowledge, 3.35 (3.17, 3.54) for attitude and 2.90 (2.74, 3.05) for practice in the intervention arm.

CONCLUSIONS

Well designed and community-based iodine nutrition education is an effective strategy to improve the KAP of iodine deficiency disorders and iodized salt utilization. Trial registration PACTR201809544276357 (Retrospectively registered on 14, Sept. 2018). https://www.pactr.org .

Impact of Dietary Habit, Iodine Supplementation and Smoking Habit on Urinary Iodine Concentration During Pregnancy in a Catalonia Population

(1) Background: The nutritional status of women during pregnancy can have a considerable effect on maternal and fetal health, and on the perinatal outcome. Aim: to assess the changes occurring in dietary iodine intake, potassium iodide supplementation, and smoking habit, and the impact of these changes on the urinary iodine concentration (UIC) during pregnancy in a population of women in Catalonia (Spain). (2) Methods: Between 2009–2011, an observational study included a cohort of women whose pregnancies were monitored in the public health system in the Central and North Metropolitan areas of Catalonia. Women received individual educational counseling, a dietary questionnaire was completed, and a urine sample was collected for iodine determination at each trimester visit. (3) Results: 633 (67.9%) women answered the questionnaire at all 3 visits. The percentage of women with a desirable UIC (≥150 μg/L) increased from the first to the second trimester and remained stable in the third (57.3%, 68.9%, 68%; p < 0.001). Analysis of the relationship between UIC ≥ 150 μg/L and the women’s dietary habits showed that the percentage with UIC ≥ 150 μg/L increased with greater consumption of milk in the first trimester, and the same was true for iodized salt use in all three trimesters and iodine supplementation in all three. (4) Conclusion: During pregnancy, increased intake of milk, iodized salt, and iodine supplements were associated with an increase in the UIC.

Adequate Iodine Intake among Young Adults in Jiangsu Province, China Despite a Medium Iodine Knowledge Score

Lack of iodine knowledge might be a risk factor for inadequate iodine intake in populations. Therefore, we aimed to determine the relationship between iodine knowledge and intake in young Chinese adults. A cross-sectional study was conducted in Suzhou, China. Iodine intake was assessed using a validated 33-item iodine-specific Chinese food frequency questionnaire (FFQ) and iodine knowledge was determined using a Chinese iodine knowledge questionnaire. A total of 150 participants (mean age 20.3 years) completed the study. The median iodine intake plus iodized salt was 260 μg/d, indicating iodine sufficiency (>150 µg/d). The median iodine knowledge score was 16/24, suggesting a medium level of knowledge. The majority of participants correctly recognized fish and seafood (95%) and iodized salt (83%) as the most important dietary iodine sources. After adjusting for age and sex, studying in the science cluster and having received iodine education were the predictors of having a higher iodine knowledge score, with adjusted odd ratios (OR) of 4.33 (1.49, 12.61) and 2.73 (1.21, 6.14), respectively. In conclusion, young Chinese adults had an adequate iodine intake despite a medium iodine knowledge score. This study provides support that iodine fortification in China has been successful, but further research is required to more fully substantiate this finding.

Mild to Moderate Iodine Deficiency and Inadequate Iodine Intake in Lactating Women in the Inland Area of Norway

Breastfed infants are dependent on an adequate supply of iodine in human milk for the production of thyroid hormones, necessary for development of the brain. Despite the importance of iodine for infant health, data on Norwegian lactating women are scarce. We measured iodine intake and evaluated iodine status and iodine knowledge among lactating women. From October to December 2018, 133 mother-infant pairs were recruited in a cross-sectional study through two public health care centers in Lillehammer and Gjøvik. Each of the women provided two human milk specimens, which were pooled, and one urine sample for analysis of iodine concentration. We used 24-hour dietary recall and food frequency questionnaire (FFQ) to estimate short-term and habitual iodine intake from food and supplements. The median (P25, P75) human milk iodine concentration (HMIC) was 71 (45, 127) µg/L-of which, 66% had HMIC <100 µg/L. The median (P25, P75) urinary iodine concentration (UIC) was 80 µg/L (52, 141). The mean (± SD) 24-hour iodine intake and habitual intake was 78 ± 79 µg/day and 75 ± 73 µg/day, respectively. In conclusion, this study confirms inadequate iodine intake and insufficient iodine status among lactating women in the inland area of Norway and medium knowledge awareness about iodine.

Insufficient iodine status in pregnant women as a consequence of dietary changes

Background

Historically, Iceland has been an iodine-sufficient nation due to notably high fish and milk consumption. Recent data suggest that the intake of these important dietary sources of iodine has decreased considerably.

Objective

To evaluate the iodine status of pregnant women in Iceland and to determine dietary factors associated with risk for deficiency.

Methods

Subjects were women (n = 983; 73% of the eligible sample) attending their first ultrasound appointment in gestational weeks 11–14 in the period October 2017–March 2018. Spot urine samples were collected for assessment of urinary iodine concentration (UIC) and creatinine. The ratio of iodine to creatinine (I/Cr) was calculated. Median UIC was compared with the optimal range of 150–249 μg/L defined by the World Health Organization (WHO). Diet was assessed using a semiquantitative food frequency questionnaire (FFQ), which provided information on main dietary sources of iodine in the population studied (dairy and fish).

Results

The median UIC (95% confidence interval (CI)) and I/Cr of the study population was 89 μg/L (42, 141) and 100 (94, 108) μg/g, respectively. UIC increased with higher frequency of dairy intake, ranging from median UIC of 55 (35, 79) μg/L for women consuming dairy products <1 time per week to 124 (98, 151) μg/L in the group consuming dairy >2 times per day (P for trend <0.001). A small group of women reporting complete avoidance of fish (n = 18) had UIC of 50 (21, 123) μg/L and significantly lower I/Cr compared with those who did not report avoidance of fish (58 (34, 134) μg/g vs. 100 (94, 108) μg/g, P = 0.041). Women taking supplements containing iodine (n = 34, 3.5%) had significantly higher UIC compared with those who did not take supplements (141 (77, 263) μg/L vs. 87 (82, 94), P = 0.037).

Conclusion

For the first time, insufficient iodine status is being observed in an Icelandic population. There is an urgent need for a public health action aiming at improving iodine status of women of childbearing age in Iceland.

Poverty and immigration as a barrier to iodine intake and maternal adherence to iodine supplementation

PURPOSE

Iodine deficiency still remains a significant health issue worldwide. Pregnant and lactating women are at risk for iodine deficiency when living in mild iodine-deficient areas such as Italy. This study aims at evaluating the consumption of iodized salt, iodine-rich-foods and maternal micronutrient supplements in a group of women with limited access to the Italian National Health System.

METHODS

A cross-sectional survey was conducted among immigrant and Italian women living in poverty and referring to 40 Non-Governmental Organization throughout Italy for their health needs. 3483 women answered the ad hoc questionnaire between January 2017 and February 2018.

RESULTS

The consumption of iodized salt was very low, and even lower among immigrant women. Determinants of iodized salt consumption were the period spent in Italy for immigrant women and living in a family-type setting, parity and, particularly, the degree of education for Italian ones. 17.5% of immigrant women and 8.6% of the Italian ones reported a diagnosis of thyroid disease. 521 women, 75.4% of whom were immigrants, were pregnant or breast-feeding. The majority (57.3%) had no specific maternal supplementation.

CONCLUSIONS

Both Italian and immigrating women with a low income or without access to the public health system have a poor adherence both to the salt iodization policy and to folic acid and iodine supplements in preconception and pregnancy. They also referred a low-frequency intake of iodine-rich-foods. The identification of barriers to health care access could be useful to promote specific health interventions in this target population.

Knowledge about iodine requirements during pregnancy and breastfeeding among pregnant women living in Northern Ireland

Background

Iodine is an essential micronutrient important for foetal nerve and brain development, especially in the early stages of pregnancy. The re-emergence of mild to moderate iodine deficiency has recently been reported in the United Kingdom (UK). The level of knowledge amongst pregnant women regarding iodine nutrition is poorly understood. The aim of this study was to determine the level of knowledge about iodine nutrition during pregnancy among pregnant women living in Northern Ireland (NI).

Methods

A cross-sectional study in pregnant women was carried out in Royal Jubilee Maternity Hospital Belfast, from March to June 2015. Two hundred pregnant women were provided with a short questionnaire on iodine knowledge during routine clinic visits and comparisons were made across trimester and parity.

Results

Only 20% of women were aware of the potentially increased iodine requirements during pregnancy and breast feeding; 45% were unable to identify any foods they thought would be iodine rich. The three main sources of dietary iodine in the UK are fish, dairy and eggs and 30, 9 and 15% correctly identified these as good sources respectively. When asked about whether they felt they had been given sufficient advice about folic acid and iodine in pregnancy, 90% felt this was so for folic acid, but only 5% for iodine.

Conclusions

This study suggests that iodine knowledge among pregnant women living in NI is poor. In the absence of any iodine fortification programme, women in the UK may be vulnerable to iodine deficiency in pregnancy. At present they are poorly equipped to make positive dietary changes to meet their increasing iodine requirements during pregnancy and breastfeeding. Public health strategies should be considered to target this population group.

Poor Iodine Knowledge, Coastal Region, and Non-Iodized Salt Consumption Linked to Low Urinary Iodine Excretion in Zhejiang Pregnant Women

Background: Iodine deficiency in pregnant women, defined as a median urinary iodine concentration (UIC) of less than 150 μg/L, is an important public health issue. To improve their iodine intake, it is important to understand the knowledge and practices regarding iodine. Methods: A cross-sectional investigation was conducted on 2642 pregnant women during 2016–2017 in Zhejiang province, China. A 3-point Likert scale questionnaire was used to record knowledge. The UIC and iodine content in household salt were determined. Results: Coastal participants were iodine deficient (median UIC 127.6 μg/L) while inland participants were iodine sufficient (median UIC 151.0 μg/L). The average knowledge scores were significantly lower for the coastal participants (24.2 points vs. 25 points for the inland participants; p < 0.001). The percentage for iodized salt consumption was significantly lower for the coastal participants (88.9% vs. 96.0% for those inland; p < 0.001). A generalized linear model analysis showed that non-iodized salt consumption, coastal region, and low knowledge scores were independently associated with a low UIC. Conclusions: Comprehensive interventional strategies are needed to develop to achieve an optimal iodine status. We recommend that coastal pregnant women should take iodine supplements based on the consumption of iodized salt, and improvement of iodine-related knowledge.

A systematic review of iodine deficiency among women in the UK

OBJECTIVE

The 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.

DESIGN

A systematic review was conducted to examine the literature and critically evaluate study design.

SETTING

Studies were identified in PubMed, Web of Science, Scopus and Ovid MEDLINE databases, as well as from secondary references.

PARTICIPANTS

Women of childbearing age or pregnant, living in the UK.

RESULTS

Fifty-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.

CONCLUSIONS

No 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.

Suboptimal Iodine Status and Low Iodine Knowledge in Young Norwegian Women

Previous studies have documented mild to moderate iodine deficiency in pregnant and lactating women in Norway. This study focused on non-pregnant young women because their future children may be susceptible to the adverse effects of iodine deficiency. We assessed urinary iodine concentration (UIC), iodine intake from food and supplements, and iodine knowledge in 403 non-pregnant women, mainly students, aged 18–30 years. Iodine concentration was measured in spot urine samples analyzed by inductively coupled plasma mass spectrometry and iodine intake was calculated from a self-reported food frequency questionnaire. Knowledge about iodine was collected through the self-administered, paper-based questionnaire. Median (p25–p75) UIC was 75 (42–130) µg/L and 31% had UIC < 50 µg/L. Habitual iodine intake was 100 (69–136) µg/day. In multiple regression models, supplemental iodine, use of thyroid medication, and iodine intake from food were positively associated with UIC, while vegetarian practice was negatively associated, explaining 16% of the variance. Approximately 40% of the young women had low iodine knowledge score and no differences were found between women in different study programs. Young women in Norway are mild to moderately iodine-deficient, and public health strategies are needed to improve and secure adequate iodine status.

Iodine and Pregnancy-A Qualitative Study Focusing on Dietary Guidance and Information

Iodine is essential for thyroid hormones synthesis and normal neurodevelopment; however, ~60% of pregnant women do not meet the WHO (World Health Organization) recommended intake. Using a qualitative design, we explored the perceptions, awareness, and experiences of pregnancy nutrition, focusing on iodine. Women in the perinatal period (n = 48) were interviewed and filled in a food frequency questionnaire for iodine. Almost all participants achieved the recommended 150 μg/day intake for non-pregnant adults (99%), but only 81% met the increased demands of pregnancy (250 μg/day). Most were unaware of the importance, sources of iodine, and recommendations for iodine intake. Attitudes toward dairy products consumption were positive (e.g., helps with heartburn; easy to increase). Increased fish consumption was considered less achievable, with barriers around taste, smell, heartburn, and morning sickness. Community midwives were the main recognised provider of dietary advice. The dietary advice received focused most often on multivitamin supplements rather than food sources. Analysis highlighted a clear theme of commitment to change behaviour, motivated by pregnancy, with a desired focus on user-friendly documentation and continued involvement of the health services. The study highlights the importance of redirecting advice on dietary requirements in pregnancy and offers practical suggestions from women in the perinatal period as the main stakeholder group.

Cow Milk Consumption Increases Iodine Status in Women of Childbearing Age in a Randomized Controlled Trial

Background

Recent evidence has highlighted the prevalence of mild-to-moderate iodine deficiency in women of childbearing age and pregnant women, with important public health ramifications due to the role of iodine, which is required for thyroid hormone production, in neurodevelopment. Cow milk contributes the greatest amount to iodine intakes in several countries.

Objective

The objective of this study was to investigate the effect of increased cow milk consumption on iodine status, thyroid hormone concentrations, and selenium status.

Methods

A 12-wk randomized controlled trial was conducted in 78 low-moderate milk-consuming (<250 mL/d) healthy women (aged 18-45 y). The intervention group was asked to consume 3 L semiskimmed milk/wk, whereas the control group continued their usual milk consumption (baseline median: 140 mL/d; IQR: 40-240 mL/d). At baseline and weeks 6 and 12, participants provided a spot urine sample [urinary iodine concentration (UIC), creatinine] and a fasting blood sample (thyroid hormone concentrations, serum total selenium, selenoprotein P).

Results

At baseline, the median (IQR) UIC of all participants was 78.5 µg/L (39.1-126.1 µg/L). Changes in the median UIC from baseline to week 6 (35.4 compared with 0.6 µg/L; P = 0.014) and week 12 (51.6 compared with -3.8 µg/L; P = 0.045) were significantly greater in the intervention group compared with the control group. However, despite being higher within the intervention group at weeks 6 and 12, the change in the iodine:creatinine ratio from baseline was not significantly different between groups at either week 6 (P = 0.637) or week 12 (P = 0.178). There were no significant differences in thyroid hormone concentrations or selenium status between groups at any time point.

Conclusions

The present study shows that the consumption of additional cow milk can significantly increase UIC in women of childbearing age. These results suggest that cow milk is a potentially important dietary source of iodine in this population group. This trial was registered at www.clinicaltrials.gov as NCT02767167.

Suboptimal Iodine Concentration in Breastmilk and Inadequate Iodine Intake among Lactating Women in Norway

Breastfed infants depend on sufficient maternal iodine intake for optimal growth and neurological development. Despite this, few studies have assessed iodine concentrations in human milk and there is currently no published data on iodine status among lactating women in Norway. The aim of this study was to assess iodine concentrations in breast milk (BMIC) in lactating women and estimate iodine intake. Five Mother and Child Health Centres in Oslo were randomly selected during 2016, and 175 lactating women between 2nd and 28th weeks postpartum participated. Each of the women provided four breastmilk samples which were pooled and analysed for iodine concentrations. Participants also provided information on iodine intake from food and supplements covering the last 24 h and the habitual iodine intake (food frequency questionnaire). The median (p25, p75 percentiles) BMIC was 68 (45, 98) µg/L and 76% had BMIC <100 µg/L. Only 19% had taken an iodine-containing supplement during the last 24 h. The median 24 h iodine intake from food (p25, p75) was 121 (82, 162) µg/day and the total intake (food and supplements) was 134 (95, 222) µg/day. The majority of lactating women had suboptimal BMIC and inadequate intake of iodine from food and supplements.

Knowledge about Iodine in Pregnant and Lactating Women in the Oslo Area, Norway

Background: Lack of knowledge about iodine may be a risk factor for iodine deficiency in pregnant and lactating women. The aim of this study was to assess knowledge about iodine and predictors of iodine knowledge scores among pregnant and lactating women. The study also examined whether iodine knowledge scores were associated with iodine status. Methods: A cross-sectional study was performed on 804 pregnant women and 175 lactating women from 18 to 44 years of age in 2016 in the Oslo area, Norway. Knowledge about iodine was collected through a self-administered, paper-based questionnaire. Iodine concentrations in urine and breast milk were measured using an inductively coupled plasma mass spectrometer (ICPMS). Results: 74% of the pregnant women and 55% of the lactating women achieved none to low iodine knowledge scores. Higher educated pregnant women and those who had received information about iodine had significantly higher knowledge scores. In lactating women, increased age was associated with higher knowledge scores. Knowledge scores were not associated with participants’ iodine status. Conclusion: This study revealed a lack of knowledge about the importance of iodine in pregnant and lactating women, as well as about the most important dietary sources. Public education initiatives are required to increase the awareness about iodine in these population groups.