Iodine status in Danish pregnant and breastfeeding women including studies of some challenges in urinary iodine status evaluation

Dietary protein intake affects the association between urinary iodine and clinically relevant depression: Evidence from NHANES 2007-2018

Both iodine concentration and protein intake are important nutritional factors that may influence the development of depressive symptoms. However, there are no studies on the effect of protein intake on the relationship between iodine concentration and the risk of depression. The study aimed to explore the relationship between iodine and the risk of clinically relevant depression (CRD) according to protein intake. This study analyzed the adults (≥18 years) who participated in the 2007-2018 National Health and Nutrition Cross-sectional Survey (N = 10,462). CRD was assessed using the Patient Health Questionnaire (PHQ-9). Protein intake was assessed using two 24-h dietary recalls and urinary iodine concentration (UIC) was measured using inductively coupled plasma dynamic response cell mass spectrometry. Weighted multivariate logistic regression and restrictive cubic splines were performed to assess the relationship between UIC and CRD according to protein category (low protein intake <0.8 g/kg/day; high protein intake: ≥0.8 g/kg/day). After controlling for sociodemographic, behavioral, chronic diseases, and dietary factors, a positive correlation was observed between UIC (log10) and CRD (OR: 1.36, 95% CI: 1.026, 1.795). Low UIC (<100 μg/L) was associated with a lower prevalence of CRD (OR: 0.73, 95% CI: 0.533, 0.995) in high protein intake individuals, whereas this relationship did not exist in those with low protein intake. Moreover, restrictive cubic splines confirmed a near L-shaped relationship between UIC and CRD in the low-protein group (nonlinear p = .042) and a linear relationship between them in the high-protein group (nonlinear p = .392). This study illustrates that protein intake affects the relationship between UIC and CRD. Combining lower UIC and high protein intake may help reduce the prevalence of CRD, which would have significant implications for managing patients with depressive CRD in the clinical setting.

Associations between urinary iodine concentration and the prevalence of metabolic disorders: a cross-sectional study

Background

Few studies have examined the role of iodine in extrathyroidal function. Recent research has shown an association between iodine and metabolic syndromes (MetS) in Chinese and Korean populations, but the link in the American participants remains unknown.

Purpose

This study aimed to examine the relationship between iodine status and metabolic disorders, including components associated with metabolic syndrome, hypertension, hyperglycemia, central obesity, triglyceride abnormalities, and low HDL.

Methods

The study included 11,545 adults aged ≥ 18 years from the US National Health and Nutrition Examination Survey (2007-2018). Participants were divided into four groups based on their iodine nutritional status(ug/L), as recommended by the World Health Organization: low UIC, < 100; normal UIC, 100-299; high UIC, 300-399; and very high, ≥ 400. The Odds ratio (OR) for MetS basing the UIC group was estimated using logistic regression models for our overall population and subgroups.

Results

Iodine status was positively associated with the prevalence of MetS in US adults. The risk of MetS was significantly higher in those with high UIC than in those with normal UIC [OR: 1.25; 95% confidence intervals (CI),1.016-1.539; p = 0.035). The risk of MetS was lower in the low UIC group (OR,0.82; 95% CI: 0.708-0.946; p = 0.007). There was a significant nonlinear trend between UIC and the risk of MetS, diabetes, and obesity in overall participants. Participants with high UIC had significantly increased TG elevation (OR, 1.24; 95% CI: 1.002-1.533; P = 0.048) and participants with very high UIC had significantly decreased risk of diabetes (OR, 0.83; 95% CI: 0.731-0.945, p = 0.005). Moreover, subgroup analysis revealed an interaction between UIC and MetS in participants aged < 60 years and ≥ 60 years, and no association between UIC and MetS in older participants aged ≥ 60 years.

Conclusion

Our study validated the relationship between UIC and MetS and their components in US adults. This association may provide further dietary control strategies for the management of patients with metabolic disorders.

Iodine nutrition among the adult population of the Faroe Islands: a population-based study

The WHO recommends monitoring iodine status in all populations with median urinary iodine concentration (UIC) below 100 µg/l suggesting iodine deficiency. There are no data on the iodine intake among the population of the Faroe Islands. This study aimed to provide data on iodine nutrition in a representative sample of the general adult population from the Faroe Islands. We conducted a population-based cross-sectional survey in 2011–2012 and measured iodine in urine from 491 participants (294/197 men/women) using the ceri/arsen method after alkaline ashing. Participants include about 100 subjects in each of four adult decades and included participants from both the capital city and villages. The median UIC was low within the recommended range 101 µg/l (range 21–1870 µg/l). No samples were in the range suggesting severe iodine deficiency, but half of the samples were in the range of just adequate or mildly insufficient iodine intake with UIC markedly lower in women than in men (86 v. 115 µg/l; P < 0·001). Intake of fish and whale meals affected the UIC. In conclusion, nearly half of the population had an iodine excretion in the range of borderline or mild iodine deficiency. The lowest iodine nutrition level among Faroese women is a concern as it may extend to pregnancy with increased demands on iodine nutrition. In addition, we found that large variations and the intermittently excessive iodine intakes warrant follow-up on thyroid function in the population of the Faroe Islands.

Perfluoroalkyl Substances and Maternal Thyroid Hormones in Early Pregnancy; Findings in the Danish National Birth Cohort

BACKGROUND

Maternal thyroid hormones are essential for fetal brain development in early gestation. Perfluoroalkyl substances (PFASs)-widespread and persistent pollutants-have been suggested to interfere with maternal thyroid hormones in the second or third trimesters, but evidence for an association in the early pregnancy period is sparse.

OBJECTIVES

Our goal was to evaluate the gestational-week specific associations of maternal thyroid-stimulating hormone (TSH) and free thyroxine (fT4) levels with plasma concentrations of six PFAS chemicals in the first and second pregnancy trimester.

METHODS

A cross-sectional analysis was conducted using 1,366 maternal blood samples collected between gestational weeks (GWs) 5 and 19 (median, 8 gestational weeks) in the Danish National Birth Cohort (DNBC) during 1996-2002. We estimated the percentage changes of serum TSH and fT4 levels according to concentrations (in nanograms per milliliter) of six PFAS chemicals modeled as per interquartile range (IQR) increase or by exposure quartiles. Moreover, we contrasted the estimated week-specific TSH or fT4 levels by PFAS quartile and estimated ORs for binary high or low TSH and fT4 status based on the week-specific distribution according to IQR increase of PFAS.

RESULTS

TSH levels followed a U-curve trend in early pregnancy with a nadir at GW10, whereas fT4 levels were less fluctuated in the samples. There were no apparent associations between any of the PFASs and changes of average TSH or fT4 levels in total samples. In gestational-week-specific analyses, we found that the estimated TSH values were higher among the highest perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonate (PFHxS), and perfluoroheptane sulfonate (PFHpS) quartiles compared with the lower quartiles from GW5 to GW10, but the difference became null or even reversed after GW10. For binary outcomes, perfluorodecanoic acid (PFDA) was associated with high fT4 status before GW10 [OR=1.46 (95% CI: 1.04, 2.05)].

CONCLUSIONS

We observed some gestational-week-specific associations between high exposure to several PFAS and TSH level in early gestations. Further research of the biology and the potential clinical impact regarding thyroid hormones disruptions in early pregnancy is needed. https://doi.org/10.1289/EHP5482.

Iodine in dairy milk: Sources, concentrations and importance to human health

Milk and dairy products are major iodine sources in industrialized countries. However, consumption of milk and dairy, as well as their iodine concentrations, vary widely, making them an unpredictable iodine source. Milk iodine concentrations in industrialized countries range from 33 to 534 μg/L and are influenced by the iodine intake of dairy cows, goitrogen intake, milk yield, season, teat dipping with iodine-containing disinfectants, type of farming and processing. We estimate milk and dairy contribute ≈13-64% of the recommended daily iodine intake based on country-specific food intake data. To ensure adequate iodine levels but avoid the risk of iodine excess through milk and dairy, it is crucial to reduce the wide variations in milk iodine. If iodine intakes from iodized salt fall because of public health efforts to reduce salt intake, milk and dairy products may become increasingly important sources of dietary iodine in the future.

An Increase in Consuming Adequately Iodized Salt May Not Be Enough to Rectify Iodine Deficiency in Pregnancy in an Iodine-Sufficient Area of China

Universal salt iodization (USI) has been implemented for two decades in China. It is crucial to periodically monitor iodine status in the most vulnerable population, such as pregnant women. A cross-sectional study was carried out in an evidence-proved iodine-sufficient province to evaluate iodine intake in pregnancy. According to the WHO/UNICEF/ICCIDD recommendation criteria of adequate iodine intake in pregnancy (150-249 µg/L), the median urinary iodine concentration (UIC) of the total 8159 recruited pregnant women was 147.5 µg/L, which indicated pregnant women had iodine deficiency at the province level. Overall, 51.0% of the total study participants had iodine deficiency with a UIC < 150 µg/L and only 32.9% of them had adequate iodine. Participants living in coastal areas had iodine deficiency with a median UIC of 130.1 µg/L, while those in inland areas had marginally adequate iodine intake with a median UIC of 158.1 µg/L (p < 0.001). Among the total study participants, 450 pregnant women consuming non-iodized salt had mild-moderate iodine deficiency with a median UIC of 99.6 µg/L; 7363 pregnant women consuming adequately iodized salt had a lightly statistically higher median UIC of 151.9 µg/L, compared with the recommended adequate level by the WHO/UNICEF/ICCIDD (p < 0.001). Consuming adequately iodized salt seemed to lightly increase the median UIC level, but it may not be enough to correct iodine nutrition status to an optimum level as recommended by the WHO/UNICEF/ICCIDD. We therefore suggest that, besides strengthening USI policy, additional interventive measure may be needed to improve iodine intake in pregnancy.

Iodine status in the Nordic countries - past and present

Background

Adequate iodine nutrition is dependent on ground water content, seafood, and, as many countries use iodized cow fodder, dairy products. In most countries, salt fortification programs are needed to assure adequate iodine intake.

Objectives

The objectives are threefold: 1) to describe the past and present iodine situation in the Nordic countries, 2) to identify important gaps of knowledge, and 3) to highlight differences among the Nordic countries’ iodine biomonitoring and fortification policies.

Design

Historical data are compared with the current situation. The Nordic countries’ strategies to achieve recommended intake and urine iodine levels and their respective success rates are evaluated.

Results

In the past, the iodine situation ranged from excellent in Iceland to widespread goiter and cretinism in large areas of Sweden. The situation was less severe in Norway and Finland. According to a 1960 World Health Organization (WHO) report, there were then no observations of iodine deficiency in Denmark. In Sweden and Finland, the fortification of table salt was introduced 50–75 years ago, and in Norway and Finland, the fortification of cow fodder starting in the 1950s helped improve the population's iodine status due to the high intake of milk. In Denmark, iodine has been added to household salt and salt in bread for the past 15 years. The Nordic countries differ with regard to regulations and degree of governmental involvement. There are indications that pregnant and lactating women, the two most vulnerable groups, are mildly deficient in iodine in several of the Nordic countries.

Conclusion

The Nordic countries employ different strategies to attain adequate iodine nutrition. The situation is not optimal and is in need of re-evaluation. Iodine researchers, Nordic national food administrations, and Nordic governmental institutions would benefit from collaboration to attain a broader approach and guarantee good iodine health for all.

Canadian Consensus on Female Nutrition: Adolescence, Reproduction, Menopause, and Beyond

OBJECTIVES

To provide health care professionals in Canada with the basic knowledge and tools to provide nutrition guidance to women through their lifecycle.

OUTCOMES

Optimal nutrition through the female lifecycle was evaluated, with specific focus on adolescence, pre-conception, pregnancy, postpartum, menopause, and beyond. The guideline begins with an overview of guidance for all women, followed by chapters that examine the evidence and provide recommendations for the promotion of healthy nutrition and body weight at each life stage. Nutrients of special concern and other considerations unique to each life stage are discussed in each chapter.

EVIDENCE

Published literature, governmental and health agency reports, clinical practice guidelines, grey literature, and textbook sources were used in supporting the recommendations made in this document.

VALUES

The quality of evidence was rated using the criteria described in the report of the Canadian Task Force on Preventive Health Care. CHAPTER 2: GENERAL FEMALE NUTRITION: Summary Statements Recommendations CHAPTER 3: ADOLESCENCE NUTRITION: Summary Statements Recommendations CHAPTER 4: PRE-CONCEPTUAL NUTRITION: Summary Statement Recommendations CHAPTER 5: NUTRITION IN PREGNANCY: Summary Statements Recommendations CHAPTER 6: POSTPARTUM NUTRITION AND LACTATION: Summary Statements Recommendations CHAPTER 7: NUTRITION DURING MENOPAUSE AND BEYOND: Summary Statement Recommendations.