The work reported in this paper addresses the iodine nutritional deficiency that still affects a large number of people. For this purpose, we analyzed the possibility to use, as iodine vehicle, a hard typical ewe cheese, called Canestrato d'Abruzzo, derived from milk of ewes fed with an iodine-fortified diet. Both in the milk and the cheese of these animals, the iodine level was higher than that measured in sheep with a normal diet. An increase in the lactoferrin and iron content was evident in the whey derived from milk of the iodine group. Furthermore, in derived cheese, the caseins seemed more efficiently transformed in small peptides making the product more digestible and, for this reason, particularly suitable for feeding the elderly. In conclusion, the dairy products obtained from ewes fed with iodine diet contain more bioactive compounds so that they represent a useful food to prevent iodine and iron deficiency in lamb and humans.

Epidemiological studies have focused on the effects of iodine intake on the risk of thyroid cancer. However, their relationship is still obscure. The objective of the present study was to examine the association in the Chinese population. A new ecological study which combined the Data of Annual Report of Cancer, the Survey of Iodine Deficiency Disorders (IDD) surveillance and the Water Iodine Survey was conducted to analyse the relationship between iodine intake and the thyroid cancer incidence in China. In total, 281 counties were included. Thyroid cancer incidence was negatively correlated with the consumption rate of qualified iodised salt (CRQIS) and positively correlated with goiter prevalence (GP) of children aged 8–10 years, residents’ annual income and coastal status. Areas with a low CRQIS and areas with a high GP had a relatively high incidence of thyroid cancer. Regression models showed that a low CRQIS and a high GP in children aged 8–10 years (both reflecting iodine deficiency status) play a substantial role in thyroid cancer incidence in both males and females. Additionally, living in coastal areas and having a high annual income may also increase the risk of thyroid cancer. These findings suggest that mild iodine deficiency may contribute to the exceptionally high incidence of thyroid cancer in some areas in China. Maintaining appropriate iodine nutrition not only helps to eliminate IDD but also may help to reduce the occurrence of thyroid cancer.

Lack of knowledge about iodine has been suggested as a risk factor for iodine deficiency in pregnant women, but no studies have addressed this issue in Portugal. So, the aim of this study was to investigate iodine knowledge among Portuguese pregnant women and its association with iodine status. IoMum, a prospective observational study, included 485 pregnant women recruited at Centro Hospitalar e Universitário de S. João, Porto, between the 10th and 13th gestational weeks. Partial scores for knowledge on iodine importance, on iodine food sources or on iodised salt were obtained through the application of a structured questionnaire. Then, a total iodine knowledge score was calculated and grouped into low, medium and high knowledge categories. Urinary iodine concentration (UIC) was measured in spot urine samples by inductively coupled plasma MS. Of the pregnant women, 54 % correctly recognised iodine as important to neurocognitive development, 32 % were unable to identify any iodine-rich food and 71 % presented lack of knowledge regarding iodised salt. Of the women, 61 % had a medium total score of iodine knowledge. Knowledge on iodine importance during pregnancy was positively associated with iodine supplementation and also with UIC. Nevertheless, median UIC in women who correctly recognised the importance of iodine was below the cut-off for adequacy in pregnancy (150 µg/l). In conclusion, knowledge on iodine importance is positively associated with iodine status. Despite this, recognising iodine importance during pregnancy may not be sufficient to ensure iodine adequacy. Literacy-promoting actions are urgently needed to improve iodine status in pregnancy.

Iodine intake affects the occurrence of thyroid disorders. However, the association of iodine intake with longevity remains to be described. This led us to perform a 20 years’ follow-up on participants from the Randers–Skagen (RaSk) study. Residents in Randers born in 1920 (n 210) and Skagen born in 1918–1923 (n 218) were included in a clinical study in 1997–1998. Mean iodine content in drinking water was 2 µg/l in Randers and 139 µg/l in Skagen. We collected baseline data through questionnaires, performed physical examinations and measured iodine concentrations in spot urine samples. Income data were retrieved from Danish registries. We performed follow-up on mortality until 31 December 2017 using Danish registries. Complete follow-up data were available on 428 out of 430 of participants (99·5 %). At baseline, the median urinary iodine concentration was 55 µg/l in Randers and 160 µg/l in Skagen residents. Participants were long-term residents with 72·8 and 92·7 % residing for more than 25 years in Randers and Skagen, respectively. Cox regression showed that living in Skagen compared with Randers was associated with a lower hazard ratio (HR) of death in both age- and sex-adjusted analyses (HR 0·60, 95 % CI 0·41, 0·87, P = 0·006), but also after adjustment for age, sex, number of drugs, Charlson co-morbidity index, smoking, alcohol and income (HR 0·60, 95 % CI 0·41, 0·87, P = 0·008). Residing in iodine-replete Skagen was associated with increased longevity. This indicates that long-term residency in an iodine-replete environment may be associated with increased longevity compared with residency in an iodine-deficient environment.

Excess iodine intake by the pregnant dam reduces lamb serum antibody concentration, specifically immunoglobulin G (IgG). An experiment was conducted to investigate the mechanisms under pinning the reduced serum IgG concentration at 24 h postpartum in the progeny of iodine supplemented dams. Forty-five mature twin bearing ewes (n=15/treatment) were allocated to one of three dietary treatments as follows: basal diet (Control); basal diet plus 26.6 mg of iodine per ewe per day as calcium iodate (CaIO3); or potassium iodide (KI). Ewes were individually housed and fed from d 119 of gestation until parturition. All lambs received colostrum at 1, 10 and 18 h postpartum via stomach tube. At 1 h postpartum lambs from the control and an iodine supplemented treatment (n=10 per treatment from control and CaIO3) were euthanised before colostrum consumption and ileal segments isolated to determine the gene expression profile of a panel of genes identified as having a role in antibody transfer. Preceding euthanasia, lambs were blood sampled for determination of serum IgG, total thyroxine and free tri-iodothyronine concentrations. Progeny of CaIO3 supplemented dams had lower tri-iodothyronine concentrations (P<0.01) at 1 h postpartum and lower serum IgG concentrations (P<0.001) at 24 h postpartum when compared with the progeny of control dams. Iodine (CaIO3) supplementation of the dam increased the relative expression (P<0.05) of the B2M, PIGR and MYC genes in the ileum of the lamb, before colostrum consumption; while the expression of THRB declined when compared with the progeny of C dams (P<0.01). In conclusion, the results of this study show that it is the actual inclusion of excess iodine in the diet of the ewe, regardless of the carrier element, that negatively affects passive transfer in the newborn lamb. This study presents novel data describing the relationship between maternal iodine nutrition and its effect on the thyroid hormone status and subsequent gene expression in the newborn lamb; which results in a failure of passive transfer and a decline in serum IgG concentration.

Areas with low, adequate and excessive I content in water co-exist in China. Limited data are currently available on I nutrition and thyroid disease in lactating women and their breast-fed infants with different I intakes. This study aimed to evaluate I nutrition in both lactating women and their infants and the prevalence of thyroid disease in areas with different levels of I in water. From January to June 2014, a total of 343 healthy lactating women (excluding those taking anti-thyroid drugs or I supplements within a year of the study, consuming seafood at the time of the study or those diagnosed with congenital thyroid disease) from Beihai in Guangxi province and Jiajiazhuang, Yangcheng, Jicun and Pingyao townships in Shanxi province were selected. Compared with the I-sufficient group, median urinary I concentrations in both lactating women and infants as well as breast milk I levels were significantly lower in the I-deficient group (P<0·001). The prevalence of thyroid disease in lactating women, particularly subclinical hypothyroidism, was higher in the I-excess group than in the I-sufficient group (P<0·05). In areas with excessive water I content, high thyroid peroxidase antibody and high thyroglobulin levels were risk factors for abnormal thyroid-stimulating hormone levels. Our data collectively suggest that excessive I intake potentially causes subclinical hypothyroidism in lactating women. Moreover, enhanced monitoring of I status is important to avoid adverse effects of I deficiency or excess, particularly in susceptible populations such as pregnant or lactating women and infants.