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.

This study examined the contribution of long-term use of Lipiodol capsules, as a supplement to iodised salt to the control of iodine deficiency disorders among women in Xinjiang of China. A total of 1220 women across Kashgar, Aksu, Turpan and Yili Prefectures were surveyed in 2017. Lipiodol capsules were administered twice yearly in Kashgar and once yearly in Aksu and Turpan, but not in Yili. Urinary iodine concentration (UIC), free triiodothyronine (FT3), free thyroxine (FT4), thyroid-stimulating hormone (TSH), thyroglobulin antibody, thyroid peroxidase antibody and thyroid volume values were assessed. All the women in the four areas were in a state of non-iodine deficiency by UIC. The UIC were higher than adequate in Kashgar and Aksu (619·4 v. 278·6 μg/l). Thyroid hormone levels differed significantly in Turpan and Yili (FT3: 4·4 v. 4·6 pmol/l, FT4: 13·8 v. 14·2 pmol/l, TSH: 2·0 v. 2·7 mIU/l), but did not differ significantly in Kashgar, Aksu and Yili. The four areas did not differ significantly with regard to thyroid nodules, autoimmune thyroiditis or goitre. However, the detection rates of subclinical hypothyroidism (16·6 %) and total thyroid dysfunction (25·4 %) were higher among women in Yili. The supplementation with Lipiodol capsules had improved the iodine nutrition status of women in iodine-deficient areas of Xinjiang since 2006. To avoid negative effects of excess iodine, we suggest a gradual discontinuation of Lipiodol capsules in women with special needs based on the existing iodine nutrition level of local women.

Iodine (I) is a micronutrient that mammals need for proper functionality of thyroid gland since it is the main component of thyroid hormones. Besides studies that have investigated the role of I in livestock nutrition, it is also important to know the transcriptomics changes in small ruminants following I supplementation. Therefore, the aim of this study was to investigate the effects of I on the whole blood transcriptome in sheep. Fifteen lactating cross-bred ewes (3 to 4-year-old, 55 to 65 kg BW) at their late lactation period were enrolled in this study. At the beginning, all the animals had a 2-week acclimation period where they were fed with a basal diet which includes an adequate level of I (2 mg I/animal per day) in the form of calcium iodate (CaI2O6). Then, the ewes were randomly divided into two groups and fed in individual troughs: the control group (n = 5) was maintained on basal diet and the experimental group (I, n = 10) was fed for 40 days with a diet containing a high I supplementation (equivalent to 30 mg I/animal per day), in the form of potassium iodide. Whole blood and milk were collected individually at the beginning (T0) and after the 40 days of supplementation (T40). Iodine quantification was assessed in serum and milk sample. Microarray gene expression analysis was performed on whole blood and, filtering data using a fold change >2 with an adjusted P < 0.05, we identified 250 differentially expressed genes (DEGs) in the I group (T40 v. T0). Looking for biological processes associated with our DEGs, we found significant association with cell growth regulation. Thus, our study unveils the role of I supplementation on gene expression in sheep improving the knowledge about micronutrients in animal nutrition.

The contribution of milk and dairy products to daily iodine intake is high but variable in many industrialised countries. Factors that affect iodine concentrations in milk and dairy products are only poorly understood. Our aim was to: (1) assess the effect of feed iodine concentration on milk iodine by supplementing five groups of five cows each with one of five dosages from 0–2 mg iodine/kg DM; (2) quantify iodine losses during manufacturing of cheese and yogurt from milk with varying iodine concentrations and assess the effect of cellar-ripening; and (3) systematically measure iodine partitioning during heat treatment and skimming of milk. Milk iodine reached a near-steady state after 3 weeks of feeding. Median milk iodine (17–302 μg/l for 0–2 mg iodine/kg DM) increased linearly with feed iodine (R2 0·96; P < 0·001). At curd separation, 75–84 % of iodine was lost in whey. Dairy iodine increased linearly with milk iodine (semi-hard cheese: R2 0·95; P < 0·001; fresh cheese and yogurt: R2 1·00; P < 0·001), and cellar-ripening had no effect. Heat treatment had no significant effect, whereas skimming increased (P < 0·001) milk iodine concentration by only 1–2 μg/l. Mean daily intake of dairy products by Swiss adults is estimated at 213 g, which would contribute 13–52 % of the adults’ RDA for iodine if cow feed is supplemented with 0·5–2 mg iodine/kg DM. Thus, modulation of feed iodine levels can help achieve desirable iodine concentrations in milk and dairy products, and thereby optimise their contribution to human iodine nutrition to avoid both deficiency and excess.

I is essential for thyroid hormone synthesis and neurological development. Various changes occur in thyroid hormone metabolism during pregnancy and I requirements increase significantly. The purpose of this study was to investigate I status among pregnant women in Trabzon, formerly a severely I-deficient area but shown to have become I sufficient following mandatory iodisation of table salt based on monitoring studies among school-age children (SAC) in the area. A total of 864 healthy pregnant women with a median age of 28 (25th–75th percentile 17–47) years participated in the study. None of them were using I-containing supplement. All of them were screened for use of iodised salt, obstetric history, thyroid function tests and urinary I concentrations (UIC), and thyroid ultrasonography was performed. Median UIC was 102 (25th–75th percentile=62–143) μg/l. Median UIC of the patients according to trimesters were 122 µg/l at the 1st, 97 µg/l at the 2nd and 87 µg/l at the 3rd trimester. UIC in the 1st trimester was higher compared with the 2nd and 3rd trimesters (P<0·017). Nodules were present in 17·7 % of women (n 153). The rate of iodised salt usage among pregnant women was 90·7 %. Our study demonstrates that, although the I status among SAC has been rectified, I deficiency (ID) is still prevalent among pregnant women. Current knowledge is in favour of I supplementation in this group. Until the effects of maternal I supplementation in mild ID have been clarified by large-scale prospective controlled trials, pregnant women living in borderline defficient and I-sufficient areas, such as Trabzon city, should receive 100–200 µg/d of I-containing supplements in addition to iodised salt.