Iodine status of teenage girls on the island of Ireland.

PURPOSE: The trace element iodine is a vital constituent of thyroid hormones. Iodine requirements increase during pregnancy, when even mild deficiency may affect the neurocognitive development of the offspring. Urinary iodine concentration (UIC) is the means of assessing iodine status in population surveys; a median UIC of 100-199 µg/L is deemed sufficient in a non-pregnant population. Milk is the main dietary source of iodine in the UK and Ireland. METHODS: We surveyed the iodine status of 903 girls aged 14-15 years in seven sites across the island of Ireland. Urine iodine concentration was measured in spot-urine samples collected between March 2014 and October 2015. Food group intake was estimated from iodine-specific food-frequency questionnaire. Milk-iodine concentration was measured at each site in summer and winter. RESULTS: The median UIC overall was 111 µg/L. Galway was the only site in the deficient range (median UIC 98 µg/L). All five of the Republic of Ireland sites had UIC ≤ 105 µg/L. In the two sites surveyed twice, UIC was lower in summer vs winter months [117 µg/L (IQR 76-165) vs 130 µg/L (IQR 91-194) (p < 0.01)]. Milk samples collected from Galway and Roscommon had a lower mean iodine concentration than those from Derry/Londonderry (p < 0.05). Milk intake was positively associated with UIC (p < 0.001). CONCLUSIONS: This is the largest survey of its kind on the island of Ireland, which currently has no iodine-fortification programme. Overall, the results suggest that this young female population sits at the low end of sufficiency, which has implications if, in future, they enter pregnancy with borderline status.

Iodine deficiency among pregnant women living in Northern Ireland.

OBJECTIVE: Mild iodine deficiency has re-emerged among school girls in the UK. We wished to study a contemporaneous pregnant population because a relationship between maternal iodine deficiency and offspring cognitive scores has recently been reported. The WHO has set a median population urinary iodine concentration (UIC) of ≥100 and ≥150 µg/L to define adequacy outside of and during pregnancy, respectively. Iodine creatinine ratio (ICR) is also used to correct for dilution effects (sufficiency ≥150 µg/g creatinine in pregnancy). DESIGN AND METHODS: A total of 241 women were followed across trimesters (T) into the postpartum period (PPP) along with 80 offspring with spot urine sampling and food frequency questionnaires. RESULTS: Median UIC was 73 µg/L in the 1st T (ICR 102 µg/g creatinine) despite 55% taking iodine-containing supplements. Median UICs were 94, 117 and 90 µg/L in the 2nd T, 3rd T and PPP, respectively. Corresponding ICRs were 120, 126 and 60 µg/g creatinine. ICR was associated with volume of milk consumed throughout pregnancy. Median UIC among the offspring was 148 µg/L, with no difference between the breast- and formula-fed babies. CONCLUSIONS: Pregnant women living in Northern Ireland may be at risk of iodine deficiency across pregnancy and into the PPP while the offspring are iodine sufficient. This is the first study of its kind in the UK with data for pregnant women and their offspring. The UK does not provide an iodine fortification programme nor offer routine iodine dietary advice in pregnancy and this requires consideration by public health agencies.

Neonatal TSH levels in Northern Ireland from 2003 to 2014 as a measure of population iodine status.

OBJECTIVE: The re-emergence of iodine deficiency in the UK has recently been reported in a large cohort of teenage girls including from Northern Ireland (NI) using the gold standard spot urinary iodine concentration. We wished to explore and confirm this by analysing neonatal thyroid-stimulating hormone (nTSH) levels in the NI population. DESIGN: We analysed the nTSH heel prick tests results from the NI national screening database between 2003 and 2014. The WHO proposes a definition for population iodine sufficiency at <3% of the population with nTSH results >5 mIU/L. METHODS: Anonymized results from 288 491 nTSH tests were retrieved, and prevalence rates of results at increasing cut-offs including >2 mIU/L and >5 mIU/L calculated. We also assessed for possible seasonal variation in nTSH results. RESULTS: An overall population prevalence of 0.49% with TSH >5 mIU/L was found, indicating population iodine sufficiency with no year attaining a prevalence >3%. The prevalence of nTSH >2 mIU/L decreased to 4.1% in 2007 and subsequently increased to 9.8% in 2014. Modest seasonal variation was also detected, with higher levels among April/May births. CONCLUSIONS: The neonatal TSH database suggests iodine sufficiency in the NI population. However, the rising frequency of results >2 mIU/L may indicate an emerging mild iodine deficiency. This is one of the largest and longest studies of its kind in the UK and the first carried out in NI. The summer months may be a time of increased risk of iodine deficiency in our pregnant women whose requirements are increased and who are not currently targeted by any iodine fortification programme in the UK.

Visual attention to food cues in obesity: an eye-tracking study.

OBJECTIVE: Based on the theory of incentive sensitization, the aim of this study was to investigate differences in attentional processing of food-related visual cues between normal-weight and overweight/obese males and females. METHODS: Twenty-six normal-weight (14M, 12F) and 26 overweight/obese (14M, 12F) adults completed a visual probe task and an eye-tracking paradigm. Reaction times and eye movements to food and control images were collected during both a fasted and fed condition in a counterbalanced design. RESULTS: Participants had greater visual attention towards high-energy-density food images compared to low-energy-density food images regardless of hunger condition. This was most pronounced in overweight/obese males who had significantly greater maintained attention towards high-energy-density food images when compared with their normal-weight counterparts however no between weight group differences were observed for female participants. CONCLUSIONS: High-energy-density food images appear to capture visual attention more readily than low-energy-density food images. Results also suggest the possibility of an altered visual food cue-associated reward system in overweight/obese males. Attentional processing of food cues may play a role in eating behaviors thus should be taken into consideration as part of an integrated approach to curbing obesity.