A multi-centre pilot study of iodine status in UK schoolchildren, aged 8–10 years

Abstract

PurposeIodine, as an essential constituent of thyroid hormones, is required for brain development. Iodine status is low in some UK population groups, notably in teenage girls, women of childbearing age and pregnant women. We aimed to assess iodine status of UK schoolchildren as there are no data on children below 14 years of age.MethodsChildren (boys and girls) aged 8–10 years were recruited to a cross-sectional study from schools in three areas of the UK (Omagh, Northern Ireland; Glasgow, Scotland, and Guildford, South-East England). Spot urine samples, for measurement of urinary iodine concentration, were collected in the winter months (November 2012 to March 2013) and in the summer, in Omagh only (September 2013). A food frequency questionnaire was completed.ResultsA total of 168 schoolchildren provided 165 urine samples. The median urinary iodine concentration was 161 µg/L in winter samples (n = 134) and 127 µg/L in summer samples (n = 31). The median urinary iodine concentration for the whole group was 144 µg/L, weighted to account for the unequal proportion of samples from the two seasons. The children are classified as iodine-sufficient by WHO criteria (100–199 µg/L), even in the summer. Milk intake was positively associated with iodine status.ConclusionsThis pilot study suggests that iodine deficiency is unlikely to be a problem in UK children aged 8–10 years. This could be a result of higher intake of milk, the principal UK dietary iodine source, in this age group than in teenagers and adults. Further assessment of iodine status in a representative sample of UK schoolchildren is required.

Revisiting the Iodine Global Network’s definition of iodine status by country

“…Correspondingly, a recent study of children of the same age in three UK centres found a UIC of 161 µg/ l in winter (n 134) and 127 µg/l in summer (n 31) (19) , classifying these children as I sufficient with a higher median UIC than that seen in the New Zealand study.…”

“…We suggest that, for consistency, the IGN should define I status using children of the same age groups across countries, and that the 2016 IGN scorecard should define the UK as having sufficient I status among children based on the UIC of 161 µg/l found in 8-10-year-old children (19) . However, adequate status among children does not mean that the whole population has a sufficient intake, as seen in both the UK and New Zealand, where intakes for adults and children are adequate but pregnant and lactating women have insufficient intakes.…”

Are plant‐based milk alternatives putting people at risk of low iodine intake?

“…The data demonstrate that the food group 'milk and milk products' is the principal source of iodine in the UK diet and that milk is the individual product contributing most to the population's intake. Positive associations between milk intake and the iodine status of children (Bath et al 2016), adolescents (Vanderpump et al 2011), pregnant women (Bath et al 2014a) and women of childbearing age (Bath et al 2014b) provide further evidence for the important contribution of milk to iodine intake in the UK. The average iodine content of conventional UK cows' milk is 44 lg/100 g (SACN 2014), and this means that just over 300 ml of milk would be enough to meet the UK recommendation of 140 lg of iodine per day for an adult.…”

“…Positive associations between milk intake and the iodine status of children (Bath et al . ), adolescents (Vanderpump et al . ), pregnant women (Bath et al .…”

Has iodized salt reduced iodine-deficiency disorders among school-aged children in north-west Iran? A 9-year prospective study

“…Some complications of iodine deficiency include goitre, lack of physical and mental development, and poor learning ability in children (9)(10)(11) . Iodine deficiency also leads to abortion, stillbirth and congenital anomalies, and increases prenatal death and infant mortality (1,(12)(13)(14) . IDD are preventable using methods such as iodized salt (15,16) .…”