Availability of iodised table salt in the UK - is it likely to influence population iodine intake?

Abstract

Objective: Iodine deficiency has recently been found in UK young and pregnant women, which is of concern given the importance of adequate iodine intake in pregnancy for fetal brain development. The WHO recommends that iodine deficiency in a population should be corrected through salt iodisation but there is a lack of UK data on iodised-salt availability, a situation that the present study aimed to address.

Design: Availability of iodised salt for household use was determined by a shelf survey in five supermarket chains in each of sixteen UK areas (in Southern England, Wales and Northern Ireland) encompassing a total of seventy-seven supermarkets. All branches of a sixth supermarket chain that had 2·3% of the market share sold exclusively iodised salt. Weighted iodised-salt availability was calculated taking the market share of supermarkets into account.

Setting: The UK.

Subjects: Not applicable.

Results: Iodised salt was available in thirty-two of the seventy-seven supermarkets (41·6%). After accounting for market share and including all six UK supermarket chains, the weighted availability of iodised salt was 21·5%. The iodine concentration of the major UK brand of iodised salt is low, at 11·5 mg/kg.

Conclusions: In contrast to other countries, iodised household table salt is unlikely to contribute meaningful amounts to UK iodine intake as (i) availability is low, (ii) table salt is only a small percentage of total UK salt intake and (iii) UK public-health campaigns have encouraged reduced salt consumption. As iodine intake in the UK is dependent entirely on food choices, regular monitoring of iodine status is essential.

Fig. 1

Iodised-salt availability () according to UK supermarket chain, based on a survey of seventy-seven supermarket stores (fifteen or sixteen stores from each chain in Southern England, Wales and Northern Ireland) between June and August 2009 or based on information from the buying department for Lidl. Weighted iodised-salt availability () is shown for each chain, taking into account the market share () of the supermarket chain^{( 15 )}