Joanne Kate Tattersall

There is no salt iodisation policy in the UK, and the majority of iodine intake is from milk and dairy products(1). The availability of iodised table salt in the UK was last investigated in 2009, and was found to be low(2). As table salt contributes only approximately 15% to total salt intake, it is important to know whether any of the salt in processed foods is iodised. This study therefore aimed to update the availability of iodised table salt and review its use in processed foods that are available in the UK.Iodised table salt availability was investigated in ten supermarket chains (nine online and one instore), covering 96.6% of the market share(3). Data was collected on price per kilogram for iodised and own-brand table salt. A Google-site search of the supermarket wesbites was conducted between 28 February and 4 April 2024; both the terms “iodised” and “iodized” were searched to identify all processed foods containing iodised salt. Data on product name, ingredients, salt content per 100 g and per portion, and country of origin were extracted. Duplicate products and items no longer available were removed. Salt per portion was calculated using serving sizes on the product label or equivalent products, and estimated portion sizes were used if these were unavailable. Iodine per portion was then calculated by assuming that salt was iodised at a concentration of 20 mg/kg.Iodised table salt was available in three of the ten (30%) supermarkets (as one brand). Iodised salt was over four-times more expensive than own-brand table salt (£4.17/kg vs.£1.02/kg); the difference was smaller than in 2009 when it was six-times the price. The iodine concentration of the iodised table was 20 mg/kg, an increase from 2009 when it was 11.5 mg/kg(2).A total of 240 processed foods containing iodised salt were identified across all supermarkets. The country of origin was mostly unspecified (46.7%, n = 112) but where it was, most products were from Germany (19.6%, n = 47). The most common (35.4%, n = 85) food group containing iodised salt was meat products (including hot dogs, pâté, salami), followed by stock/sauce/spices/condiments (22.5%, n = 54) and pasta/noodle products (12.9%, n = 31). Average iodine per portion was 19.4 µg (range 0.44-94 µg), which would provide 13% (range 0.3-63%) of adult recommendations (150 µg/day).Iodised table salt is available at fewer supermarket chains than in 2009. Iodised salt is used in some processed foods available in the UK though the iodine content is not provided on the nutrition label. When estimating iodine intake in dietary assessments, the potential contribution from iodised salt in some processed foods should be considered. Salt intake, even if iodised, should not exceed recommendations.

Iodine is essential for thyroid hormone production. Milk and dairy products are important sources of iodine in many countries. We aimed to review systematically the variation in milk‑iodine concentration between countries, seasons and farming practice. We searched online food composition tables and published literature for data since 2006. Milk‑iodine concentration was available for 34 countries (from 66 sources) and ranged from 5.5 to 49.9 μg/100 g (median 17.3 μg/100 g). Meta-analyses identified that iodine concentration is significantly higher in: (i) winter than summer milk (mean difference 5.97 μg/100 g; p = 0.001), and (ii) in conventional than in organic milk (mean difference 6.00 μg/100 g; p