In February 2019 researchers from Australia published their review of the medical scientific literature to assess the effect of fortifying foods, beverages, condiments, or seasonings with iodine alone or in conjunction with other micronutrients. This was with the exception of salt which, in many countries, is already fortified with iodine. Iodine deficiency disorders affect almost 1.9 billion people worldwide and amongst children, iodine deficiency is the main cause of central nervous system development and impairment of cognitive function, as well as goitre and hypothyroidism in people of all ages. A total of 11 studies, involving 4,317 individuals (3,636 school children, 648 women of reproductive age and 33 infants) were included in the review. The foods used for iodine fortification included biscuits, milk, fish sauce, drinking water, yoghurt, fruit beverage, seasoning powder, and infant formula milk with the daily amounts of iodine ranging from 35 µg/day to 220 µg/day. The studies lasted between 11 days to 48 weeks. Four studies were assessed to have a low risk of bias and seven a high risk of bias. Results showed very low quality evidence that the effect of iodine fortification of foods other than salt was uncertain in respect to risk of goitre, weight, height, weight-for-age, height-for-age and weight-for-height. However, there was moderate quality evidence that iodine levels significantly increased following the iodine fortification of foods other than salt.
Santos JAR et al. Iodine fortification of foods and condiments, other than salt, for preventing iodine deficiency disorders. Cochrane Database Syst Rev. 2019 Feb 12;2:CD010734.