Assessment of the contribution of industrially processed foods to salt and iodine intake in Thailand

Abstract

Iodization of food grade salt has been mandated in Thailand since 1994. Currently, processed food consumption is increasing, triggered by higher income, urbanization, and lifestyle changes, which affects the source of salt and potentially iodized salt among the population. However, adequate information about the use of iodized salt in processed foods in Thailand is still lacking. Therefore, this study aimed to assess iodine intake through salt-containing processed foods and condiments which were identified using national survey data. Potential iodine intake from iodized salt in food products was modelled using consumption data and product salt content from food labelling and laboratory analysis. Fish sauce, soy sauce and seasoning sauces (salty condiments) have alternative regulation allowing for direct iodization of the final product, therefore modelling was conducted including and excluding these products. Daily salt intake from household salt and food industry salt (including salty condiments) was estimated to be 2.4 g for children 0-5 years of age, 4.6 g for children 6-12 years of age, and 11.5 g for adults. The use of iodized salt in processed foods (excluding salty condiments) met approximately 100% of the estimated average requirement (EAR) for iodine for non-pregnant adults and for children 6 to 12 years of age, and 50% of the EAR for iodine for children aged 0 to 5 years of age. In all cases, iodine intake from processed food consumption was greater than from estimated household iodized salt consumption. Findings suggest that iodized salt from processed foods is an important source of iodine intake, especially in adults. The use of iodized salt by the food industry should be enforced along with population monitoring to ensure sustainability of optimal iodine intake. Currently, the addition of iodine into fish sauce, soy sauce and seasoning sauces has an important role in achieving and sustaining optimal iodine intake.

Fig 1. Key guidance framework for Module 4—Assessing the contribution of industrially processed foods to salt and iodine intake.

* Population groups included: Children 0–5 years of age, 6–12 years of age and non-pregnant adults. ** The term “Non-pregnant adults” was used in this paper to describe data for the non-pregnant population group above 13 years of age. *** Based on an assumption that, if salt is iodized, it will be iodized to the mean of national standard (30mg/kg).

Fig 2. Estimated iodine intake (μg) from the five different scenarios, modelled to show the different contribution from iodization of household salt, processed food salt, and salt in fish sauce, soy sauce and seasoning sauce, in relation to the EAR, RNI and UL for iodine.

(A) Non-pregnant adults, (B) Children 6–12 years of age, (C) Children 0–5 years of age. Scenarios: (1)– 100% iodized household and food industry salt, (2)– 78% household salt iodized, 100% food industry salt iodized, (3)– 90% household salt iodized, 100% food industry salt iodized, (4)–Scenario 2 with 30% reduction in salt consumption from all products, (5)–Scenario 3 with 30% reduction in salt consumption from all products.