Iodine is an essential micronutrient required in small amounts for the normal physiological function of the human body. Iodine is a critical component of the thyroid hormones, which are necessary for various metabolic and enzymatic processes. These processes include control of the body's metabolic rate, growth and development, and neuron function and development. The recommended dietary intake for adult men and women is 150 mg/d (IOM 2000; WHO 2004a). Seafood, dairy products, and plants grown in iodine-rich soils are good food sources of iodine. Most other foods contain low amounts of iodine so individuals require additional sources to meet the recommended amounts.
Insufficient intake of iodine results in a spectrum of disorders referred to as iodine deficiency disorders (IDD). They include mental impairment, goiter (enlargement of the thyroid gland), hypothyroidism, and dwarfism. IDD is especially damaging during the early stages of pregnancy and in early childhood. In their most severe form, IDD include cretinism (extreme case of neurological damage from fetal hypothyroidism), stillbirth and miscarriage, and increased infant mortality. IDD is a significant public health problem in more than 50 countries. According to the World Health Organization (WHO) (2004b) an estimated 2 billion people worldwide (35.2% of the world population) suffer from insufficient iodine intake, defined as urinary iodine (UI) levels below 100 μg/L.
Universal salt iodization (USI), or iodization of all salt for human and animal consumption, is regarded as the global strategy of choice for feasible and effective control of iodine deficiency. Iodization levels are determined based on estimated consumption of salt. On average, it is estimated that individuals consume around 10 g of salt per day in countries where most of the salt in the diet comes from table salt, used for cooking and at the table. The WHO, United Nations Children's Fund (UNICEF), and Intl. Council for Control of Iodine Deficiency Disorders (ICCIDD) recommend an addition rate of 20 to 40 mg of iodine per kg salt, depending on local salt intake (Klemm and others 2009).
In recent years, a developing issue related to the levels of salt intake and salt used in processed foods has drawn the attention of organizations interested in addressing IDD. In countries where most meals are prepared and consumed within the household, the iodization of household salt alone may be adequate for eliminating IDD. However, changes in salt consumption imply that the need for iodization goes beyond table salt as more individuals forgo this ingredient when cooking and consuming food at home. It has become clear that increasingly more people consume salt from processed foods rather than table salt. In countries where more salt is consumed from processed foods, the iodization of household salt alone is unlikely to assure sufficient dietary iodine. Mattes and Donnelly (1991) estimate that in the United States and United Kingdom approximately 75% of sodium intake is from processed or restaurant foods, only 10% to 12% occurs naturally in foods, and 10% to 15% is from salt use at the table or in cooking, but data to verify the assumption that iodized salt is not typically used in processed foods are scarce. Though the trend to consume more salt from processed foods is particularly observed in industrialized countries, it is perceived to be expanding into many developing countries of interest to the Micronutrient Initiative's (MI) USI program. The use of iodized salt in processed foods and its implications for USI strategies were reviewed by the MI in collaboration with the Iodine Network. In June 2009, a session, “Ensuring the Public Health Triumph of Iodine Nutrition,” was also held at the IFT Annual Meeting as this issue became more widely discussed. This specific session had more than 20 international attendees from universities, companies, government, and nonprofit organizations in the United States, Canada, Argentina, Ecuador, Singapore, South Korea, and Russia.
The WHO recommends that average consumption of sodium chloride should be less than 5 g/d (less than 2 g/d of sodium) (WHO 1983; WHO/FAO 2003). This is in recognition that a high level of dietary salt intake is associated with chronic diseases such as high blood pressure and other cardiovascular diseases. Various iodization methods can be used to fortify salt to provide the recommended iodine intakes even if per capita total salt intakes are reduced. It is generally understood that recommendations to reduce salt consumption to prevent chronic diseases and the policy of salt iodization to eliminate iodine deficiency do not conflict or compromise one another; however, there are no policies and guidance on these 2 combined issues to countries implementing USI programs.
To address these 2 emerging issues, it is important to understand the contribution salt-containing processed foods make to overall iodine intake, and the extent to which iodized salt is used in processed foods in order to provide adequate guidelines consistent with both objectives: (1) a decrease in total salt consumption, and (2) using salt iodization to prevent IDD (at appropriate levels based on consumption patterns). In addition, since there has been little engagement of food processors on this issue, there is a need to bring them into discussions about iodine nutrition, to study the potential connection and contribution that processed foods using iodized salt can play in the provision of iodine. Discussions held from April 14 through 17, 2010, during the Iodine Network meetings showed that partners such as the Salt Inst., Global Alliance for Improved Nutrition (GAIN), UNICEF, and WHO are also interested in the issues around salt and iodine intakes through processed foods.
In May 2010, MI issued IFT a project to assess the extent of usage of iodized salt in processed foods and the level of knowledge on iodine nutrition among food processors. To the extent possible, the project also attempted to determine the potential impact of salt reduction initiatives on iodine nutrition and to provide recommendations on the best practices to ensure adequate iodine nutrition. The project had 2 phases: Phase I was to conduct an environmental scan/desk review of processed food consumption patterns in 39 countries selected by MI; Phase II was to conduct an electronic survey of food processors and detailed telephone interviews with a small sample of select company representatives from 16 countries. IFT shared results from both Phases at a session entitled “The Role of Food Processors Worldwide in Preventing Iodine Deficiency Disorders” during IFT's 2011 Annual Meeting held on July 13 in New Orleans, La. Speakers representing IFT, the Iodine Network, Nestlé, and the Pan American Health Organization shared strategies for iodine fortification combined with reduced sodium consumption with more than 25 international attendees from industry, academia, government, and nonprofit organizations.