Table salt, iodine supplementation

Iodized Salt. Iodized table salt has been used to provide supplemental iodine to the U.S. population since 1924, when producers, in cooperation with the Michigan State Medical Society (24), began a voluntary program of salt iodization in Michigan that ultimately led to the elimination of iodine deficiency in the United States. More than 50% of the table salt sold in the United States is iodized. Potassium iodide in table salt at levels of 0.006% to 0.01% KI is one of two sources of iodine for food-grade salt approved by the U.S. Food and Dmg Administration. The other, cuprous iodide, is not used by U.S. salt producers. Iodine may be added to a food so that the daily intake does not exceed 225 p.g for adults and children over four years of age. Potassium iodide is unstable under conditions of extreme moisture and temperature, particularly in an acid environment. Sodium carbonate or sodium bicarbonate is added to increase alkalinity, and sodium thiosulfate or dextrose is added to stabilize potassium iodide. Without a stabilizer, potassium iodide is oxidized to iodine and lost by volatilization from the product. Potassium iodate, far more stable than potassium iodide, is widely used in other parts of the world, but is not approved for use in the United States. 

A deficiency of iodine is one of the possible causes of the enlargement of the thyroid gland (goitre). Dietary sources of iodine are often supplemented by iodinated table salt, for which potassium iodide and sodium iodide are used. 

Deficiency of iodine, a component of thyroid hormones, may result in goiter formation (see Chap. 73). However, not everyone with an iodine-deficient diet will develop a goiter. Thyroxine (T4) and triiodothyronine (T3) can be used to assess iodine status (see Table 135-8). Intravenous iodine supplements typically are not necessary except during long-term parenteral nutrition with minimal enteral intake. Iodine needs generally are met by cutaneous absorption of iodine from germicides (e.g., povidone-iodine) used in catheter care or consumption of iodized salt. " Use of povidone-iodine wiU likely decrease with the increased use of chlorhexidine for catheter care, and the need for iodine supplementation must be individualized. Iodine excess is rarely a clinical concern when thyroid function is normal. 

The daily requirement for iodine in adults is 1-2 /ag/kg body weight. In the U.S., recommended daily allowances for iodine range from 40 to 120 /xg for children, 150 fxg for adults, 220 fxg for pregnancy, and 270 p,g for lactation. Dairy products and fish have relatively high iodine contents. Because of concerns of iodine insufficiency, iodine supplementation has been widely used for prophylaxis and therapy. The most practical form of this supplementation has been addition of iodide or iodate (now preferred) to table salt. In the U.S., such supplementation is optional and iodized salt provides 100 fxg of iodine/g. 

A fluorescence-based method was successfully tested for iodine determination in iodine-supplemented food, such as table salt and milk powder. It is based on the fluorescent quenching capability of iodine/triodide using a highly fluorescent compound consisting of a synthetic metal ion receptor coupled with a signaling element. The detection limit for triodide down to a concentration of 10 mol was reported (Zhao et al., 2003). 

Iodi2ed salt is the most important source of iodine worldwide, and is also the agreed strategy for achieving iodine sufficiency (WHO/UNICEF/ICCIDD, 2001). Although Norway has never had mandatory iodization of salt, some brands of table salt are fortified with iodine, and regulations permit the addition of 5 pg of iodine per gram of NaCl (Ministry of Health, 2002). Industrial salt used in food production is not supplemented with iodine (Frey, 1986). 

Generally, the iodine content of foods varies across regions and countries, according to the amounts of naturally occurring iodine and the levels and extent of iodine supplementation in table salt, animal feed and processed foods. This is illustrated in Tables 54.3-54.5, which also reflect differences in reference tables used in various countries to describe the nutritional content of common foods (Krajcovicova-Kudlackova et al., 2003 Lightowler etal., 1996). 

Vitamin supplements that contain Iodine, cough medicine. Iodized table salt or sea salt... 

In 1982 an application was received by the National Board of Health for an authorization to place table salt fortified with iodine on the market. As food policies were that vitamins and minerals should not be added to food without documentation of a need for this, no authorization was given. However, it was legal to add iodine (mostly 150 pg) to vitamin-plus-mineral tablets, and such supplements were (and are) taken by a considerable part of the population (Knudsen et aL, 2002d). 

Monitoring of table salt quality is crucial for providing optimal iodine supplementation. Furthermore, the high use of table salt (1—3 times above the recommended quantity) is one of the unfavorable tendencies in the nutrition of the Bulgarian population that may also contribute to excessive iodine supplementation. 

Products and Uses Dietary supplement added to table salt to prevent goiters. Source of iodine in table salt. 

Uses Feed additive nutrient dietary supplement in table salt as source of dietary iodine catalyst in Sandmeyer reactions cloud seeding heat stabilizer for glass fiber-reinforced polyamides antioxidant/stabilizer... 

Iodine has also been used for the disinfection of swimming pool water. The concentration range in which it shows strong bactericidal, virucidal, or amoebicidal action is 5-50 mg/cm, leaving a 0.2-0.6 mg/dm residual iodine concentration. Traces of iodine or iodide ions are found in raw waters. The iodine is an essential trace element for humans. The adult daily requirement of iodine or iodide is 80-150 xg. Iodide content of the drinking water is sometimes checked to decide the amount of supplement needed. The iodide is usually supplied as a table-salt additive in areas where it is needed. As a matter of fact, the determination of iodine or iodide content of water samples is not needed very often. However, the titration or back titration of iodine content is an everyday trick in iodometric analytical procedures. 

The iodine supplementation by iodised salt was in the last decades (1970-90) absolutely irregular the only development are in this field the increase of iodine content of table... 

In order to combat the prevalence of iodine deficiency disorders, the World Health Organization has recommended that all food salt should be iodized (WHO, 1999), although compliance with this varies. Salt sold in Canada for table use must be iodized according to federal law. The proportion of households using iodized salt is lowest in Europe at 27% compared with 90% in the US (WHO, 1999). The UK has a diet sufficient in iodine, and salt is not routinely supplemented with iodine. There are only trace levels of iodine in noniodized salt, which is therefore entirely safe within a low-iodine diet. Studies testing levels of iodine in sea and rock salt have found only trace levels of iodine (Aquaron, 2000). In one comparison 1.2—1.4p,g iodine/g of noniodized sea salt compared with 52.9— 84.6 rg iodine/g of iodized salt (Fisher, 1980). However, due to the significant quantity of iodine in seawater a common misconception exists that sea salt is also rich in iodine. 

SPECIALTY FOODS AND HIGHLY POTENT NUTRITIONAL SUPPLEMENTS. It is fortunate that most consumers are not able to purchase pure mineral salts and to mix them into their foods, because without special measuring equipment and experience in preparing such mixtures, it is very easy to add toxic excesses of trace elements like iodine and selenium to foods. However, even some of the products that are sold by health food stores may have undesirable, or even toxic effects, because they are very rich in certain minerals. The potentially hazardous products may be considered as highly potent nutritionai suppiements, in order to distinguish them from the less potent specialty foods, which are usually safe in the amounts consumed. Table M-27 shows the approximate amounts of these minerals that are provided by various specialty foods and nutritional supplements. 

The prevalence data of table 4, even though taken before the iodide in salt was raised to the optimal level of 15 ppm, clearly suggest that in elderly persons, goiters acquired previously before supplementation do persist even after correction of iodine deficiency... 

Table 6 gives an overview over idodine turnover data from 1923 -1988. Supplementation by iodized salt has lowered the previously high radioiodine uptake to values reported from iodine-sufficient countries such as the USA. 

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