Iodine deficiency developing countries

The major natural food source of iodine is fish. The iodine content of fish reflects that of the water they inhabit thus, high levels of iodine are present in marine fish and shellfish compared to freshwater fish (Figure 45.1). Milk and dairy products contain relatively high amounts of iodine and are considered to be the most important sources of iodine in developed countries. The iodine content of milk is largely influenced by the use of iodophors as teat sterilants and equipment sanitizers in dairy husbandry, and the supplementation of animal feeds due to iodine deficiency in dairy cattle, exacerbated by the inclusion of goitrogenic feeds in the diet (COT, 2003). In addition, seasonal variations in the iodine content of foods are particularly evident in cows milk, with greater iodine... 

Iodine deficiency in less developed countries is still a serious problem. Whereas, iodized and iodated salt technology is readily available and relatively inexpensive, market distribution conditions, as well as a lack of understanding by consumers, prevents iodized salt from reaching much of the population in less-developed countries. 

Globally, undernutrition is widespread, leading to impaired growth, defective immune systems, and reduced work capacity. By contrast, in developed countries, there is often excessive food consumption (especially of fat), leading to obesity and to the development of cardiovascular disease and some forms of cancer. Deficiencies of vitamin A, iron, and iodine pose major health concerns in many countries, and deficiencies of other vitamins and minerals are a major cause of iU health. In developed countries, nutrient deficiency is rare, though there are vulnerable sections of the population at risk. Intakes of minerals and vitamins that are adequate to prevent deficiency may be inadequate to promote optimum health and longevity. 

Countries affected by iodine deficiency require to develop national programmes to assess the extent and severity of the problem. Once an IDD control programme is initiated monitoring and evaluation are required. There are three major components needed to meet this goal, namely determination of thyroid size and goitre prevalence, the determination of urinary iodine excretion, and the measurement of thyroid function, including serum TSH levels. 

Some degree of iodine dietary deficiency was estimated to affect 750 million people in the developing world in 1990 with around 10 million were suffering from stunted growth and mental retardation. In 1993 the WHO published a database of iodine deficiency based on the number of goitre victims in 121 countries where the element was in short supply. This shortage was most prevalent where soils have suffered repeated glaciations or heavy rainfall which had removed most of the iodide that may once have been present, because this is a particularly soluble material and so easily washed away. Those most at risk lived in India and China. 

Primary goitrous hypothyroidism results when the synthesis of T4 and T3 is impaired, either because of some extrinsic factor or because of an intrinsic, inherited defect in thyroid hormone biosynthesis. As a result, the positive feedback loop causes compensatory thyroid enlargement (goiter) through the hypersecretion of TRH and TSH. Primary nongoitrous hypothyroidism is characterized by loss or atrophy of thyroid tissue, resulting in decreased production of thyroid hormones despite maximum stimulation by TSH. Hashimotos thyroiditis is the most frequent cause of primary hypothyroidism in developed countries where iodine intake is sufficient. Worldwide, iodine deficiency is the most common cause of goitrous hypothyroidism. The... 

In developed countries, where iodine deficiency is rare because of the use of iodized salt, autoimmune disorders are a leading cause of thyroid disease. 

Without iodine supplements in the form of marine fishmeal or mineral mixtures, the farm animals of most countries worldwide would suffer of iodine deficiency. Germany and most industrially developed countries unconsciously supply farm animals (and in turn the population) with iodine by fertilizing the land with Chile saltpeter, which has a high iodine content. During World War I, the importation of Chile saltpeter to Europe was stopped, and thereafter synthetic nitrogen containing no iodine was produced worldwide. Consequently, iodine deficiencies in both animals and man reap-... 

Most countries in the world are affected by iodine deficiency to some extent, and it remains a major threat to the health and development of populations worldwide particularly among preschool children and pregnant women. Iodine deficiency is the world s greatest single cause of preventable brain damage, and the primary motivation behind the current worldwide drive to eliminate iodine deficiency. 

Iodine deficiency is the worlds leading cause of preventable mental retardation and impaired psychomotor development in young children. In its extreme form, iodine deficiency causes cretinism. Globally, about 740 million people are affected by goiter and more than 2 biUion fiv-ing in 130 countries are estimated to be at risk for IDD. 

In summary, it seems that the number of people who consistently follow strict vegetarian diets is small, probably less than 0.1% of the populations in the US and European countries there is a lack of data on the numbers who adhere to such diets in developing countries. These are the vegetarians most likely to be iodine-deficient. By contrast, a substantial proportion of self-identified vegetarians regularly consume iodine-rich dairy products and a smaller proportion eat meat, poultry, or fish at least occasionally. 

Early correction of hypothyroidism due to congenital defects in neonates has now become a standard practice in most developed countries in order to prevent longterm brain damage (Dussault and Glorieux, 1989). The more severe the fetal hypothyroidism, as indicated by bone retardation, the more Hkely are residual effects (Dussault and Glorieux, 1989). Such considerations indicate the urgent need for a preventive approach to the correction of iodine deficiency for developing countries, because treatment of individual cases is not usually possible. 

Pregnant Women with Iodine Deficiency in Iodine-Sufficient Areas How Common is Hypothyroxinemia in Pregnant Women in Developed Countries ... 

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