present among large populations that live in iodine-deficient environments where the soil has been leached of iodine by glaciation, flood, or high rainfall. This occurs generally in mountainous areas of the region i.e. Himalayan region and the mountainous ranges of China. Severe iodine deficiency is also prevalent in the Ganges Valley in India and Bangladesh due to low-lying areas prone to flooding. Most people in these areas consume only food grown on local iodine-deficient soil.
16. In the South-East Asian countries alone it has been estimated that 277 million people are at risk for IDD, about 102 million have goitre, and 1 .5 million are cretins. The percentages of people with endemic goitre, endemic cretinism and those at risk of IDD in some countries of the Region are given in Table 5.
17. It is abundantly clear that IDD is a serious problem in the Region and is responsible for enormous damage to human resources. In view of this, countries of the Region have adopted two main approaches, i.e., iodation of common salt and injection of iodized oil. The latter is a short-term measure whereas the former is a medium or long-term measure.
18. Suggestions have been made that iodine rich seaweed should be mixed with soil to enrich its iodine contents so that iodine uptake in the food plants is enhanced. At present such intervention measures are costly. Research and trials are at an early stage and more work will be needed to make iodization of the soil a realistic possibility.
3.5 Other Micronutrients
19. There is now convincing evidence that human zinc deficiency is not a rare condition. The principal clinical manifestations of zinc deficiency are growth retardation, loss of appetite and increased susceptibility to infections. Foods with high zinc content are generally animal products, while cereals can limit the bio-availability of dietary zinc. In Beijing, 22.3% of pre-schoolers were categorized as being zinc deficient.
20. Vitamin D deficiency, characterized by severe bone deformities is generally due to lack of exposure to sunlight necessary for the vitamin's manufacture by the skin. Its clinical manifestations are childhood rickets and its adult counterpart osteomalacia, both widely prevalent for centuries in the northern European countries. It continues to present a serious problem in northern regions of Asia with limited sunlight, in regions where exposure
sunlight is restricted by socio-cultural customs or by intensive urbanization, and in societies where dietary intake of vitamin D is very low. Few studies of the prevalence of rickets have been conducted in Asia. In the northern provinces of China, figures as high as 56 to 87 percent of young children have been recorded, while an earlier study of urban pre-schoolers in Bombay, India, indicated a prevalence of 5.2%.
to
21. Deficiencies of thiamine and riboflavin, both associated with the rice diets of Asia which were widely prevalent in the past, no longer present serious problems. Reports of cases continue to be recorded, however, in China, Myanmar, Thailand and Viet Nam.
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