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3.2 Deficiency of Vitamin A
8. Vitamin A is widely recognized as a vital factor for normal vision. Its deficiency is a major problem which afflicts more than 10 million children. According to recent estimates as many as half a million new cases of acute vitamin A deficiency (xerophthalmia with corneal involvement) annually occur in just four of the 27 developing countries of the Region namely, Bangladesh, India, Indonesia and the Philippines. Half of those affected are threatened with total blindness. Table 4 presents figures of percentage prevalence in countries for which national-level survey data exist.
Inter-country comparison is difficult due to the different sampling techniques and to differing criteria for the definition of vitamin A deficiency, criteria that range from the early symptoms of night blindness and xerosis through to the advanced eye-lesions known as keratomalacia, a precursor of blindness. While the prevalence of vitamin A deficiency is low in comparison to those of iodine or iron, it should be noted that vitamin A deficiency is an acute disorder leading to irreversible blindness, and associated with high morbidity and mortality.
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9. Vitamin A, chemically known as retinol, occurs in foods such as fish liver, egg yolk, and other dairy and animal products. As provitamin A in the form of carotenes it is found in green and yellow vegetables, such as broccoli, spinach, amaranths and carrots, and in yellow-red fruits, such mango, papaya and apricots. Vitamin A levels are conventionally expressed in terms of micrograms (a millionth of a gram) of retinol, or as retinol equivalents (1
R.E. ug
1 ug retinol) for provitamin A (carotenes). The safe level of intake from age 10 to adulthood is 500-600 ug RE per day, and for infants and young children the level varies from 350 to 400. It needs to be emphasized here that only about 4 to 5 grams of liver, about 30 grams of hen's egg yolk, about 45 grams of carrots and about 425 grams of ripe papaya will provide the necessary 500 micrograms of the retinol equivalent. The presence and the amount of dietary fat, however, are crucial to the absorption
provitamin carotenes. Diets of many of the less developed countries of the Region such as Viet Nam and Bangladesh are low in dietary fat, and most dietary vitamin is in the form of carotenoids, not all of which are provitamin A. It is clearly important to ensure an adequate fat intake if dietary vitamin A or even oral supplements are to be fully utilized.
3.3 Deficiency of Iron
10. Iron deficiency is the most widespread nutritional deficiency in the Region. Although the characteristic sign of iron deficiency is anaemia, a state of deficiency exists
well before the anaemia becomes apparent. Highest prevalences are found among pre-school children, women in the reproductive age group, and pregnant women. However, significant levels of anaemia are found in all age groups, particularly among low- income households. Anaemia seriously impairs work capacity and hence productivity. It also affects learning capability and the ability of the individual to resist disease.
11. Foods that are particularly rich in iron include animal foods such as meat, liver and other internal organs, eggs, fish and seafood. Some vegetable foods, especially dark green leafy vegetables and beans, are also significant sources of dietary iron. Not all the iron consumed in a diet is absorbed. Its bio-availability depends upon the type of iron present in
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