虽然我国人民生活水平逐年提高,营养状况已有根本改善,严重的蛋白质一热能营养不良的发生率已减少,然而近年的流行病学调查资料仍然表明,营养紊乱性疾病在儿童时期非常突出。地区性人群普查发现微量元素锌和铁缺乏的患病率分别高达25%～50%和30%～60%;亚临床维生素 A 缺乏(血清维生素 A< Although the standard of living of our people has been increasing year by year, the nutritional status has been fundamentally improved and the incidence of severe protein-heat malnutrition has decreased. However, epidemiological survey data in recent years still show that nutritional disorders are very prominent in childhood. Regional population census found that the prevalence of trace elements zinc and iron deficiency were as high as 25% to 50% and 30% to 60%; subclinical vitamin A deficiency (serum vitamin A <