A similar, less severe and metabolic disorder is congenital lactase deficiency. 类似的，病症略轻为一点的代谢紊乱疾病是乳糖分解酶素缺乏症。
Sweden has one of the world's highest percentages of lactase tolerant people. 其中瑞典为乳糖耐受性比例最高的国家。
Lactose intolerance stems from a deficiency of the enzyme lactase, which is needed to help digest lactose, a sugar in milk. 乳糖不耐症的病因是缺乏乳糖酶，这些乳糖酶是消化乳糖的必需物质，牛奶中的糖就属于此类。
