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。

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Rather than being caused by an overenthusiastic immune system, milk intolerance, for example, results from a lack of the enzyme the body needs to break down lactose, the main sugar in milk.

举例来说，不耐乳症不是由免疫系统的过分热情引起的，而是缺乏一种酶的结果，而身体需要这种酶来分解牛奶中主要的糖——乳糖。

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These allergies shouldn't be confused with lactose intolerance, which is when the body doesn't produce enough of the enzyme lactase to break down lactose, a sugar in cow's milk.

这些过敏症不应和乳糖不耐症混淆，乳糖不耐症指的是身体不能制造足够的乳糖酶来分解乳糖，这正是牛奶中所含的一种糖分。

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