对铁吸收的抑制作用

对铁吸收的抑制作用是因为茶叶中的单宁酸和铁在消化道内形成不溶解的单宁酸铁。这种物质不能被小肠粘膜上皮细胞吸收。我们不能因为有抑制铁吸收的缺点而喝茶，但从预防缺铁性贫血的角度来看，对于有缺铁性贫血的人和容易发生缺铁性贫血的人，例如妊娠期、哺乳期、月经过多的育龄妇女、青少年和婴幼儿，最好不要喝茶。上述人群有茶癖者，也要酌情控制饮茶量。

近年来，科研人员以三氯化铁溶液为人体铁源，通过比较试验发现，服用三氯化铁饮水者，铁的吸收率为21.7%，服用同量三氯化铁饮茶者，铁的吸收率仅为6.2%。用硫酸亚铁和维生素c进行试验，饮水者，铁的吸收率为30.9%的饮茶者为11.2%。另外，用面包做试验，吃面包喝水的人，面包中铁的吸收率为10.4%的茶的人为3.3%。最后，科学家们又以米饭和土豆洋葱汤做试验，吃上述食品并饮水者，铁的吸收率为10.8%；饮茶者则只有2.5%。这项实验表明，饮茶对饮食中非血红素铁的吸收有明显的抑制作用。

夜茶

夜茶

夜茶实验发现，维生素c可以促进饮食中非血红素铁的吸收，还可以抑制非血红素铁的吸收。

。发烧禁止喝茶

叶片中咖啡因不仅能提高体温，还能降低药效。

　　2.醉酒慎饮茶

　　茶叶有兴奋神经中枢的作用，醉酒后喝浓茶会加重心脏负担。

饮茶还会加速利尿作用，使酒精中有毒的醛还没有分解就从肾脏排出，对肾脏有很大的刺激性，危害健康。因此，对于心肾病或功能差的人来说，不要喝茶，尤其是不要喝大量浓茶。对于健康的人来说，他们可以喝少量浓茶。醒来后，他们可以吃大量水果或少量醋，以加快人体的新陈代谢速度，缓解酒醉。

3.溃疡患者慎饮茶

杏仁茶是胃酸分泌刺激剂，饮茶会增加胃酸分泌量，增加对溃疡面的刺激，经常喝浓茶会加重病情。但是对于轻微患者来说，服药两小时后可以喝一些淡茶，加糖红茶、加奶红茶有助于消炎和保护胃粘膜，对溃疡也有一定的作用。喝茶还能阻断体内亚硝基化合物的合成，防止癌前突变。

4.营养不良忌饮茶

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。尿路结石患者禁止喝茶

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