Beware of grapefruit if you are... 请避免食用西柚，如果您...

Some of us might have a habit of drinking grapefruit juice, especially among those who are on diet. Grapefruit is one of the nutraceutical food that shows benefit in reducing the risk of some disease like cancer. However, when you are on medication, you should be aware of grapefruit due to its possible interaction with drug. It is believed that furanocoumarins (a compound that is naturally present in grapefruit) is responsible for this interaction. Grapefruit blocks the enzymes in the intestines that normally break down many drugs. As a result, drug will be rushed into bloodstream, which at worst can cause toxicity, leading to serious side effects. Grapefruit effect does not happen in every drug, but it does affect some popular and widely known medications such as cholesterol drug, blood pressure drug, anti-anxiety and some other drugs.

Just one glass of grapefruit juice is enough to exhibit the maximum blocking effect. For many cases, interaction can be avoided as long as the two interacting agents are taken separately after several hours of interval. For grapefruit, this is not the case, because the effect can last for more than 24 hours, perhaps up to 72 hours. Therefore, grapefruit should be avoided throughout the whole course of medication. 

Are there other fruits that might have the same effect? 

Besides grapefruit, furanocoumarins also present naturally in pomelo and Seville oranges, citrus fruits (lemons, limes and orange) are generally safe.  

我们当中，可能有些有饮用西柚汁的习惯，尤其是用西柚减肥法的。西柚属于营养保健食物，能减少患上一些疾病的风险，如癌症。可是，如果您是需要长期服药的，您可能要特别留意了，因为西柚会产生药物反应。研究人员相信 furanocoumarins 是造成药物反应的成分。西柚阻挡肠道内的酵素，使它们不能分解药物。因而，造成血液内的药物分量提高。在最坏的情况下，可能会引起药物中毒，导致严重的副作用。虽然，西柚并不是对每一种药物都会产生药物反应，但它却影响着一些热门和家喻户晓的的药物，如降胆固醇药，降血压药，抗焦虑等等的药物。

一杯柚子汁的分量已足够造成阻挡作用。一般情况，只要避免一起服用两个有药物反应的药物和食物，将它们相隔几个小时才服用，就可以避免药物反应。但西柚却不能。因为其效果是可持续超过24小时，可能长达72小时。因此，在整个服药期间，都要避免食用西柚。

除了西柚， 还有那些水果也有着药物反应？

柚子和塞维利亚桔子也有天然的 furanocoumarins 。而柑橘类水果（柠檬，酸柑，橙）则属于安全的。