颠覆你的认知:水果并不是越多吃越好

We're always being told by the Department of Health to eat five portions of fruit and vegetables a day. But it's not clear where the evidence for this comes from and a large study by the European Prospective Investigation Into Cancer and Nutrition (Epic) two years ago of the dietary intake of more than 400,000 people found only a weak link between eating fruit and vegetables and a reduction in overall cancer risk. There's no evidence it reduces breast or prostate cancer.

我们总是被健康部门告知一天要吃五份水果和蔬菜。但这不清楚这项结论来自于何方，一个由欧洲癌症与营养前瞻性调查(Epic)两年前对超过40万人的饮食摄入量的大型研究发现食用水果和蔬菜与降低整体罹患癌症的风险之间只有微弱的联系。没有证据表明它可以减少乳腺癌或前列腺癌的几率。

Even so, how could anyone argue against eating more fruit and vegetables? Well, it depends what fruit you're eating. A review article in the Canadian Medical Association Journal warns that a chemical in grapefruits can interact lethally with certain medicines. Even apple juice, the staple of many breakfast tables, may reduce our absorption of some drugs. Parents also often think fruit juice is a healthy alternative to fizzy drinks but juices contain sugar and calories too – as much as a glass of Coke (160 calories) – so should be drunk in moderation.

即便如此，怎么会有人反对吃更多的水果和蔬菜呢？好吧，这取决于你在吃什么水果。加拿大医学协会杂志上的一篇评论文章警告称葡萄柚中的一种化学物质可以与某些药物相互反应而致命。甚至苹果汁，许多早餐中的主食，可能会减少我们对一些药物的吸收。父母也常常认为果汁是碳酸饮料的健康替代但果汁也含有糖分和卡路里——高达一杯可口可乐的热量(160卡路里)，所以应该适度引用。

Grapefruit has also been linked to an increase in breast cancer. A study in the British Journal of Cancer (BJC) of 500,000 post-menopausal women found that eating a quarter of the fruit a day increased the risk by 30%.

葡萄柚也与乳腺癌的增加有关。《英国癌症杂志》(BJC) 对50万名绝经后的妇女的一项研究发现一天吃四分之一的水果使几率提高了30%。

The solution

解决方法

There is one good reason for not eating grapefruits – they taste sour. But they are unlikely to increase your risk of breast cancer: further research in the BJC showed no increase of breast cancer in pre- or post-menopausal women who tuck into grapefruits or drink juice.

有一个好的理由不吃葡萄柚——他们吃起来很酸。但它们不太可能增加患乳腺癌的风险： 《英国癌症杂志》 进一步的调查显示没有增加那些绝经前后海吃葡萄柚或海喝果汁的妇女患乳腺癌的几率。

Grapefruit contains a type of chemical called furanocoumarin (also found in seville oranges and limes but not valencia or other sweet oranges), which, by inhibiting the enzyme CYP3A4, stops the breakdown of some prescription drugs.

葡萄柚含有一种叫做furanocoumarin的化学物质(还发现在塞维利亚橘子和酸橙中但不是瓦伦西亚或其他甜橙)，通过抑制CYP3A4这种酶可以阻止一些处方药的分解。

So the concentrations of these drugs rise and can have serious side-effects, including kidney damage, heart block, and deep vein thrombosis (which occurred when an oral contraceptive was taken by a woman who also ate grapefruit three days in a row).

所以这些药物的浓度上升会产生严重的副作用，包括肾脏损害、心肌梗死和深静脉血栓形成(这发生在一个女人口服避孕药的同时也连续三天吃着葡萄柚的时候)。

Patient information leaflets should tell you what foods to avoid with which drugs. If in doubt, ask your doctor. So you don't need to eat less fruit, and may still need to eat more. Another paper from the Epic study found a 22% reduction in deaths from heart attacks in people who ate eight portions of fruit and vegetables a day compared to those who ate three or fewer. The way the study is designed, however, means that it can only suggest a link – it can't prove one.

病人须知应该告诉你吃药时要避免与什么食物一起食用。如果有疑问，问你的医生。所以你不需要少吃水果，可能仍然需要多吃。Epic研究的另一篇论文发现心脏病人一天吃八份水果和蔬菜与每天吃三份或更少相比降低了22%的死亡率。然而这项研究的设计方法意味着它只是暗示了这种联系，但不能证明。