How much water should we drink?我们每天应该喝多少水？

　　我们都知道 “多喝水有益身体健康” 的说法。确实，水中含有人体必需的营养，水还可以帮助我们的身体排出毒素、促进消化。有些人相信 “8x8” 的 “饮水法则”，即每天分8次喝8大杯水。不过实际上，每个人每天应该喝多少水是由个体的年龄、体重和运动量等多重因素而决定的。本期 “随身英语” 讨论我们是否应该严格定时定量地喝水。

　　词汇：water水

　　In school, kids are told to drink water in class, tannoy announcers encourage us to remember our bottles on public transport, and we're reminded by experts that water will help us have glowing skin and regulate our weight. But how much should we actually be drinking?

　　For many years, people have followed the unofficial advice of drinking eight glasses of water, eight times a day, known as the '8x8 rule'. According to Jessica Brown, writing for BBC Future, this seems to have partly come from not understanding guidance that was published almost 80 years ago. In 1945, the US Food and Nutrition Board of National Research Council advised drinking one millilitre of liquid for every recommended calorie of food. This is equivalent to around two litres of water a day, or eight glasses per person. But, Jessica says, the reality is that individuals have different needs. Weight, age and activity level all affect how much water someone should drink.

　　So, should we control our water intake at all? It's not that important, according to Dr Stanley Goldfarb from the University of Pennsylvania. He told BBC podcast More or Less that our body is very good at hydration control– it tells us when we are dehydrated. First, there is 'the thirst system, which tells us go drink because your body water content is slightly reduced. And secondly, we have the kidney system which helps to retain any water and kicks in well before we really sense any thirst'.

　　There are, of course, benefits to drinking water. It helps our bodies regulate temperature, flushes outtoxins, aids digestion and acts as a shock absorber for our joints. It also contains essential nutrients like calcium and magnesium, which are important for bone strength.

　　So, next time you feel thirsty, reach for a glass of water, but otherwise, don't worry about it! Your body knows what it's doing.

　　词汇表

　　bottle 水瓶

　　glowing 容光焕发的，水灵的

　　millilitre 毫升

　　liquid 液体

　　calorie （热量单位）卡路里

　　litre 升

　　intake 摄入量

　　hydration control 人体内水分控制

　　dehydrated 缺水的 ，脱水的

　　thirst system 口渴感知系统

　　body water content 人体内水分含量

　　kidney system 肾脏系统

　　retain 保持，留存

　　kick in 开始起作用，见效

　　flush out 清除，排出

　　toxin 毒素

　　digestion 消化

　　shock absorber 起减震缓冲功能的物体

　　calcium 钙

　　magnesium 镁