每天要喝八杯水的說法大家都可能聽過，但廣為流傳的健康觀念就代表是真確的嗎？到底這說法有何理據？
每日八杯水差不多是每個小學生都奉若圭臬的格言，但其實每日要攝取幾多水，是和每日攝取的卡路量有關。根據英國醫學期刊，每1卡的熱量攝取，應對應1毫升的水分攝取。[1]即是說你食完一碗白飯(約220卡熱量)後，應該補充2又4份1支益力多的水份。[2]這樣看來，「每日八杯水」這句口號的原版可能是咁的：「大部份情況下，每人每日應攝取2.5升水，但實際量取決於熱量攝取。」一知半解捨後取前，就難免以訛傳訛。
即使有醫護背景，亦不代表可幸免於謠言。每日飲8杯水的建議，亦曾出自營養師之口和美國生理學雜誌的專訪中，兩次均無文獻佐證。[3][4]現有研究亦指出，單靠日常生活中飲用的果汁、牛奶甚至咖啡，都已足夠應付身體所需。[5]
文: Crystal
參考資料
[1] Board FaN. Recommended dietary allowances. In: Sciences NAo, ed. National Research Council, 1945:3-18.
[2] Nutrition and Health Facts. (2015). Calories in Rice, White, Medium-grain, Cooked. Retrieved 2015, from http://www.caloriecount.com/calories-rice-white-medium-grain-cooked-i20051.
[3] Stare FJM, McWilliams M. Nutrition for good health. Fullerton, CA: Plycon, 1974.
[4] Valtin H. “Drink at least eight glasses of water a day.” Really? Is there scientific evidence for “8 × 8”? Am J Physiol Regul Integr Comp Physiol 2002;283:R993-1004.
[5] Grandjean AC, Reimers KJ, Bannick KE, Haven MC. The effect of caffeinated, noncaffeinated, caloric and non-caloric beverages on hydration. J Am Coll Nutr 2000;19:591- 600.