Coffee may protect against cancer

By Nick White

An influential panel of experts convened by the World Health Organization concluded on Wednesday,June 15,2016，that regularly drinking coffee could help protect against some types of cancer,a decision that followed decades of research pointing to the beverage’s many health benefits.

The announcement marked a rare reversal for the panel,which had previously described coffee as “possibly carcinogenic”in 1991 and linked it to bladder cancer.But since then a large body of research has portrayed coffee as a surprising elixir,finding lower rates of heart disease,Type 2 diabetes,neurological disorders and several cancers in those who drink it regularly.

In their report issued Wednesday,the scientists did identify one surprising risk for coffee and tea drinkers.They said that drinking “very hot” beverages was “probably carcinogenic”because the practice was linked to esophageal cancer in some studies.But researchers say that may be caused by excessively hot beverages inflaming the lining of the throat—something that people could easily avoid by letting their hot tea or coffee cool off for a few minutes before drinking them.

Much of the evidence for coffee’s health benefits stems from observational studies,which cannot prove cause and effect.But the favorable findings on coffee consumption have been so consistent across so many studies that numerous health authorities have endorsed it as part of a healthy diet.

Last year,a panel of scientists that shaped the United States government’s 2015 dietary guidelines said there was“strong evidence” that three to five cups of coffee daily was not harmful,and that“moderate” consumption might reduce chronic disease.Another group,the World Cancer Research Fund International,reported in recent years that coffee protects against multiple cancers.And the authors of one systematic review of studies said that coffee consumption should be encouraged in people with chronic liver disease because it seems to lower their risk of dying.

The World Health Organization is the latest group to suggest a daily cuppa Joe might be good for health.The organization’s International Agency for Research on Cancer,or IARC,said it assembled a team of 23 scientists who reviewed more than 1,000 studies and found no conclusive proof that coffee causes cancer.But the studies did suggest it was protective against some types of cancer,such as liver and uterine cancers.

The reason is not entirely clear.But scientists say coffee contains many antioxidants and other compounds that are being studied for their anti-cancer properties.Studies have linked decaffeinated coffee consumption to lower rates of chronic disease too,suggesting coffee’s benefits are not simply due to caffeine.

Whatever the mechanism,the news is sure to be welcomed by many Americans—about half of whom drink coffee every day.Around the world,more than 1.6 billion cups of coffee are consumed daily,making it one of the world’s most popular drinks behind tea.

2016年6月15日，周三，世界衛生組織一個頗有影響力的專家小組得出結論，經常喝咖啡有助于預防某些癌癥。數十年來，很多研究發現這種飲料具有很多健康益處。

這一結論標志著這個研究小組罕見的逆轉，1991年它曾認為咖啡“可能致癌”，認為它與膀胱癌有關。但是后來，很多研究發現咖啡是一種令人驚喜的靈丹妙藥，經常喝咖啡的人患心臟病、Ⅱ型糖尿病、神經障礙和數種癌癥的概率較低。

在周三發布的報告中，科學家們也指出了喝咖啡和茶的一項意外風險。他們說，喝“很熱的”飲料“可能致癌”，因為某些研究發現這種行為與食道癌有關。但是研究者稱，那可能是因為過熱的飲料會導致喉嚨外壁發炎，這很好避免，喝熱茶或咖啡前晾幾分鐘就行了。咖啡健康益處的很多證據來自觀察性研究，不能證明因果關系。但是大量研究得出的飲用咖啡的發現是如此一致地樂觀，很多權威衛生機構都已經認可它是健康飲食的一部分。

去年，為美國政府2015年膳食指南提供咨詢的一個科學家小組稱，“有力的證據”表明，每天喝三至五杯咖啡是無害的，“適度”喝咖啡也許能減少慢性病。另一個名叫世界癌癥研究基金會（World Cancer Research Fund Inter national）的組織稱，咖啡能預防多種癌癥。一個對研究進行系統性回顧的項目的作者們稱，應該鼓勵慢性肝病患者飲用咖啡，因為咖啡似乎能降低他們的死亡風險。

世界衛生組織是最近一個表明每天喝咖啡可能有益健康的組織。該組織的國際癌癥研究機構（International Agency for Research on Cancer）稱，它召集了一個由23名科學家組成的團隊，回顧了1000多項研究，發現沒有確定性證據表明咖啡致癌。但是，那些研究表明，它能預防某些癌癥，比如肝癌和子宮癌。

原因不太明確。不過，科學家們稱，咖啡包含很多抗氧化物以及其他化合物，后者的抗癌功能正得到研究。很多研究還發現，飲用無咖啡因咖啡可以降低患慢性病的幾率，這表明咖啡的益處不只是來自咖啡因。

不管背后的機制是什么，這條新聞無疑會受到很多美國人歡迎——差不多有一半美國人每天都喝咖啡。全世界每天消耗逾16億杯咖啡，咖啡是世界上最受歡迎的飲品之一，僅次于茶。