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，世界卫生组织一个颇有影响力的专家小组得出结论，经常喝咖啡有助于预防某些癌症。数十年来，很多研究发现这种饮料具有很多健康益处。

这一结论标志着这个研究小组罕见的逆转，1991年它曾认为咖啡“可能致癌”，认为它与膀胱癌有关。但是后来，很多研究发现咖啡是一种令人惊喜的灵丹妙药，经常喝咖啡的人患心脏病、Ⅱ型糖尿病、神经障碍和数种癌症的概率较低。

在周三发布的报告中，科学家们也指出了喝咖啡和茶的一项意外风险。他们说，喝“很热的”饮料“可能致癌”，因为某些研究发现这种行为与食道癌有关。但是研究者称，那可能是因为过热的饮料会导致喉咙外壁发炎，这很好避免，喝热茶或咖啡前晾几分钟就行了。咖啡健康益处的很多证据来自观察性研究，不能证明因果关系。但是大量研究得出的饮用咖啡的发现是如此一致地乐观，很多权威卫生机构都已经认可它是健康饮食的一部分。

去年，为美国政府2015年膳食指南提供咨询的一个科学家小组称，“有力的证据”表明，每天喝三至五杯咖啡是无害的，“适度”喝咖啡也许能减少慢性病。另一个名叫世界癌症研究基金会（World Cancer Research Fund Inter national）的组织称，咖啡能预防多种癌症。一个对研究进行系统性回顾的项目的作者们称，应该鼓励慢性肝病患者饮用咖啡，因为咖啡似乎能降低他们的死亡风险。

世界卫生组织是最近一个表明每天喝咖啡可能有益健康的组织。该组织的国际癌症研究机构（International Agency for Research on Cancer）称，它召集了一个由23名科学家组成的团队，回顾了1000多项研究，发现没有确定性证据表明咖啡致癌。但是，那些研究表明，它能预防某些癌症，比如肝癌和子宫癌。

原因不太明确。不过，科学家们称，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。很多研究还发现，饮用无咖啡因咖啡可以降低患慢性病的几率，这表明咖啡的益处不只是来自咖啡因。

不管背后的机制是什么，这条新闻无疑会受到很多美国人欢迎——差不多有一半美国人每天都喝咖啡。全世界每天消耗逾16亿杯咖啡，咖啡是世界上最受欢迎的饮品之一，仅次于茶。