Credit Fred R. Conrad for The New York Times
An influential panel of experts convened by the World Health Organization concluded on Wednesday 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.
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, the panel of scientists that shaped the federal government’s 2015 dietary guidelines said there was “strong evidence” that 3 to 5 cups of coffee daily was not harmful, and that “moderate” consumption might reduce chronic disease. The World Cancer Research Fund International reported in recent years that coffee protects against multiple cancers. And the authors of one systematic review said that coffee consumption should be encouraged in people with chronic liver disease because it seems to lower their mortality.
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, also known as IARC, said it assembled a team of 23 scientists who reviewed more than 1,000 studies which showed 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.
It is not entirely clear why. 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.
In their report issued Wednesday, the IARC 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.