I have written so much about the health benefits of coffee, almost always while sipping a hot cup while sharing information on one of my favorite beverages. Recently, the World Health Organization (WHO) had been evaluating whether the extremely popular beverage was carcinogenic, and I crossed my fingers and held my breath. The agency announced its conclusion yesterday: it will not classify coffee as carcinogenic.
Oh, but very hot drinks are “probably carcinogenic.”
The WHO reversed its previous warning that coffee might cause cancer, citing “no conclusive evidence for a carcinogenic effect” of coffee drinking. Coffee had been listed as a “possible carcinogen in the organization’s 2B category, alongside chloroform, lead, and other substances.
Coffee wound up in the 2B category in 1991, when studies linking coffee consumption to a higher risk of bladder cancer.
After reviewing more than 1,000 scientific studies in humans and animals, the WHO said it said could neither classify coffee as carcinogenic or not carcinogenic. The agency also pointed to studies which suggest that drinking coffee may actually prevent cancer.
Well, I guess that settles it, right? Coffee is great, right?
Coffee: Good, Bad, or … ?
Dana Loomis, the deputy head of the International Agency for Research on Cancer’s (IARC) Monograph classification department, said:
“(This) does not show that coffee is certainly safe … but there is less reason for concern today than there was before.”
Then, the agency presented other scientific evidence suggesting that drinking very hot beverages probably does cause cancer of the esophagus. “Very hot,” in this case, refers to 65 degrees Celsius – 149 degrees Fahrenheit – and above.
IARC said animal studies suggest carcinogenic effects likely occur with drinking liquids at 65 degrees Celsius and higher. Some experiments in rats and mice found “very hot” liquids – including even water – could promote the development of tumors.
Additionally, the agency said studies of hot drinks such as mate, an infusion consumed mainly in South America, tea, and other beverages in several countries including China, Iran, Japan, and Turkey, show the risk of esophageal cancer “may increase with the temperature of the drink.”
IARC director Christopher Wild said:
“These results suggest that drinking very hot beverages is one probable cause of esophageal cancer and that it is the temperature, rather than the drinks themselves, that appears to be responsible.”
Esophageal cancer is the 8th most common cancer worldwide, and one of the main causes of cancer deaths, with about 400,000 deaths recorded in 2012.
CNN points out that drinking at 149 degrees Celsius and higher can cause significant scald burns in the esophagus, and beverages are not typically consumed this hot in Europe and North America. But drinking warm beverages at these scalding hot temps is commonplace in regions such as South America, the Middle East, and East Africa, especially when drinking teas.
Water boils at 100 degrees Celsius, or 212 degrees Fahrenheit. The hot water that comes out of your kitchen faucet is typically no hotter than 60 degrees Celsius, or about 140 degrees Fahrenheit.
If 149 degrees Celsius is hot enough to scald your esophagus, it can also burn your tongue. That’s actually good news, because you’re not going to start chugging a drink that is that hot.
That’s also cooler than the coffee people purchase from most take-out spots.
The WHO’s official spokesman in Geneva, Gregory Hartl, told Reuters that smoking and drinking alcohol is far more risky than drinking hot beverages, but offered some common-sense recommendations for people who are concerned.
“We say: be prudent, let hot drinks cool down.”
If you yell “ouch!” when you take a sip of your drink, that’s a sign you should follow Hartl’s advice.
The IARC’s review is published in The Lancet.