ARI SHAPIRO, HOST:
This week, the World Health Organization turned its attention to everybody's favorite morning pick-me-up, coffee. The group's cancer research arm gave java a green light, concluding that coffee does not cause cancer. And, in fact, it might help protect against certain types of cancer. The announcement created a lot of buzz, especially the warning that came with it which boils down to this - don't drink your coffee or tea scalding hot. NPR's Allison Aubrey is here in the studio to explain.
ALLISON AUBREY, BYLINE: Hi there, Ari.
SHAPIRO: You brought a prop that we'll talk about in a moment.
AUBREY: I've got a nice cup of coffee here. It's...
SHAPIRO: What did this study find?
AUBREY: What the World Health Organization's cancer research arm is really concluding is that they've looked at over 500 studies now, and they say there is no evidence that a regular coffee habit - so drinking a cup or two of this every day - is linked to a higher risk of cancer.
And, in fact, there's gathering evidence that drinking a couple or two a day may actually decrease the risk of kidney and colorectal cancer. So I'd say, yes, the World Health Organization is giving us the green light. As long as we drink coffee in moderation, go ahead. Drink up.
SHAPIRO: Sort this out for me because 25 years ago, the World Health Organization said there might be a link between drinking coffee and cancer. How did they get this wrong? I feel like first it was wine then chocolate, now coffee that first we thought was bad for us now may be good for us.
AUBREY: Sure. They just didn't have the complete picture. So back in 1991 when they listed coffee as a possible carcinogen, they had very limited data. As I just mentioned, they've now reviewed 500 studies. And what they see is a much more complete picture. For many years, the habit of drinking coffee went hand-in-hand with cigarette smoking. So it was tough to disentangle the risk. What looked like a risk from drinking coffee was really from the smoking.
And the World Health Organization pointed this out this week. They say a lot of the early research, the research that pointed to perhaps a higher risk of bladder cancer linked to coffee drinking didn't account for this tobacco smoking. And, of course, now we know that tobacco smoking is a major risk for bladder cancer and coffee's not.
SHAPIRO: So I want to talk about one part of this study. In front of you, you have a cup of coffee with an enormous thermometer sticking out of it. Why is extremely hot coffee or tea something to worry about?
AUBREY: Sure. So the World Health Organization also looked at studies from South America and China and Japan, and they found that drinking very hot beverages - so in those countries tea and mate - was linked to an increased risk of cancer of the esophagus.
Now, the thought is that this extreme heat might play a role in producing tumors, at least that's what's been shown in animal experiments. And so the World Health Organization looked into this, and what they found is it's not the mate, it's not the tea. It's actually the temperature. They say...
SHAPIRO: How hot is too hot?
AUBREY: Right. They say that the risk starts at about 150 degrees. So what I did, I've just gotten a cup of coffee here from the coffeemaker down the hallway. It's too late in the day to be drinking caffeine, so this is decaf. When I first brewed it, it was coming out right at about 140.
Now it's down - way down because we've been sitting here a few minutes. So I have to say I'm not concerned. It seems that for most of us by the time we brewed it, put a little cream in it and get it to our lips, we're down under 150 degrees.
SHAPIRO: NPR's Allison Aubrey, thank you.
AUBREY: Thank you so much.
(SOUNDBITE OF SONG, "FORTY CUPS OF COFFEE")
ELLA MAE MORSE: (Singing) ...pulling out my hair. I drink 40 cups of coffee, 40 cups of coffee.
NPR transcripts are created on a rush deadline by Verb8tm, Inc., an NPR contractor, and produced using a proprietary transcription process developed with NPR. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.