Oh, em, gee: there’s a new health drink in town, and everybody’s drinking it. Alicia Silverstone, Matt Dillon—I’ve even heard Madonna can’t live without it. It’s called Yerba maté, and it’s this totally amazing tea drink that, like, comes from South America or something. It doesn’t taste so great, but it’s supposed to cure cancer and stuff. Seriously!
OK—before you jump on the celebrity bandwagon, consider this: Not only is there no good evidence that Yerba maté cures cancer, there’s some evidence that it might actually cause it, as I explained briefly in Glamour’s July issue. The drink is a hot or cold tea made from the leaves of the herb Ilex paraguariensis, and it has been drunk by South Americans for centuries. But in 1991, the International Agency for Research on Cancer (IARC) concluded that hot Yerba maté was “probably carcinogenic for humans,” based on findings from a number of case-controlled studies that suggest that South Americans who drink a lot of it are more likely than non-drinkers to have oral, esophageal, lung, kidney and bladder cancer.
It’s possible, of course, that Yerba maté drinkers share other lifestyle factors that put them at an increased cancer risk. It’s also feasible that the temperature of the drink, not the drink itself, has something to do with it—a hot drink can irritate the mouth and esophagus and could, in theory, up cancer risk. A 2000 study published in the International Journal of Cancer compared the drinking habits of people with esophageal cancer to those without and found that regular consumption of hot Yerba maté, hot coffee with milk, and other hot teas were all associated with cancer (black coffee was not). But the risk associated with the maté was the worst: heavy hot maté drinkers were 4.14 times more likely to have esophageal cancer than non-drinkers were, while hot tea drinkers were at 3.73 more likely and hot coffee-with-milk drinkers were only 2.29 times more likely (sorry, I can’t find details on absolute risk).
So while heat may have something to do with it, it’s probably not the whole story. In 2008, researchers at the National Cancer Institute analyzed Ilex paraguariensis leaves for polycyclic aromatic hydrocarbons (PAHs), known chemical carcinogens found in cigarette smoke, among other things. The researchers found “very high concentrations of carcinogenic PAHs” in both hot and cold infusions made from the leaves. The PAH levels ranged from 536 to 2,906 nanograms per gram (ng/g) of dry leaves, and the concentration of one well-known cancer-causing PAH, benzo[a]pyrene, ranged from 8.03 to 53.3 ng/g. This is amazingly high—as a comparison, one cigarette only contains 3.36 ng to 28.39 of benzo[a]pyrene.
Before you go out and stock up on Yerba maté, then, consider that it might be healthier to smoke a cigarette. I’m kidding, of course—well, kind of—but the moral of the story is, “health” drinks aren’t always healthy, and celebs don’t always know what they’re doing. But I guess we already knew that.