Tempest In a Teapot

If you haven't tried it yet, you've doubtless seen it on the shelves of your local natural foods store or on the drink menu of your favorite coffeehouse. For many people, a strong-tasting, South American tea-like drink called yerba mate has replaced their daily cup of joe. But along with mate's new popularity in the U.S. comes a number of snake-oily claims made by the growing number of companies that sell it.

Consumed centuries ago by Guarani Indian tribes in Paraguay (and later perfected by Spanish colonizers and Jesuit priests), yerba mate is widely considered to be a good natural stimulant that may be healthier than coffee, due to a unique combination of alkaloids and relatively small caffeine content. Critics, however, say rising U.S. sales to fad dieters and health food junkies overplay such benefits, offering consumers false science and overblown claims about the drink's chemical consistency and physiological benefits.

Jolt Without the Jitters

Controversy accompanies vendor claims that mate contains not caffeine, but a safer chemical called mateine, as its major psychoactive drug. Ma-Tea, a mate importer based in Atlanta, Ga., and Noborders.net, are two examples of companies that advertise their product with a commonly found quote attributed to Dr. Jose Martin, director of the National Institute of Technology in Paraguay: "New research and better technology have shown that while mateine has a chemical consistency similar to caffeine, the molecular binding is different."

But when contacted at his home in Asuncion, Paraguay, the now ex-director (whose name is actually Jose Martino), said there is no unique chemical structure for mateine and that yerba mate contains caffeine, just like coffee.

That's no surprise, say many experts.

"In recent U.S. campaigns, yerba mate marketers claim that yerba mate contains mateine," says Dr. Leslie Taylor, an herbalist and author of "The Healing Power of Rainforest Herbs." "The only studies reporting the presence of 'mateine' have been funded and paid for by companies selling yerba mate. Scientists can go into the laboratory to prove or disprove what they want to, or are paid to. This kind of research simply does not disprove the many years of research proving the opposite by scientists and university students that have never sold any yerba mate product and had no ulterior motives to conduct or report their research."

Renowned health expert Andrew Weil agrees. Writing on his Web site, he finds "very little scientific support for this distinction, but you will certainly see health claims to that effect on packages of yerba mate and in advertisements for it."

Though many mate fans cite the absence of coffee-like jitters, experts say the distinction could be a matter of dosage or differences in accompanying minerals or related alkaloids. Even smell, taste, circumstance and expectations can cause psychoactive effects to vary.

Taylor, who has compiled dozens of studies from universities and academic journals, said yerba mate has been assayed to only contain between .7 and 2 percent, with the average leaf yielding about 1 percent caffeine. Relatively speaking, that's much less than coffee.

"In living plants, xanthines such as caffeine are bound to sugars, phenols and tannins, and are set free or unbound during the roasting or fermenting processes used to process yerba mate leaves, coffee beans and even cacao beans," she says. "The mateine chemical 'discovered' is probably just caffeine bound to a tannin or phenol in the raw leaf."

Pound Foolish

Other seemingly exaggerated claims center on yerba mate's ability to help shed pounds. Though the leaves already appear in a number of weight loss pills, the drink itself is becoming popular as an appetite suppressant and meal substitute, thanks to lopsided media coverage and heavy marketing by vendors.