Teas from across the globe are becoming more and more popular in the U.S. One relative newcomer, yerba mate, is attracting fans for its allegedly jitter-free caffeine boost and high antioxidant content.
Lab research suggests some potential health benefits from drinking yerba mate, but studies of lifelong yerba mate drinkers in the tea's native South America suggest the brew increases the risk of some cancers -- a fact most marketing campaigns omit.
Yerba mate, leaves of the Ilex paraguariensis tree, is traditionally brewed and served in a dried-out gourd and sipped through a metal straw with a filter on one end to stop drinkers from ending up with a mouthful of leaves.
In the U.S., the tea is rarely served in gourds (although a few upscale tea lounges preserve the tradition). A small but growing number of companies, however, sell the loose or bagged tea leaves, and some are now offering cold bottled blends of the tea.
Ads, Web chatter and positive press promote yerba mate's clean buzz -- a caffeine high without the shakes and "crash" that sometimes follows. If that is true, it could be because yerba mate contains about 80 milligrams of caffeine per cup -- almost twice the amount in black tea but less than half that of coffee, which usually contains 100 to more than 200 milligrams per cup.
But scientists disagree about the bottom line on yerba mate, says K. Simon Yeung, clinical coordinator and research pharmacist at Memorial Sloan-Kettering Cancer Center in New York City. The tea does contain a long list of vitamins, minerals and antioxidants, including B vitamins and vitamin C; manganese, potassium and zinc; and the beneficial plant compounds quercetin, theobromine and theophylline.
Because of yerba mate's high antioxidant content, comparisons to green tea are common (one commercial yerba mate blend claims to contain 90% more antioxidants than green tea). But that is slightly misleading, says Elvira de Mejia, associate professor of food science and human nutrition at the University of Illinois at Urbana-Champaign.
The two teas have very different arrays of antioxidants: Green tea is rich in epigallocatechin gallate compounds, while yerba mate's main antioxidant is chlorogenic acid. Studies have suggested that both sets of plant compounds have the potential to reduce risk for heart disease and cancer, but the research on both is far from conclusive.
