Yerba mate tea is a drink made by steeping the leaves and twigs of a rainforest tree, yerba mate, in hot water. The yerba mate tree is native to the subtropical forests of Paraguay, Brazil, and Argentina, and the residents of these countries prize yerba mate tea for its strong, coffee-like stimulating properties. Recently, advocates of the tea have claimed that it is as potent a source of antioxidants as green tea and can support immune system function as well as providing a better source of mental stimulation than coffee. However, some research suggests that yerba mate tea consumption may contribute to a number of medical problems.
Digestive System Problems
According to MDAdvice.com, yerba mate tea use can exacerbate already existing digestive system conditions, such as gastric reflux, stomach or intestinal ulcers, and colitis, a digestive problem characterized by either acute or chronic inflammation of the bowel lining. Additionally, disorders such as diverticular disease--the presence of weakened bulges in the wall of the large intestine that become inflamed and cause bowel disruptions--can become more painful and symptomatic with regular yerba mate tea use. Individuals without pre-existing digestive system problems have also reported digestion-related symptoms after using the tea, including extreme nausea and vomiting.
The Memorial Sloan-Kettering Cancer Center reports that yerba mate tea contains large amounts of xanthene alkaloids, compounds known for their strong stimulant properties. These compounds include caffeine, theobromine, and theophylline. Because of these stimulants, some yerba mate tea users have complained of symptoms of nervous system over-stimulation: difficulty falling asleep, nervousness or agitation, insomnia, and restlessness. The Cancer Center recommends that people with anxiety disorders should not use yerba mate tea.
The high stimulant content of yerba mate tea also makes it dangerous for people with cardiovascular problems, such as high blood pressure or heart disease, to consume on a regular basis. Yerba mate can increase blood pressure levels and pulse rate and may cause heart palpitations.
Regular Yerba mate use is linked to the development of certain types of cancers, including cancers of the esophagus, mouth, pharynx, larynx, and lungs. (See Reference 4) In many instances, the risk of developing these cancers is significant and increases proportionally with the amount of yerba mate tea consumed; the Los Angeles Times cites two Cancer Epidemiology Biomarkers & Prevention studies that found yerba mate drinkers were 60 percent more likely to develop lung cancer and three times more likely to develop throat cancer than people who didn't drink yerba mate. The Memorial Sloan-Kettering Cancer Center reports that regular yerba mate consumers are also more likely to develop bladder and head cancers.