Yerba Mate Tea Benefits and Side Effects

yerba mate tea
man drinking yerba mate tea. Michael Hanson/Aurora/Getty Images

What is Yerba Mate Tea?

Yerba mate (Ilex paraguayenis) is a tree native to the rainforests of South America. A member of the holly family, the tree produces leaves and stems that have long been used to make tea in Brazil, Paraguay, Argentina, and Uruguay. Yerba mate tea (or just mate) is wildly popular in these countries: Argentinians consume 11 pounds per capita annually; in Uruguay, it's double that amount, reports Michael Castleman, author of "The New Healing Herbs." If you want to try it, be forewarned: The bitter-tasting beverage is often described as an acquired taste.

How to Prepare Yerba Mate Tea

Yerba mate got its name because it's normally prepared in a mate, the Spanish word for gourd. But there are many ways to prepare and enjoy the tea.

There doesn't appear to be an exact science to preparing the tea: Recipes range from using one teaspoon to five tablespoons of tea, depending on your preference, and adding hot, but not boiling water (somewhere between 170 degrees F and 185 degrees F). Add honey or lemon to taste.

Cultivation and processing influence the chemical composition of yerba mate and research has demonstrated their importance in the production and maintenance of the herb's beneficial bioactive compounds. When selecting a tea or supplement, read labels to be sure you buy a high-quality brand.

Yerba Mate Tea Caffeine Content

Though yerba mate was introduced to America as a non-caffeinated beverage, it does contain caffeine—six ounces delivers about 50 milligrams, so you'll get a mild jolt when you enjoy the brew. By comparison though, coffee contains almost twice as much of the stimulant.

Yerba Mate Tea Health Benefits

As beverages go, yerba mate is packed with nutrients, including 24 vitamins and minerals like vitamin C and calcium, amino acids, and more antioxidants than are found in green tea. It's no surprise then that many have kicked their coffee habit in favor of this healthier alternative. It also explains the use of yerba mate in traditional medicine to treat various health problems.

Though there are a host of advertised benefits for yerba mate, the Natural Medicines Comprehensive Database (NMCD), which scores numerous studies on herbs and supplements, finds no studies that have sufficient evidence to rate yerba mate's effectiveness for any condition. Though studies are ongoing, much more research is needed to prove that yerba mate tea and/or extract is useful for the following:

Weight Loss

The first study to evaluate the anti-obesity role of yerba mate was conducted in 2001 on 47 healthy overweight adults. Researchers found that taking an herbal preparation containing yerba mate, guarana, and damiana three times daily for 45 days resulted in significant weight loss. It also helped people feel full more quickly while eating.

There's also a growing body of animal research showing how yerba mate can assist with weight loss, including by reducing appetite and decreasing fat cells and the amount of fat they hold. A 2009 study on mice also found that yerba mate might modulate the expression of several obesity-related genes and, in turn, produce a potent anti-obesity effect.

In one 12-week study in 2015, obese men and women who took 3 grams of yerba mate capsules a day saw decreases in body fat mass and percent body fat, losing on average 1.5 pounds, a statistically significant difference from the placebo group. Those who took yerba mate also reduced their waist-to-hip ratio by two percent.

Cholesterol and Heart Health

One study looked at the effects of drinking yerba mate on cholesterol levels. After drinking 11 ounces (about one and a third cups) of yerba mate three times a day for 40 days, both groups of participants—people with normal cholesterol and people with high cholesterol who were on statin treatment—saw an eight to 13 percent reduction in LDL "bad" cholesterol and up to a six percent increase in HDL "good" cholesterol.

Another study helps explain the yerba mate-cholesterol connection. It found that mate tea drinkers experienced a significant increase (an average of 10 percent) in the activity of an enzyme that promotes HDL good cholesterol while lowering LDL cholesterol.

Drinking at least four cups of yerba mate tea was associated with significantly fewer diagnoses of coronary disease, dyslipidemia (abnormal levels of cholesterol), and high blood pressure in one 2018 study of postmenopausal women.

Cancer Prevention

A study published in 2008 found that yerba mate helped neutralize free radicals and protect mice from DNA damage, a hallmark of cancer and other diseases.

And a 2012 study from the University of Illinois suggests that bioactive compounds found in one cup of mate can disrupt colon cancer cells, at least in the lab. The researchers reported that caffeine derivatives in the tea damaged cancer cell DNA causing the cells to self-destruct. Though the authors believe there's ample evidence to support drinking mate for its bioactive benefits, no human studies have yet linked drinking the brew to a lower risk of colon cancer.

Yerba Mate Tea Side Effects

There's not enough scientific information at this time to determine an appropriate range of doses for yerba mate, so experts advise drinking it in moderation. The NMCD rates it as "likely unsafe" when taken in very large amounts, due to its caffeine content. It also warns about a host of drug interactions, particularly with other stimulants; the combination can enhance the effects on the nervous system. People with high blood pressure, heart disease, and anxiety should avoid the tea or extract. In some cases, consumption of yerba mate may trigger adverse effects such as anxiety, insomnia, nausea, and headache.

Another reason for not drinking excessive amounts of mate: Studies have linked chronic consumption of yerba mate with an increased risk of bladder, esophageal, lung, and head and neck cancers among people who drink it habitually. One possible reason for the increased cancer risk is that mate contains polycyclic aromatic hydrocarbons, compounds that are known to be carcinogenic. One study found very high concentrations of these in yerba mate leaves and in both hot and cold infusions of them. There's also evidence that steeping the tea at high temperatures may promote absorbing certain carcinogenic compounds found in the plant.

If you opt to try yerba mate supplements, keep in mind that supplements haven't been tested for safety and because dietary supplements are largely unregulated, the content of some products may differ from what is specified on the product label. Also, be aware that the safety of supplements in pregnant women, nursing mothers, children, and those with medical conditions or who are taking medications has not been established. You can get tips on using supplements, but if you're considering the use of yerba mate, talk with your primary care provider first. Self-treating a condition and avoiding or delaying standard care may have serious consequences.

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