The 17th century had just begun. Hernando Arias de Saavedra, Governorate of Spanish-colonized Paraguay , issued a stern warning to the indigenous population: Yerba Mate will be the ruin of your race. 
Yerba was not a God they worshiped. Instead, it referred to yerba mate, a beverage the indigenous people of Paraguay consumed to gain more vigor and energy. Despite being on good terms with the native population, Arias held firm opinions about this beverage. His fear? It was a terrible vice; its addictive qualities could make desperate men and women sell their belongings.
The History of Yerba Mate
In 1616, Arias banned yerba mate as his coup de grâce, fearful of the implications it had on his working population. Paraguay, which housed indigenous people, Spanish colonists, and mixed-race citizens, called mestizos, faced institutional poverty due to financial mismanagement from the conquistadors’ homeland. This made the labor of Paraguay’s citizens critical.
Arias’ ban did not meet the favor of many citizens, however. In fact, few obeyed his order, and the ruling was hard to enforce . Ultimately, it was a lost cause. Arias died in 1634. Little would he know that Spanish Jesuits would seize on the opportunity decades later to make yerba mate a commercial commodity, starting plantations in Paraguay  . Yerba mate would see a resurgence that would last for centuries.
It would take centuries before yerba mate found another resurgence–and that was in the weight loss market in North America . In the 2000s, American travelers noticed South Americans couldn’t keep their hands off yerba mate; and soon, rumors spread that it was an appetite suppressant .
For diet-crazed America, this was their elixir. Few knew what it was, however.
What is Yerba Mate?
In the native tongue of the Guaraní people, the indigenous people of Paraguay, they call it ka’a. The Spanish conquistadors gave it a different name: Yerba mate.
Reports from Spanish colonists say that the Guaraní drank yerba mate at every waking moment; and, they gossiped, lent them mystical powers .
How is Yerba Mate Prepared
Yerba mate is produced by grinding up leaves from Ilex paraguariensis, an evergreen tree found in South America  . Starting as a small, flowering shrub, it can eventually reach 18 meters in height. Its leaves, which are called yerba or erva (both meaning herb) , contain caffeine, a psychoactive drug used to reduce drowsiness and fatigue . Approximately one serving of Yerba Mate contains 135 milligrams of caffeine, yielding 1.4 times more caffeine than coffee  .
After cultivating the leaves, it is then ground into a fine powder and placed into a gourd. To sip it, a special type of metal straw, called a bombilla, is placed inside of it . Due to its bitter taste, some people opt to add in additional ingredients, such as lemon juice, milk, or sugar .
Surprisingly, yerba mate is rarely a solitary activity  . South Americans commonly share the beverage with friends, family members, or even strangers as a way of bonding and social engagement . Typically, the mixture is sipped by one person until all of the water is gone. Another person then volunteers to fill the gourd back up with warm water, passing it on to another group member. This continues until the yerba mate mixture loses its flavor.
Due to the preparation of yerba mate, many people, including scientists, have erroneously referred to it as a type of tea. However, this is not accurate terminology, as tea is prepared using Camellia sinensis leaves . This makes yerba mate a type of infusion, not tea.
The Chemical Makeup of Yerba Mate
Theobromine. An alkaloid is bearing similar property to caffeine; it helps dilate blood vessels, lowering blood pressure. Unlike caffeine, however, it does not affect the central nervous system, providing a weaker stimulant effect .
Caffeic acid. This is best known as a derivative of the hydroxycinnamic acid, boasting some health benefits. Research shows it possesses antiviral, antioxidant, anticarcinogenic, and anti-inflammatory properties. It may also reduce oxidative damage in the liver and kidneys caused by alcohol consumption .
Chlorogenic acid. Belonging to the phenolic acid group, its effects on human health are similar to caffeic acid . Its most potent effect is on blood pressure, lowering the risk of high blood pressure. As a caveat, however, it could also trigger a laxative effect if consumed in excess .
Quercitin. This is a type of flavonoid found commonly in flowers, fruits, and vegetables. A significant amount of research suggests it could protect against many conditions, including heart disease, high cholesterol, allergies, high blood pressure, rheumatoid arthritis, and cancer . One study suggests it inhibits the growth of tumors better than the antioxidant resveratrol.
Rutin. A type of bioflavonoid, it is metabolized into quercetin when consumed orally. Not surprisingly, it shares similar properties to quercetin. Most notably, it produces strong antioxidant and anti-inflammatory effects, helping improve a variety of conditions .
Together, these ingredients promote unique antioxidant and anti-inflammatory effects associated with some health benefits. Combined with caffeine, it may be one of the different stimulants on the market.
Yerba Mate’s Uses
Since colonial times, yerba mate has earned a reputation of boasting many benefits, some even of a mystical quality. Today, yerba mate is used to treating a multitude of health conditions due to these beliefs. Research spins a different tale, however.
Due to its high concentration of caffeine, it is plausible to suggest yerba mate decreases fatigue. Studies dating back to 1981 emphasize its effects on focus, alertness, and reaction time   , though doses over 300 milligrams can produce adverse effects . There is no empirical research that substantiates these claims, however. More research on yerba mate’s effects on fatigue is necessary.
Along with guarana and green tea, yerba mate is part of the golden trio of appetite suppressants. One study found that people given capsules containing yerba mate lost weight , which they maintained over a 12 month period. However, another study, reported in the Journal of the American College of Nutrition, found that it did not cause diabetic and pre-diabetic adults to eat fewer calories . It is uncertain how yerba mate affects appetite loss at this point. Products like Triactiburn based some of their claims on this effect.
Though clinical evidence is limited, yerba mate shows potential as a treatment for atherosclerosis . In a 2015 study appearing in Experimental Gerontology, 142 participants with high blood viscosity who consumed yerba mate had improved blood viscosity and microcirculation biomarkers. This reduced the pressure on the heart to pump more blood and improved oxygen availability to critical organ tissues .
Its effects on type 2 diabetes are not well established . A 2011 pilot study found that diabetic and pre-diabetic adults who consumed yerba mate three times a day had significantly lower levels of fasting glucose, low-density lipoprotein cholesterol [LDL-c] and triglycerides . Lower fasting glucose usually indicates an improvement in the disease. However, as this is the only major study to establish a connection, it would be premature to make any recommendations. If this claim is true, we’re curious why supplements like Glucocil and Melabic don’t include yerba mate.
Early research suggests yerba mate could prevent osteoporosis by increasing bone mineral density. In a study appearing in the journal Bone  , post-menopausal women who drank 1 liter of yerba mate daily had 9.7 percent greater lumbar spine bone mineral density. Considering that bone mineral density decreases with age, especially for women undergoing menopause, this finding suggests a strong protective effect. Its effects on people who have not experienced menopause have not been established, however.
While it is plausible to hypothesize yerba mate could prevent cancer, due to the anti-inflammatory and anticarcinogenic effects of its active ingredients, research indicates otherwise  . A study appearing in the Pan American Journal of Public Health found that yerba mate, when served hot, actually increased the risk of several cancers, including esophageal, larynx, and oral cancer  . It has also been correlated with an increased risk of lung, bladder, and kidney cancer.
However, the reason why is not necessarily due to its chemical makeup. Researchers believe that the temperature of yerba mate damages cells in the oral cavity, raising the risk of cancer. Yerba mate served cold, on the other hand, is not associated with any serious health conditions, such as cancer. This indicates that hot beverages, in general, have the potential to promote carcinogenic activity.
Overall, yerba mate is ineffective for a variety of conditions. Some research shows new potential to prevent or improve osteoporosis and type 2 diabetes, however.
Yerba Mate Side Effects & Contraindications
Certain side effects and contraindications are associated with yerba mate, due to its high caffeine content, something many Hydroxycut products rely on. These side effects include:
- Stomach upset
- Increased heart rate
- Irregular heartbeat
Also, yerba mate also can cause serious contraindications . People with the following conditions should avoid using it:
- Pregnancy. The caffeine content in yerba mate could trigger caffeine withdrawal after birth, making it potentially unsafe. Research also shows it could raise the risk of miscarriage or premature delivery .
- Bleeding disorders. Yerba mate slows blood clotting, so it can potentially make these diseases harder to control.
- Anxiety disorder. Due to the stimulant effects of caffeine, yerba mate could worsen anxiety . People with anxiety disorders should avoid using it.
- A family history of cancer. Multiple studies show that yerba mate can increase the risk of several cancers of the oral cavity. Other research shows it could trigger kidney, bladder, or lung cancer  .
Overall, research indicates that used in moderation; yerba mate is safe for most people. Taking it in excess can trigger a range of side effects, however, some of which can be life-threatening.
Should You Use Yerba Mate?
While indigenous people spin a mystical tale about yerba mate’s origins, clinical research weaves a different one. Unfortunately, the story is filled with holes, consistencies, and potential dangers.
Though its stimulant effects are established , research shows claims of its weight loss potential are unfounded. Worse yet, it is hardly safe as well; research shows it can also trigger some cancers  . For its limited range of benefits, which, at this time, include bone-strengthening and better glucose control, it is hardly an appealing beverage .
So what is the appeal of yerba mate? In this case, it may just be a tradition. Although the culture of the Guaraní people is long lost, the mestizos that inhabit Paraguay today keep their indigenous ancestors’ tradition alive through its consumption. It’s a beverage that ultimately has survived brutal colonization. Its significance, in this case, is more cultural than scientific.
Summer Banks, Director of Content at Dietspotlight, has researched over 5000 weight-loss programs, pills, shakes and diet plans. Previously, she managed 15 supplement brands, worked with doctors specializing in weight loss and completed coursework in nutrition at Stanford University. full bio.