What is yerba mate

Yerba mate (Ilex paraguariensis A.St.-Hil., Aquifoliaceae) is a native tree growing in the subtropics of South America, present in Southern Brazil, Northeastern Argentina, Eastern Paraguay, and Uruguay ¹⁾. Toasted yerba mate tea is an herbal infusion obtained from dried leaves of Ilex paraguariensis ²⁾. Yerba mate is traditionally consumed either as hot yerba mate or cold yerba mate. The hot yerba mate infusion consumed in South America is made by placing 20–50 g of yerba mate in a vessel where very hot water (70–85 °C) is slowly poured over the material and after each pouring, the water is sucked through a special drinking straw fitted with a filter on the end immersed in the mate infusion ³⁾. Cold yerba mate may be consumed in the same way or in a glass like a regular drink, at 4–8 °C ⁴⁾. Polycyclic aromatic hydrocarbons in mate are produced by fire or high temperature exposure during traditional drying using direct fire and/or during roasting of the mate leaves ⁵⁾. The commercial processing of yerba mate may involve two successive drying stages namely an initial rapid drying process at 400–750 °C by use of direct flames followed by final drying at 90–350 °C in rotating cylinders heated by burning wood before grinding ⁶⁾.

It is believed that consumption of Yerba mate is associated with increased risk of oral cancer ⁷⁾, esophageal cancer ⁸⁾, cancer of the larynx ⁹⁾ and squamous cell cancers of the head and neck ¹⁰⁾, but the carcinogenic mechanism is unclear ¹¹⁾, ¹²⁾. Commercial brands of Yerba mate contain high levels of carcinogenic polycyclic aromatic hydrocarbons, which are acquired during the traditional drying process. Some authors believe that it’s the very hot (> 65 °C) Yerba mate beverages is probably associated with increased risk of oesophageal cancer ¹³⁾, ¹⁴⁾, whilst others believe it’s the high levels of carcinogenic polycyclic aromatic hydrocarbons from drinking Yerba mate ¹⁵⁾ as measured from increased urinary concentrations of some polycyclic aromatic hydrocarbon metabolites in Yerba mate drinkers which is as much as smoking cigarettes. While it is true that the temperature of hot infusions may influence the risk of esophageal squamous cell carcinoma ¹⁶⁾, ¹⁷⁾, ¹⁸⁾, the polycyclic aromatic hydrocarbon content in Yerba mate is not affected by the water temperature ¹⁹⁾. These results confirm that drinking yerba mate is a source of exposure to potentially carcinogenic polycyclic aromatic hydrocarbons, consistent with the hypothesis that the polycyclic aromatic hydrocarbon content of Yerba mate may contribute to the increased risk of esophageal squamous cell carcinoma in Yerba mate drinkers.

While the epidemiological data indicate that Yerba mate users have an increased risk of oral and oro-pharyngeal cancer, little is known about whether this increased risk is due to the high temperature of the beverage when it is consumed or due to certain carcinogenic constituents that are present in Yerba mate. More human and animal studies are needed before a conclusion can be made on the oral and oro-pharyngeal carcinogenic risk of Yerba mate to humans.

The yerba mate beverage has been consumed traditionally by Guarani indigenous people since before the conquest of South America by the Spaniards ²⁰⁾. The commercial potential of Yerba mate plant was discovered by the Jesuits, who brought wild growing yerba mate into cultivation. The Guarani name for yerba mate is ka’a which means “a plant” or “a herb”; hence yerba mate has been considered by this group as the plant par excellence ²¹⁾. Yerba mate was also known as Jesuit tea or Paraguayan tea and shipped as such to Europe ²²⁾. With the expulsion of the Jesuits in 1768, the plantations went wild. By this time, the yerba mate beverage was already popular among Mestizo people (of Spanish and Guarani origin). Since the end of the 19th century, Yerba mate also became a daily beverage for the European migrants who partly colonized Southern Brazil, Northeastern Argentina, and, to a lesser extent, Eastern Paraguay ²³⁾. Nowadays yerba mate is consumed at the rate of more than one liter per day by millions of people in the above-mentioned countries ²⁴⁾. Yerba mate is used both as a source of caffeine, in lieu or in parallel with tea and coffee, but also as a therapeutic agent for its alleged pharmacological properties ²⁵⁾. Caffeine (1,3,7-trimethylxanthine) is an alkaloid that occurs naturally in the leaves, seeds and fruit of tea, coffee, cacao, kola trees, yerba mate and more than 60 other plants ²⁶⁾. When ingested, caffeine is a central nervous system stimulant and can temporarily increase blood pressure and heart rate ²⁷⁾. Yerba mate plays a very special social role and constitutes a very important form of caffeine intake ²⁸⁾. Its popularity is also increasing outside South America due to its pharmacological properties, proven to be beneficial to health ²⁹⁾. Yerba mate also a very important drink in Syria and Lebanon due to Syro-Lebanese migration to Argentina in the second half of the 19th century. Many migrants who returned to the Levant in the 1920s took the habit of drinking Yerba mate with them ³⁰⁾.

Using liquid chromatography–mass spectrometry analysis on four commercial brands of yerba mate, 58 polyphenols were observed of which 4-sinapoylquinic acid, di- and tri-methoxycinnamoylquinic acids, two isomers of trimethoxycinnamoylshikimic acid and four isomers of caffeoyl-2,7-anhydro-3-deoxy-2-octulopyranosonic acid were identified for the first time in Yerba mate ³¹⁾. Additionally, 46 polyphenols and 2 methylxanthines were quantified by high-performance liquid chromatography with diode-array detection. Hydroxycinnamic acid derivatives and flavonols comprised 90% and 10% of yerba mate phenols, respectively, 3-caffeoylquinic (26.8-28.8%), 5-caffeoylquinic (21.1-22.4%), 4-caffeoylquinic (12.6-14.2%) and 3,5-dicaffeoylquinic acids (9.5-11.3%) along with rutin (7.1-7.8%) were the most abundant polyphenols, whereas caffeine was the main methylxanthine (90%). Yerba mate is an important source of polyphenols with moderate methylxanthines content; therefore its high antioxidant capacity was mainly associated to its polyphenolic composition.

Yerba mate (Ilex paraguariensis) has antioxidant properties due to its phenolic compounds, such as caffeoyl derivatives, flavonoids, methylxanthines, tannins, ursolic acid-derived saponins, and vitamins ³²⁾. Over the last 20 years there has been an increase in studies of the pharmacologic properties of Yerba mate (Ilex paraguariensis). Numerous active compounds have been identified in yerba mate. Phenolic compounds predominate caffeoyl derivatives (caffeic acid, chlorogenic acid) ³³⁾, xanthines (caffeine and theobromine), which are a class of purine alkaloids found in many other plants such as tea and coffee, flavonoids (quercetin, kaempferol, and rutin), and tannins ³⁴⁾. Numerous triterpenoid saponins have also been identified, including those derived from ursolic acids known as metasaponins ³⁵⁾. Saponins are responsible for the distinct flavor of yerba mate extracts ³⁶⁾. Yerba mate also contains minerals (Phosphorus, Iron, and Calcium) and vitamins (C, B1, and B2) ³⁷⁾.

Research on extracts and isolated compounds from yerba mate has provided a number of pharmacological applications. Studies have demonstrated that yerba mate leaves have antioxidant ³⁸⁾, antiobesity ³⁹⁾, antidiabetic, digestive improvement and cardiovascular properties ⁴⁰⁾, and chemopreventative ones (preventing cellular damage that may cause chronic diseases) ⁴¹⁾. The consumption of yerba mate infusion reduces LDL “bad” cholesterol in parallel with an increase in HDL “good” cholesterol, as observed in studies on humans ⁴²⁾. Yerba mate extract also reduces acute lung inflammation, as observed in the animal model ⁴³⁾. Antimicrobial activity of yerba mate has been recently studied as well ⁴⁴⁾.

Some ethnobotanical studies from South America report medicinal uses of yerba mate beverage ⁴⁵⁾. Few ethnobotanical and ethnopharmacological studies mention that various medicinal plants are consumed together with the yerba mate beverage by Mestizo and European migrants living in Argentina and Paraguay ⁴⁶⁾. However, very little is known about how medicinal plants are combined with yerba mate beverage by local people. Additionally, medicinal plant use by Paraguayan Mestizo people is poorly documented in the English-language scientific literature, with very few exceptions ⁴⁷⁾.

Is Yerba mate safe to drink?

Yerba mate isn’t likely to pose a risk for healthy adults who occasionally drink it. However, some studies indicate that people who drink large amounts of yerba mate over prolonged periods may be at increased risk of some types of cancer, such as cancer of the mouth, esophagus and lungs. Smoking in combination with yerba mate seems to greatly increase the cancer risk.

One possible explanation is that mate contains polycyclic aromatic hydrocarbons (PAHs), which are known to be carcinogenic. Tobacco smoke and grilled meat also contain polycyclic aromatic hydrocarbons. Whilst others believe it is very hot Yerba mate beverages that probably causes cancer of the esophagus in humans. More investigation needs to be done into the safety and side effects of Yerba mate.

In summary: The epidemiological data indicate that Yerba mate users have an increased risk of oral and oro-pharyngeal cancer, little is known about whether this increased risk is due to the high temperature of the beverage when it is consumed or due to certain carcinogenic constituents that are present in Yerba mate ⁴⁸⁾. More human and animal studies are needed before a conclusion can be made on the oral and oro-pharyngeal carcinogenic risk of maté to humans.

Figure 1. Yerba mate

Figure 2. Yerba mate gourd

What is Caffeine ?

Caffeine (1,3,7-trimethylxanthine) is an adenosine and benzodiazepine receptor antagonist, phosphodiesterase inhibitor, and central nervous system stimulant ⁴⁹⁾, ⁵⁰⁾. Caffeine is a pharmacologically active component of many foods, beverages, dietary supplements, and drugs; it is also used to treat very ill newborns afflicted with apnea (temporary cessation of breathing) ⁵¹⁾. Caffeine occurs naturally in some plant leaves, seeds, and fruits, where it serves as an herbicide, insect repellant, and even attractant for pollination ⁵²⁾. This botanically sourced compound is the most commonly consumed stimulant worldwide ⁵³⁾. Caffeine enters the human food chain through plant-derived foods such as coffee beans, tea leaves, guarana, cocoa beans, yerba mate and kola nuts ⁵⁴⁾. In healthy adults, a caffeine intake of ≤400 mg/day is considered safe; acute clinical toxicity begins at 1 g, and 5 to 10 g can be lethal ⁵⁵⁾.

Caffeine is the world’s most popular drug, and coffee is possibly the second most valuable product after oil. The common dietary sources of caffeine are coffee, chocolate, tea, and some soft drinks. The amount of caffeine in food products varies, depending on the serving size, the type of product and the preparation method ⁵⁶⁾. Up to 90% of Americans of all ages consume some caffeine daily with more than 50% consuming coffee daily ⁵⁷⁾. More than 50% average 300mg caffeine per day, with an average daily dosage for all consumers of about 200mg. One report estimates nearly 95% of Brazil’s population consumes caffeine daily, whereas only about 63% of Canadian adults do so. The average dietary caffeine consumption in some Scandinavian countries is more than 400 mg per person per day. It is not hard to reach 200-300mg of caffeine daily since a standard eight-ounce cup of coffee made by the American drip method contains between 125mg and 250mg of caffeine. A 12-ounce can of Coca-Cola contains 34mg. Also, the usual ‘cup’ of coffee for many individuals is often actually 12 or even 16 ounces and sometimes more.

Most people consume caffeine from drinks. The amounts of caffeine in different drinks can vary a lot, but it is generally

• An 8-ounce cup of coffee: 95-200 mg
• A 12-ounce can of cola: 35-45 mg
• An 8-ounce energy drink: 70-100 mg
• An 8-ounce cup of tea: 14-60 mg

Caffeine has many effects on your body’s metabolism

• Caffeine stimulates your central nervous system, which can make you feel more awake and give you a boost of energy.
• Caffeine is a diuretic, meaning that it helps your body get rid of extra salt and water by urinating more.
• Caffeine increases the release of acid in your stomach, sometimes leading to an upset stomach or heartburn.
• Caffeine may interfere with the absorption of calcium in the body.
• Caffeine increases your blood pressure.

Within one hour of eating or drinking caffeine, it reaches its peak level in your blood. You may continue to feel the effects of caffeine for four to six hours.

For most people, it is not harmful to consume up to 400mg of caffeine a day. If you do eat or drink too much caffeine, it can cause health problems, such as:

• Restlessness and shakiness
• Insomnia. Most adults need seven to eight hours of sleep each night. But caffeine, even in the afternoon, can interfere with this much-needed sleep. Chronically losing sleep — whether it’s from work, travel, stress or too much caffeine — results in sleep deprivation. Sleep loss is cumulative, and even small nightly decreases can add up and disturb your daytime alertness and performance. Using caffeine to mask sleep deprivation can create an unwelcome cycle. For example, you may drink caffeinated beverages because you have trouble staying awake during the day. But the caffeine keeps you from falling asleep at night, shortening the length of time you sleep.
• Headaches
• Dizziness
• Rapid or abnormal heart rhythm
• Stomach upset
• Dehydration
• Anxiety
• Dependency, so you need to take more of it to get the same results.

Some people are more sensitive to the effects of caffeine than others. If you’re susceptible to the effects of caffeine, just small amounts — even one cup of coffee or tea — may prompt unwanted effects, such as restlessness and sleep problems. How you react to caffeine may be determined in part by how much caffeine you’re used to drinking. People who don’t regularly drink caffeine tend to be more sensitive to its negative effects. Other factors may include genetics, body mass, age, medication use and health conditions, such as anxiety disorders.

Do not underestimate the power or potency of caffeine. An abrupt decrease in caffeine may cause withdrawal symptoms, such as headaches, fatigue, irritability and difficulty focusing on tasks. Fortunately, these symptoms are usually mild and resolve after a few days. Caffeine dependency can occur after as little as seven days of exposure. 100mg per day can sustain dependency. In fact, many individuals can avoid caffeine withdrawal symptoms by as little as 25mg—the equivalent of about two tablespoons of most “gourmet” coffees. Carefully controlled studies show that caffeine doses as low as about 10mg can be reliably noticed by particularly sensitive people. These studies also show that more than 30 percent of people can feel the effects of 18mg or less.

Studies of caffeine dependency and tolerance show that daily caffeine users are actually more motivated to consume it to avoid withdrawal symptoms, than to experience the lift that its stimulant properties may provide. Caffeine’s combination of a punishing syndrome of withdrawal, along with a rewarding sense of wakefulness, has made coffee, tea, and chocolate, some of humanity’s best-loved foods. One might say that caffeine-producing plants have succeeded in motivating humans to cultivate them widely and with very great care.

Not everyone consuming daily caffeine is equally likely to develop dependency and withdrawal syndrome. Studies indicate that genetics make some people more likely than others. Scientists do not know whether the inherited tendency to experience caffeine withdrawal syndrome relates to the genetic factors that cause migraine. In summary, caffeine may lead to the development of medication-overuse headache (so-called “rebound” headache). As such, patients should limit caffeine use as recommended for other acute medications for migraine. This use should not exceed two days per week. Removing caffeine alone is rarely enough to solve the problem. For patients with high daily caffeine intake, this reduction in use should be achieved over a gradual taper of days or even weeks to limit the impact of withdrawal syndrome.

Does yerba mate have caffeine?

Yes, Yerba mate contains caffeine and other chemicals which stimulate the brain, heart, muscles lining blood vessels, and other parts of the body.

How much caffeine in yerba mate?

Because label instructions varied so widely among the products (from 1 tablet/day to 4 tablets/serving and 3 servings/day), Yerba mate has about 489 mg/day of caffeine based on the average analyzed caffeine content ⁵⁸⁾.

Yerba mate vs coffee

According to the USDA food composition database, one cup (8 oz, 240 ml) of brewed coffee contains approximately 95 mg of caffeine.

Coffee is a brewed drink prepared from roasted coffee beans, which are the seeds of berries from the Coffea plant. The genus Coffea is native to tropical Africa (specifically having its origin in Ethiopia and Sudan) and Madagascar, the Comoros, Mauritius, and Réunion in the Indian Ocean. Several species of shrub of the genus Coffea produce the berries from which coffee is extracted. The two main species commercially cultivated are Coffea canephora (predominantly a form known as ‘Robusta’) and Coffea Arabica ⁵⁹⁾. Coffea arabica, the most highly regarded species, is native to the southwestern highlands of Ethiopia and the Boma Plateau in southeastern Sudan and possibly Mount Marsabit in northern Kenya ⁶⁰⁾. Coffea canephora is native to western and central Subsaharan Africa, from Guinea to Uganda and southern Sudan ⁶¹⁾. Less popular species are Coffea liberica, Coffea stenophylla, Coffea mauritiana, and Coffea racemosa.

Once ripe, coffee berries are picked, processed, and dried. Dried coffee seeds (referred to as beans) are roasted to varying degrees, depending on the desired flavor. Roasted beans are ground and brewed with near-boiling water to produce coffee as a beverage.

The degree of roast has an effect upon coffee flavor and body. Darker roasts are generally bolder because they have less fiber content and a more sugary flavor. Lighter roasts have a more complex and therefore perceived stronger flavor from aromatic oils and acids otherwise destroyed by longer roasting times. Roasting does not alter the amount of caffeine in the bean, but does give less caffeine when the beans are measured by volume because the beans expand during roasting.

Roasted coffee beans contain 0.8–2.5% caffeine. Generally, dark-roast coffee has less caffeine than lighter roasts because the roasting process reduces the bean’s caffeine content. Arabica coffee normally contains less caffeine than the Robusta variety. In general, one serving of coffee ranges from 64 mg for a single cup (30 ml) of espresso to about 145 mg for an 8-oz. ounce cup (237 ml) of automatic drip coffee.

Yerba mate benefits

In foods, yerba mate is used to make a tea-like beverage. Some people take yerba mate by mouth to relieve mental and physical tiredness (fatigue), as well as chronic fatigue syndrome. Yerba mate is also taken by mouth for heart-related complaints including heart failure, irregular heartbeat, and low blood pressure.

Some people also take yerba mate by mouth to improve mood and depression; for diabetes; high cholesterol; weak bones (osteoporosis); to relieve headache and joint pains; to treat urinary tract infections (UTIs), and bladder and kidney stones; for weight loss; and as a laxative.

Yerba Mate beverages are reported to have biological activities, probably due to their high polyphenol content. Phenolic compounds have long been known to possess biological functions. In addition to polyphenols such as flavonoids (quercetin and rutin) and phenolic acids (chlorogenic and caffeic acids), Yerba Mate is also rich in caffeine and saponins ⁶²⁾. Yerba Mate extracts are especially rich in chlorogenic acids that might contribute to hypocholesterolemic ⁶³⁾ and weight loss effects ⁶⁴⁾. Chlorogenic acid inhibits adipogenesis by reducing the expression of genes regulating adipogenesis in 3T3-L1 cells and in mouse model of high fat diet-induced obesity ⁶⁵⁾. In these regards, it is likely that Yerba Mate may potential alternative for controlling body fat accumulation and weight. In vitro and in vivo studies have demonstrated that Yerba Mate modulates signaling pathways, has chemopreventive activities ⁶⁶⁾, enhance intestinal propulsion ⁶⁷⁾, has vasodilatation effects ⁶⁸⁾, inhibits glycation ⁶⁹⁾, inhibits oxidative stress ⁷⁰⁾ and has inflammatory effects ⁷¹⁾.

Currently there’s insufficient evidence to rate effectiveness of Yerba mate for these conditions:

• Mental function. Early research shows that drinking a beverage containing yerba mate does not improve memory, reaction time, or mental accuracy in healthy females.
• Diabetes. Early research shows that drinking yerba mate tea three times daily for 60 days can lower blood sugar in people with type 2 diabetes.
• High cholesterol (hyperlipidemia). Early research shows that drinking tea containing yerba mate three times daily for 40 days can lower total cholesterol and low-density lipoprotein (LDL or “bad”) cholesterol, and increase high-density lipoprotein (HDL or “bad”) cholesterol, in people with high cholesterol. This includes people already taking statin drugs.
• Obesity. Early research shows that taking yerba mate by mouth might decrease fat and cause weight loss when used alone or in combination with guarana and damiana.
• Weak bones (osteoporosis). Drinking yerba mate tea every day for at least 4 years might reduce the rate of bone loss in postmenopausal women.
• Prediabetes. Early research shows that drinking yerba mate tea three times daily for 60 days does not reduce fasting blood sugar in people with prediabetes. However, it might reduce glycated hemoglobin (HbA1C), a measure of average blood sugar.
• Chronic fatigue syndrome (CFS).
• Constipation.
• Depression.
• Fluid retention.
• Headaches.
• Heart conditions.
• Kidney and bladder stones.
• Low blood pressure (hypotension).
• Mental and physical tiredness (fatigue).
• Urinary tract infections (UTIs).
• Other conditions.

More evidence is needed to rate the effectiveness of yerba mate for these uses.

Yerba mate weight loss

Yerba Mate leaf extracts contain components such as chlorogenic acid (monocaffeoylquinic and dicaffeoylquinic acids), hydroxycinnamic acids (caffeic acid, quinic acid) and numerous triterpenic saponins ⁷²⁾. Chlorogenic acid is one of the most abundant polyphenols in fruits such as plums, apples and cherries and has been shown to reduce body weight as well as improve lipid metabolism and levels of obesity-related hormones in mice ⁷³⁾. Chlorogenic acid inhibits adipogenesis by reducing the expression of genes regulating adipogenesis in 3T3-L1 cells and in mouse model of high fat diet-induced obesity ⁷⁴⁾. The mechanisms of Yerba Mate on fat decrease, while not directly known, might be due to effects of single components, as investigated in previous studies.

Yerba Mate suppresses body weight gain and visceral fat accumulation and decreases serum levels of cholesterol, triglycerides, LDL cholesterol ⁷⁵⁾. Previous study ⁷⁶⁾ reported that Yerba Mate reduces body weight in mice with obesity induced by a high-fat diet. After feeding animals Yerba Mate for 4 weeks, we observed a decrease in total cholesterol, leptin levels and blood glucose that ultimately led to reduce their body weight ⁷⁷⁾. Taking into account that Yerba Mate is especially rich in chlorogenic acid and several bioactive compounds, it suggest that it is possible to inhibit obesity.

In a 12 weeks, randomized, double-blind, placebo-controlled clinical trial involving 30 obese Korean people who met the study criteria (age, 43.2 ± 10.6 years; weight, 71.56 ± 10.14 kg; BMI 27.98 ± 2.68 kg/m²) were randomly divided into two groups (n = 15 each) and given either Yerba Mate (3150 mg/day) or a placebo (3150 mg/day) ⁷⁸⁾. The Yerba Mate was a standardized product containing chlorogenic acid 35 mg/g and was prepared by Jeju, Republic of Korea. Dried Yerba Mate leaves were collected from Argentina and extracted with water at 100 °C for 2 h. Extracts were filtered and concentrated under reduced pressure to 20 brix at 40–50 °C, dried at 160–180 °C using a spray dryer. Yerba Mate was administered in capsule form (333.38 mg Yerba Mate and 16.6 mg diluting agents in a 350 mg capsule). Administration was 3 g/day Yerba Mate water extract, the recommended daily dose from Korea Food & Drug Administration (KFDA) in that clinical trial. The appearance of the Yerba Mate and placebo capsules was identical. The Yerba Mate used in this study contained 35 mg/g chlorogenic acid. Yerba Mate extracts are especially rich in chlorogenic acids that might contribute to hypocholesterolemic ⁷⁹⁾ and weight loss effects ⁸⁰⁾.

Subjects take three capsules per each meal, total three times in a day (before breakfast, lunch and dinner). Yerba Mate and placebo capsule packaging was indistinguishable and was labeled with the subject number. Subjects were instructed to bring all remaining supplements to each visit and were withdrawn if supplement consumption was < 70 % of the recommended dose.

After 12 weeks of supplementation, the research authors observed a significant decreased in body fat mass and percent body fat. Waist hip ratio also decreased significantly in the Yerba Mate group compared to the placebo group. Unlike currently prescribed anti-obesity drugs, subjects did not report any specific adverse events. Results of subjects’ complete blood cell count, liver and kidney function tests and vital signs were within normal ranges for both the Yerba Mate and placebo groups throughout the study. Suggesting that Yerba Mate supplementation did not cause any adverse side effects ⁸¹⁾.

This clinical study ⁸²⁾ was the first controlled trial ascribing an anti-obesity effect to the ingestion of yerba mate herb. Yerba Mate was previously tested in a supplement with other ingredients such as green tea, asparagus, black tea, guarana and kidney bean extracts ⁸³⁾. Another clinical trial of 6 weeks of treatment with green yerba mate powder extract (1200 mg/day) showed significant decreased in body fat mass and percent body fat ⁸⁴⁾.

Previous animal study showing that adipocyte size decreased in a group given Yerba Mate ⁸⁵⁾. Yerba Mate decreases the differentiation of preadipocytes and reduces accumulation of lipids in adipocytes ⁸⁶⁾. Additionally, Yerba Mate inhibits body weight gain and visceral fat accumulation and decreases serum levels of cholesterol, triglycerides, LDL cholesterol ⁸⁷⁾. These results indicate that decreasing adipose tissue growth, body fat mass (kg), percent body fat (%) and obesity of Yerba Mate. The potential thermogenic properties of significantly increasing resting energy expenditure for at least four hours post-ingestion in moderated-level habitual caffeine consumers ⁸⁸⁾. The increase in resting energy expenditure might have been due to a 340-mg proprietary blend of caffeine anhydrous, guarana, yerba mate and green tea extract. Another study evaluated the acute effects of oral administration of 12 commercially available plant preparations aimed at treating human obesity. Only treatment with a green Yerba mate extract changed the respiratory quotient, indicating a rise in the proportion of oxidized fat that might have led to decreased body fat. These results suggest the potential of mate leaves for treatment of obesity ⁸⁹⁾.

The study author concluded by stating that the study is an exploratory clinical trial using standardized Yerba Mate and the study is insufficient to show the effects of Yerba Mate when associated with lifestyle modification. For full determination of the long-term effects of Yerba Mate clinical application, a larger sample size is needed.

Yerba mate side effects

Yerba mate is possibly safe for most people, when taken by mouth for short periods of time. Yerba mate contains caffeine, which in some people can cause side effects such as inability to sleep (insomnia), nervousness and restlessness, upset stomach, nausea and vomiting, increased heart rate and breathing, high blood pressure, headache, ringing in the ears, irregular heartbeats, and other side effects.

Yerba mate is possibly UNSAFE when taken in large amounts or for long periods of time. It increases the risk of esophageal cancer, kidney cancer, stomach cancer, bladder cancer, cervical cancer, prostate cancer, lung cancer, and possibly laryngeal or mouth cancer. This risk is especially high for people who smoke or drink alcohol.

Yerba mate is likely UNSAFE when taken in very large amounts, due to its caffeine content.

Special precautions and warnings

Yerba mate and cancers

It is believed that consumption of Yerba mate is associated with increased risk of oral cancer ⁹⁰⁾, esophageal cancer ⁹¹⁾, cancer of the larynx ⁹²⁾ and squamous cell cancers of the head and neck ⁹³⁾, but the carcinogenic mechanism is unclear ⁹⁴⁾, ⁹⁵⁾. Commercial brands of Yerba mate contain high levels of carcinogenic polycyclic aromatic hydrocarbons, which are acquired during the traditional drying process. Some authors believe that it’s the very hot (> 65 °C) Yerba mate beverages is probably associated with increased risk of oesophageal cancer ⁹⁶⁾, ⁹⁷⁾, whilst others believe it’s the high levels of carcinogenic polycyclic aromatic hydrocarbons from drinking Yerba mate ⁹⁸⁾ as measured from increased urinary concentrations of some polycyclic aromatic hydrocarbon metabolites in Yerba mate drinkers which is as much as smoking cigarettes. While it is true that the temperature of hot infusions may influence the risk of esophageal squamous cell carcinoma ⁹⁹⁾, ¹⁰⁰⁾, ¹⁰¹⁾, the polycyclic aromatic hydrocarbon content in Yerba mate is not affected by the water temperature ¹⁰²⁾. These results confirm that drinking yerba mate is a source of exposure to potentially carcinogenic polycyclic aromatic hydrocarbons, consistent with the hypothesis that the polycyclic aromatic hydrocarbon content of maté may contribute to the increased risk of esophageal squamous cell carcinoma in Yerba mate drinkers.

While the epidemiological data indicate that Yerba mate users have an increased risk of oral and oro-pharyngeal cancer, little is known about whether this increased risk is due to the high temperature of the beverage when it is consumed or due to certain carcinogenic constituents that are present in Yerba mate. More human and animal studies are needed before a conclusion can be made on the oral and oro-pharyngeal carcinogenic risk of Yerba mate to humans.

Children: Yerba mate is possibly UNSAFE for children when taken by mouth. Yerba mate is linked with an increased risk of esophageal cancer, kidney cancer, stomach cancer, bladder cancer, cervical cancer, prostate cancer, lung cancer, and possibly laryngeal or mouth cancer.

Pregnancy and breast-feeding: Yerba mate is possibly UNSAFE when taken by mouth during pregnancy. One concern is that using yerba mate seems to increase the risk of getting cancer. It’s not known whether that risk is transferred to the developing fetus. Another concern is the caffeine content of yerba mate. Caffeine crosses the placenta and enters the fetus’ bloodstream, producing caffeine levels in the fetus that resemble the caffeine level in the mother. In general, mothers should avoid consuming more than 300 mg of caffeine daily; that’s about 3 cups of coffee or tea. Infants born to mothers who consume a lot of caffeine during pregnancy sometimes show symptoms of caffeine withdrawal after birth. High doses of caffeine have also been linked with miscarriage, premature delivery, and low birth weight. However, researchers studied mothers who drank yerba mate tea during pregnancy and found no strong link between drinking yerba mate and premature delivery or small birth weight. But this study has been criticized because it did not consider the amount of yerba mate or caffeine used by the mothers; it looked only at how often they used yerba mate.

Yerba mate is also possibly UNSAFE during breast-feeding. It is not known whether the cancer-causing chemicals in yerba mate pass into breast milk, but that is a concern. The caffeine in yerba mate is also a problem. It might cause irritability and increased bowel movements in nursing infants.

Alcoholism: Heavy alcohol use combined with long-term yerba mate use increases the risk of cancer from 3-fold to 7-fold.

Anxiety disorders: The caffeine in yerba mate might make anxiety disorders worse.

Bleeding disorders: Caffeine might slow clotting. As a result, there is a concern that the caffeine in yerba mate might make bleeding disorders worse. But so far, this effect has not been reported in people.

Heart conditions: Caffeine in yerba mate can cause irregular heartbeats in certain people. If you have a heart condition, discuss using yerba mate with your healthcare provider.

Diabetes: Some research shows that the caffeine in yerba mate may affect the way people with diabetes process sugar and may complicate blood sugar control. There is also some interesting research that shows caffeine may make the warning symptoms of low blood sugar in people with type 1 diabetes more noticeable. Some studies show that the symptoms of low blood sugar are more intense when they start in the absence of caffeine, but as low blood sugar continues, symptoms are greater with caffeine. This might increase the ability of people with diabetes to detect and treat low blood sugar. However, the downside is that caffeine might actually increase the number of low-sugar episodes. If you have diabetes, talk with your healthcare provider before using yerba mate.

Diarrhea: Yerba mate contains caffeine. The caffeine in yerba mate, especially when taken in large amounts, can worsen diarrhea.

Glaucoma: Using yerba mate increases the pressure inside the eye due to the caffeine it contains. The increase in pressure occurs within 30 minutes and lasts for at least 90 minutes. If you have glaucoma, discuss your use of yerba mate with your healthcare provider.

High blood pressure: The caffeine in yerba mate might increase blood pressure in people with high blood pressure. Consuming 250 mg of caffeine can increase blood pressure in healthy people, but this doesn’t seem to happen in people who use caffeine all the time.

Irritable bowel syndrome (IBS): Yerba mate contains caffeine. The caffeine in yerba mate, especially when taken in large amounts, can worsen diarrhea and might worsen symptoms of IBS.

Weak bones (osteoporosis): Some researchers have found that postmenopausal women who drink a liter or more daily of a traditional South American yerba mate tea have higher bone density. However, the caffeine in yerba mate tends to flush calcium out of the body in the urine. This can contribute to weak bones. For this reason, many experts recommend that caffeine intake be limited to less than 300 mg per day (approximately 2-3 cups of yerba mate). Taking extra calcium may help to make up for the calcium that is flushed out.

There are some women who are at special risk for weak bones. These women have an inherited condition that makes it hard for them to use vitamin D properly. Vitamin D works with calcium to build strong bones. These women should be especially careful to limit the amount of caffeine they get from yerba mate as well as other sources.

Smoking: The risk of getting cancer is 3 to 7 times higher in people who smoke and use yerba mate for long periods of time.

Interactions with medications

Major

Do NOT take this combination.

Amphetamines

Stimulant drugs such as amphetamines speed up the nervous system. By speeding up the nervous system, stimulant medications can make you feel jittery and increase your heart rate. The caffeine in yerba mate might also speed up the nervous system. Taking yerba mate along with stimulant drugs might cause serious problems including increased heart rate and high blood pressure. Avoid taking stimulant drugs along with yerba mate.

Cocaine

Stimulant drugs such as cocaine speed up the nervous system. By speeding up the nervous system, stimulant medications can make you feel jittery and increase your heart rate. The caffeine in yerba mate might also speed up the nervous system. Taking yerba mate along with stimulant drugs might cause serious problems including increased heart rate and high blood pressure. Avoid taking stimulant drugs along with yerba mate.

Ephedrine

Stimulant drugs speed up the nervous system. Caffeine (contained in yerba mate) and ephedrine are both stimulant drugs. Taking caffeine along with ephedrine might cause too much stimulation and sometimes serious side effects and heart problems. Do not take caffeine-containing products and ephedrine at the same time.

Moderate

Be cautious with this combination

Adenosine (Adenocard)

Yerba mate contains caffeine. The caffeine in yerba mate might block the effects of adenosine (Adenocard). Adenosine (Adenocard) is often used by doctors to do a test on the heart. This test is called a cardiac stress test. Stop consuming yerba mate or other caffeine-containing products at least 24 hours before a cardiac stress test.

Antibiotics (Quinolone antibiotics)

The body breaks down caffeine to get rid of it. Some antibiotics might decrease how quickly the body breaks down caffeine. Taking these antibiotics along with yerba mate can increase the risk of side effects including jitteriness, headache, increased heart rate, and other side effects.

Some antibiotics that decrease how quickly the body breaks down caffeine include ciprofloxacin (Cipro), enoxacin (Penetrex), gatifloxacin (Tequin), levofloxacin (Levaquin), lomefloxacin (Maxaquin), moxifloxacin (Avelox), norfloxacin (Noroxin), ofloxacin (Floxin), sparfloxacin (Zagam), and trovafloxacin (Trovan).

Carbamazepine (Tegretol)

Carbamazepine is a drug used to treat seizures. Caffeine can decrease the effects of carbamazepine. Since yerba mate contains caffeine, in theory taking yerba mate with carbamazepine might decrease the effects of carbamazepine and increase the risk of seizures in some people.

Cimetidine (Tagamet)

Yerba mate contains caffeine. The body breaks down caffeine to get rid of it. Cimetidine (Tagamet) can decrease how quickly your body breaks down caffeine. Taking cimetidine (Tagamet) along with yerba mate might increase the chance of caffeine side effects including jitteriness, headache, fast heartbeat, and others.

Clozapine (Clozaril)

The body breaks down clozapine (Clozaril) to get rid of it. The caffeine in yerba mate seems to decrease how quickly the body breaks down clozapine (Clozaril). Taking yerba mate along with clozapine (Clozaril) can increase the effects and side effects of clozapine (Clozaril).

Dipyridamole (Persantine)

Yerba mate contains caffeine. The caffeine in yerba mate might block the effects of dipyridamole (Persantine). Dipyridamole (Persantine) is often used by doctors to do a test on the heart. This test is called a cardiac stress test. Stop consuming yerba mate or other caffeine-containing products at least 24 hours before a cardiac stress test.

Disulfiram (Antabuse)

The body breaks down caffeine to get rid of it. Disulfiram (Antabuse) can decrease how quickly the body gets rid of caffeine. Taking yerba mate (which contains caffeine) along with disulfiram (Antabuse) might increase the effects and side effects of caffeine including jitteriness, hyperactivity, irritability, and others.

Estrogens

The body breaks down caffeine (contained in yerba mate) to get rid of it. Estrogens can decrease how quickly the body breaks down caffeine. Decreasing the breakdown of caffeine can cause jitteriness, headache, fast heartbeat, and other side effects. If you take estrogens, limit your caffeine intake.

Some estrogen pills include conjugated equine estrogens (Premarin), ethinyl estradiol, estradiol, and others.

Ethosuximide

Ethosuximide is a drug used to treat seizures. Caffeine in yerba mate can decrease the effects of ethosuximide. Taking yerba mate with ethosuximide might decrease the effects of ethosuximide and increase the risk of seizures in some people.

Felbamate

Felbamate is a drug used to treat seizures. Caffeine in yerba mate might decrease the effects of felbamate. Taking yerba mate with felbamate might decrease the effects of felbamate and increase the risk of seizures in some people.

Flutamide (Eulexin)

The body breaks down flutamide (Eulexin) to get rid of it. Caffeine in yerba mate might decrease how quickly the body gets rid of flutamide. This could cause flutamide to stay in the body too long and increase the risk of side effects.

Fluvoxamine (Luvox)

The body breaks down the caffeine in yerba mate to get rid of it. Fluvoxamine (Luvox) can decrease how quickly the body breaks down caffeine. Taking yerba mate along with fluvoxamine (Luvox) might cause too much caffeine in the body, and increase the effects and side effects of yerba mate.

Lithium

Your body naturally gets rid of lithium. The caffeine in yerba mate can increase how quickly your body gets rid of lithium. If you take products that contain caffeine and you take lithium, stop taking caffeine products slowly. Stopping yerba mate too quickly can increase the side effects of lithium.

Medications for asthma (Beta-adrenergic agonists)

Yerba mate contains caffeine. Caffeine can stimulate the heart. Some medications for asthma can also stimulate the heart. Taking caffeine with some medications for asthma might cause too much stimulation and cause heart problems.

Some medications for asthma include albuterol (Proventil, Ventolin, Volmax), metaproterenol (Alupent), terbutaline (Bricanyl, Brethine), isoproterenol (Isuprel), and others.

Medications for depression (MAOIs)

The caffeine in yerba mate can stimulate the body. Some medications used for depression can also stimulate the body. Drinking yerba mate and taking some medications for depression might cause too much stimulation to the body and serious side effects including fast heartbeat, high blood pressure, nervousness, and others could occur.

Some of these medications used for depression include rasagiline (Azilect), selegiline (Eldepryl, Zelapar), tranylcypromine (Parnate), phenelzine (Nardil), and others.

Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)

Yerba mate contains caffeine. Caffeine might slow blood clotting. Taking yerba mate along with medications that also slow clotting might increase the chances of bruising and bleeding.

Some medications that slow blood clotting include aspirin, clopidogrel (Plavix), diclofenac (Voltaren, Cataflam, others), ibuprofen (Advil, Motrin, others), naproxen (Anaprox, Naprosyn, others), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, warfarin (Coumadin), and others.

Nicotine

Stimulant drugs such as nicotine speed up the nervous system. By speeding up the nervous system, stimulant medications can make you feel jittery and increase your heart rate. The caffeine in yerba mate might also speed up the nervous system. Taking yerba mate along with stimulant drugs might cause serious problems including increased heart rate and high blood pressure. Avoid taking stimulant drugs along with yerba mate.

Pentobarbital (Nembutal)

The stimulant effects of the caffeine in yerba mate can block the sleep-producing effects of pentobarbital.

Phenobarbital

Phenobarbital is a drug used to treat seizures. Caffeine in yerba mate might decrease the effects of phenobarbital and increase the risk of seizures in some people.

Phenylpropanolamine

Yerba mate contains caffeine. Caffeine can stimulate the body. Phenylpropanolamine can also stimulate the body. Taking yerba mate and phenylpropanolamine together might cause too much stimulation and increase heartbeat and blood pressure and cause nervousness.

Phenytoin

Phenytoin is a drug used to treat seizures. Caffeine in yerba mate can decrease the effects of phenytoin. Taking yerba mate with phenytoin might decrease the effects of phenytoin and increase the risk of seizures in some people.

Riluzole (Rilutek)

The body breaks down riluzole (Rilutek) to get rid of it. Taking yerba mate can decrease how fast the body breaks down riluzole (Rilutek) and increase the effects and side effects of riluzole.

Sedative medications (Benzodiazepines)

Benzodiazepines are drugs that cause sleepiness and drowsiness. The body breaks down benzodiazepines to get rid of them. The caffeine in yerba mate might reduce the breakdown of benzodiazepines. This might increase the effects of benzodiazepines and cause too much sleepiness. Do not drink beer if you are taking benzodiazepines.

Some benzodiazepines include alprazolam (Xanax), clonazepam (Klonopin), diazepam (Valium), lorazepam (Ativan), and others.

Stimulant drugs

Stimulant drugs speed up the nervous system. By speeding up the nervous system, stimulant medications can make you feel jittery and speed up your heartbeat. The caffeine in yerba mate can also speed up the nervous system. Consuming yerba mate along with stimulant drugs might cause serious problems including increased heart rate and high blood pressure. Avoid taking stimulant drugs along with yerba mate.

Some stimulant drugs include diethylpropion (Tenuate), epinephrine, nicotine, cocaine, amphetamines, phentermine (Ionamin), pseudoephedrine (Sudafed), and many others.

Theophylline

Yerba mate contains caffeine. Caffeine works similarly to theophylline. Caffeine can also decrease how quickly the body gets rid of theophylline. Taking yerba mate along with theophylline might increase the effects and side effects of theophylline.

Valproate

Valproate is a drug used to treat seizures. Caffeine in yerba mate might decrease the effects of valproate and increase the risk of seizures in some people.

Verapamil (Calan, Covera, Isoptin, Verelan)

The body breaks down the caffeine in yerba mate to get rid of it. Verapamil (Calan, Covera, Isoptin, Verelan) can decrease how quickly the body gets rid of caffeine. Drinking yerba mate and taking verapamil (Calan, Covera, Isoptin, Verelan) can increase the risk of side effects for caffeine including jitteriness, headache, and an increased heartbeat.

Water pills (Diuretic drugs)

Caffeine can decrease potassium levels. Water pills can also decrease potassium levels. Taking yerba mate along with water pills might increase the risk of decrease potassium too much.

Some “water pills” that can deplete potassium include chlorothiazide (Diuril), chlorthalidone (Thalitone), furosemide (Lasix), hydrochlorothiazide (HCTZ, HydroDiuril, Microzide), and others.

Minor – Be watchful with this combination

Alcohol

The body breaks down the caffeine in yerba mate to get rid of it. Alcohol can decrease how quickly the body breaks down caffeine. Taking yerba mate along with alcohol might cause too much caffeine in the bloodstream and caffeine side effects including jitteriness, headache, and fast heartbeat.

Birth control pills (Contraceptive drugs)

The body breaks down the caffeine in yerba mate to get rid of it. Birth control pills can decrease how quickly the body breaks down caffeine. Taking yerba mate along with birth control pills can cause jitteriness, headache, fast heartbeat, and other side effects.

Some birth control pills include ethinyl estradiol and levonorgestrel (Triphasil), ethinyl estradiol and norethindrone (Ortho-Novum 1/35, Ortho-Novum 7/7/7), and others.

Fluconazole (Diflucan)

Yerba mate contains caffeine. The body breaks down caffeine to get rid of it. Fluconazole (Diflucan) might decrease how quickly the body gets rid of caffeine. This could cause caffeine to stay in the body too long and increase the risk of side effects such as nervousness, anxiety, and insomnia.

Medications for diabetes (Antidiabetes drugs)

Diabetes medications are used to lower blood sugar. Yerba mate contains caffeine. Reports claim that caffeine might increase or decrease blood sugar. Yerba mate might interfere with blood sugar control and decrease the effectiveness of diabetes medications. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed.

Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), chlorpropamide (Diabinese), glipizide (Glucotrol), tolbutamide (Orinase), and others.

Medications that change the liver (Cytochrome P450 1A2 (CYP1A2) inhibitors)

Yerba mate contains caffeine. Caffeine is broken down by the liver. Some medications decrease how well the liver breaks down other medications. These medications that change the liver might decrease how fast caffeine in yerba mate is broken down in the body. This might increase the effects and side effects of caffeine in yerba mate. Some medications that change the liver include cimetidine (Tagamet), fluvoxamine, mexiletine, clozapine, theophylline, and others.

Metformin (Glucophage)

Yerba mate contains caffeine. The body breaks down caffeine to get rid of it. Metformin (Glucophage) can decrease how quickly the body breaks down caffeine. Taking yerba mate along with metformin might cause too much caffeine in the body, and increase the effects and side effects of caffeine.

Methoxsalen (Oxsoralen)

Yerba mate contains caffeine. The body breaks down caffeine to get rid of it. Methoxsalen (Oxsoralen) can decrease how quickly the body breaks down caffeine. Taking caffeine along with methoxsalen might cause too much caffeine in the body, and increase the effects and side effects of caffeine.

Mexiletine (Mexitil)

Yerba mate contains caffeine. The body breaks down caffeine to get rid of it. Mexiletine (Mexitil) can decrease how quickly the body breaks down caffeine. Taking Mexiletine (Mexitil) along with yerba mate might increase the caffeine effects and side effects of yerba mate.

Terbinafine (Lamisil)

The body breaks down caffeine (contained in yerba mate) to get rid of it. Terbinafine (Lamisil) can decrease how fast the body gets rid of caffeine and increase the risk of side effects including jitteriness, headache, increased heartbeat, and other effects.

Tiagabine

Yerba mate contains caffeine. Taking caffeine over a period of time along with tiagabine can increase the amount of tiagabine in the body. This might increase the effects and side effects of tiagabine.

Ticlopidine (Ticlid)

The body breaks down the caffeine in yerba mate to get rid of it. Ticlopidine (Ticlid) can decrease how quickly the body gets rid of caffeine. Taking yerba mate along with ticlopidine might increase the effects and side effects of caffeine, including jitteriness, hyperactivity, irritability, and others

Interactions with herbs and supplements

Bitter orange

Do not use yerba mate with bitter orange. The combination might overstimulate the body, resulting in increased blood pressure and heart rate, even in people with normal blood pressure.

Calcium

The caffeine in yerba mate tends to increase the body’s elimination of calcium. If you use a lot of yerba mate, ask your healthcare provider if you should take additional calcium to help make up for the calcium that is lost in the urine.

Creatine

There is some concern that combining caffeine, a chemical found in yerba mate, with ephedra and creatine might increase the risk of serious harmful health effects. One athlete who took 6 grams of creatine monohydrate, 400-600 mg of caffeine, 40-60 mg of ephedra, and a variety of other supplements daily for 6 weeks had a stroke. Caffeine might also decrease creatine’s ability to improve athletic performance.

Ephedra (Ma huang)

Don’t use yerba mate with ephedra. This combination can overstimulate the body and increase the risk of serious life-threatening or disabling conditions, such as high blood pressure, heart attack, stroke, and seizures. This combination can also cause death.

Herbs and supplements that contain caffeine

Yerba mate contains caffeine. Using it along with other herbs or supplements that also contain caffeine might increase the risk of caffeine-related side effects. Other natural products that contain caffeine include cocoa, coffee, cola nut, black tea, oolong tea, and guarana.

Herbs and supplements that slow blood clotting

Yerba mate might slow blood clotting. Using it along with other herbs or supplements that have this same effect might increase the risk of bruising and bleeding in some people. Some of these herbs include angelica, clove, danshen, garlic, ginger, ginkgo, Panax ginseng, and others.

Magnesium

Yerba mate contains caffeine. The caffeine in yerba mate might increase how much magnesium is released in the urine.