Yerba mate consists of dried leaves from the Ilex paraguariensis plant, a species in the holly family native to subtropical South America. What makes it interesting is the sheer density of active compounds packed into those leaves: stimulants similar to those in coffee and tea, a high concentration of antioxidants, cholesterol-modulating plant compounds, and a range of vitamins and minerals. Here’s what’s actually in it.
The Plant Itself
Ilex paraguariensis is an evergreen tree traditionally cultivated in Brazil, Argentina, Paraguay, and Uruguay. The leaves and small stems are harvested, dried (often over wood smoke), and then ground into the coarse mixture sold as yerba mate. That mixture is brewed into several traditional drinks: chimarrão (hot water, common in southern Brazil), tereré (cold water, popular in Paraguay), and mate tea (steeped like a conventional tea bag). The specific preparation method changes how much of each compound ends up in your cup, but the raw material is the same.
Caffeine and Other Stimulants
The stimulant effect of mate comes from a group of compounds called methylxanthines, the same family that gives coffee and chocolate their kick. Caffeine is the dominant one, making up 1 to 2% of the dry leaf weight. A standard 150 mL cup of mate delivers roughly 80 mg of caffeine, comparable to a cup of coffee.
Theobromine, the compound responsible for chocolate’s mild stimulant effect, shows up at 0.3 to 0.9% of dry weight. A typical first brew contains around 3 to 8 mg of theobromine per 100 mL. Theophylline, a compound also found in tea that relaxes smooth muscle and opens airways, appears only in trace amounts.
The balance of these three stimulants is part of why mate drinkers often describe the energy as smoother than coffee. Caffeine provides alertness, theobromine adds a gentler, longer-lasting lift, and the combination with mate’s other compounds may slow the absorption curve slightly. If you re-brew the same leaves repeatedly (a common practice with chimarrão), the caffeine concentration drops significantly. By the 30th infusion of the same leaves, caffeine levels can fall to as little as 1.5 mg per 100 mL, down from over 20 mg in the first pour.
Antioxidants and Polyphenols
Mate’s antioxidant profile is dominated by chlorogenic acids, a type of polyphenol also found in coffee and certain fruits. The three main forms (chlorogenic acid, neochlorogenic acid, and cryptochlorogenic acid) together account for roughly 40 to 65% of the total identified organic compounds in the leaf. Chlorogenic acid alone makes up about 27 to 29% of the polyphenol profile, with neochlorogenic acid close behind at 21 to 22%.
These compounds are what give mate its strong antioxidant reputation. They neutralize reactive molecules in the body that contribute to cell damage and inflammation. Beyond the chlorogenic acids, mate contains smaller amounts of flavonoids like rutin (7 to 8% of the polyphenol profile) and astragalin, plus caffeic acid and other phenolic compounds. The total antioxidant content is competitive with green tea and, by some measures, exceeds it.
Saponins
One feature that sets mate apart from coffee and tea is its saponin content. These are plant-based compounds found in concentrations up to 4% of dry leaf weight. Saponins are responsible for the slight foaminess you see when mate is brewed, and they have a mildly bitter taste.
Biologically, saponins are linked to cholesterol reduction. They interfere with cholesterol absorption in the gut and have demonstrated anti-inflammatory and liver-protective effects in studies. This saponin content is one reason mate has drawn attention for its potential role in supporting healthy lipid levels.
Vitamins, Minerals, and Other Compounds
Mate leaves contain a range of micronutrients, including potassium, magnesium, manganese, and smaller amounts of other minerals. The leaves also carry vitamins, though these are present in modest quantities and vary depending on how the mate was processed and brewed. The mineral content is notable enough that regular mate consumption contributes measurably to daily intake of several trace elements.
Beyond vitamins and minerals, mate contains pigments like chlorophyll (which gives unroasted mate its green color) and small amounts of indole derivatives, nitrogen-containing compounds with their own biological activity.
How Brewing Changes What You Get
The composition of your cup depends heavily on how you prepare it. Hot water extracts significantly more active compounds than cold water. Hot infusions contain roughly twice the total polyphenols and flavonoids compared to cold-brewed versions, and up to four times higher concentrations of certain compounds. Alkaloid levels (caffeine plus theobromine) range from 29 to 76 micrograms per milliliter in hot brews versus 5.9 to 40 in cold ones.
Interestingly, water temperature within the hot range matters too, but not in the way you might expect. Brewing at around 70°C (158°F) actually extracts more caffeine and total polyphenols than boiling water at 100°C. This may be because very high temperatures degrade some compounds even as they extract others. So the traditional practice of using hot but not boiling water, common in chimarrão preparation, turns out to be chemically optimal.
Cold-brewed tereré still delivers a meaningful dose of active compounds, just at lower concentrations. Its first pour can contain around 35.8 mg of caffeine per 100 mL, which is actually higher than some hot preparations that use less leaf material, because tereré recipes tend to use a generous ratio of mate to water.
A Note on Smoke-Dried Mate
Most commercially available yerba mate is dried over wood smoke, and this introduces a class of compounds called polycyclic aromatic hydrocarbons (PAHs). These are the same potentially harmful chemicals found in charred meat and cigarette smoke. Testing of various mate brands has found total PAH levels ranging from 536 to 2,906 nanograms per gram of dry leaves, with the specific carcinogen benzo[a]pyrene present at 8 to 53 nanograms per gram.
Air-dried or “unsmoked” mate products avoid this issue almost entirely. If PAH exposure concerns you, look for brands labeled as air-dried, sun-dried, or “barbacuá” processed with indirect heat. The underlying nutrients and stimulants remain the same regardless of drying method.