A study published on January 16, 2026, in Current Developments in Nutrition — a peer-reviewed, open-access journal listed in PubMed and PubMed Central (PMC) — has produced results that challenge a common marketing claim in the yerba mate beverage industry: that drinking yerba mate before exercise enhances metabolic performance. The study, titled 'Acute Effects of Commercial Yerba Mate Products on Cardiometabolic Responses during Submaximal Cycling: Brewed to Perform?' [1], was conducted at the American University of Beirut and found that acute ingestion of brewed yerba mate did not significantly enhance metabolic or cardiovascular responses during low- to moderate-intensity cycling, regardless of the commercial brand consumed.
Study Design: Two Brands, Multiple Metrics
The researchers employed a randomized crossover design with 29 healthy adults (15 men and 14 women), who consumed four different drinks across separate visits: two commercially brewed yerba mate brands (designated AYM and KYM), water, and water with 135 mg of caffeine [1]. The two yerba mate brands had similar caffeine concentrations but different phenolic content — a design feature that allowed the researchers to control for caffeine's known effects and test whether yerba mate's non-caffeine bioactive compounds (primarily polyphenols) contributed any additional metabolic benefit. Following each drink, participants underwent graded cycling exercise (20–80W at 60 rpm, 5 min per stage) while energy expenditure (EE), respiratory exchange ratio (RER), heart rate (HR), and delta efficiency (DE) were measured using indirect calorimetry [1].
The Null Result and What It Means
The study's central finding was a null result — but in clinical research, null results can be as informative as positive findings. Neither yerba mate brand produced a statistically significant improvement in substrate oxidation, total energy expenditure, heart rate, or delta efficiency compared to control drinks during the cycling protocol [1]. This does not mean that yerba mate has no metabolic effects whatsoever; caffeine is a well-established mild ergogenic aid, and yerba mate contains it in meaningful quantities. What the study suggests is that the additional bioactive compounds in yerba mate — the polyphenols, saponins, and other phytochemicals that distinguish it from a simple caffeine delivery vehicle — do not provide measurable acute metabolic benefits during submaximal exercise at the doses and timing used in this protocol.
Sex Differences and a Notable Interaction
The study also revealed sex-based differences in metabolic responses. Women exhibited higher RER and heart rate at similar workloads compared to men, though no drink × sex interactions were found for most outcomes [1]. However, a significant three-way interaction (drink × intensity × sex) was observed for RER (P = 0.013), particularly in men — suggesting that the metabolic response to yerba mate may not be entirely uniform across sexes and exercise intensities, even if the overall effect was null. This nuance is worth noting: while the headline finding is that yerba mate did not enhance performance, the interaction pattern indicates that future studies with larger samples or different protocols might detect sex-specific effects.
Body Composition: The Stronger Variable
Perhaps the most significant finding was that body composition — specifically, obesity status — had a more consistent and meaningful influence on exercise efficiency than yerba mate consumption [1]. Obesity status influenced HR, EE, and DE, with obese participants showing altered physiological responses during cycling regardless of whether they had consumed yerba mate. Notably, no drink × obesity interactions were detected, meaning that yerba mate had no differential effect in overweight/obese versus healthy-weight individuals. This finding aligns with the broader exercise physiology literature, which consistently shows that metabolic responses to exercise are primarily determined by baseline physiological factors (body composition, aerobic fitness, insulin sensitivity) rather than by acute dietary interventions.
Implications for the Industry
For the yerba mate industry, the study presents a nuanced message. Brands that market yerba mate as a 'performance-enhancing' pre-workout beverage — and several RTD brands explicitly target the fitness and athletic consumer segment — should note that the peer-reviewed evidence does not currently support claims of acute metabolic enhancement beyond what caffeine alone provides [1]. This does not invalidate yerba mate's other evidence-based attributes: its antioxidant capacity, its anti-inflammatory properties, and its emerging role as a modulator of glycemic responses. But it does suggest that the exercise-performance marketing angle requires either stronger clinical evidence or more modest claims.
It is important to note the scope of this study: it tested the acute (single-dose) effect of brewed yerba mate during submaximal cycling in a university student population. Whether chronic yerba mate consumption, different doses, higher exercise intensities, or different preparation methods (e.g., traditional gourd-brewed mate chimarrão) would produce different results remains an open question.