Effects of Caffeine–Taurine Co-Supplementation on Exercise Performance: A Systematic Review and Meta-Analysis

Background: Caffeine–taurine combinations are widely used in commercial sports products. Whether this combination improves exercise performance is still unclear. This study aimed to estimate the effect of caffeine–taurine co-supplementation versus placebo on exercise performance. Methods: Randomized controlled trials comparing caffeine plus taurine versus placebo were searched in PubMed, Embase, Web of Science, Cochrane Library, and related databases up to June 1, 2026. Outcomes included heart rate (HR), reaction time (RT), time to exhaustion (TTE), rating of perceived exertion (RPE), and peak/maximal anaerobic power (PP). A random-effects model was applied. Risk of bias was assessed with RoB 2.0. Results: A total of 11 randomized controlled trials involving 234 participants were included in the meta-analysis. Compared with placebo, caffeine–taurine co-supplementation was associated with improvements in time to exhaustion (SMD = 0.54, 95% CI: 0.03 to 1.05) and PP (SMD = 0.55, 95% CI: 0.21 to 0.89); an expanded secondary product-level analysis that additionally included one commercial multi-ingredient energy drink yielded a smaller estimate (SMD = 0.48, 95% CI: 0.19 to 0.78) that cannot be attributed specifically to caffeine and taurine. The pooled estimate for reaction time favored supplementation (SMD = −1.49, 95% CI: −2.78 to −0.20), but very high heterogeneity and a prediction interval crossing the null indicated that the effect was not consistent across settings, whereas no meaningful effect was observed for heart rate (WMD = −0.11, 95% CI: −5.76 to 5.53). Rating of perceived exertion was significantly reduced (SMD = −0.44, 95% CI: −0.83 to −0.04). Conclusions: Caffeine–taurine-only formulations were associated with possible benefits for selected performance outcomes, including PP. However, the evidence was derived from few, generally small studies and did not establish the independent contribution of caffeine, taurine, or their interaction. Results from commercial multi-ingredient products should be interpreted at the product level rather than as evidence of an isolated caffeine–taurine effect.