Caffeine and taurine: a systematic review and network meta-analysis of their individual and combined effects on physical capacity, cognitive function, and physiological markers.

Abstract

Background: Caffeine (CAF) and taurine (TAU) have each demonstrated ergogenic effects across physical and cognitive domains. Often co-formulated in commercial energy drinks, they are widely regarded as the two principal bioactive compounds. However, findings regarding their combined efficacy remain inconclusive. This systematic review and Bayesian network meta-analysis aimed to quantify the individual and combined effects of CAF and TAU on physical capacity, cognitive function, and physiological responses, with a focus on identifying potential synergistic or antagonistic interactions.

Methods: Cochrane Library, PubMed, SciELO, SportsDiscus-EBSCO and Web of Science were searched through 25 July 2025. The pooled effect of each outcome was summarized using SMD (Hedge's g) by Bayesian arm-based multilevel network meta-analysis, and SUCRA ranking was applied to estimate the relative treatment effect.

Results: Twelve studies were included (8 on physical capacity, 7 on blood lactate (B[la]), and 6 each on cognitive function, heart rate (HR), and rating of perceived exertion (RPE)). Posterior estimates indicated that CAF+TAU was associated with a credible positive effect on anaerobic capacity (g = 0.46, 95% CrI [0.19, 0.71]) and reaction time (g = 0.75, 95% CrI [0.29, 1.18]) compared to CAF or TAU alone. CAF showed the greatest posterior reduction in RPE (g = -0.64, 95% CrI [-1.20, -0.10]), while its posterior mean estimate suggested a potential increase in B[la] (g = 0.24, 95% CrI [-0.48, 0.96]). In contrast, TAU showed a possible tendency toward reducing B[la] (g = -0.30, 95% CrI [-1.01, 0.42]). No credible differences in HR were observed across conditions. Effects on aerobic performance and physiological measures were variable and appeared to be context-dependent. SUCRA rankings consistently favored CAF+TAU across most outcome domains.

Conclusions: CAF+TAU co-supplementation provides a balanced ergogenic effect, combining the central stimulation of CAF with the neuromodulatory and metabolic support of TAU, particularly beneficial for high-intensity, reaction-based tasks. Its effects on endurance and physiological indices vary by condition, highlighting the need for personalized application.