|While almost all energy drinks appear to have it, the evidence that taurine adds to the effects of caffeine has hitherto been unconvincing. Does this change with the latest study by a group of researchers from Brazil and Spain?|
The fact that Souza, et al. observed in their latest meta-analysis that "a signifcant association between taurine dosage (mg) and performance (slope = 0.0001; p = 0.04), but not between caffeine dosage (mg) and performance (slope = 0.0009; p = 0.21)," caught my attention.
Before we discuss how relevant this result of the authors' meta-regression actually is, it would be prudent to take a brief look at the methodology section of the paper: As you would expect, the scientists performed a systematic review and meta-analysis of published prior to January 2016 disregarding: (1) case reports; (2) review articles; (3) the use of drugs/substances which inﬂu enced the outcome; (4) caffeine use without ED; (5) ED use without caffeine; (6) subjects on energy-restricted diets and/or weight reduction programs; (7) articles with animal models; (8) studies with samples that were ill or had physical limitations for exertion; (9) longitudinal studies.
Eventually N=34 articles that were (1) original; done with healthy adults; (2) reported the caffeine dose in the ED; (3) measured of physical performance pre- and post-intervention; (4) had a placebo group/session; (7) and offered enough data for effect size calculation were included in the scientists' statistical analysis.
|Figure 1: Effects on endurance (left) and jumping (right) performance according to meta-analysis (Souza. 2016).|
- the effects on muscle strength and endurance (ES = 0.49; p < 0.001), and
- sport-specifc actions (ES = 0.51; p < 0.001; cf. Table 1).
Note: This article does not say that caffeine doesn't work! That caffeine works is beyond doubt. What the article does claim, however, is that the results of the meta-analysis, when combined with previous research, suggest that the ratio of caffeine to taurine could explain differences between the efficacy of various drinks (see bottom line for further discussion).With a borderline significant effect and an increase of 16% in a study by Alford, et al., I would not discount the possibility that EDs would help Usain Bolt, as well.
|Table 1: Subgroup analyses of categorical variables (Souza. 2016).|
|Figure 2: Illustration of the subject- and supplement dependent continuous variables and their impact on the effect size indicated by the slope and significance of the results of the meta-regression (Souza. 2016).|
- Alford, Chris, Harriet Cox, and Robert Wescott. "The effects of red bull energy drink on human performance and mood." Amino acids 21.2 (2001): 139-150.
- HaeMi, Lee, Paik IlYoung, and Park TaeSun. "Effects of dietary supplementation of taurine, carnitine or glutamine on endurance exercise performance and fatigue parameters in athletes." Korean Journal of Nutrition 36.7 (2003): 711-719.
- Ripps, Harris, and Wen Shen. "Review: taurine: a “very essential” amino acid." (2012).
- Rutherford, Jane A., Lawrence L. Spriet, and Trent Stellingwerff. "The effect of acute taurine ingestion on endurance performance and metabolism in well-trained cyclists." International journal of sport nutrition 20.4 (2010): 322.
- Souza, Diego B., et al. "Acute effects of caffeine-containing energy drinks on physical performance: a systematic review and meta-analysis." European journal of nutrition (2016): 1-15.
- Zhang, M., et al. "Role of taurine supplementation to prevent exercise-induced oxidative stress in healthy young men." Amino acids 26.2 (2004): 203-207.