Probiotic consumption and inflammatory markers in athletes: a systematic review and meta-analysis

Abstract

Existing evidence on the possible effects of probiotics on inflammatory status is inconclusive. Therefore, this systematic review and meta-analysis aimed to clarify the effects of probiotic consumption on inflammatory markers among athletes. A systematic literature search was performed in the databases PubMed, Scopus, ISI Web of science, Cochrane's library, and Google Scholar (up to July 2020). Randomized controlled trials (RCTs) investigating the effects of probiotics on inflammatory markers in athletes were included. Jadad scale was used for quality assessment. In fixed-effects meta-analysis model, standard mean difference (SMD) and 95 confidence interval (CI) demonstrated the overall effect. Any possibility of publication bias was inspected through Egger's and Begg's statistics. A total of 14 RCTs with 393 participants were included. Probiotic consumption resulted in a significant decrease in plasma concentrations of interleukin-6 (SMD = -0.58; 95 CI, -0.87 to -0.28; P<0.001) and tumor necrosis factor-alpha (SMD = -0.72; 95 CI, -1.11 to -0.33;P< .001), and significant increase in interferon-gamma (SMD = 0.43; 95 CI: 0.09 to 0.76;P= .012). The effects were more pronounced when probiotics were consumed in Asian, male athletes, using a single strain capsule or when they were consumed for lower than 4 weeks. Probiotic supplements may be beneficial to improve inflammatory markers, including interleukin-6, tumor necrosis factor-alpha, and interferon-gamma.