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Several scientific papers refer to the cacao flavanol l-epicatechin (EPI) as the first and only discovered dietary source of myostatin (MTSN) inhibition. However, although pre-clinical models strongly support this, there is a lack of high-quality human studies; to examine the response association between the consumption of EPI in humans and the effect on MSTN and follistatin (FST). By systematically reviewing the literature and qualitatively meta-analyzing with statistical methods, it becomes possible to quantify a conclusion from several lower quality human studies instead of a few high-quality studies. Two investigators searched Scopus® for the relevant human studies, which were pooled and meta-analyzed. Heterogeneity in the findings was explored with various subgroup analyses. Nine published articles with 11 intervention arms met the inclusion criteria. A significant improvement of the FST: MSTN ratio was observed in participants who ingested EPI, with a Common Language Effect Size (CLES) for Cohen's d of 0.92 (95% CI: 0.74 to 0.99). Strong evidence of an association between EPI consumption and FST induction was noted, with weaker evidence for MSTN inhibition. Respectively, 0.98 (95% CI: 0.88 to 1.00) and 0.71 (95% CI: 0.50 to 0.88). This meta-analysis provides evidence that EPI ingestion significantly improves the FST:MSTN ratio in humans by inducing FST and inhibiting MSTN. However, there was substantial variation in the results that could not be explained by the characteristics that were explored, and there were significant risk-of-bias concerns, with a large majority of the studies being small populations and not blinded. Nevertheless, considering the heterogeneity of children and the elderly and the lack of exercise intervention or alternatively high-quality exercise regime interventions. EPI consumption is the only feasible explanation for the drastic FST:MSTN ratio improvement. [ABSTRACT FROM AUTHOR]