The global diffusion of benign prostatic hyperplasia (BPH) demands the search for safe and effective treatment alternatives to the drugs commonly used, which exert both side and adverse effects. Among plant-based products, the extracts of Epilobium angustifolium L. (EAEs) could improve BPH symptoms thanks to the presence of ellagitannins and their anti-inflammatory metabolites, urolithins. This study focused its attention on a commercial EAE, standardized to contain ≥ 15 % oenothein B, to determine a) the metabolic profile and the chemical degradation induced by digestion, b) in vivo bioavailability after acute and prolonged treatments of CD1 mice, and c) in vitro antioxidant activity. Utilizing RP-HPLC-PDA-ESI-MSn analysis, 20 different compounds were identified. Polyphenols suffered from degradation after both orogastric and duodenal digestion processes, suggesting that gastro-resistant coating agents are required to preserve the bioactive components occurring in the EAE phytocomplex from orogastric digestion. In vivo data underlined the presence of urolithins only after the prolonged treatment, confirming that the gut fermentation process requires at least 24 h to produce urolithins. Finally, an increase of Superoxide Dismutase-1 (SOD-1), which represents one of the fundamental endogenous antioxidant defenses, was determined in an EAE pretreated LNCap cell model system, confirming EAE antioxidant activity.