Efficacy and Safety of Enzyme-Derived Deer Velvet Extract Supplementation on Adults with Chronic Fatigue: a Randomized, Placebo-Controlled, Double-Blind Trial.

Chronic Fatigue Syndrome (CFS) significantly impairs health-related quality of life in working-age populations, leading many individuals to use nutritional supplements for fatigue management. YC-1101, an enzymatically derived deer velvet extract, has demonstrated anti-fatigue potential in preclinical studies; however, clinical evidence in humans remains limited. This study aimed to evaluate the efficacy and safety of YC-1101 in adults with CFS. In an 8-week randomized controlled trial, 100 patients with CFS were assigned to either the YC-1101 or the placebo group. Subjective fatigue was assessed at baseline, at an interim point, and at the end of the intervention. Fatigue-related blood biomarkers and cardiorespiratory endurance were measured at baseline and postintervention. Compared with placebo, YC-1101 significantly improved Factor 1 (general and physical fatigue) of the Multidimensional Fatigue Inventory (MFI) at weeks 4 and 8, with a significant group-by-time interaction (p = 0.002), and improved the MFI items "I feel tired" and "I get tired easily" at both time points (group-by-time interaction p = 0.014 for each). YC-1101 also significantly improved fatigue-related motivation and functional interference on the Fatigue Severity Scale (FSS) at weeks 4 and 8, with significant group-by-time interactions (p = 0.040). After excluding outliers, the exercise distance to exhaustion was significantly greater in the YC-1101 group (p = 0.031), and lactate levels showed a significant group-by-time interaction at week 8 (p = 0.049). No significant differences in the safety outcomes were observed between the groups, and no adverse events were reported. Daily supplementation with YC-1101 for 8 weeks was safe, enhanced fatigue resistance, and improved exercise performance in adults with CFS, supporting its potential use in treating chronic fatigue.