Efficacy and safety of fermented Prunus mume vinegar on fatigue improvement in adults with unexplained fatigue: A randomized controlled trial

BACKGROUND: The accumulation of fatigue leads to reduced physical, emotional, psychological, and social functions. OBJECTIVES: Fermented Prunus mume vinegar (PV) improves fatigue in animals; however, studies in humans have not been conducted. We aimed to examine the effects and safety of consuming fermented PV for 8 weeks on fatigue indices in adults with unexplained fatigue while considering the placebo effect. METHODS: A randomized, double-blind, placebo-controlled trial was conducted in adults of >19 years, who were diagnosed with unexplained fatigue for at least 1 month. Eighty participants were randomly assigned to receive daily 70 mL of fermented PV (2.56 mg/g, chlorogenic acid, and 15.3 mg/g, citric acid) or a placebo for 8 weeks. At baseline and 4 and 8 weeks after treatment, the participants were visited for blood tests (liver enzyme, glucose, creatinine, lactate, malondialdehyde [MDA], and creatine kinase [CK]) and questionnaires (Fatigue Severity Scale [FSS], fatigue visual analog scale [VAS], Beck Depression Inventory [BDI], the Korean version of the Brief Encounter Psychosocial Instrument [BEPSI-K], EQ-5D-3L, and EQ-VAS]). RESULTS: Fermented PV supplementation for 8 weeks did not remarkably improve the fatigue indices when compared to placebo. Additionally, differences in fatigue VAS, BDI, BEPSI-K, EQ-5D-3L, EQ-VAS, lactate, CK, and MDA concentrations between the groups were not observed. However, FSS had positively correlated with fatigue VAS, BDI, and BEPSI-K, whereas it was negatively correlated with EQ-5D-3L and EQ-VAS at the baseline and 8 weeks. None of the participants reported adverse events. CONCLUSION: The efficacy of fermented PV did not exceed the efficacy of placebo in adults with unexplained fatigue. CLINICAL TRIAL REGISTRATION: [ClinicalTrials.gov], identifier [NCT04319692].