Multiday Pomegranate Extract Supplementation Decreases Oxygen Uptake During Submaximal Cycling Exercise, but Cosupplementation With N-acetylcysteine Negates the Effect.
Level 2 - randomized trial
Randomized crossover trial
PubMed 29431536 · doi:10.1123/ijsnem.2017-0407
What was done
Eight trained cyclists completed four 8-day supplementation periods: pomegranate extract (POMx) only, N-acetylcysteine (NAC) only, POMx plus NAC, and placebo. Following each period, participants performed submaximal cycling and a 5-minute time trial while oxygen uptake (VO2) and muscle oxygen saturation (SmO2) were measured.
What was found
Submaximal exercise VO2 was significantly lower with POMx compared to placebo (-2.6 ml·min⁻¹·kg⁻¹, p = .009) and compared to POMx + NAC (-2.5 ml·min⁻¹·kg⁻¹, p < .05). NAC alone increased submaximal VO2 (+1.9 ml·min⁻¹·kg⁻¹, p < .03). There was no significant main effect of any treatment on SmO2 or time-trial performance.
Why it matters
This study shows that multiday pomegranate polyphenol supplementation improves submaximal oxygen efficiency in trained cyclists, but co-supplementing with the antioxidant NAC negates this benefit.
Limits
The sample size is very small (n = 8). The abstract does not report participant demographics, specific supplement dosages, washout periods between crossover arms, or actual time-trial performance numbers.