Effects of OXXYSLAB Probiotic Supplementation on Blood Oxygenation and Hypoxic Symptoms in Healthy Individuals: A Controlled Normobaric Hypoxia Trial

Marzola, Manuel, Massimiliano Marazzato, Roberto Nutini, Adriano Di Marzio, Francesca Baroli, Manuel Paolucci, Matteo De Angelis, Joanna Giuliano, Ambra Menichelli, Guglielmo Sferrati, Carmen Santangelo, Danilo Bondi, Gerardo Bosco, and Vittore Verratti. Effects of OXXYSLAB probiotic supplementation on blood oxygenation and hypoxic symptoms in healthy individuals: A controlled normobaric hypoxia trial. High Alt Med Biol. 27:168–176, 2026. Background: OXXYSLAB, a high-dose, multi-strain probiotic, has shown promise in pathological hypoxemia but remains untested under acute normobaric hypoxia (NH) in healthy volunteers. We evaluated whether OXXYSLAB alters peripheral oxygen saturation (SpO 2 ) and alleviates hypoxia-related symptoms in healthy adults exposed to NH. Methods: In two randomized, double-blind, crossover phases, young adults were exposed to ∼13.5% inspired O 2 for 1 hour (Phase 1: n = 12, 21.6 ± 1.3 years, body mass index [BMI] = 23.2 ± 2.8 kg/m 2 ) or 40 minutes (Phase 2: n = 20, 21.7 ± 1.5 years, BMI = 22.9 ± 3.2 kg/m 2 ). Participants received either a single (8 × 10 11 colony-forming unit [CFU]) or double (1.6 × 10 12 CFU) dose of OXXYSLAB or matched placebo in randomized order. Results: NH induced the expected SpO 2 decrease (Phase 1: 90.0 ± 2.1%; Phase 2: 86.7 ± 2.9%), with no significant effect of probiotic supplementation on SpO 2 . In Phase 1, a trend toward lower heart rate (Δ = –3.2 bpm) under OXXYSLAB approached significance ( p = 0.053); no effect was seen in Phase 2. Notably, headache incidence under probiotic conditions was reduced by 50% (Phase 1) and 62.5% (Phase 2) compared to placebo ( p = 0.046 and p = 0.059, respectively). Conclusion: While OXXYSLAB did not enhance systemic oxygenation during acute NH, it significantly attenuated headache, a common symptom of hypoxia. Further research should assess its efficacy under prolonged or clinical hypoxemic conditions.