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<p>Astronauts face multiple physiological challenges during spaceflight, including exposure to microgravity, ionizing radiation, altered circadian rhythms, and psychological stress due to confinement. Among these hazards, microgravity is a significant disruptor of gastrointestinal homeostasis. This review synthesizes evidence from human spaceflight missions, ground-based analogue studies, and preclinical models to characterize microgravity-induced gut dysbiosis and its downstream effects on central nervous system function via the gut–brain axis. Consistent findings across studies include shifts in the Firmicutes-to-Bacteroidetes ratio, depletion of beneficial commensal bacteria (notably <i>Akkermansia muciniphila</i>, <i>Faecalibacterium prausnitzii</i>, and <i>Bifidobacterium</i> species), and enrichment of potentially pathogenic taxa. These compositional changes correlate with reduced production of short-chain fatty acids and other neuroprotective metabolites, compromised intestinal barrier integrity, and systemic low-grade inflammation. Through immune, neuroendocrine, and vagal pathways, these peripheral perturbations propagate to the central nervous system, contributing to neuroinflammation, blood–brain barrier dysfunction, and altered neurotransmitter metabolism. We critically evaluate the mechanistic pathways linking microbial changes to neurocognitive outcomes, address methodological limitations and confounding factors in current research, and propose candidate countermeasures and priorities for future evidence based. Understanding these gut–brain interactions are essential for developing interventions to protect astronaut cognitive performance and psychological well-being during long-duration space exploration.</p>

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Microgravity-Induced Gut Dysbiosis and its Consequences for Brain Health

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年8月1日

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  • Srija Sappa,
  • Prakrathi Keremane,
  • Kamalesh Dattaram Mumbrekar

摘要

Astronauts face multiple physiological challenges during spaceflight, including exposure to microgravity, ionizing radiation, altered circadian rhythms, and psychological stress due to confinement. Among these hazards, microgravity is a significant disruptor of gastrointestinal homeostasis. This review synthesizes evidence from human spaceflight missions, ground-based analogue studies, and preclinical models to characterize microgravity-induced gut dysbiosis and its downstream effects on central nervous system function via the gut–brain axis. Consistent findings across studies include shifts in the Firmicutes-to-Bacteroidetes ratio, depletion of beneficial commensal bacteria (notably Akkermansia muciniphila, Faecalibacterium prausnitzii, and Bifidobacterium species), and enrichment of potentially pathogenic taxa. These compositional changes correlate with reduced production of short-chain fatty acids and other neuroprotective metabolites, compromised intestinal barrier integrity, and systemic low-grade inflammation. Through immune, neuroendocrine, and vagal pathways, these peripheral perturbations propagate to the central nervous system, contributing to neuroinflammation, blood–brain barrier dysfunction, and altered neurotransmitter metabolism. We critically evaluate the mechanistic pathways linking microbial changes to neurocognitive outcomes, address methodological limitations and confounding factors in current research, and propose candidate countermeasures and priorities for future evidence based. Understanding these gut–brain interactions are essential for developing interventions to protect astronaut cognitive performance and psychological well-being during long-duration space exploration.