Probiotics on Immune Function and Intestinal Microbiota in Astronauts Under Closed Microgravity Environment

Study for Evaluating the Impact of Continuous Consumption of Probiotics on Immune Function and Intestinal Microbiota in Astronauts Under Closed Microgravity Environment

Status

Completed

Phases

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT02618005

Enrollment

Registered

2015-12-01

Start date

2015-10-31

Completion date

2022-04-30

Last updated

2025-11-25

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Immune Function and Intestinal Microbiota

Keywords

Astronauts, Probiotics, Immune function, Intestinal microbiota

Brief summary

Human immune function and intestinal microbiota are suggested to be altered within long-duration stay in space. Accumulated evidences on earth support that Lacticaseibacillus paracasei strain Shirota (LcS) is a promising probiotic strain on improvement of immune function and intestinal microbiota. This study aims to investigate the impact of long-duration spaceflight as well as intake of LcS on the international space station (ISS), on immune system and intestinal microbiota in astronauts.

Interventions

DIETARY_SUPPLEMENTProbiotic capsule

Continuously take five capsules containing freeze-dried LcS on ISS for four weeks, from four weeks before the return (R-4W) to one day before the return (R-1d)

Study design

Allocation

RANDOMIZED

Intervention model

PARALLEL

Primary purpose

BASIC_SCIENCE

Masking

NONE

Eligibility

Sex/Gender

ALL

Age

25 Years to 80 Years

Healthy volunteers

Yes

Inclusion criteria

* Individuals who are scheduled to stay on the ISS for at least 3 months * Individuals who fully understand the study protocol and provide written informed consent for the study participation

Exclusion criteria

* Individuals who routinely use antibiotic, laxative, and/or bowel regulating medicine * Individuals who participate in other research that competes with this study in terms of the purpose and field, e.g., study with dietary management or intake of bifidobacteria/lactic acid bacteria, oligosaccharides, antibiotic, laxative, and/or bowel regulating medicine

Design outcomes

Primary

Measure	Time frame	Description
Longitudinal changes in the level of immune markers	9-18 months	Levels of immune markers in blood/saliva will be assessed by ELISA and bioassay, during pre-flight, in-flight and post-flight.
Longitudinal changes in the number of LcS in feces	9-18 months	Number of LcS in feces will be assessed by PMA-qPCR, during pre-flight, in-flight and post-flight.
Longitudinal changes in numbers and composition of intestinal microbiota	9-18 months	Numbers and composition of bacteria in feces will be assessed by RT-qPCR/qPCR and next generation sequencer analysis, during pre-flight, in-flight and post-flight.

Countries

Japan

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026