TL;DR — Ostojic 2021
Ostojic published a review proposing that creatine plays a role in the gut-brain axis — the bidirectional communication network between the gastrointestinal tract and the central nervous system.
The paper explored how gut microbiome composition may influence creatine metabolism, how creatine supports intestinal energy needs, and how these interactions ultimately affect brain creatine availability and neural function.
This emerging area of research opens new perspectives on creatine’s systemic importance.
Background
The gut-brain axis has become one of the most active areas of biomedical research, with the gut microbiome increasingly recognized as a regulator of neural function, mood, and cognition.
Creatine, understood primarily through the lens of the creatine kinase energy system (Wallimann et al., 2011) , had not been systematically examined in this context until Ostojic’s work.
The intestinal epithelium is metabolically active and expresses creatine transporters.
Brain creatine availability, as reviewed by Roschel et al. (2021) (Roschel et al., 2021) , is critical for cognitive function.
Ostojic connected these observations into a unified hypothesis.
Key Concepts
Gut Microbiome and Creatine Degradation
Certain gut bacteria possess enzymes capable of degrading creatine and creatinine. This microbial creatine metabolism could influence:
- The amount of orally ingested creatine that survives gut transit for absorption
- The production of creatine-derived metabolites that may have biological activity
- Individual variation in creatine supplementation response based on microbiome composition
Intestinal Energy Metabolism
The intestinal epithelium has high energy demands for nutrient absorption, barrier function, and immune surveillance.
The creatine kinase system is expressed in intestinal cells, suggesting that creatine supports gut energy metabolism.
This may have implications for gut health and barrier integrity.
Brain Creatine Supply Chain
Ostojic proposed that the gut functions as a critical node in the creatine supply chain to the brain.
Factors that affect gut creatine handling — absorption efficiency, microbial degradation, intestinal creatine transporter expression — ultimately determine how much creatine reaches the brain.
Practical Implications
- Gut health may affect creatine response: Individual differences in microbiome composition could explain why some people respond better to creatine supplementation than others
- Probiotics and creatine interaction: Future research may identify gut bacteria that optimize creatine absorption
- Systemic view of creatine: Creatine should be understood as a whole-body metabolite, not just a muscle supplement
- Standard supplementation still recommended: Despite these emerging insights, the ISSN-recommended 3-5 g/day protocol remains evidence-based (Kreider et al., 2017)
Malaysian Relevance
The gut-brain axis perspective is relevant in Malaysia where dietary diversity and fermented food traditions (tempeh, tapai, fermented condiments) may influence microbiome composition.
Understanding how gut bacteria interact with creatine metabolism could inform personalized nutrition strategies for Malaysian consumers.
Limitations
- This is a hypothesis-generating review, not a primary research study
- Direct evidence for microbial creatine metabolism in humans is limited
- Causal relationships between gut microbiome composition and creatine bioavailability are not yet established
- Clinical applications remain speculative at this stage
Full Citation
Ostojic SM. Creatine and the gut-brain axis. Amino Acids.
2021;53(11):1639-1647. doi:10.1007/s00726-021-03076-x
Where This Fits in the Evidence
Ostojic’s 2021 paper is a hypothesis-generating review rather than a primary study, and it should be read as such. Its contribution is conceptual: it reframes creatine as a whole-body metabolite by proposing that the gut microbiome, intestinal energy metabolism and brain creatine supply form a single connected pathway. That framing could one day help explain why individuals respond differently to supplementation, but the direct human evidence for microbial creatine handling is still thin, so it does not change current practice. For the established recommendations this review builds upon, see the ISSN position stand and the wider research library.
Sources & References
This article is based on the review by Ostojic published in Amino Acids (2021) and contextualized with Roschel et al. (2021), Wallimann et al. (2011), and Kreider et al. (2017).
All citations reference PubMed-indexed publications.