Creatine and Microbiomes
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A new 2026 Cell Metabolism study explores a compelling and increasingly central idea in modern biology: the gut/brain/immune/metabolism axis is not just associative, it is mechanistic. Specifically, Dr. Lu and colleagues investigate how the gut microbiota can directly influence depressive behavior by reshaping systemic and neural metabolism. This is another in a long running list of papers describing the amazing work that bacterial commensal microbes do for us. In this case, our minds and moods.
"Although peripheral-brain crosstalk regulates energy metabolism, its role in depression remains unclear. Here, we used metabolic profiling to reveal elevated fecal creatine alongside reduced plasma and cerebrospinal fluid creatine in both patients with depression and mouse depression models. Exogenous creatine produced antidepressant-like effects mediated by gut microbiota. Bifidobacterium pseudolongum was identified as a significantly reduced gut bacterial species in depression, correlating with impaired creatine absorption. Subsequent supplementation with Bifidobacterium enhanced the antidepressant effects of creatine. Mechanistically, B. pseudolongum-derived acetate promoted the creatine transporter (Slc6a8) expression in intestinal epithelial cells via histone acetylation. The Slc6a8 mediated the antidepressant-like effects of creatine. Neuronal creatine deficiency influenced energetic metabolism and neurophysiological function. In patients with depression taking antidepressants, co-administration of creatine and Bifidobacterium increased plasma creatine levels and reduced depression scores. These findings identify the Bifidobacterium-creatine combination as a promising antidepressant strategy and highlight the critical role of gut-brain energy metabolism in depression." "The brain, as an energy-intensive organ, relies on precise metabolic regulation to maintain synaptic plasticity, neurotransmitter synthesis, and stress response systems. Accumulating evidence implicates energy metabolism dysregulation as a hallmark of depression. Neuroimaging studies using positron emission tomography (PET) have identified marked glucose hypometabolism in the medial prefrontal cortex (mPFC) of patients with depression. Cerebral mitochondrial dysfunction and ATP imbalance have been mechanistically linked to depression progression. Notably, emerging studies emphasize the bidirectional interplay between peripheral metabolic signals and central energy regulation, which is fundamental to neural metabolism. Clinical observations such as fatigue, appetite dysregulation, and unexplained weight fluctuations in patients with depression further suggest systemic metabolic disturbances spanning peripheral organs and the CNS.." (Lu et. al. 2026)
This is next-level medicine. Mental health can no longer be framed as a disorder of genetics, experience, or circumstance alone. This work opens a clearer window, showing how the microbiome participates as an active partner, shaping brain function through the metabolites it helps produce and deliver. Compounds like creatine are no longer just peripheral players. They become signals, fuel, structure, and information, bridging gut and brain, metabolism and behavior.
The implication is simple, and profound: the mind is not isolated. It is metabolically connected, ecologically influenced, and far more modifiable than we once believed.
More on Creatine: (Science Heavy)
Creatine sits at a fascinating crossroads of energy metabolism, cellular signaling, and methylation biology, far beyond its reputation as a muscle supplement. Methylation biology is at the heart of adaptation through the one carbon metabolism pathway and the work of Randy Jirtle.
At its core, creatine is an energy buffer. Through the creatine–phosphocreatine system, it allows cells with high and fluctuating energy demands, skeletal muscle, brain, heart, to rapidly regenerate ATP.
Phosphocreatine donates a phosphate group to ADP via creatine kinase, restoring ATP in milliseconds. This system is especially critical in tissues like neurons, where energy demand spikes quickly and continuously. In the brain, creatine supports synaptic transmission, membrane potential stability, and overall neuronal resilience. the reverse also happens during periods of energy excess in these same tissues.
But the story gets more interesting upstream. Creatine synthesis is one of the body’s largest consumers of methyl groups. The pathway begins with arginine and glycine forming guanidinoacetate (GAA), which is then methylated by S-adenosylmethionine (SAMe) to form creatine. This final step uses a methyl group, meaning creatine production can consume up to 40–50% of the body’s methylation capacity in some estimates. That places creatine squarely in the center of one-carbon metabolism. (Pratt et. al. 2026)
This has two important implications. First, when dietary creatine intake is low (as in vegetarian or low-meat diets), the body must synthesize more, increasing demand on methyl donors like folate, B12, choline, and betaine. Over time, this can influence homocysteine levels and methylation balance which are tied to diseases of aging. Second, when creatine is supplemented, endogenous synthesis decreases, effectively sparing methyl groups. In this way, creatine functions as a “methylation modulator,” indirectly supporting pathways involved in DNA methylation, neurotransmitter synthesis, and phospholipid production.
Creatine also plays structural and protective roles. It stabilizes mitochondrial function, helping maintain membrane integrity and reducing reactive oxygen species under stress. It has been shown to buffer intracellular calcium, modulate apoptosis, and protect against excitotoxic injury, particularly relevant in neurologic and neurodegenerative conditions. (Pratt et. al. 2026)
In muscle, creatine enhances performance not just by increasing energy availability, but by supporting cellular hydration and osmotic balance. It draws water into muscle cells, which may act as an anabolic signal, promoting protein synthesis and reducing protein breakdown. This contributes to improved strength, recovery, and lean mass over time. This has been well established and studied in the body building sports space. Safety and efficacy are solid. (Wu et. al. 2022)
Emerging research highlights creatine’s role in brain health and mental health. Lower brain creatine levels have been observed in depression and certain neurodevelopmental conditions as pointed out in the Cell Metabolism article by Lu. Supplementation has shown promise as an adjunct in mood disorders, likely through its effects on cellular energetics and neurotransmitter systems.
There are also immunologic and metabolic effects. Creatine influences macrophage polarization, T-cell function, TLR activity and inflammatory signaling, suggesting a role in immune regulation. In metabolic tissues, it may improve insulin sensitivity and glucose handling, though these effects are still being clarified. There is also research that it enhances anti tumor immune activity. (Peng et. al. 2022)(Castillo et. al. 2025)(Bredahl et. al. 2021)
So while creatine is often reduced to a performance enhancer, it is better understood as a systems molecule—linking energy, methylation, cellular protection, and signaling across multiple organ system.
It is not just about power output.
It is about cellular capacity.
Dr. M
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