Research Trends in Photobiomodulation and the Microbiome: A Snapshot

Photobiomodulation with red and near-infrared (NIR) light is emerging as a low-stress tool to modulate biology. Beyond established uses for skin and recovery, recent studies investigate how targeted light exposures may influence the oral microbiome, the gut microbiome, inflammation, and the gut–brain axis. This snapshot highlights the current evidence, plausible mechanisms, and research gaps.

Key findings

• Oral microbiome:

  Targeted light can alter oral microbial communities. Blue light shows direct antimicrobial effects on certain pigment-rich periodontal species, while red and near-infrared exposures have shown effects on Candida and other cavity-linked bacteria in controlled studies[1].

• Gut microbiome and the gut–brain axis:

  NIR and red light applied to the abdomen may influence the gut microbiome via metabolic and immune signaling, shifting Firmicutes:Bacteroidetes ratios and promoting short-chain-fatty-acid–associated bacteria in early studies[2][3][4]. Results are promising but still preliminary in humans.

• Mechanistic rationale:

  Light can engage cytochrome-c oxidase, modulate nitric oxide and redox balance, and influence cytokine signaling. These effects may improve cellular metabolism and tissue environment in ways that favor beneficial microbes. The broader concept—“photobiomics”—considers light as one modifiable lever alongside diet, sleep, stress, and movement[5].

Practical takeaways

1. Evidence is growing — small controlled and preclinical studies support microbiome modulation by light, but robust large human trials are lacking.
2. Target and dosage matter — wavelength (blue vs red vs NIR), power density, exposure duration, and anatomical target (oral cavity vs abdominal region) all influence outcomes.
3. Mechanisms align with clinical plausibility — mitochondrial and immune signaling pathways provide biologic rationale for downstream microbiome effects.
4. Clinical translation is cautious — promising trends do not yet support routine therapeutic recommendations for microbiome modulation via photobiomodulation.

Research gaps and next steps

• Large, well-controlled randomized trials in humans that include standardized light protocols and deep microbiome sequencing.
• Mechanistic human studies linking tissue photophysiology to specific microbial community shifts and metabolite changes (e.g., short-chain fatty acids).
• Comparative studies to determine optimal wavelengths and dosing for oral versus gut targets.
• Safety and long-term outcome studies to assess sustained microbiome changes and clinical endpoints such as inflammation, metabolic markers, or neurological outcomes.

Bottom line

Near-infrared and red light show potential to modulate oral and gut microbiomes toward balance. The overall trend in the literature is positive, but larger and better-controlled human trials are required before practical clinical recommendations can be made.

References

1. Pourhajibagher, M., Gharibpour, F., Nikparto, N., Bahrami, R. & Bahador, A. The effect of photobiomodulation on oral microbiota dysbiosis: A literature review. Photodiagnosis and Photodynamic Therapy 52, 104525 (2025). https://doi.org/10.1016/j.pdpdt.2025.104525
2. Bicknell, B., Liebert, A., McLachlan, C. S. & Kiat, H. Microbiome Changes in Humans with Parkinson’s Disease after Photobiomodulation Therapy: A Retrospective Study. Journal of Personalized Medicine 12, 49 (2022). https://doi.org/10.3390/jpm12010049
3. da Silva, L. E. et al. Photobiomodulation of gut microbiota with low-level laser therapy: a light for treating neuroinflammation. Lasers in Medical Science 40, 64 (2025). https://doi.org/10.1007/s10103-025-04319-9
4. Hakimiha, N., Jahani Sherafat, S., Laakso, E.-L. & Fekrazad, R. Photobiomodulation and the oral-gut microbiome axis: therapeutic potential and challenges. Frontiers in Medicine 12 (2025). https://doi.org/10.3389/fmed.2025.1555704
5. Liebert, A. et al. “Photobiomics”: Can Light, Including Photobiomodulation, Alter the Microbiome? Photobiomodulation, Photomedicine, and Laser Surgery 37, 681–693 (2019). https://doi.org/10.1089/photob.2019.4628