Program FMT

This condition typically develops after antibiotic use disrupts the normal gut flora, allowing C. difficile to proliferate. It is characterised by watery diarrhoea, abdominal cramping, fever, and in severe cases, pseudomembranous colitis and toxic megacolon. Recurrence is common due to persistence of spores and impaired microbial defences.

Faecal microbiota transplantation restores microbial diversity and re-establishes colonisation resistance, limiting the ability of C. difficile to re-expand. It also promotes bile acid metabolism that inhibits spore germination and supports recovery of a stable, resilient gut ecosystem, reducing relapse rates.

Studies:

• Baunwall, S. M. D., Lee, M. M., Eriksen, M. K., Mullish, B. H., Marchesi, J. R., Dahlerup, J. F., & Hvas, C. L. (2020). Faecal microbiota transplantation for recurrent Clostridioides difficile infection: An updated systematic review and meta-analysis. EClinicalMedicine, 29–30. https://doi.org/10.1016/j.eclinm.2020.100642
• Hvas, C. L., Dahl Jørgensen, S. M., Jørgensen, S. P., Storgaard, M., Lemming, L., Hansen, M. M., Erikstrup, C., & Dahlerup, J. F. (2019). Fecal Microbiota Transplantation Is Superior to Fidaxomicin for Treatment of Recurrent Clostridium difficile Infection. Gastroenterology, 156(5). https://doi.org/10.1053/j.gastro.2018.12.019
• Juul, F. E., Bretthauer, M., Johnsen, P. H., Samy, F., Tonby, K., Berdal, J. E., Hoff, D. A. L., Ofstad, E. H., Abraham, A., Seip, B., Wiig, H., Rognstad, Ø. B., Glad, I. F., Valeur, J., Nissen-Lie, A. E., Ness-Jensen, E., Lund, K. M. A., Skjevling, L. K., Hanevik, K., … Garborg, K. K. (2025). Fecal Microbiota Transplantation Versus Vancomycin for Primary Clostridioides difficile Infection: A Randomized Controlled Trial. Annals of Internal Medicine, 178(7). https://doi.org/10.7326/ANNALS-24-03285
• Roshan, N., Clancy, A. K., & Borody, T. J. (2020). Faecal Microbiota Transplantation is Effective for the Initial Treatment of Clostridium difficile Infection: A Retrospective Clinical Review. Infectious Diseases and Therapy, 9(4). https://doi.org/10.1007/s40121-020-00339-w

IBS is a functional gastrointestinal disorder defined by recurrent abdominal pain associated with defecation, alongside changes in stool frequency or form (diarrhoea, constipation, or both). It is often accompanied by bloating, excess gas, and a heightened sensitivity to normal gut activity. Psychological stress and gut–brain signalling play a central role.

FMT may help by reshaping microbial composition and restoring metabolic balance within the gut. Increased production of short-chain fatty acids can support epithelial health, while reduced gas-producing or pro-inflammatory species may alleviate bloating and discomfort. These microbial shifts may also influence enteric nervous system signalling, potentially reducing visceral hypersensitivity.

Studies:

• El-Salhy, M., Hatlebakk, J. G., Gilja, O. H., Bråthen Kristoffersen, A., & Hausken, T. (2020). Efficacy of faecal microbiota transplantation for patients with irritable bowel syndrome in a randomised, double-blind, placebo-controlled study. Gut, 69(5). https://doi.org/10.1136/gutjnl-2019-319630

• El-Salhy, M., Winkel, R., Casen, C., Hausken, T., Gilja, O. H., & Hatlebakk, J. G. (2022). Efficacy of Fecal Microbiota Transplantation for Patients With Irritable Bowel Syndrome at 3 Years After Transplantation. Gastroenterology, 163(4). https://doi.org/10.1053/j.gastro.2022.06.020

• Jamshidi, P., Farsi, Y., Nariman, Z., Hatamnejad, M. R., Mohammadzadeh, B., Akbarialiabad, H., Nasiri, M. J., & Sechi, L. A. (2023). Fecal Microbiota Transplantation in Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. In International Journal of Molecular Sciences (Vol. 24, Issue 19). https://doi.org/10.3390/ijms241914562

• Wu, Y., Li, Y., Zheng, Q., & Li, L. (2024). The Efficacy of Probiotics, Prebiotics, Synbiotics, and Fecal Microbiota Transplantation in Irritable Bowel Syndrome: A Systematic Review and Network Meta-Analysis. In Nutrients (Vol. 16, Issue 13). https://doi.org/10.3390/nu16132114

• Jamshidi, P., Farsi, Y., Nariman, Z., Hatamnejad, M. R., Mohammadzadeh, B., Akbarialiabad, H., Nasiri, M. J., & Sechi, L. A. (2023). Fecal Microbiota Transplantation in Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. In International Journal of Molecular Sciences (Vol. 24, Issue 19). https://doi.org/10.3390/ijms241914562
• Wu, Y., Li, Y., Zheng, Q., & Li, L. (2024). The Efficacy of Probiotics, Prebiotics, Synbiotics, and Fecal Microbiota Transplantation in Irritable Bowel Syndrome: A Systematic Review and Network Meta-Analysis. In Nutrients (Vol. 16, Issue 13). https://doi.org/10.3390/nu16132114

• Holvoet, T., Joossens, M., Vázquez-Castellanos, J. F., Christiaens, E., Heyerick, L., Boelens, J., Verhasselt, B., van Vlierberghe, H., de Vos, M., Raes, J., & de Looze, D. (2021). Fecal Microbiota Transplantation Reduces Symptoms in Some Patients With Irritable Bowel Syndrome With Predominant Abdominal Bloating: Short- and Long-term Results From a Placebo-Controlled Randomized Trial. Gastroenterology, 160(1). https://doi.org/10.1053/j.gastro.2020.07.013

• El Hage Chehade, N., Ghoneim, S., Shah, S., Chahine, A., Mourad, F. H., Francis, F. F., Binion, D. G., Farraye, F. A., & Hashash, J. G. (2023). Efficacy of Fecal Microbiota Transplantation in the Treatment of Active Ulcerative Colitis: A Systematic Review and Meta-Analysis of Double-Blind Randomized Controlled Trials. In Inflammatory Bowel Diseases(Vol. 29, Issue 5). https://doi.org/10.1093/ibd/izac135

• Liu, H., Li, J., Yuan, J., Huang, J., & Xu, Y. (2023). Fecal microbiota transplantation as a therapy for treating ulcerative colitis: an overview of systematic reviews. BMC Microbiology, 23(1). https://doi.org/10.1186/s12866-023-03107-1

• Moayyedi, P., Surette, M. G., Kim, P. T., Libertucci, J., Wolfe, M., Onischi, C., Armstrong, D., Marshall, J. K., Kassam, Z., Reinisch, W., & Lee, C. H. (2015). Fecal Microbiota Transplantation Induces Remission in Patients With Active Ulcerative Colitis in a Randomized Controlled Trial. Gastroenterology, 149(1). https://doi.org/10.1053/j.gastro.2015.04.001

• Costello, S. P., Soo, W., Bryant, R. v., Jairath, V., Hart, A. L., & Andrews, J. M. (2017). Systematic review with meta-analysis: faecal microbiota transplantation for the induction of remission for active ulcerative colitis. In Alimentary Pharmacology and Therapeutics (Vol. 46, Issue 3). https://doi.org/10.1111/apt.14173

• Sood, A., Mahajan, R., Singh, A., Midha, V., Mehta, V., Narang, V., Singh, T., & Singh Pannu, A. (2019). Role of Faecal Microbiota Transplantation for Maintenance of Remission in Patients with Ulcerative Colitis: A Pilot Study. Journal of Crohn’s and Colitis, 13(10). https://doi.org/10.1093/ecco-jcc/jjz060

IBD encompasses chronic inflammatory conditions such as Crohn’s disease and ulcerative colitis, characterised by relapsing episodes of intestinal inflammation. Symptoms commonly include persistent diarrhoea, rectal bleeding, weight loss, fatigue, and mucosal ulceration visible on endoscopy. The disease reflects a dysregulated immune response to intestinal microbes.

FMT may contribute to restoring immune tolerance by increasing beneficial commensal species that promote regulatory T-cell activity. It can also enhance production of anti-inflammatory metabolites and strengthen tight junction integrity within the intestinal lining, helping to reduce permeability and dampen chronic inflammation.

Studies:

• Wu, Y., Li, Y., Zheng, Q., & Li, L. (2024). The Efficacy of Probiotics, Prebiotics, Synbiotics, and Fecal Microbiota Transplantation in Irritable Bowel Syndrome: A Systematic Review and Network Meta-Analysis. In Nutrients (Vol. 16, Issue 13). https://doi.org/10.3390/nu16132114
• Holvoet, T., Joossens, M., Vázquez-Castellanos, J. F., Christiaens, E., Heyerick, L., Boelens, J., Verhasselt, B., van Vlierberghe, H., de Vos, M., Raes, J., & de Looze, D. (2021). Fecal Microbiota Transplantation Reduces Symptoms in Some Patients With Irritable Bowel Syndrome With Predominant Abdominal Bloating: Short- and Long-term Results From a Placebo-Controlled Randomized Trial. Gastroenterology, 160(1). https://doi.org/10.1053/j.gastro.2020.07.013
• El Hage Chehade, N., Ghoneim, S., Shah, S., Chahine, A., Mourad, F. H., Francis, F. F., Binion, D. G., Farraye, F. A., & Hashash, J. G. (2023). Efficacy of Fecal Microbiota Transplantation in the Treatment of Active Ulcerative Colitis: A Systematic Review and Meta-Analysis of Double-Blind Randomized Controlled Trials. In Inflammatory Bowel Diseases(Vol. 29, Issue 5). https://doi.org/10.1093/ibd/izac135
• Liu, H., Li, J., Yuan, J., Huang, J., & Xu, Y. (2023). Fecal microbiota transplantation as a therapy for treating ulcerative colitis: an overview of systematic reviews. BMC Microbiology, 23(1). https://doi.org/10.1186/s12866-023-03107-1
• Moayyedi, P., Surette, M. G., Kim, P. T., Libertucci, J., Wolfe, M., Onischi, C., Armstrong, D., Marshall, J. K., Kassam, Z., Reinisch, W., & Lee, C. H. (2015). Fecal Microbiota Transplantation Induces Remission in Patients With Active Ulcerative Colitis in a Randomized Controlled Trial. Gastroenterology, 149(1). https://doi.org/10.1053/j.gastro.2015.04.001

• Costello, S. P., Soo, W., Bryant, R. v., Jairath, V., Hart, A. L., & Andrews, J. M. (2017). Systematic review with meta-analysis: faecal microbiota transplantation for the induction of remission for active ulcerative colitis. In Alimentary Pharmacology and Therapeutics (Vol. 46, Issue 3). https://doi.org/10.1111/apt.14173
• Sood, A., Mahajan, R., Singh, A., Midha, V., Mehta, V., Narang, V., Singh, T., & Singh Pannu, A. (2019). Role of Faecal Microbiota Transplantation for Maintenance of Remission in Patients with Ulcerative Colitis: A Pilot Study. Journal of Crohn’s and Colitis, 13(10). https://doi.org/10.1093/ecco-jcc/jjz060
• Cheng, F., Huang, Z., Wei, W., & Li, Z. (2021). Fecal microbiota transplantation for Crohn’s disease: a systematic review and meta-analysis. In Techniques in Coloproctology (Vol. 25, Issue 5). https://doi.org/10.1007/s10151-020-02395-3
• Xiang, L., Ding, X., Li, Q., Wu, X., Dai, M., Long, C., He, Z., Cui, B., & Zhang, F. (2020). Efficacy of faecal microbiota transplantation in Crohn’s disease: a new target treatment? Microbial Biotechnology, 13(3). https://doi.org/10.1111/1751-7915.13536
• Paramsothy, S., Paramsothy, R., Rubin, D. T., Kamm, M. A., Kaakoush, N. O., Mitchell, H. M., & Castaño-Rodríguez, N. (2017). Faecal microbiota transplantation for inflammatory bowel disease: A systematic review and meta-analysis. Journal of Crohn’s and Colitis, 11(10). https://doi.org/10.1093/ecco-jcc/jjx063
• Cui, B., Feng, Q., Wang, H., Wang, M., Peng, Z., Li, P., Huang, G., Liu, Z., Wu, P., Fan, Z., Ji, G., Wang, X., Wu, K., Fan, D., & Zhang, F. (2015). Fecal microbiota transplantation through mid-gut for refractory Crohn’s disease: Safety, feasibility, and efficacy trial results. Journal of Gastroenterology and Hepatology (Australia), 30(1). https://doi.org/10.1111/jgh.12727
• He, Z., Li, P., Zhu, J., Cui, B., Xu, L., Xiang, J., Zhang, T., Long, C., Huang, G., Ji, G., Nie, Y., Wu, K., Fan, D., & Zhang, F. (2017). Multiple fresh fecal microbiota transplants induces and maintains clinical remission in Crohn’s disease complicated with inflammatory mass. Scientific Reports, 7(1). https://doi.org/10.1038/s41598-017-04984-z
• Fang, H., Fu, L., & Wang, J. (2018). Protocol for Fecal Microbiota Transplantation in Inflammatory Bowel Disease: A Systematic Review and Meta-Analysis. In BioMed Research International (Vol. 2018). https://doi.org/10.1155/2018/8941340

ASD is a neurodevelopmental condition characterised by differences in social communication, restricted interests, and repetitive behaviours. Many individuals also experience gastrointestinal issues such as constipation, diarrhoea, and abdominal discomfort, suggesting a link between neurological and gut function.

By modifying the gut microbiome, FMT may alter the production of microbial metabolites involved in neurotransmitter pathways, including precursors to serotonin and other neuroactive compounds. Improvements in gut barrier function and reduced intestinal inflammation may also influence signalling along the gut–brain axis, with potential downstream effects on both gastrointestinal and behavioural symptoms.

Studies:

• Zhang, J., Zhu, G., Wan, L., Liang, Y., Liu, X., Yan, H., Zhang, B., & Yang, G. (2023). Effect of fecal microbiota transplantation in children with autism spectrum disorder: A systematic review. In Frontiers in Psychiatry (Vol. 14). https://doi.org/10.3389/fpsyt.2023.1123658

• Hassib, L., Kanashiro, A., Pedrazzi, J. F. C., Vercesi, B. F., Higa, S., Arruda, Í., Soares, Y., de Jesus de Souza, A., Barichello, T., Guimarães, F. S., & Ferreira, F. R. (2025). Microbiota-based therapies as novel targets for autism spectrum disorder: A systematic review and meta-analysis. In Progress in Neuro-Psychopharmacology and Biological Psychiatry(Vol. 139). https://doi.org/10.1016/j.pnpbp.2025.111385

• Yang, J., Fu, X., Liao, X., & Li, Y. (2020). Effects of gut microbial-based treatments on gut microbiota, behavioral symptoms, and gastrointestinal symptoms in children with autism spectrum disorder: A systematic review. In Psychiatry Research (Vol. 293). https://doi.org/10.1016/j.psychres.2020.113471

• Gao, X., Fu, N., Ben, Q., & Bu, X. (2025). A Meta-Analysis of the Effects of Gut Microbiota–Based Interventions on Gastrointestinal and Behavioral Symptoms in Children With Autism Spectrum Disorder. Nutrition Reviews. https://doi.org/10.1093/nutrit/nuaf050

• Maniscalco, I., Bartochowski, P., Priori, V., Iancau, S. P., de Francesco, M., Innamorati, M., Jagodzinska, N., Giupponi, G., Masucci, L., Conca, A., & Mroczek, M. (2025). The Effects of Fecal Microbial Transplantation on the Symptoms in Autism Spectrum Disorder, Gut Microbiota and Metabolites: A Scoping Review. In Microorganisms (Vol. 13, Issue 6). https://doi.org/10.3390/microorganisms13061290

Also known as myalgic encephalomyelitis (ME), this condition is characterised by profound, persistent fatigue that is not relieved by rest, along with post-exertional malaise, unrefreshing sleep, cognitive impairment (brain fog), and often pain or flu-like symptoms. Its presentation is heterogeneous and can fluctuate over time.

FMT may support a more balanced immune profile by reducing pro-inflammatory microbial signals and enhancing anti-inflammatory pathways. Changes in microbial metabolites could also influence energy regulation, mitochondrial function, and neuroimmune communication, potentially contributing to improvements in fatigue and cognitive symptoms.

Studies:

• Kenyon, J. N., Coe, S., & Izadi, H. (2019). A retrospective outcome study of 42 patients with Chronic Fatigue Syndrome, 30 of whom had Irritable Bowel Syndrome. Half were treated with oral approaches, and half were treated with Faecal Microbiome Transplantation. Human Microbiome Journal, 13. https://doi.org/10.1016/j.humic.2019.100061

• König, R. S., Albrich, W. C., Kahlert, C. R., Bahr, L. S., Löber, U., Vernazza, P., Scheibenbogen, C., & Forslund, S. K. (2022). The Gut Microbiome in Myalgic Encephalomyelitis (ME)/Chronic Fatigue Syndrome (CFS). In Frontiers in Immunology (Vol. 12). https://doi.org/10.3389/fimmu.2021.628741

• Xiong, R., Gunter, C., Fleming, E., Vernon, S. D., Bateman, L., Unutmaz, D., & Oh, J. (2023). Multi-‘omics of gut microbiome-host interactions in short- and long-term myalgic encephalomyelitis/chronic fatigue syndrome patients. Cell Host and Microbe, 31(2). https://doi.org/10.1016/j.chom.2023.01.001

• Salonen, T., Jokinen, E., Satokari, R., & Lahtinen, P. (2023). Randomized, double-blinded, placebo-controlled pilot study: efficacy of faecal microbiota transplantation on chronic fatigue syndrome. Journal of Translational Medicine, 21(1). https://doi.org/10.1186/s12967-023-04227-y

• Wang, J. H., Choi, Y., Lee, J. S., Hwang, S. J., Gu, J., & Son, C. G. (2024). Clinical evidence of the link between gut microbiome and myalgic encephalomyelitis/chronic fatigue syndrome: a retrospective review. In European Journal of Medical Research (Vol. 29, Issue 1). https://doi.org/10.1186/s40001-024-01747-1

This autoimmune disorder is characterised by progressive destruction of the thyroid gland, leading to reduced hormone production. Common features include fatigue, weight gain, cold intolerance, dry skin, hair thinning, and slowed metabolism, often alongside elevated anti-thyroid antibodies (e.g., anti-TPO).

Rebalancing the gut microbiome may help regulate systemic immune responses by promoting tolerance and reducing autoreactive activity. Improved gut barrier integrity can limit the translocation of inflammatory triggers, while microbial metabolites may influence endocrine and immune signalling pathways linked to thyroid function.

Studies:

• Abubakar, D., Abdullahi, H., & Ibrahim, I. (2025). Bridging Microbiomes: Exploring Oral and Gut Microbiomes in Autoimmune Thyroid Diseases- New Insights and Therapeutic Frontiers. Gut Microbes Reports, 2(1). https://doi.org/10.1080/29933935.2025.2452471

• Yan, K., Sun, X., Fan, C., Wang, X., & Yu, H. (2024). Unveiling the Role of Gut Microbiota and Metabolites in Autoimmune Thyroid Diseases: Emerging Perspectives. In International Journal of Molecular Sciences (Vol. 25, Issue 20). https://doi.org/10.3390/ijms252010918

• Seida, I., al Shawaf, M., & Mahroum, N. (2024). Fecal microbiota transplantation in autoimmune diseases – An extensive paper on a pathogenetic therapy. In Autoimmunity Reviews (Vol. 23, Issues 7–8). https://doi.org/10.1016/j.autrev.2024.103541

• Jiang, T., Yang, X., Wu, B., Tao, R., Chen, R., Jin, L., Sun, D., & Weng, H. (2025). Gut microbiota in hypothyroidism: pathogenic mechanisms and opportunities for precision microbiome interventions. In Frontiers in Microbiology (Vol. 16). https://doi.org/10.3389/fmicb.2025.1661211

Fibromyalgia is characterised by widespread musculoskeletal pain, tenderness, fatigue, sleep disturbances, and cognitive difficulties. It is associated with central sensitisation, where the nervous system amplifies pain signals, and is frequently accompanied by mood disturbances.

FMT may influence pain processing indirectly through changes in microbial-derived metabolites that interact with the nervous system. Reductions in low-grade inflammation and modulation of gut–brain signalling pathways could contribute to decreased pain sensitivity, improved sleep, and better overall symptom regulation.

Studies:

• Fang, H., Hou, Q., Zhang, W., Su, Z., Zhang, J., Li, J., Lin, J., Wang, Z., Yu, X., Yang, Y., Wang, Q., Li, X., Li, Y., Hu, L., Li, S., Wang, X., & Liao, L. (2024). Fecal Microbiota Transplantation Improves Clinical Symptoms of Fibromyalgia: An Open-Label, Randomized, Nonplacebo-Controlled Study. Journal of Pain, 25(9). https://doi.org/10.1016/j.jpain.2024.104535

• Cai, W., Haddad, M., Haddad, R., Kesten, I., Hoffman, T., Laan, R., Westfall, S., Defaye, M., Abdullah, N. S., Wong, C., Brown, N., Tansley, S., Lister, K. C., Hooshmandi, M., Wang, F., Lorenzo, L. E., Hovhannisyan, V., Ho-Tieng, D., Kumar, V., … Khoutorsky, A. (2025). The gut microbiota promotes pain in fibromyalgia. Neuron, 113(13). https://doi.org/10.1016/j.neuron.2025.03.032

• Lesmana, I., Qian, C., & Hsiao, E. Y. (2025). Fibromyalgia pain may have a gut solution. In Neuron (Vol. 113, Issue 13). https://doi.org/10.1016/j.neuron.2025.06.005

• Waterman, A., Doumas, S. A., Fischer, M., Mattar, M., Charbel, S., Jennings, J., & Doman, D. B. (2025). Uncovering the Hidden Link Between the Aberrant Intestinal Microbiome and Fibromyalgia. Gastroenterology and Hepatology, 21(2).
• Thurm, T., Ablin, J. N., Buskila, D., & Maharshak, N. (2017). Fecal Microbiota Transplantation for Fibromyalgia: A Case Report and Review of the Literature. Open Journal of Gastroenterology, 07(04). https://doi.org/10.4236/ojgas.2017.74015

MS is an autoimmune disorder of the central nervous system characterised by immune-mediated demyelination and neurodegeneration. It commonly presents with relapsing neurological symptoms such as visual disturbances, muscle weakness, impaired coordination, and sensory deficits, reflecting damage to nerve signalling pathways.

FMT is being explored for its capacity to reshape gut microbial communities that influence systemic immunity. By increasing populations of anti-inflammatory commensals, it may promote regulatory T-cell responses and reduce pro-inflammatory signalling, potentially dampening the autoimmune activity that drives myelin damage.

Studies:

• Role of Fecal Microbiota Transplant in the Reversal or Stabilization of Multiple Sclerosis Symptoms: A Literature Review on Efficacy and Safety. In Microorganisms (Vol. 11, Issue 12). https://doi.org/10.3390/microorganisms11122840

• Zhanel, G. G., Keynan, R., Keynan, Y., & Karlowsky, J. A. (2023). The role of Fecal Microbiota Transplantation (FMT) in treating patients with multiple sclerosis. In Expert Review of Neurotherapeutics (Vol. 23, Issue 10). https://doi.org/10.1080/14737175.2023.2250919

• Sanzone, J., Life, M., Reiss, D., May, D., Hartley, B., Spiddle, P., Al-Kirwi, J., Grigoryan, T., & Costin, J. (2024). Uses of Fecal Microbiota Transplantation in Neurodegenerative Disease: A Scoping Review. Cureus. https://doi.org/10.7759/cureus.62265

• Al, K. F., Craven, L. J., Gibbons, S., Parvathy, S. N., Wing, A. C., Graf, C., Parham, K. A., Kerfoot, S. M., Wilcox, H., Burton, J. P., Kremenchutzky, M., Morrow, S. A., Casserly, C., Meddings, J., Sharma, M., & Silverman, M. S. (2022). Fecal microbiota transplantation is safe and tolerable in patients with multiple sclerosis: A pilot randomized controlled trial. Multiple Sclerosis Journal – Experimental, Translational and Clinical, 8(2). https://doi.org/10.1177/20552173221086662

This neurodegenerative condition is defined by the progressive loss of dopaminergic neurons in the substantia nigra and the accumulation of α-synuclein aggregates. Clinically, it manifests with tremor, rigidity, bradykinesia, and postural instability, often preceded by gastrointestinal symptoms such as constipation.

Given the early involvement of the gut, FMT has been proposed as a way to alter the intestinal environment that may contribute to disease progression. Modifying the microbiome could influence neuroinflammatory pathways, reduce production of pro-inflammatory metabolites, and potentially interfere with the gut-origin hypothesis of α-synuclein propagation.

Studies:

• Bruggeman, A., Vandendriessche, C., Hamerlinck, H., de Looze, D., Tate, D. J., Vuylsteke, M., de Commer, L., Devolder, L., Raes, J., Verhasselt, B., Laukens, D., Vandenbroucke, R. E., & Santens, P. (2024). Safety and efficacy of faecal microbiota transplantation in patients with mild to moderate Parkinson’s disease (GUT-PARFECT): a double-blind, placebo-controlled, randomised, phase 2 trial. eClinicalMedicine, 71. https://doi.org/10.1016/j.eclinm.2024.102563
• Cheng, Y., Tan, G., Zhu, Q., Wang, C., Ruan, G., Ying, S., Qie, J., Hu, X., Xiao, Z., Xu, F., Chen, L., Chen, M., Pei, Y., Zhang, H., Tian, Y., Chen, D., Liu, X., Huang, H., & Wei, Y. (2023). Efficacy of fecal microbiota transplantation in patients with Parkinson’s disease: clinical trial results from a randomized, placebo-controlled design. Gut Microbes, 15(2). https://doi.org/10.1080/19490976.2023.2284247
• Xue, L. J., Yang, X. Z., Tong, Q., Shen, P., Ma, S. J., Wu, S. N., Zheng, J. L., Wang, H. G., & Zhu, Y. (2020). Fecal microbiota transplantation therapy for Parkinson’s disease: A preliminary study. Medicine (United States), 99(35). https://doi.org/10.1097/MD.0000000000022035

RA is a chronic systemic autoimmune disease characterised by persistent synovial inflammation, joint swelling, pain, and eventual joint destruction. It involves complex interactions between T cells, B cells, and pro-inflammatory cytokines, often accompanied by systemic features such as fatigue and cardiovascular risk.

Alterations in the gut microbiome, particularly the expansion of pro-inflammatory species—have been implicated in disease onset and progression. FMT may help restore microbial equilibrium, thereby reducing systemic inflammatory tone and modulating immune cell activity that contributes to joint pathology.

Studies:

• Lin, L., Zhang, K., Xiong, Q., Zhang, J., Cai, B., Huang, Z., Yang, B., Wei, B., Chen, J., & Niu, Q. (2023). Gut microbiota in pre-clinical rheumatoid arthritis: From pathogenesis to preventing progression. In Journal of Autoimmunity(Vol. 141). https://doi.org/10.1016/j.jaut.2023.103001

• Wen, Y., Li, M., Hao, Y., Peng, J., Wei, X., Zhang, Z., Liu, B., Wang, Y., Peng, T., & Ma, Y. (2025). HDAC/NF-κB signaling pathway mediates gut microbiota dysbiosis in rheumatoid arthritis: Intervention mechanisms of Fengshining decoction. Phytomedicine, 145. https://doi.org/10.1016/j.phymed.2025.156976

• Tong, Z. (2025). Multitargeted Regulation of Rheumatoid Arthritis by Gut Microbiota. Theoretical and Natural Science, 124(1). https://doi.org/10.54254/2753-8818/2025.au26103

• Zeng, J., Peng, L., Zheng, W., Huang, F., Zhang, N., Wu, D., & Yang, Y. (2021). Fecal microbiota transplantation for rheumatoid arthritis: A case report. Clinical Case Reports, 9(2). https://doi.org/10.1002/ccr3.3677

• Mahroum, N., Seida, R., & Shoenfeld, Y. (2023). Triggers and regulation: the gut microbiome in rheumatoid arthritis. Expert Review of Clinical Immunology, 19(12). https://doi.org/10.1080/1744666X.2023.2260103

Caused by infection with Borrelia burgdorferi, Lyme disease can affect multiple systems, presenting with symptoms like flu-like illness to neurological, cardiac, and musculoskeletal complications. A subset of individuals reports persistent symptoms even after antibiotic treatment.

While FMT does not target the underlying infection, it may have a role in addressing secondary effects of prolonged antibiotic use. By restoring microbial diversity and gut barrier function, it could help rebalance immune responses and reduce lingering inflammation associated with post-treatment syndromes.

Studies:

• Napier, E. G., Cinco, I. R., Wagner, S. B., Stuart, E. v., Qiao, Q., Taylor, J., Stevenson, B., & Messaoudi, I. (2025). Borreliosis and doxycycline treatment disrupt gut microbiota and immune responses in nonhuman primates. mBio, 16(8). https://doi.org/10.1128/mbio.01437-25

• Morrissette, M., Pitt, N., González, A., Strandwitz, P., Caboni, M., Rebman, A. W., Knight, R., D’onofrio, A., Aucott, J. N., Soloski, M. J., & Lewis, K. (2020). A distinct microbiome signature in posttreatment lyme disease patients. mBio, 11(5). https://doi.org/10.1128/mBio.02310-20

Long Covid refers to a constellation of persistent symptoms following infection with SARS-CoV-2, including fatigue, cognitive dysfunction (brain fog), shortness of breath, dysautonomia, and chronic inflammation. The condition is heterogeneous, with proposed mechanisms spanning immune dysregulation, viral persistence, endothelial dysfunction, and metabolic disturbance.

Emerging evidence points to significant alterations in the gut microbiome, including reduced diversity and depletion of beneficial commensal species. FMT has therefore been hypothesised as a therapeutic approach to restore microbial balance, enhance production of anti-inflammatory metabolites, and recalibrate immune and gut–brain axis signalling, which may collectively contribute to symptom improvement.

Studies:

• Lau, R. I., Su, Q., Ching, J. Y. L., Lui, R. N., Chan, T. T., Wong, M. T. L., Lau, L. H. S., Wing, Y. K., Chan, R. N. Y., Kwok, H. Y. H., Ho, A. H. Y., Tse, Y. K., Cheung, C. P., Li, M. K. T., Siu, W. Y., Liu, C., Lu, W., Wang, Y., Chiu, E. O. L., … Ng, S. C. (2024). Fecal Microbiota Transplantation for Sleep Disturbance in Post-acute COVID-19 Syndrome. Clinical Gastroenterology and Hepatology, 22(12). https://doi.org/10.1016/j.cgh.2024.06.004

• Lau, R. I., Su, Q., & Ng, S. C. (2025). Long COVID and gut microbiome: insights into pathogenesis and therapeutics. In Gut Microbes (Vol. 17, Issue 1). https://doi.org/10.1080/19490976.2025.2457495

• Mendes de Almeida, V., Engel, D. F., Ricci, M. F., Cruz, C. S., Lopes, Í. S., Alves, D. A., d’ Auriol, M., Magalhães, J., Machado, E. C., Rocha, V. M., Carvalho, T. G., Lacerda, L. S. B., Pimenta, J. C., Aganetti, M., Zuccoli, G. S., Smith, B. J., Carregari, V. C., da Silva Rosa, E., Galvão, I., … Vieira, A. T. (2023). Gut microbiota from patients with COVID-19 cause alterations in mice that resemble post-COVID symptoms. Gut Microbes, 15(2). https://doi.org/10.1080/19490976.2023.2249146

• Yousef, M., Rob, M., Varghese, S., Rao, S., Zamir, F., Paul, P., & Chaari, A. (2024). The effect of microbiome therapy on COVID-19-induced gut dysbiosis: A narrative and systematic review. In Life Sciences (Vol. 342). https://doi.org/10.1016/j.lfs.2024.122535

• Jiang, X., Gao, X., Ding, J., Pang, B., Pei, Y., Zhao, Z., Zhao, N., Wang, Z., Chen, C., Gao, D., Yan, F., Wang, F., Liu, C., Zhang, Z., Li, Z., & Zhao, Z. (2024). Fecal microbiota transplantation alleviates mild-moderate COVID-19 associated diarrhoea and depression symptoms: A prospective study of a randomized, double-blind clinical trial. Journal of Medical Virology, 96(8). https://doi.org/10.1002/jmv.29812