SUMMARY: Recent advances in therapeutic probiotics have shown promising results across various health conditions, reflecting a growing understanding of the human microbiome’s role in health and disease. However, comprehensive reviews integrating the diverse therapeutic effects of probiotics in human subjects have been limited. By analyzing randomized controlled trials (RCTs) and meta-analyses, this review provides a comprehensive overview of key developments in probiotic interventions targeting gut, liver, skin, vaginal, mental, and oral health. Emerging evidence supports the efficacy of specific probiotic strains and combinations in treating a wide range of disorders, from gastrointestinal (GI) and liver diseases to dermatological conditions, bacterial vaginosis, mental disorders, and oral diseases. We discuss the expanding understanding of microbiome-organ connections underlying probiotic mechanisms of action. While many clinical trials demonstrate significant benefits, we acknowledge areas requiring further large-scale studies to establish definitive efficacy and optimal treatment protocols. The review addresses challenges in standardizing probiotic research methodologies and emphasizes the importance of considering individual variations in microbiome composition and host genetics. Additionally, we explore emerging concepts such as the oral-gut-brain axis and future directions, including high-resolution microbiome profiling, host-microbe interaction studies, organoid models, and artificial intelligence applications in probiotic research. Overall, this review offers a comprehensive update on the current state of therapeutic probiotics across multiple domains of human health, providing insights into future directions and the potential for probiotics to revolutionize preventive and therapeutic medicine.

The oral cavity is the gateway for microorganisms into your body where they disseminate not only to the directly connected respiratory and digestive tracts but also to the many remote organs. Oral microbiota, travelling to the end of the intestine and circulating in our bodies through blood vessels, not only affect a gut microbiome profile but also lead to many systemic diseases. By gathering information accumulated from the era of focal infection theory to the age of revolution in microbiome research, we propose a pivotal role of “leaky gum”, as an analogy of “leaky gut”, to underscore the importance of the oral cavity in systemic health. The oral cavity has unique structures, the gingival sulcus (GS) and the junctional epithelium (JE) below the GS, which are rarely found anywhere else in our body. The JE is attached to the tooth enamel and cementum by hemidesmosome (HD), which is structurally weaker than desmosome and is, thus, vulnerable to microbial infiltration. In the GS, microbial biofilms can build up for life, unlike the biofilms on the skin and intestinal mucosa that fall off by the natural process. Thus, we emphasize that the GS and the JE are the weakest leaky point for microbes to invade the human body, making the leaky gum just as important as, or even more important than, the leaky gut.

Hwang J, et al. J Periodontal Implant Sci. 2024 Jul;54:e17. https://doi.org/10.5051/jpis.2304520226

Objectives: Probiotic supplementation, integrated into routine oral care, may improve periodontal status and metabolic function. In this retrospective longitudinal study, we evaluated the efficacy of probiotics added to non-surgical periodontal treatment (NSPT) in reducing the burden of oral pathogens and improving metabolic dysfunction. Methods: Twenty outpatients with chronic periodontitis and at least one metabolic abnormality underwent NSPT with daily probiotic supplementation for 12 weeks. Baseline and post-intervention assessments included clinical indices, blood pressure, and blood biomarkers (HbA1c, fasting glucose, and lipid profiles), with analysis of oral pathogens using qPCR. Results: Among the 13 eligible participants, probiotics with NSPT resulted in significant reductions in HbA1c (-0.3%, p<0.001), and systolic blood pressure (-9.6 mmHg, p<0.001), and Tannerella forsythia (p<0.05) levels, along with decreasing trends in other pathogens. However, no significant changes were noted in periodontal indices, including probing pocket depth and bleeding on probing, nor in lipid profiles. Conclusions: These f indings suggest that probiotic supplementation with NSPT may improve glycemic control and systolic blood pressure but may have a limited effect on periodontal indices, warranting larger trials to confirm its potential.

Objectives: This case study aimed to evaluate changes in periodontal pathogens and systemic disease indicators following the adjunctive use of probiotics for periodontal treatment. Methods: Two adults, a 64-year-old male and 71-year-old female, were selected with ethical approval and underwent comprehensive oral and systemic health assessments before and after probiotic intake with periodontal debridement. Results: There was a significant reduction in the periodontal pathogens, particularly Porphyromonas gingivalis and Treponema forsythia, and no adverse systemic indicators were observed. Moreover, a trend toward improved lipid profiles was noted, suggesting a potential positive impact on systemic health. Conclusions: This study shows the potential role of probiotics in enhancing oral health and preventing systemic diseases, thus highlighting the need for further research and clinical trials.