This article presents the latest science-based research on the microbiome and illustrates how the use of probiotics is transforming patient care.
Humans are a dynamic ecosystem, formed by trillions of microbes, such as bacteria, fungi and viruses, that comprise the microbiome. When discussing the microbiome with patients, I often describe it as a vast ocean, teeming with life. Ideally, this ocean contains thriving microbial communities that perform essential duties: breaking down food, producing beneficial nutrients and metabolites, keeping undesirable pathogens in check and promoting immune tolerance.
Unfortunately, this vital ecosystem faces constant challenges from our modern lifestyle; ultra-processed foods, microplastics, chronic stress and frequent antibiotic use all contribute to dysbiosis, or a state of microbial imbalance that can adversely affect our health.1
A unique microbial fingerprint
The microbiome is remarkably individualized, like a fingerprint, completely unique from person to person. Even identical twins may only share up to 50% of their microbiome composition, highlighting the impact that environmental factors can have.2 Despite this tremendous variance, the majority of healthy adult microbiomes share a common theme. About 80% of the gut bacterial species belong to three dominant phyla: Bacteroidetes, Firmicutes (which include Lactobacillus species) and Actinobacteria (which include Bifidobacterium species).3
An expansion of awareness and applications
As the awareness of the microbiome continues to grow, so do the scientifically-validated applications of probiotics. When searching “probiotics” on PubMed.gov, there were a mere 13 studies published in 1994. Fast forward 30 years later and there were more than 7,000 studies published in 2024 alone; a remarkable 500-fold increase in probiotic research. We are now beginning to see the true potential of probiotics and their therapeutic uses across numerous acute and chronic conditions.
Gastrointestinal benefits: Where it all began
Probiotics are perhaps best known for their digestive benefits. Most of the early research on probiotics focused on conditions, such as irritable bowel syndrome (IBS) and its accompanying symptoms of diarrhea, constipation, bloating and abdominal pain. In a study involving people with IBS-D (diarrhea predominant), lower amounts of Lactobacillus spp. were found in fecal samples and colonic biopsies compared to healthy controls.4
In a randomized, double-blind, placebo-controlled trial, a probiotic blend (including Bifidobacterium spp. and Lactobacillus spp.) administered twice daily for one month significantly relieved IBS symptoms in almost 70% of the participants versus only 37.5% of the placebo group. Improvements in abdominal discomfort and bloating were noted only in the probiotic group.5
Beyond digestion: Probiotics and chronic inflammation
Research has discovered probiotics can exert benefits far beyond the gut by helping alleviate chronic, low-grade inflammation. Dysbiosis, or a state of imbalance in the microbiome, is a key driver of this inflammation. Adverse changes from dysbiosis include an increase in intestinal permeability (leaky gut) and subsequent activation of the immune system, which ramps up pro-inflammatory cytokine production.6 With chronic inflammation underpinning virtually every chronic disease, using probiotics to address this root cause can be part of the solution to many health problems.
Emerging frontier: Gut-joint axis
A novel area of probiotic research is focusing on the gut-joint axis. The hallmark of many joint diseases is chronic, low-grade inflammation, which may be driven by dysbiosis. With more than 70% of adults over the age of 55 being impacted by osteoarthritis, there is a pressing need for safe and effective treatments.7 Could probiotics be part of this treatment strategy?
Recent animal studies showing promising results
In a 2021 model of osteoarthritis, oral administration of Lactobacillus rhamnosus reduced pro-inflammatory compounds, such as interleukin-1β (IL-1β) and lipopolysaccharide (LPS), along with reducing pain scores and markers of intestinal damage. When human chondrocytes were treated with L. rhamnosus, anti-inflammatory actions were observed, including upregulation of protective interleukin-10 (IL-10) and decreases in harmful matrix metalloproteinases (MMPs).8
In another study, the probiotic L. plantarum was used in an animal model of surgically-induced osteoarthritis (OA). Six weeks of treatment improved bone structure, protected cartilage from damage and reduced synovial inflammation. Additionally, probiotic treatment reduced pro-inflammatory cytokines, such as IL-1β and TNF-α, which are known contributors to pain hypersensitivity.9
There’s even some preliminary research on probiotics alleviating postsurgical pain and visceral pain.10 Because this is such a new area of research, much of the research remains pre-clinical. At the time of writing this article, fewer than 100 publications contained the term “gut-joint axis.” However, these promising results suggest human clinical applications may soon follow.11
LPS and joint health
LPS (lipopolysaccharide) is an endotoxin found in the outer membrane of many gram-negative pathogens. Higher levels of circulating LPS are common in states of dysbiosis and chronic inflammatory conditions. As an activator of the immune system, LPS has been implicated in the pathogenesis and severity of osteoarthritis (OA). Researchers have found increased levels of LPS in the synovial fluid is positively associated with severity of knee osteophytes, joint space narrowing and overall pain scores in knee OA.12,13
Restoring balance with probiotics
We need to be vigilant about protecting and nourishing the microbiome. We may not be able to control how our microbiome originally developed; method of birth (vaginal or Caesarean section), whether we were breastfed and for how long, antibiotic usage during childhood, exposure to nature as children and our household environment; we can do our best to help our patients (and ourselves) optimize the microbiome moving forward.
When considering probiotic supplementation, certain key species have demonstrated particular benefit. I often recommend human strain probiotics, such as Lactobacillus plantarum, Lactobacillus rhamnosus and Bifidobacterium bifidum, to help restore balance.
Lactobacillus species are bacteria that make lactic acid and are found throughout the body in the oral cavity, gastrointestinal tract and female reproductive tract.14 Bifidobacterium species are among the first probiotics that colonize the gastrointestinal tract, partly because they help break down monosaccharides, such as those found in breast milk.15
Both Lactobacillus and Bifidobacterium produce short-chain fatty acids that play crucial roles in immune function, reducing inflammation, promoting intestinal tight junction integrity and protecting against pathogenic bacteria.
A safe and effective combination
When recommending a probiotic supplement, I look for specific characteristics that Lactobacillus plantarum, Lactobacillus rhamnosus and Bifidobacterium bifidum fulfill:
- Well-researched: As noted above, these strains have robust research verifying their uses for gastrointestinal issues, joint conditions, mood disorders and more.
- Dairy-free: These probiotics can be cultured on a non-dairy medium, making them suitable for vegans and people with dairy sensitivities.
- Human strain: These bacteria are native to the human digestive system and therefore can survive the digestive processes and implant in the intestinal tract.
- Shelf-stable: Being able to store probiotics with other supplements usually translates to a higher adherence. Personally, if I have to keep a supplement in the refrigerator, there’s about a 99% chance I’ll forget to take it; many of my patients share this sentiment.
- Potency at time of use: Quality probiotics are guaranteed to contain their stated potency of live, colony forming units (CFUs) at the time of use, not just at manufacture.
- Appropriate dosage: One capsule daily delivering 20 billion CFUs is generally sufficient. While there may be applications that call for higher doses, I find that 20 billion CFUs provides an excellent daily maintenance dose for most patients.
- Prebiotic inclusion: Formulations containing fructooligosaccharides (FOS) provide a food source for the probiotics themselves, which can enhance their effectiveness.
Final thoughts
As research continues to expand, the therapeutic applications of these magnificent microbes will only become more pronounced and offer new insights into supporting patients with acute and chronic health conditions.
Lexi Loch, ND, received her Doctorate in Naturopathic Medicine from the National University of Natural Medicine, where she graduated with highest honors. In addition to her practice, she is a medical writer and editor, researcher, educator and patient advocate. Her articles have been published in various natural health periodicals and reference books. Prior to her education as a physician, Loch worked in veterinary medicine as a certified veterinary technician. She is also an accomplished athlete, playing collegiate volleyball and participating in overseas tournaments, an avid snowboarder and has been world ranked in downhill longboarding. Loch is a member of the Scientific Affairs and Education team for EuroMedica.
References
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