What This Strain Does
Lactobacillus gasseri has emerged as one of the most intriguing probiotic strains in recent years, particularly for its associations with weight management and metabolic health. Named after French microbiologist Francois Gasser, this bacterium is a natural inhabitant of the human gastrointestinal tract and is one of the dominant Lactobacillus species in healthy individuals. It’s also commonly found in the vaginal tract, where it plays an important role in maintaining healthy microbial balance.
What makes L. gasseri particularly interesting is its apparent ability to influence fat metabolism and body composition. Unlike many probiotic strains that primarily affect digestive function, L. gasseri appears to work through mechanisms that affect how the body stores and utilizes fat. Research suggests it may reduce dietary fat absorption in the intestines, increase fat oxidation, and influence hormones involved in appetite regulation and metabolism.
In the gastrointestinal tract, L. gasseri produces lactic acid that helps maintain optimal pH levels and creates conditions unfavorable for pathogenic bacteria. It also produces bacteriocins, natural antimicrobial compounds that directly inhibit harmful microorganisms. The strain demonstrates good survival through stomach acid and can effectively colonize the intestinal mucosa.
L. gasseri’s role in vaginal health is well-established. As one of the predominant Lactobacillus species in the healthy vaginal microbiome, it produces lactic acid and hydrogen peroxide that maintain the acidic environment essential for preventing bacterial vaginosis, yeast infections, and urinary tract infections. Women with healthy vaginal flora typically have higher levels of L. gasseri compared to those with dysbiosis.
Emerging research also suggests potential benefits for acid reflux and digestive comfort. L. gasseri may help reduce symptoms of gastroesophageal reflux disease through mechanisms that aren’t yet fully understood but may involve modulation of gut motility and inflammation.
Research Highlights
L. gasseri has accumulated particularly notable research for weight management and metabolic health, distinguishing it from most other probiotic strains.
A landmark study published in the European Journal of Clinical Nutrition in 2010 examined L. gasseri SBT2055 in Japanese adults with significant visceral fat. After twelve weeks of daily consumption, participants experienced a significant reduction in abdominal visceral fat, subcutaneous fat, body weight, and waist circumference compared to placebo. Importantly, these effects diminished after supplementation stopped, suggesting the probiotic needed to be taken continuously for ongoing benefits.
Follow-up research published in the British Journal of Nutrition confirmed these findings and explored potential mechanisms. The study found that L. gasseri SBT2055 reduced dietary fat absorption by increasing fat excretion in feces, suggesting it may partially block the absorption of calories from dietary fat.
A 2015 study in Beneficial Microbes examined L. gasseri BNR17 for its effects on body composition in overweight adults. After twelve weeks, participants showed reductions in visceral fat area and improvements in waist and hip circumference, with the benefits most pronounced in those who were most overweight at baseline.
For vaginal health, research published in the Journal of Clinical Microbiology demonstrated that L. gasseri is one of the key species associated with healthy vaginal microbiota. Studies show that vaginal application of L. gasseri can help restore normal flora in women with bacterial vaginosis and reduce recurrence rates of vaginal infections.
Research in Digestive Diseases and Sciences found that certain L. gasseri strains may help reduce symptoms of functional dyspepsia, including bloating, fullness, and epigastric discomfort. The improvements were associated with reduced inflammation and potentially accelerated gastric emptying.
Specific Strains to Look For
Several L. gasseri strains have been specifically researched and are available in commercial products.
L. gasseri SBT2055 (often called LG2055) is the most researched strain for weight management and metabolic health. Developed in Japan, this strain has accumulated the strongest evidence for reducing visceral fat and body weight. It’s the active ingredient in several Japanese functional foods and is increasingly available in international markets as consumer interest grows.
L. gasseri BNR17 is another strain studied specifically for its effects on body composition. Research shows it may help reduce fat accumulation and support healthy weight management, particularly in overweight individuals. This strain originated from Korean research and is available in some specialty supplements.
L. gasseri PA 16/8 has been studied in combination with other strains as part of multi-species probiotics targeting metabolic health. While less data exists for this strain alone, it contributes to formulations with documented metabolic benefits.
L. gasseri KS-13 has been specifically researched for gut health and symptom relief in functional digestive disorders. Studies show potential benefits for reducing digestive discomfort and improving overall gut function.
For vaginal health applications, L. gasseri strains are often combined with other vaginal Lactobacillus species like L. crispatus and L. rhamnosus in formulations designed to restore healthy vaginal flora.
What to Look For in Products
Selecting an effective L. gasseri product requires attention to strain specificity, dosage, and formulation quality.
For weight management applications, the most researched doses fall in the range of 10 billion CFU daily, typically taken once per day. The landmark studies on L. gasseri SBT2055 used this dose level and demonstrated significant effects on visceral fat reduction.
Strain identification is particularly important for L. gasseri products. The weight management research has been conducted on specific strains like SBT2055, and these benefits shouldn’t be assumed for unspecified L. gasseri products. Look for products that clearly identify which strain they contain.
Delivery format may influence effectiveness. The original Japanese research used fermented milk products, though capsule formulations with verified viability should also be effective. Some products offer targeted-release capsules designed to protect bacteria through stomach acid.
For vaginal health, L. gasseri is often most effective as part of multi-species formulations combining several vaginal Lactobacillus species. Both oral supplements and vaginal suppositories are available, with some evidence suggesting direct vaginal application may provide faster results for active infections.
Third-party testing verification from organizations like USP, NSF, or ConsumerLab provides assurance of potency and purity. Given the specific research linking particular strains to weight management benefits, identity verification through genetic testing is particularly valuable.
Potential Side Effects
L. gasseri has demonstrated good safety in clinical trials and is classified as GRAS (Generally Recognized as Safe) for food applications.
Initial supplementation may cause temporary mild gas, bloating, or digestive changes as the gut microbiome adjusts to the new bacterial population. These symptoms typically resolve within the first one to two weeks and can be minimized by starting with a lower dose.
Those who are severely immunocompromised, have central venous catheters, or are critically ill should consult healthcare providers before using L. gasseri or any probiotic due to theoretical infection risks in these vulnerable populations.
Individuals with dairy allergies should check product formulations, as some L. gasseri products, particularly fermented milk drinks, contain dairy. Capsule formulations are typically dairy-free but may contain trace amounts depending on the culture medium used.
The weight loss effects, while modest in clinical studies, are real and should be considered by individuals who are already underweight or have eating disorders. The strain may not be appropriate for those who need to maintain or gain weight.
L. gasseri appears to be a low histamine-producing strain, making it generally suitable for those with histamine sensitivity who need to avoid certain other probiotic strains.
How to Take
L. gasseri can be taken with or without food. The Japanese studies showing weight management benefits used consumption with breakfast, which may be a reasonable approach for those seeking metabolic effects.
For weight management, consistency appears to be essential. The research showing reductions in visceral fat used twelve weeks of daily supplementation, and benefits diminished after stopping. This suggests L. gasseri should be taken continuously for ongoing effects rather than as a short-term intervention.
For vaginal health, oral supplementation taken daily can help maintain healthy vaginal flora over time. During active vaginal infections, direct vaginal application of appropriate L. gasseri formulations may provide faster relief, though oral supplementation supports long-term maintenance.
When taking L. gasseri during antibiotic treatment, separate doses by at least two hours to prevent the antibiotic from killing the probiotic bacteria. This is particularly important for those taking antibiotics that commonly disrupt vaginal flora.
Benefits for weight management typically become measurable after eight to twelve weeks of consistent use. Some digestive benefits may appear sooner, within two to four weeks, though individual responses vary.
Key Takeaways
L. gasseri stands out among probiotic strains for its unique associations with weight management and reduction of visceral belly fat.
The strain L. gasseri SBT2055 has the strongest research support for metabolic benefits, with studies showing reduced body weight, waist circumference, and abdominal fat.
Research suggests L. gasseri may reduce dietary fat absorption, partially blocking calories from fat that would otherwise be stored.
For vaginal health, L. gasseri is one of the dominant beneficial species and helps maintain the acidic environment that prevents infections.
Weight management benefits require consistent daily use, with effects diminishing after supplementation stops, indicating ongoing use is needed for sustained results.
Look specifically for researched strains like SBT2055 or BNR17 rather than generic L. gasseri for metabolic applications, as benefits are strain-specific.