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Lactobacillus acidophilus

Lactobacillus acidophilus is one of the most commonly used probiotic species, found naturally in the human GI tract and vagina, and in fermented foods like yogurt. Research supports its use as an adjuvant treatment for diarrhea, including antibiotic-associated diarrhea. Also studied for vaginal health, cholesterol, and immune function. Generally safe and well-tolerated. NO GRADED OUTCOMES but substantial overall research. Effects are strain-dependent - different L. acidophilus strains may have different properties. One of the most accessible and well-established probiotic options.

Quick Answer

What it is

Lactobacillus acidophilus is one of the most commonly used probiotic species, found naturally in the human GI tract and vagina, and in fermented foods like yogurt. Research supports its use as an adjuvant treatment for diarrhea, including antibiotic-associated diarrhea.

Key findings

  • Grade B: Acute Diarrhea Symptoms
  • Grade B: Antibiotic-Associated Diarrhea Risk
  • Grade B: Atopic Dermatitis Symptoms

Safety

  • In vitro studies show interaction with intestinal epithelial M cells and modulation of immunomodulatory activity, supporting a plausible mechanism for immune enhancement.
ℹ️ Quick Facts: Lactobacillus acidophilus

Quick Facts: Lactobacillus acidophilus

  • Best Evidence:Grade B
  • Conditions Studied:7
  • Research Outcomes:12
  • Grade B Findings:3
  • Key Effect:Acute Gastroenteritis
Outcomes by grade:
A0
B3
C5
D4
7 conditions · 12 outcomes

Detailed Outcomes

Grade:
Effect:
Size:
Sort:
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B
Acute Diarrhea Symptoms
Multiple human trials support L. acidophilus for treatment of acute diarrhea. An RCT in children hospitalized with acute diarrhea found that an L. acidophilus mixture reduced symptom duration and severity. The overall evidence for diarrhea treatment is described as reasonably good across multiple clinical studies.
moderate↓Improves
B
Antibiotic-Associated Diarrhea Risk
Multiple human trials demonstrate L. acidophilus, often in combination with other Lactobacillus strains, reduces the incidence of antibiotic-associated diarrhea. A systematic assessment of evidence for a specific probiotic combining L. acidophilus, L. casei, and L. rhamnosus supported primary prevention of C. difficile-associated diarrhea in antibiotic users.
moderate↓Improves
B
Atopic Dermatitis Symptoms
Three clinical trials using the L. acidophilus L-92 strain demonstrated improvements in atopic dermatitis symptoms. A double-blind RCT in Japanese adults and a pediatric study both showed reductions in dermatitis severity scores and serum cytokine markers. A third trial demonstrated efficacy with prolonged ingestion of L-92 in adult patients.
small↓Improves
C
Intestinal Inflammation
Multiple animal studies show L. acidophilus attenuates intestinal inflammation. It reduced Salmonella-induced intestinal inflammation via TGF-β signaling and alleviated goblet cell loss and colitis through Notch pathway modulation in rodent models. L. acidophilus XY27 also showed preventive effects against DSS-induced ulcerative colitis in mice.
moderate↓Improves
C
Immune Function
Animal studies demonstrate L. acidophilus enhances immune function, including improved immune response to Newcastle disease vaccination in chickens and enhanced skin mucosal immune parameters in fish models. In vitro studies show interaction with intestinal epithelial M cells and modulation of immunomodulatory activity, supporting a plausible mechanism for immune enhancement.
small↑Improves
D
Pathogen Virulence Inhibition
In vitro studies show L. acidophilus attenuates toxin production by Vibrio cholerae and Shigella dysenteriae following intestinal epithelial cell infection. Preclinical data also demonstrate modulation of C. difficile virulence. These findings support antimicrobial mechanisms but lack human clinical validation.
moderate↓Worsens
D
Urinary Oxalate Levels
A randomized, placebo-controlled, double-blind trial evaluated a probiotic containing L. acidophilus and Bifidobacterium animalis lactis on urine oxalate in calcium stone formers with hyperoxaluria. The combination product showed some effect on oxalate excretion, supported by in vitro oxalate degradation data.
small↓Worsens
D
Infantile Colic Symptoms
An open randomized controlled trial found that a combination of Matricariae chamomilla, Melissa officinalis, and tyndallized L. acidophilus (HA122) was effective in reducing infantile colic symptoms. However, this was an open-label design with a multi-component intervention, limiting conclusions about L. acidophilus alone.
small↓Improves
C
C. difficile Infection Risk
A review of clinical evidence assessed the use of a specific probiotic combining L. acidophilus with L. casei and L. rhamnosus for primary prevention of C. difficile infections, finding supportive evidence. Preclinical work showed L. acidophilus modulates the virulence of C. difficile in vitro, providing mechanistic support.
moderate↓Improves
C
Cholesterol Levels
In dyslipidemic rat models, L. acidophilus supplementation demonstrated potential benefits on lipid profiles. Limited human evidence suggests possible modest cholesterol-lowering effects, though effect sizes are small. The mechanism may involve bile salt hydrolase activity and cholesterol assimilation by the probiotic.
small↓Improves
C
Vaginal Health
L. acidophilus is a natural constituent of vaginal flora and has moderate evidence supporting its use for vaginal health. Studies confirm mother-to-child transmission of L. acidophilus at delivery. Clinical use for bacterial vaginosis prevention is supported by its colonization capacity, though large RCTs specific to L. acidophilus alone are limited.
small↑Improves
D
Osteoarthritis Pain and Cartilage Degradation
A single animal study found that L. acidophilus ameliorated pain and cartilage degradation in an experimental osteoarthritis model, suggesting potential anti-inflammatory effects on joint tissue. No human clinical trials have been reported for this indication.
moderate↓Improves

Research Citations (20)

Potential benefits of L. acidophilus in dyslipidemic rats
(2021)
PMID: 33731756
Effect of a Probiotic Supplement Containing Lactobacillus Acidophilus and Bifidobacterium Animalis Lactis on Urine Oxalate in Calcium Stone Formers with Hyperoxaluria: A Randomized, Placebo-controlled, Double-blind and In-vitro Trial
(2021)
PMID: 34129232
Preventive Effect of Lactobacillus acidophilus XY27 on DSS-Induced Ulcerative Colitis in Mice
(2020)
PMID: 33376308
Immune enhancing effects of Lactobacillus acidophilus on Newcastle disease vaccination in chickens
(2020)
PMID: 32721773
Lactobacillus acidophilus attenuates toxin production by Vibrio cholerae and shigella dysenteriae following intestinal epithelial cells infection
(2020)
PMID: 33010360
Primary prevention of Clostridium difficile infections with a specific probiotic combining Lactobacillus acidophilus, L. casei, and L. rhamnosus strains: assessing the evidence
(2018)
PMID: 29702133
Lactobacillus acidophilus Alleviated Salmonella-Induced Goblet Cells Loss and Colitis by Notch Pathway
(2018)
PMID: 30198100
Lactobacillus acidophilus ameliorates pain and cartilage degradation in experimental osteoarthritis
(2018)
PMID: 30003932
Efficacy of a standardized extract of Matricariae chamomilla L., Melissa officinalis L. and tyndallized Lactobacillus acidophilus (HA122) in infantile colic: An open randomized controlled trial
(2017)
PMID: 28665038
Uromodulin-SlpA binding dictates Lactobacillus acidophilus uptake by intestinal epithelial M cells
(2017)
PMID: 28992252

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