We use essential cookies (authentication, your saved goals/stack) by default. With your permission we’ll also enable privacy-respecting analytics (Vercel Web Analytics, anonymous load-time metrics) and error-replay diagnostics (Sentry — DOM snapshots only when an error fires) so we can fix bugs faster. Learn more about cookies
Lai5.0
L. acidophilus Research
Too few graded studies
10 peer-reviewed studies
What the evidence says
Too few graded studies
L. acidophilus doesn't have enough studies with structured effect-size data yet to pool a verdict. Browse the studies below for individual findings.
Most evidence is from high-quality randomised trials published 1999–2026 with a typical study size of 2,981 participants.
Based on 10 studies · 4 RCTs · 3,311 total participants
Confidence
Moderate confidence
By outcome
Safety profile
Too few graded studies3 studies
Digestive healthIn single randomised trials of the DDS-1 strain, abdominal pain in IBS fell by about 2.6 points on a 0-10 scale versus placebo, and lactose-intolerance symptoms during a lactose challenge were lower than on placebo · 4 to 6 weeks in the trials
Too few graded studies2 studies
Immune support
Too few graded studies1 study
Pain & analgesia
Too few graded studies1 study
Active research area
5 studies in the last 5 years
199920122026
1RCTCited 262×n=2,981 · very large study2013
In plain English: We identified no evidence that a multistrain preparation of lactobacilli and bifidobacteria was effective in prevention of AAD or CDD.
Allen SJ et al. · Lancet (2013)
Randomised, double-blind, placebo-controlled multicentre trial in 2,981 inpatients aged 65 and over taking antibiotics, given a multistrain preparation of lactobacilli and bifidobacteria (6 × 10^10 organisms per day for 21 days) or placebo
Antibiotic-associated diarrhoea occurred in 159 of 1470 (10.8%) on the probiotic versus 153 of 1471 (10.4%) on placebo, relative risk 1.04 (95% CI 0.84 to 1.28), p = 0.71
C. difficile diarrhoea was uncommon: 12 (0.8%) versus 17 (1.2%), relative risk 0.71 (95% CI 0.34 to 1.47), p = 0.35, not significant
In plain English: The report concludes that 'the current literature is not well equipped to answer questions on the safety of probiotic interventions with confidence', while finding no statistically significant increase in adverse events in randomised trials (RR 1.00; 95% CI 0.93 to 1.07).
AHRQ Evidence Report / Technology Assessment No. 200 — the authoritative safety synthesis for probiotics as a class
Randomised trials showed no statistically significant increase in the relative risk of experienced adverse events: RR 1.00 (95% CI 0.93 to 1.07), p=0.999
Case studies described fungaemia and some bacteraemia potentially associated with administered probiotic organisms, and suggested participants with compromised health are most likely to experience adverse events
3CrossoverCited 52×2016
In plain English: Longitudinal comparison between the DDS-1 group and placebo group demonstrated statistically significant reductions in abdominal symptom scores during the 6-h Lactose Challenge at week 4 for diarrhea (p = 0.033), abdominal cramping (p = 0.012), vomiting (p = 0.0002), and overall symptom score (p = 0.037).
Pakdaman MN et al. · Nutr J (2016)
Randomised, double-blind, placebo-controlled crossover trial in adults with self-reported lactose intolerance confirmed by a lactose challenge: 4 weeks of DDS-1 or maltodextrin placebo once daily, with a 2-week washout
Single named strain, DDS-1, rather than a blend
At week 4, DDS-1 reduced diarrhoea (p = 0.033), abdominal cramping (p = 0.012), vomiting (p = 0.0002) and overall symptom scores (p = 0.037) during a 6-hour lactose challenge compared with placebo
In plain English: In conclusion, L. acidophilus DDS-1 and B. lactis UABla-12 improved abdominal pain and symptom severity scores with a corresponding normalization of bowel habits in adults with IBS.
Martoni CJ et al. · Nutrients (2020)
Randomised, double-blind, placebo-controlled multicentre trial in 330 adults with IBS (Rome IV), allocated 1:1:1 to placebo, L. acidophilus DDS-1 alone or B. lactis UABla-12 alone, each at 1 × 10^10 CFU/day for six weeks
Because each strain had its own arm, the DDS-1 result is for L. acidophilus alone
Abdominal pain severity (APS-NRS, primary outcome) improved versus placebo with DDS-1: -2.59 ± 2.07, p = 0.001, with 52.3% significant responders (p < 0.001)
In plain English: Its ability to synergize with conventional therapies (chemotherapy, oncolytic virotherapy) and its innovative applications in the creation of postbiotics and paraprobiotics may provide a new approach to the treatment of inflammatory, allergic, and neoplastic diseases.
Olędzki R, Kerner K. · Biomolecules (2026)
L. acidophilus is a universal mediator of immunological and metabolic homeostasis.
Its ability to synergize with conventional therapies (chemotherapy, oncolytic virotherapy) and its innovative applications in the creation of postbiotics and paraprobiotics may provide a new approach to the treatment of inflammatory, allergic, and neoplastic diseases.
Further clinical studies are necessary to assess the efficacy, safety, and optimal dose of this probiotic, which are essential for the widespread use of L. acidophilus in human therapy.
Most studies reported reductions in Candida colony-forming units (CFUs) or prevalence, mainly for C. albicans and for non-albicans species, with probiotics such as Lactobacillus reuteri , L. rhamnosus , L. acidophilus , and Bifidobacterium strains.
Some studies reported improved immunological markers, while symptom relief, especially when probiotics were combined with antifungals.
Probiotics reduce Candida colonization and symptoms, with potential prolonged effects.
In plain English: Given the possible diversity of effects among different Lactobacillus strains, future research should focus on specific strains.
Abolhassani A, Esmaili H, Rahati S, Jafarnejad S. · Probiotics and antimicrobial proteins (2026)
Moreover, some anti-carcinogenic mechanisms of Lactobacillus strains may appear more prominent than others, which contribute to alleviating cancer complications.
These include interactions with the gut microbiota, modulation of the immune system, induction of apoptosis, anti-inflammatory effects, the impact of probiotic-derived agents, and epigenetic regulation.
This paper reviews the pathways related to Lactobacillus strains to understand their unique impacts on BC better and explores the potential mechanisms involved.
In plain English: Understanding the gut-lung axis and its role in immune response regulation, together with the need for a thorough characterization of the specific strains, including biochemical, genomic, and functional properties, before testing in humans, may provide deeper insights into the therapeutic potential of probiotics in viral infections.
Bertola B, Cotolí-Crespo A, San Onofre N, Soriano JM. · Microorganisms (2025)
However, some studies have found no significant impact on hospitalization rates or disease progression.
The probiotic's mechanisms of action appear to involve microbiota modulation, intestinal barrier reinforcement, and anti-inflammatory effects rather than direct viral inhibition in COVID-19 after progression.
Some L. acidophilus strains show promise, and clinical validation should follow careful preclinical studies (in vitro, cell lines, and animal models), especially in vulnerable populations such as immunocompromised individuals.
In plain English: This review synthesizes current evidence on their therapeutic applications, technological advancements, and translational potential, highlighting their role in precision health and next-generation functional nutrition.
Singh A, Bhattacharjee S, Singh Y, Kostova I. · Current microbiology (2026)
Synergistic combinations with prebiotics, postbiotics and related bioactives further enhance therapeutic outcomes in inflammatory, metabolic and infectious conditions.
Advances in metagenomics, next-generation sequencing, proteomics, metabolomics, CRISPR-Cas systems, and synthetic biology are accelerating strain characterization, functional evaluation, and scalable production.
Despite ongoing challenges in standardization and regulated harmonization, parabiotics represent a safe and effective approach for microbiome-targeted interventions.
In plain English: Combined analysis of the two L1 treatment studies demonstrated a 2.9% (p<0.01) reduction in serum cholesterol concentration.
Anderson JW, Gilliland SE · J Am Coll Nutr (1999)
Two small controlled studies in hypercholesterolaemic adults, one daily 200 ml serving of fermented milk (yogurt) carrying L. acidophilus L1, not a capsule
Study 1 (single-blind, randomised against a swine-origin strain, 3 weeks): L1 lowered serum cholesterol by 2.4% (p < 0.05)
Study 2 (double-blind, placebo-controlled crossover, 4-week periods): cholesterol fell 3.2% (p < 0.05) in the first period, with no significant change in the second period