Lactobacillus acidophilus and the acidophilus group

Q: What is Lactobacillus acidophilus?

It is a lactic acid bacterium that lives naturally in the gut, mouth and vagina and is used in yogurt, fermented milk and supplements. It is not an essential nutrient.

Q: Is acidophilus the same as a probiotic?

Acidophilus is one species used as a probiotic. A probiotic is any live microorganism intended to help health. Effects belong to the exact strain, not to the species name.

Q: Does acidophilus help with diarrhoea from antibiotics?

One named mixture of L. acidophilus CL1285 and L. casei LBC80R lowered diarrhoea in hospital adults on antibiotics, with low-certainty evidence. This is not shown for other acidophilus products.

Q: Does it help irritable bowel syndrome?

Some strains and blends improved IBS scores in single trials, but overall evidence is low certainty and one mixture did worse than placebo. NCCIH says definite conclusions cannot be drawn.

Q: Is acidophilus in yogurt the same as in capsules?

No trial compared them. NHS says there is likely a big difference between trial products and shop yogurts and supplements, and labels may not match contents.

Q: Can acidophilus help lactose intolerance?

A small old trial of strain BG2FO4 in 18 people found no clear change in lactose digestion, and it had no placebo group.

Q: Is it good for infant colic?

One 2026 trial of NCFM drops in 60 infants did not meet its main goal. Ask a paediatrician before giving any probiotic to a baby.

Q: Does it boost the immune system?

The sources read do not show a proven immune benefit in healthy people. NHS says there is little evidence for many health claims.

Q: Who should be careful with probiotics?

People with severe illness, weak immune systems, central venous catheters, bowel damage and premature infants. NCCIH reports severe or fatal infections in premature infants. Ask a doctor first.

Q: What are the usual side effects?

Gas, bloating, cramps and soft stools were the commonest events, at similar rates to placebo in the trials read.

Lactobacillus acidophilus · also called Acidophilus, L. acidophilus, Lactobacilo acidófilo

Lactobacillus acidophilus is a friendly bacterium found in the gut and in yogurt and supplements. Research shows benefits only for specific strains or mixes, such as one product that lowered diarrhoea in hospital patients taking antibiotics, with low-certainty evidence. Results for IBS are mixed. People with severe illness, weak immunity or premature babies should only use probiotics with a doctor.

General information, not medical advice. Last substantive update October 26, 2026 · Not medically reviewed. A named clinician has not signed off on this page. How this page is made

About Lactobacillus acidophilus and the acidophilus group

Lactobacillus acidophilus is a common lactic acid bacterium found in the gut, in yogurt and in many supplements. Its benefits depend on the exact strain or mix, not on the species name. The best-supported results are for one named mixture against diarrhoea during antibiotics and for a few strains in irritable bowel syndrome, all low certainty.

What it is

L. acidophilus is a species of lactic acid bacteria found in the human gut, mouth and vagina and in fermented foods. It is not an essential nutrient. NCCIH defines probiotics as live microorganisms intended to have health benefits.

In 2020 scientists split the old genus Lactobacillus into 25 genera. L. acidophilus kept the name Lactobacillus, while many other probiotic species were renamed, so labels may use old or new names.

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Why the strain matters

A review of 228 trials found that probiotic effects are specific to the strain and to the condition. For antibiotic-associated diarrhoea in adults, a mixture containing L. acidophilus CL1285 worked while other Lactobacillus strains did not. NCCIH makes the same point: a result for one kind of Lactobacillus does not mean another will work.

So 'acidophilus' on a label is not enough. Results on this page belong to the named strains and products tested: NCFM, CL1285, DDS-1, LA-5, SDC 2012 and 2013, BG2FO4 and heat-killed LB.

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Where it comes from

Acidophilus is found in yogurt, fermented milk and other fermented foods, and sold as capsules, powders and drops. NCCIH says many probiotics are the same as or similar to microbes that live in the body. No USDA or NIH amount of live bacteria per portion was found, and NHS notes a big difference between trial products and shop yogurts and supplements.

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What the research shows

The strongest signal is for one named two-strain mixture in hospital adults taking antibiotics, where C. difficile diarrhoea fell from 23.8% with placebo to 1.2% or 9.4% depending on dose in one trial. The AGA review graded this low certainty, and pooled probiotics also showed a low-certainty benefit.

For IBS, a few strains helped pain and symptom scores in single trials, but a 6-strain mixture did worse than placebo. Other uses (children's diarrhoea, colic, lactose intolerance, blood sugar, mood) have very low or insufficient evidence. Many trials were linked to the companies that make the products.

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Reading a label

NHS says products may not hold the bacteria stated. A lab study found almost none of the tested local products met label claims. Look for the full strain name and ask a pharmacist. This page gives no amounts to take.

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At a glance

Traditional uses history, not proof

A normal gut and fermented-food bacterium
Sold as capsules and added to yogurt for gut comfort

Studied for research

Diarrhoea during antibiotics, low certainty (named mixture)
Irritable bowel syndrome, low certainty
Children's diarrhoea (heat-killed), very low
Infant colic, very low
Lactose intolerance and mood, insufficient

Main compounds

Strain NCFM
Strain CL1285 (with L. casei LBC80R)
Strain DDS-1
Strain LA-5 (with BB-12)
Heat-killed LB

Common forms

Yogurt and fermented milk
Capsules and powders
Drops for infants
Heat-killed preparations

Research links: 2025 Cochrane review: probiotics and C. difficile diarrhoea (47 trials) · 2020 AGA technical review of probiotics · 2018 review: strain and disease specificity · 2020 trial: L. acidophilus DDS-1 in IBS · 2015 review: risk and safety of probiotics · Research Library · Genes & Biomarkers Library

What it is and its history

Accepted scientific name: Lactobacillus acidophilus (a species of lactic acid bacteria)
Naming authority: Species name as used in Zheng 2020; the authority string was not read
Common names: Acidophilus (English); L. acidophilus (English (abbreviation)); Lactobacilo acidófilo (Spanish); Acidófilo (Spanish)
Family or group: Lactic acid bacteria. Zheng 2020 places L. acidophilus in the narrowed genus Lactobacillus with L. delbrueckii, L. crispatus, L. johnsonii and L. iners, host-adapted vertebrate species.
Classification: Bacteria > Lactobacillaceae (per Zheng 2020, which merged Lactobacillaceae and Leuconostocaceae) > Lactobacillus (narrowed genus, 2020) > Lactobacillus acidophilus
Native range: Normal member of the human gut, mouth and vagina (existing summary; NCCIH names Lactobacillus as common probiotic bacteria).
Habitat: Gut, mouth, vagina and fermented foods (existing summary).
Harvest and processing: Products are made by growing the bacteria and drying or freezing them, or by adding them to fermented milks; this was not read from a source.
Look-alikes and adulterants: Name: Lactobacillus rhamnosus GG; Note: A different species and strain with its own page; renamed Lacticaseibacillus rhamnosus in 2020.; Name: L. casei, L. paracasei; Note: Often combined with acidophilus in products; also renamed in 2020.; Name: Heat-killed L. acidophilus LB; Note: Not alive, so not a probiotic by the strict definition.
Sustainability and conservation: Not assessed.

Traditional use and history history, not clinical proof

Tradition or era	Documented use	Source
2020	Taxonomists split the old genus Lactobacillus into 25 genera; L. acidophilus kept the name Lactobacillus, while many other species got new genus names. Product labels may use either naming.	p32293557

Traditional use shows how it was used. It does not show that it works or is safe today.

What is inside, and how it may work

What it contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.

Main compounds

Compound	Family	Where it is concentrated	Activity studied	Level of evidence
Live L. acidophilus (named strains such as NCFM, CL1285, DDS-1, LA-5)	probiotic strain	Billions of colony-forming units in trials; see studies table.	Tested for diarrhoea during antibiotics, IBS and others; effects are strain-specific. ^{5 10 11}	Human data
Heat-killed L. acidophilus LB	inactivated bacteria	Not read.	Tested in children's diarrhoea; not a probiotic by the strict definition. ^{16 12}	Human data
Mixtures and blends containing L. acidophilus	multi-strain products	Varies by product.	Many positive results come from blends, so cannot be credited to acidophilus alone. ^{12 6}	Human data

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
Gut-lining pain pathway (mu-opioid receptor)	Mu-opioid receptor and STAT3 signalling in the colon	L. acidophilus NCFM alone raised receptor activity in gut biopsies of women with abdominal pain; symptom change was not significant in this small trial. ¹³	Human data
Gut bacteria community	Not applicable	NCFM with cellobiose raised lactobacilli and branched-chain fatty acids in healthy volunteers without changing diversity. ²³	Human data
Strain and disease specificity	Not applicable	Probiotic effects are specific to the strain and to the disease; a result for one strain does not transfer to another. ^{11 20}	Human data

Absorption, metabolism and elimination

Absorption: Live bacteria are not absorbed like a nutrient; they pass through the gut.
Distribution: NCFM was detected in 75% of treated stool samples in one trial and BG2FO4 in 7 of 18 people in another, so survival varies.
Elimination: In stool; some strains persist only while taken (not studied in the sources read).
Bioavailability: Survival to the gut depends on the product (NHS).

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Isolated compounds versus whole extracts

Foods like yogurt carry bacteria with milk, protein and other things; supplements deliver named strains in chosen amounts. NHS says there is likely a big difference between the products in trials and shop yogurts and supplements. No trial compared food with capsules.

Nutritional composition

L. acidophilus is not a nutrient. No USDA or NIH amounts of live bacteria per food portion were read.

10benefits and uses looked at

23studies and sources checked

Moderate certaintybest evidence rating found

7lab markers tracked in trials

1 moderate certainty3 low certainty3 very low certainty3 not enough evidence

What was looked at

The 10 benefits and uses checked for Lactobacillus acidophilus and the acidophilus group, each with how strong the evidence is. Tap one to open it.

Diarrhoea during antibiotics, including C. difficile diarrhoeaLow certainty
Irritable bowel syndrome (IBS) symptomsLow certainty
Where acidophilus comes fromModerate certainty
Children's acute diarrhoea (heat-killed L. acidophilus LB)Very low certainty
Infant colicVery low certainty
Lactose intoleranceNot enough evidence
Insulin sensitivity and blood sugarVery low certainty
Changes in gut bacteriaLow certainty
Mood in people with IBSNot enough evidence
Pouchitis and general immune or gut-balance claimsNot enough evidence

Lab markers tracked in the studies

Antibiotic-associated diarrhoea (share of people affected)C. difficile diarrhoea (share of people affected)IBS abdominal pain scoreIBS Symptom Severity ScaleHow long children's diarrhoea lastsInsulin sensitivity (clamp test)Lactobacilli counted in stool

What is Lactobacillus acidophilus and the acidophilus group good for?

The main studied uses and how strong the human evidence is for each. Every result belongs to the named strain or mixture tested.

Diarrhoea during antibiotics, including C. difficileLow certaintyOne named mixture of L. acidophilus CL1285 with L. casei LBC80R lowered diarrhoea and C. difficile diarrhoea in hospital adults. The AGA review graded this low certainty. Not shown for other acidophilus products. Irritable bowel syndrome symptomsLow certaintyDDS-1 and an LA-5 + BB-12 blend improved IBS scores against placebo in single trials. Overall evidence is low certainty and one 6-strain mixture did worse than placebo. Where acidophilus comes fromModerate certaintyFound in yogurt, fermented milk and supplements. No amounts per portion were found; food and capsule results were never compared. Children's acute diarrhoea (heat-killed LB)Very low certaintyA heat-killed product shortened diarrhoea in hospitalised children but not outpatients; experts call the evidence limited. Infant colicVery low certaintyA 2026 trial of NCFM drops in 60 infants missed its main goal. Lactose intoleranceNot enough evidenceA small before-and-after study of strain BG2FO4 found no clear change. Insulin sensitivity and blood sugarVery low certaintyIn 45 men, NCFM preserved insulin sensitivity over 4 weeks but did not change inflammation markers. Changes in gut bacteriaLow certaintyLactobacilli counts rose in small trials; no link to health benefit was shown. Mood in people with IBSNot enough evidenceA cultured milk drink did not clearly beat placebo for depression scores. Pouchitis and general immune claimsNot enough evidenceAn 8-strain mixture for pouchitis is very low certainty; general immune and gut-balance claims lack support in the sources read.

Benefits, one by one

Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.

Diarrhoea during antibiotics, including C. difficile diarrhoea

Low certainty

One named mixture (live L. acidophilus CL1285 with L. casei LBC80R) lowered diarrhoea in hospital patients taking antibiotics. Probiotics as a group may also help, with low certainty. The result belongs to that exact product, not to acidophilus in general.

4 studiesLive bacteria in capsules or fermented milk, as named products (see s…

Studies, doses and limits

What the trials found

Gao 2010 (255 hospital adults, one proprietary two-strain formula): antibiotic-associated diarrhoea in 15.5% (higher dose), 28.2% (lower dose) and 44.1% (placebo); C. difficile diarrhoea in 1.2%, 9.4% and 23.8%. The AGA technical review (2020) rated this two-strain mixture low certainty for preventing C. difficile diarrhoea (risk ratio 0.22), and also rated two acidophilus-containing multi-strain mixtures (with L. bulgaricus and B. bifidum, with and without S. thermophilus) low certainty. McFarland 2018 found the three-strain mixture with L. acidophilus CL1285 worked for adult antibiotic-associated diarrhoea while other Lactobacillus strains did not. The 2025 Cochrane review pooled all probiotics: C. difficile diarrhoea 1.6% vs 3.2% (low certainty).

Results

For one named mixture, fewer people got diarrhoea during antibiotics. This does not apply to other acidophilus products. The pooled evidence is low certainty and many trials were linked to probiotic companies.

Effect sizes as reported

Gao 2010: C. difficile diarrhoea 1.2% / 9.4% vs 23.8% placebo. AGA 2020: RR 0.22 (95% CI 0.11 to 0.42), low certainty. Cochrane 2025 (all probiotics): RR 0.50 (0.38 to 0.64), low certainty.

Why this rating

Low for the named mixtures (AGA and Cochrane grades). Several trials had company links; one trial had a very high placebo infection rate. Not shown for other acidophilus products.

Form and dose studied

Live bacteria in capsules or fermented milk, as named products (see studies table for amounts used in trials).

Who was studied

Adult hospital patients starting antibiotics. The Cochrane review says short-term use is likely not linked to adverse effects in people who are not immunocompromised.

Limits

Single-centre trial for the key result; low-certainty grades; industry links in 28 of 47 Cochrane trials; no head-to-head trials of acidophilus strains.

Why researchers looked

Antibiotics can upset the gut and let a germ called C. difficile cause severe diarrhoea. Acidophilus products are among the most tested for this.

Traditional use

Acidophilus is a normal gut resident. Using it to protect the gut during antibiotics is a modern, trial-based use.

Proposed mechanism Hypothesis

Not proven in humans for this use. Proposed ideas include competing with harmful germs and acidifying the gut; none was shown by the trials read.

A proposed mechanism does not show that the effect happens in people.

Be careful in very ill or immunosuppressed people; see the Safety tab.

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Irritable bowel syndrome (IBS) symptoms

Low certainty

Some named acidophilus strains and blends helped IBS pain and symptom scores in single trials, but the overall evidence is low certainty and results differ between products. One 6-strain mixture was worse than placebo.

6 studiesLive capsules of named strains (DDS-1; LA-5 + BB-12 blend); amounts u…

Studies, doses and limits

What the trials found

Martoni 2020 (330 adults, 6 weeks): L. acidophilus DDS-1 improved abdominal pain and symptom severity against placebo. Ghoshal 2026 (200 adults, 84 days): a blend of L. acidophilus LA-5 and B. lactis BB-12 had more responders than placebo at day 28 (19.3% vs 8.9%). The 2023 network meta-analysis of 81 trials ranked DDS-1 first for IBS symptom severity. The AGA review (2020) lists a 2-strain L. acidophilus SDC 2012/2013 mixture as improving pain in one trial but graded IBS evidence low or very low, and found a 6-strain mixture including L. acidophilus worse than placebo. NCCIH says definite conclusions cannot be drawn.

Results

A few products showed benefit for IBS pain and overall symptom scores in single trials. The species name alone does not predict who will benefit.

Effect sizes as reported

DDS-1: pain scale change -2.59 +/- 2.07, p = 0.001 vs placebo; responders 52.3%. LA-5 + BB-12: global improvement 19.3% vs 8.9% at day 28 (p = 0.048).

Why this rating

Low: each result rests on one or two trials of a different product; AGA graded IBS evidence low or very low; some authors have company ties; one mixture failed.

Form and dose studied

Live capsules of named strains (DDS-1; LA-5 + BB-12 blend); amounts used are in the studies table.

Who was studied

Adults with IBS (Rome IV), mostly non-constipated in one trial.

Limits

Short trials (6 to 12 weeks); different strains; blends cannot be credited to acidophilus alone; one trial's authors work for the company that makes the strain.

Why researchers looked

IBS causes pain, bloating and bowel changes, and treatments are limited, so probiotics are often tried.

Traditional use

Acidophilus supplements are widely sold for gut comfort; the IBS trials are modern.

Proposed mechanism Small human lab study

For NCFM, a 2014 small trial found a rise in a gut-lining pain-pathway marker (mu-opioid receptor); this is a lab finding and has not been shown to explain symptom relief.

A proposed mechanism does not show that the effect happens in people.

Mild digestive side effects were reported at similar rates to placebo; see the Safety tab.

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Where acidophilus comes from

Moderate certainty

L. acidophilus is a normal gut, mouth and vaginal resident and is added to yogurt, fermented milk and supplements (capsules, powders, drops). Food and pill amounts and strains differ, and the trials here used supplements or named products.

3 studiesFoods and supplements; not a recommendation to eat or take any of the…

Studies, doses and limits

What the trials found

NCCIH says probiotics are found in yogurt and other fermented foods, dietary supplements and beauty products, and that many are the same as or similar to microbes that live in the body. NHS says there is likely to be a big difference between the products tested in trials and the yogurts and supplements sold in shops. Two trials used milk drinks or cultured milk (Sarkawi 2024; see mood item); none compared food with capsules.

Results

Acidophilus is found in fermented milks and supplements. No amount per portion was read from USDA or NIH sources, so none is stated.

Effect sizes as reported

No amounts available in the sources read.

Why this rating

Moderate that the species is present in these foods and products (NCCIH, NHS, existing summary). Amounts of live bacteria and the actual strain per product were not read.

Form and dose studied

Foods and supplements; not a recommendation to eat or take any of them.

Who was studied

General population.

Limits

No USDA or NIH amounts found; labels vary; 'live cultures' on a label does not name the strain.

Why researchers looked

People ask whether yogurt gives the same results as a capsule.

Traditional use

Fermented milks have long been eaten; the existing summary lists yogurt and fermented milk as food sources.

Proposed mechanism Descriptive

Not a mechanism question; this item records sources only.

A proposed mechanism does not show that the effect happens in people.

Dairy-based products contain milk; see the Safety tab.

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Children's acute diarrhoea (heat-killed L. acidophilus LB)

Very low certainty

A heat-killed product, not a live probiotic, was tested in young children with diarrhoea. It shortened diarrhoea in hospitalised children but not outpatients, and experts call the evidence limited.

2 studiesHeat-killed preparation; see studies table.

Studies, doses and limits

What the trials found

Szajewska 2014 pooled 4 trials (304 children aged 1 to 48 months): diarrhoea lasted less time in hospitalised, not outpatient, children; cure at day 3 was similar and at day 4 higher. The AGA review notes that 4 of the 7 acidophilus trials in children used heat-killed preparations that do not meet the strict probiotic definition, and rated the evidence very low to low certainty. Another review pooled L. acidophilus with B. bifidum (7 trials) and found fewer hours of diarrhoea with low certainty.

Results

Limited, mixed-quality evidence for one heat-killed product. Not shown for live acidophilus by itself.

Effect sizes as reported

AGA: L. acidophilus mean 7.79 fewer hours of diarrhoea (95% CI -23.85 to +8.28), very low certainty; diarrhoea over 3 days RR 0.59 (0.33 to 1.05), low certainty.

Why this rating

Small trials of mixed quality, heat-killed product, wide intervals that include no effect.

Form and dose studied

Heat-killed preparation; see studies table.

Who was studied

Children 1 to 48 months with acute diarrhoea.

Limits

Not a live probiotic; trials mostly old; results differ between hospital and outpatient children.

Why researchers looked

Acute diarrhoea is common in young children.

Traditional use

Modern trial-based use.

Proposed mechanism Hypothesis

Unknown; heat-killed bacteria do not multiply.

A proposed mechanism does not show that the effect happens in people.

Children with diarrhoea who are very sleepy or cannot drink need a doctor; see the Safety tab.

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Infant colic

Very low certainty

One small 2026 trial of L. acidophilus NCFM drops in 60 infants did not meet its main goal. A day-14 difference faded after correction.

2 studiesDrops of a named strain; see studies table.

Studies, doses and limits

What the trials found

Vaz 2026: 60 colicky infants got NCFM drops or placebo for 28 days. Responders at day 28 did not differ (p = 0.240). Day 14 difference (p = 0.045) was exploratory and lost after correction. Fussing and crying time did not differ (p = 0.524). The trial calls the drops safe in this group.

Results

No clear benefit shown for colic.

Effect sizes as reported

Primary outcome p = 0.240.

Why this rating

One small trial with a missed main goal, registered after it began.

Form and dose studied

Drops of a named strain; see studies table.

Who was studied

Infants with colic, Brazil.

Limits

60 infants; retrospective registration; short.

Why researchers looked

Colic distresses families; gut bacteria are one theory.

Traditional use

Modern trial-based use.

Proposed mechanism Small human lab study

Possible change in gut bacteria; the trial found some change in diversity but no change in a gut inflammation marker.

A proposed mechanism does not show that the effect happens in people.

Do not give probiotics to premature or sick infants without a doctor; see Safety tab.

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Lactose intolerance

Not enough evidence

One small old trial of a different acidophilus strain (BG2FO4) found no clear change in lactose digestion after a week.

1 studiesLive bacteria twice a day for 7 days (see studies table).

Studies, doses and limits

What the trials found

Saltzman 1999: 18 lactose-maldigesting adults took the strain twice a day for 7 days. Breath hydrogen and symptom scores did not change significantly from baseline. The strain was found in stool in 7 people. There was no placebo group. The authors note lactose intolerance is often over-reported.

Results

No benefit shown; the trial is too small and has no placebo.

Effect sizes as reported

No significant change from baseline.

Why this rating

One small before-and-after study of one strain, no placebo.

Form and dose studied

Live bacteria twice a day for 7 days (see studies table).

Who was studied

Adults who reported lactose intolerance.

Limits

Tiny; short; not NCFM or other common strains.

Why researchers looked

Lactic acid bacteria can break down lactose, so people try them.

Traditional use

Fermented milk is often better tolerated than milk.

Proposed mechanism Small human study

The strain was chosen for strong gut attachment and lactose-splitting enzyme activity; this did not translate into a change in the test.

A proposed mechanism does not show that the effect happens in people.

See the Safety tab.

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Insulin sensitivity and blood sugar

Very low certainty

In a 4-week trial in 45 men, L. acidophilus NCFM kept insulin sensitivity from falling, but did not change inflammation markers.

1 studiesLive NCFM; see studies table.

Studies, doses and limits

What the trials found

Andreasen 2010: 45 men with type 2 diabetes, impaired or normal glucose tolerance took NCFM or placebo for 4 weeks. Insulin sensitivity (clamp test) was preserved with NCFM and fell with placebo. Baseline inflammation markers and the response to a bacterial-toxin injection were unchanged.

Results

A small short trial; it shows no lowering of blood sugar.

Effect sizes as reported

No numbers in the abstract.

Why this rating

One small, short trial, men only, no blood sugar lowering shown.

Form and dose studied

Live NCFM; see studies table.

Who was studied

Men with normal or impaired glucose handling or type 2 diabetes.

Limits

45 men, 4 weeks.

Why researchers looked

Gut bacteria may influence blood sugar handling.

Traditional use

Modern research question.

Proposed mechanism Small human study

The idea was less body inflammation; the trial did not find it.

A proposed mechanism does not show that the effect happens in people.

Anyone with diabetes should talk to their clinician before adding supplements.

Changes in gut bacteria

Low certainty

NCFM raised lactobacilli and a few other gut bacteria in healthy volunteers, but overall variety did not change. Whether this helps health is not shown.

4 studiesLive NCFM, sometimes with fibre.

Studies, doses and limits

What the trials found

van Zanten 2014: 18 healthy volunteers took NCFM with a fibre (cellobiose) or placebo for 3 weeks. Lactobacilli and some other genera rose, branched-chain fatty acids rose, diversity did not change. Andreasen 2010 found NCFM in 75% of stool samples after treatment. Vaz 2026 found higher diversity in some infants. Ghoshal 2026 found no overall stool-bacteria difference between groups.

Results

Some counts change; no health benefit is shown by these markers.

Effect sizes as reported

Abundance changes p < 0.05.

Why this rating

Low that the bacteria can be detected and counts shift in small trials; no link to health outcomes.

Form and dose studied

Live NCFM, sometimes with fibre.

Who was studied

Healthy adults; infants with colic.

Limits

Small trials; markers only; fibre given with the bacteria.

Why researchers looked

People ask whether a supplement changes the gut community.

Traditional use

Marketing often links acidophilus to gut balance.

Proposed mechanism Small human lab study

Added bacteria may be counted in stool; this is a lab marker, not a health result.

A proposed mechanism does not show that the effect happens in people.

No safety concern in these abstracts.

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Mood in people with IBS

Not enough evidence

A cultured milk drink with L. acidophilus LA-5 and L. paracasei did not clearly beat placebo for depression scores; only a serotonin measure rose.

1 studiesCultured milk drink; see studies table.

Studies, doses and limits

What the trials found

Sarkawi 2024: 110 adults with IBS drank a cultured milk with two strains or a placebo drink for 12 weeks. Depression scores fell in both the probiotic and placebo groups (p < 0.001). Serotonin rose only with the probiotic in those with mild depression (p < 0.05). IBS severity improved in all groups.

Results

The placebo drink improved as much on depression scores, so a mood benefit is not shown.

Effect sizes as reported

Depression score fell in both arms.

Why this rating

Placebo improved too; two strains in a milk drink.

Form and dose studied

Cultured milk drink; see studies table.

Who was studied

Adults with IBS.

Limits

Two strains; milk drink; blood serotonin is a marker.

Why researchers looked

Gut-brain links are a popular idea.

Traditional use

Modern research question.

Proposed mechanism Hypothesis

Possible gut-brain signalling; not shown here.

A proposed mechanism does not show that the effect happens in people.

Not a treatment for depression; talk to a doctor.

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Pouchitis and general immune or gut-balance claims

Not enough evidence

An 8-strain mixture that includes L. acidophilus has very low certainty evidence for pouchitis. Common marketing claims for immunity and gut balance are not backed by the sources read.

3 studies8-strain mixture; see AGA review.

Studies, doses and limits

What the trials found

AGA review: an 8-strain mixture including L. acidophilus was tested in two studies (76 patients) for keeping chronic pouchitis in remission; there may be a benefit but certainty is very low. NHS says there is little evidence to support many health claims for probiotics. NCCIH lists the best-supported uses and does not list general immune support in healthy people.

Results

No proven benefit for healthy people; pouchitis evidence is very low certainty and cannot be credited to acidophilus alone.

Effect sizes as reported

No usable numbers read for acidophilus alone.

Why this rating

A multi-strain mixture, 76 patients, very low certainty; no trials of general immune benefit read.

Form and dose studied

8-strain mixture; see AGA review.

Who was studied

People with chronic pouchitis; healthy people for claims.

Limits

Cannot separate acidophilus from the mixture.

Why researchers looked

Pouchitis is inflammation after bowel surgery; immune and gut-balance claims are very common on labels.

Traditional use

Marketing claims.

Proposed mechanism Hypothesis

Not shown.

A proposed mechanism does not show that the effect happens in people.

See the Safety tab.

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Connections to the rest of health

How Lactobacillus acidophilus and the acidophilus group connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.

Explore every connection: goals, body systems, organs, symptoms, genes

Kind of connection Connected to Search

A. Wellness goals

Connected to	Evidence status	Context	Studies
Gut Health	Low certainty	Diarrhoea during antibiotics, including C. difficile diarrhoea: One named mixture (live L. acidophilus CL1285 with L. casei LBC80R) lowered diarrhoea in hospital patients taking antibiotics. Probiotics as a group may also help, with low certainty. The result belongs to that exact product, not to acidophilus in general. Irritable bowel syndrome (IBS) symptoms: Some named acidophilus strains and blends helped IBS pain and symptom scores in single trials, but the overall evidence is low certainty and results differ between products. One 6-strain mixture was worse than placebo.	^{5 12 11 4 10 6 18 13 20 1}
Digestive Support	Low certainty	Diarrhoea during antibiotics, including C. difficile diarrhoea: One named mixture (live L. acidophilus CL1285 with L. casei LBC80R) lowered diarrhoea in hospital patients taking antibiotics. Probiotics as a group may also help, with low certainty. The result belongs to that exact product, not to acidophilus in general. Irritable bowel syndrome (IBS) symptoms: Some named acidophilus strains and blends helped IBS pain and symptom scores in single trials, but the overall evidence is low certainty and results differ between products. One 6-strain mixture was worse than placebo.	^{5 12 11 4 10 6 18 13 20 16 17 14}
Gut Health	Moderate certainty	Where acidophilus comes from: L. acidophilus is a normal gut, mouth and vaginal resident and is added to yogurt, fermented milk and supplements (capsules, powders, drops). Food and pill amounts and strains differ, and the trials here used supplements or named products.	^{20 21 15}
Gut Health	Low certainty	Changes in gut bacteria: NCFM raised lactobacilli and a few other gut bacteria in healthy volunteers, but overall variety did not change. Whether this helps health is not shown.	^{23 1 17 6}
Mood Balance	Not enough evidence	Mood in people with IBS: A cultured milk drink with L. acidophilus LA-5 and L. paracasei did not clearly beat placebo for depression scores; only a serotonin measure rose.	¹⁵
Immune Support	Not enough evidence	Pouchitis and general immune or gut-balance claims: An 8-strain mixture that includes L. acidophilus has very low certainty evidence for pouchitis. Common marketing claims for immunity and gut balance are not backed by the sources read.	^{12 21 20}
Microbiome Balance	Not enough evidence	Pouchitis and general immune or gut-balance claims: An 8-strain mixture that includes L. acidophilus has very low certainty evidence for pouchitis. Common marketing claims for immunity and gut balance are not backed by the sources read.	^{12 21 20}

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Digestive System	Biological association	Low certainty	Studied for: Diarrhoea during antibiotics, including C. difficile diarrhoea Studied for: Irritable bowel syndrome (IBS) symptoms	^{5 12 11 4 10 6 18 13 20 21 15 16 17 14 23 1}
Metabolism	Biological association	Very low certainty	Studied for: Insulin sensitivity and blood sugar	¹
Immune System	Biological association	Not enough evidence	Studied for: Pouchitis and general immune or gut-balance claims	^{12 21 20}

E. Health conditions

Connected to	Evidence status	Context	Studies
C. difficile diarrhoea	Low certainty trial signal	Lower rates in trials of one named mixture; risk if very ill. Lower rates in trials of one named mixture. Preparation or compound: Named two-strain mixture	^{5 12}
Bloodstream infection	Documented risk (rare)	Higher risk with serious illness, weak immunity and central lines. Preparation or compound: Lactobacillus probiotics in general	^{9 7 20}
Irritable bowel syndrome	Low certainty trial signal	A few strains improved scores in single trials. Preparation or compound: DDS-1; LA-5 + BB-12 blend	^{10 6}

I. Biomarkers

Connected to	Kind of connection	Evidence status	Context	Studies
Antibiotic-associated diarrhoea (share of people affected)	Biological association	Low certainty	Measured in trials: lower in trials of named mixtures. A lab change is not the same as a health benefit.	^{5 4}
C. difficile diarrhoea (share of people affected)	Biological association	Low certainty	Measured in trials: lower in trials of named mixtures (low certainty). A lab change is not the same as a health benefit.	^{5 12 4}
IBS abdominal pain score	Biological association	Low certainty	Measured in trials: lower in single trials of DDS-1. A lab change is not the same as a health benefit.	^{10 12}
IBS Symptom Severity Scale	Biological association	Low certainty	Measured in trials: lower in trials of DDS-1 and LA-5 + BB-12. A lab change is not the same as a health benefit.	^{10 18 6}
How long children's diarrhoea lasts	Biological association	Very low certainty	Measured in trials: shorter in hospitalised children (very low certainty). A lab change is not the same as a health benefit.	^{16 12}
Insulin sensitivity (clamp test)	Biological association	Very low certainty	Measured in trials: preserved vs placebo (not improved). A lab change is not the same as a health benefit.	¹
Lactobacilli counted in stool	Biological association	Low certainty	Measured in trials: higher with NCFM. A lab change is not the same as a health benefit.	^{23 1}

J. Genes, receptors and enzymes

Connected to	Kind of connection	Evidence status	Context	Studies
Mu-opioid receptor (OPRM1)	Preliminary mechanism	Human	NCFM raised its activity in gut biopsies in one small trial.	¹³

K. Biological pathways

Connected to	Kind of connection	Evidence status	Context	Studies
Clostridioides difficile	Preliminary mechanism	Human	Named mixtures lowered C. difficile diarrhoea in trials.	^{5 12}

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
Live L. acidophilus (named strains such as NCFM, CL1285, DDS-1, LA-5)	Biological association	Human	Tested for diarrhoea during antibiotics, IBS and others; effects are strain-specific.	^{5 10 11}
Heat-killed L. acidophilus LB	Biological association	Human	Tested in children's diarrhoea; not a probiotic by the strict definition.	^{16 12}
Mixtures and blends containing L. acidophilus	Biological association	Human	Many positive results come from blends, so cannot be credited to acidophilus alone.	^{12 6}

Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 26, 2026).

Evidence at a glance: what the research found for 10 outcomes

1Moderate certainty

3Low certainty

3Very low certainty

3Not enough evidence

Each outcome below is one thing researchers measured. Certainty is how far the evidence can be trusted, not how well it works. The full studies are on the next tab.

Diarrhoea during antibiotics, including C. difficile diarrhoea 4 studies Low certainty Irritable bowel syndrome (IBS) symptoms 6 studies Low certainty Where acidophilus comes from 3 studies Moderate certainty Children's acute diarrhoea (heat-killed L. acidophilus LB) 2 studies Very low certainty Infant colic 2 studies Very low certainty Lactose intolerance 1 study Not enough evidence Insulin sensitivity and blood sugar 1 study Very low certainty Changes in gut bacteria 4 studies Low certainty Mood in people with IBS 1 study Not enough evidence Pouchitis and general immune or gut-balance claims 3 studies Not enough evidence

The evidence

The research centre for Lactobacillus acidophilus and the acidophilus group. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.

Evidence by outcome

Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).

How we rate evidence

High certainty

Several well-run trials or reviews agree; further research is unlikely to change the picture much.

Moderate certainty

Good trials point the same way, but some doubt remains.

Low certainty

Small, short or inconsistent trials. The finding could change with better research.

Very low certainty

Very little or very weak human data. Treat as a possibility only.

Mixed findings

Trials or reviews disagree with each other.

Not enough evidence

Not enough human research to say either way.

Evidence against

Good research found no benefit, or found harm.

We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We started from our existing probiotic summary, read NCCIH and NHS pages and the AGA technical review text, and re-read PubMed abstracts for the trials and reviews. Only abstracts were read for most studies. The NIH Office of Dietary Supplements page was blocked and is marked unread.

Study library: every study we checked 23

Design Research type Year from Search

Study	Design	People	Product, dose, length	Result
Andreasen 2010 Effects of Lactobacillus acidophilus NCFM on insulin sensitivity and the systemic inflammatory response in human subjects. Br J Nutr · PMID 20815975 · DOI	Randomised controlled trial	45 Men with type 2 diabetes, impaired glucose tolerance or normal glucose tolerance	Live L. acidophilus NCFM 4 weeks · vs Placebo	Insulin sensitivity stayed the same in the NCFM group while it fell in the placebo group. Inflammation markers did not change. NCFM was found in stool in 75% of treated men. Insulin sensitivity preserved vs placebo; inflammation unaffected. No numbers in the abstract. (Not given in the abstract.) Methods, limits and funding Outcomes: Insulin sensitivity (clamp test); inflammatory response to a small bacterial-toxin injection Limitations: Small, short and men only; the result is about preserving a measure, not lowering blood sugar. Funding and conflicts: Not stated in the record read. Read: abstract
Aziz 2022 Compositional Quality and Possible Gastrointestinal Performance of Marketed Probiotic Supplements. Probiotics Antimicrob Proteins · PMID 35199309 · DOI	Laboratory product testing bacteria	Probiotic products sold in local pharmacies and shops (the abstract does not name the country)	Marketed probiotic products tested in the lab Various	Almost none of the products met the label claim; 11% had no living cells, and about a quarter varied from batch to batch or contained unwanted organisms. Half held antibiotic-resistant strains. No viable cells: 11%; batch variation: 27%; undesirable organisms: about 27% of total. (Not applicable) Methods, limits and funding Outcomes: Whether products matched their labels Limitations: Local market in one place; not specific to acidophilus; results cannot be assumed for other countries or brands. Funding and conflicts: Not stated in the record read. Read: abstract
Doron 2015 Risk and safety of probiotics. Clin Infect Dis · PMID 25922398 · DOI	Narrative review	Review of probiotic safety evidence	Probiotics in general Various	Probiotics have been used safely for years, but safety reporting in trials is inconsistent. Theoretical risks include bloodstream infection, harmful metabolic effects, over-stimulation of the immune system in susceptible people, gene transfer and digestive side effects. No numbers in the abstract. (Not applicable) Methods, limits and funding Outcomes: Safety of probiotics Limitations: A narrative review; it does not give rates of harm. Funding and conflicts: No conflicts stated in the record read; NIH support. Read: abstract
Esmaeilinezhad 2025 Probiotics for the prevention of Clostridioides difficile-associated diarrhea in adults and children. Cochrane Database Syst Rev · PMID 40931979 · DOI	Systematic review meta analysis	15260 47 randomised trials in adults and children given antibiotics (mostly hospital patients); probiotics of any strain were pooled	Probiotics of any strain, pooled (not specific to L. acidophilus) Various Varied across trials Varied across trials · vs Placebo, other prevention or no treatment	Probiotics as a class may lower the chance of C. difficile diarrhoea and antibiotic-associated diarrhoea (low-certainty evidence). Adverse events were probably no more common. CDAD: 1.6% vs 3.2%, RR 0.50 (38 trials, 13,179 people, low certainty). AAD: 23% vs 27.4%, RR 0.67 (40 trials, low certainty). Adverse events: RR 0.86 (moderate certainty). Hospital stay: little or no difference. (CDAD RR 0.50 (95% CI 0.38 to 0.64); AAD RR 0.67 (0.57 to 0.78); adverse events RR 0.86 (0.72 to 1.01).) Methods, limits and funding Outcomes: CDAD incidence; C. difficile in stool; adverse events; antibiotic-associated diarrhoea; hospital stay Limitations: Pools many different strains, so it cannot say what acidophilus alone does. The review notes missing data in most trials and publication bias. It says the results suit people who are not immunocompromised. Funding and conflicts: Review says no funding. It also notes that 28 of the included trials had authors linked to, or funding from, probiotic companies. Review authors report no relevant disclosures. Read: abstract
Gao 2010 Dose-response efficacy of a proprietary probiotic formula of Lactobacillus acidophilus CL1285 and Lactobacillus casei LBC80R for antibiotic-associated diarrhea and Clostridium difficile-associated diarrhea prophylaxis in adult patients. Am J Gastroenterol · PMID 20145608 · DOI	Randomised controlled trial	255 Adult hospital inpatients starting antibiotics, one centre	Live L. acidophilus CL1285 + L. casei LBC80R (proprietary capsule formula) Capsule (two a day or one a day) Two dose levels tested (50 and 100 billion colony-forming units a day) From within 36 hours of the first antibiotic until 5 days after the last, then 21 days of follow-up · vs Placebo capsules	Both probiotic groups had less AAD and less CDAD than placebo, with a larger effect at the higher dose. AAD: 15.5% (higher dose), 28.2% (lower dose), 44.1% (placebo). CDAD: 1.2%, 9.4%, 23.8%. Days of diarrhoea in those who got AAD: 2.8, 4.1, 6.4. (Confidence intervals are not given in the abstract.) Methods, limits and funding Outcomes: Antibiotic-associated diarrhoea (AAD); Clostridium difficile-associated diarrhoea (CDAD); symptom days Limitations: Single centre, hospital patients, one proprietary two-strain formula; the result belongs to that product only. Placebo CDAD rate (23.8%) is much higher than in most other trials. Funding and conflicts: Funding is not stated in the abstract. A proprietary commercial formula was tested, so a company link is possible. Registration: NCT00958308 Read: abstract
Ghoshal 2026 Probiotic Blend of Lactobacillus acidophilus LA-5 and Bifidobacterium animalis ssp. Lactis BB-12 in Non-constipated Irritable Bowel Syndrome: A Double-Blind Randomized Placebo-Controlled Trial. J Gastroenterol Hepatol · PMID 41255078 · DOI	Randomised controlled trial	200 Adults with non-constipated IBS	Live L. acidophilus LA-5 + B. animalis subsp. lactis BB-12 blend Capsule or sachet (not stated in abstract) 84 days, then 180 days follow-up · vs Placebo	More people improved with the blend than with placebo, and abdominal pain, bloating and quality-of-life scores fell. Stool bacteria were not different between groups overall. Global improvement at day 28: 19.3% vs 8.9% (p = 0.048). Mild or moderate adverse events: 4.0% vs 0.9% (p = 0.167). (Not given in the abstract.) Methods, limits and funding Outcomes: IBS global improvement; IBS symptom severity; quality of life; adverse events; stool bacteria Limitations: A blend, so the result cannot be credited to acidophilus alone. The response at day 28 was small in absolute terms. Funding and conflicts: Funding and conflicts are not stated in the record read. Read: abstract
Hefter 2023 An 11-Year Review of Lactobacillus Bacteremia at a Pediatric Tertiary Care Center. Hosp Pediatr · PMID 37203378 · DOI	Case series	127845 Children admitted to one US children's hospital over 11 years (127,845 admissions)	Not an intervention (chart review)	8 cases in 11 years. Most had impaired gut function and a central venous catheter; 3 had used probiotics. Cases did not follow the number of children given probiotics. 8 cases among 127,845 admissions. (Not applicable) Methods, limits and funding Outcomes: Cases of Lactobacillus bloodstream infection and risk factors Limitations: One hospital; very few cases; species not given in the abstract. Funding and conflicts: Not stated in the record read. Read: abstract
Hempel 2011 Safety of probiotics used to reduce risk and prevent or treat disease. Evid Rep Technol Assess (Full Rep) · PMID 23126627	Systematic review	622 studies of Lactobacillus, Bifidobacterium and other probiotics (search to August 2010)	Probiotics in general, mostly Lactobacillus alone or with Bifidobacterium Various Varied Short-term use mostly · vs Placebo or control	In randomised trials, short-term probiotic use did not raise the risk of side effects or serious side effects, but harms were poorly reported and long-term effects are unknown. Case reports describe bloodstream infection with probiotic organisms, mostly in people with poor health. Any adverse event RR 1.00; serious adverse events RR 1.06. (Any adverse event 0.93 to 1.07; serious adverse events 0.97 to 1.16.) Methods, limits and funding Outcomes: Adverse events Limitations: Search ended in 2010. The authors say the literature is not well equipped to answer safety questions with confidence. Funding and conflicts: US government evidence report; no conflicts stated in the record read. Read: abstract
Kullar 2023 Lactobacillus Bacteremia and Probiotics: A Review. Microorganisms · PMID 37110319 · DOI	Narrative review	Review of reports of Lactobacillus bloodstream infection	Lactobacilli and probiotics in general Various	Lactobacillus bloodstream infection is uncommon but carries higher risk of death. Risk factors are severe illness, weak immunity, intensive care and central venous catheters. It is more common in people taking probiotics. Only three probiotics (L. rhamnosus GG, L. plantarum and L. paracasei) were directly linked by DNA matching to blood isolates. No numbers in the abstract. (Not applicable) Methods, limits and funding Outcomes: Epidemiology and probiotic link in Lactobacillus bloodstream infection Limitations: A narrative review. No link to L. acidophilus by DNA matching is mentioned in the abstract. Funding and conflicts: Authors list advisory or consulting ties to the maker of an acidophilus-based product (Bio-K+) and to another probiotic company; the funders had no role. Read: abstract
Martoni 2020 Lactobacillus acidophilus DDS-1 and Bifidobacterium lactis UABla-12 Improve Abdominal Pain Severity and Symptomology in Irritable Bowel Syndrome: Randomized Controlled Trial. Nutrients · PMID 32019158 · DOI	Randomised controlled trial	330 Adults 18 to 70 with irritable bowel syndrome (Rome IV), multi-centre	Live L. acidophilus DDS-1 (one arm); B. lactis UABla-12 (another arm) 1 x 10^10 colony-forming units a day in each probiotic arm 6 weeks · vs Placebo	Both strains improved pain and symptom scores against placebo; DDS-1 showed the larger change. Pain scale change with DDS-1: -2.59 +/- 2.07 (p = 0.001 vs placebo); pain responders 52.3% (p < 0.001). IBS Symptom Severity Scale: -133.4 +/- 95.19 (p < 0.001). (Not given in the abstract.) Methods, limits and funding Outcomes: Abdominal pain severity (numeric scale); IBS symptom severity score; stool form Limitations: Six weeks only; one strain tested in one trial; the result belongs to DDS-1. Funding and conflicts: Two authors are employees of UAS Laboratories; the abstract says they were not involved in running the study, data handling or statistics. A company link to the tested product is likely but is not spelled out. Read: abstract
McFarland 2018 Strain-Specificity and Disease-Specificity of Probiotic Efficacy: A Systematic Review and Meta-Analysis. Front Med (Lausanne) · PMID 29868585 · DOI	Systematic review meta analysis	228 trials of probiotics with an identified strain, at least two trials per use	Named probiotic strains and mixtures, including L. acidophilus CL1285 + L. casei LBC80R + L. rhamnosus CLR2 Various Varied Varied · vs Placebo or no treatment	Efficacy was strain-specific and disease-specific. For preventing antibiotic-associated diarrhoea in adults the three-strain mixture containing L. acidophilus CL1285 worked, while other Lactobacillus strains did not. No pooled numbers are given in the abstract. (Not given in the abstract.) Methods, limits and funding Outcomes: Whether efficacy is specific to the strain and to the disease Limitations: Read from the abstract only. Does not say how large the effect was or how good the trials were. Funding and conflicts: No conflict statement appears in the record read. A later (2023) review by the same lead author lists advisory or consulting ties to the maker of the CL1285 mixture. Read: abstract
Preidis 2020 AGA Technical Review on the Role of Probiotics in the Management of Gastrointestinal Disorders. Gastroenterology · PMID 32531292 · DOI	Systematic review meta analysis	Systematic review of randomised trials of probiotics in digestive conditions (C. difficile, IBS, pouchitis, children's diarrhoea, preterm infants and others)	Named probiotic strains and mixtures, including several that contain L. acidophilus Various Varied Varied · vs Placebo	Some acidophilus-containing products have low-certainty benefit for C. difficile diarrhoea prevention; IBS results were low or very low certainty; heat-killed L. acidophilus LB had very low certainty evidence in children; an 8-strain mixture for pouchitis was very low certainty. C. difficile: L. acidophilus CL1285 + L. casei LBC80R RR 0.22 (low certainty); 3-strain acidophilus/bulgaricus/bifidum RR 0.35; 4-strain acidophilus/bulgaricus/bifidum/thermophilus RR 0.28 (both low). IBS: 2-strain L. acidophilus SDC 2012 + SDC 2013 improved pain in one trial; a 6-strain mixture including L. acidophilus was worse than placebo for overall relief. (C. difficile 2-strain RR 0.22 (95% CI 0.11 to 0.42); 3-strain RR 0.35 (0.15 to 0.85); 4-strain RR 0.28 (0.11 to 0.67).) Methods, limits and funding Outcomes: Prevention of C. difficile diarrhoea; IBS symptoms; pouchitis; children's acute diarrhoea Limitations: PubMed has no abstract for this record, so the article text was read on PubMed Central (first 171,000 characters of the page text). The guideline recommendations themselves were not read. Several of the mixtures cannot be credited to acidophilus alone. Funding and conflicts: Two of the four authors disclose advisory-board or consulting ties to drug or biotech companies unrelated to this species; the panel reports no disqualifying conflicts. NIH extramural support. Read: full-text
Ringel-Kulka 2014 Lactobacillus acidophilus NCFM affects colonic mucosal opioid receptor expression in patients with functional abdominal pain - a randomised clinical study. Aliment Pharmacol Ther · PMID 24853043 · DOI	Randomised controlled trial	20 Women 18 to 70 with mild to moderate abdominal pain; bowel biopsies taken	Live L. acidophilus NCFM alone, or with B. lactis Bi-07 2 x 10^10 colony-forming units twice a day 21 days · vs Two active arms; no placebo arm	NCFM alone raised a gut-lining pain-pathway marker (mu-opioid receptor); the combination did not. Symptoms trended better in both groups but the trial was too small to say. Receptor RNA and protein rose with NCFM alone; symptom change not significant. (Not given in the abstract.) Methods, limits and funding Outcomes: Gut lining opioid-receptor activity (lab measure); symptom diary Limitations: 20 women, no placebo group, and the main result is a lab marker rather than how people felt. Funding and conflicts: One author is a paid consultant for an unrelated company; others declare none. NIH support. Read: abstract
Saltzman 1999 A randomized trial of Lactobacillus acidophilus BG2FO4 to treat lactose intolerance. Am J Clin Nutr · PMID 9925136 · DOI	Randomised trial no placebo	18 Adults who reported lactose intolerance; 18 of 24 lactose maldigesters took part	Live L. acidophilus BG2FO4 Twice a day 7 days · vs Before-and-after (no placebo group); some took omeprazole	Breath hydrogen and symptoms did not change significantly after 7 days. Live bacteria were found in stool in 7 people. No significant change from baseline. (Not given in the abstract.) Methods, limits and funding Outcomes: Breath hydrogen after lactose; symptom scores Limitations: Small, short, and there was no placebo group, so it cannot show benefit or its absence for the strain firmly. Funding and conflicts: Not stated in the record read. Read: abstract
Sarkawi 2024 A randomized, double-blinded, placebo-controlled clinical trial on Lactobacillus-containing cultured milk drink as adjuvant therapy for depression in irritable bowel syndrome. Sci Rep · PMID 38658619 · DOI	Randomised controlled trial	110 Adults with IBS, with normal mood or mild (subthreshold) depression	Cultured milk drink with L. acidophilus LA-5 and L. paracasei L. CASEI-01 Milk drink Two bottles a day, each with 10^9 colony-forming units 12 weeks · vs Placebo drink	Depression scores fell in both the probiotic and placebo groups. Only the probiotic group with mild depression had a rise in serotonin in the blood. IBS severity improved in all groups. Depression scores fell from baseline (p < 0.001) in both arms; serotonin rose only with the probiotic (p < 0.05). (Not given in the abstract.) Methods, limits and funding Outcomes: Depression scores; quality of life; IBS severity; serotonin level Limitations: Placebo also improved, so the drink's own effect on mood is unclear; two strains, so not acidophilus alone. Funding and conflicts: Authors declare no competing interests. Read: abstract
Szajewska 2014 Meta-analysis shows limited evidence for using Lactobacillus acidophilus LB to treat acute gastroenteritis in children. Acta Paediatr · PMID 24175943 · DOI	Systematic review meta analysis	304 4 randomised trials in children aged 1 to 48 months with acute diarrhoea	Heat-killed L. acidophilus LB Heat-inactivated preparation Varied Varied · vs Placebo	Diarrhoea was shorter in hospitalised children, not in outpatients. The authors conclude there is limited evidence to recommend it. No numbers in the abstract. (Not given in the abstract.) Methods, limits and funding Outcomes: Duration of diarrhoea; cure on day 3 and day 4 Limitations: Trials of mixed quality. The product is heat-killed, which is not a probiotic by the strict definition. Funding and conflicts: Not stated in the record read; the record is tagged as non-US government supported. Read: abstract
Vaz 2026 Lactobacillus acidophilus for infant colic and microbiota modulation: a randomized clinical trial. BMC Pediatr · PMID 41998618 · DOI	Randomised controlled trial	60 Infants with colic in Brazil	Live L. acidophilus NCFM drops Oral drops Five drops (1 x 10^9 colony-forming units) 28 days · vs Placebo	The main goal (more responders at day 28) was not met. A day-14 difference was seen in a secondary analysis but faded after correction for multiple comparisons. No difference in fussing and crying time. Primary outcome p = 0.240; day 14 p = 0.045 (not kept after correction); fussing and crying time p = 0.524. (Not given in the abstract.) Methods, limits and funding Outcomes: Share of infants whose crying and fussing fell by half or more; gut bacteria; calprotectin; adverse effects Limitations: Small trial (60 infants); registered after it began (retrospectively); microbiota results are a lab marker. Funding and conflicts: Authors declare no competing interests. Registration: RBR-5pp4nks Read: abstract
Xie 2023 Outcome-Specific Efficacy of Different Probiotic Strains and Mixtures in Irritable Bowel Syndrome: A Systematic Review and Network Meta-Analysis. Nutrients · PMID 37686889 · DOI	Network meta analysis	9253 81 randomised trials in adults with IBS	Many strains and mixtures compared, including L. acidophilus DDS-1 Various Varied Varied · vs Placebo	Only some strains and mixtures beat placebo, and which ones depends on the outcome. L. acidophilus DDS-1 ranked first for the IBS symptom severity score. DDS-1 ranked first for IBS-SSS (ranking value 92.9%). (Rankings only; no certainty grading in the abstract.) Methods, limits and funding Outcomes: IBS Symptom Severity Scale; quality of life; abdominal pain; bloating; stool outcomes Limitations: A ranking is not proof. DDS-1 rests on one trial. The authors say further studies are needed to confirm. Funding and conflicts: Authors declare no conflict of interest. Read: abstract
Zheng 2020 A taxonomic note on the genus Lactobacillus: Description of 23 novel genera, emended description of the genus Lactobacillus Beijerinck 1901, and union of Lactobacillaceae and Leuconostocaceae. Int J Syst Evol Microbiol · PMID 32293557 · DOI	Taxonomy paper bacteria	Whole-genome study of 261 Lactobacillus species	Not an intervention (classification)	The old genus was split into 25 genera. L. acidophilus stays in the narrowed genus Lactobacillus together with L. delbrueckii, L. crispatus and L. johnsonii; many other well-known probiotic species were given new genus names. 261 species reviewed; 25 genera proposed. (Not applicable) Methods, limits and funding Outcomes: Reclassification of the genus Lactobacillus Limitations: A naming paper, not a health study. Label names may still use the older genus names. Funding and conflicts: Not stated in the record read. Read: abstract
s-nccih-probiotics NCCIH: Probiotics: Usefulness and Safety (page footer: Last Updated August 2019) · Source	Reference database n/a			Methods, limits and funding Read: full-text
s-nhs-probiotics NHS: Probiotics (page last reviewed 24 November 2022) · Source	Reference database n/a			Methods, limits and funding Read: full-text
s-ods-probiotics NIH Office of Dietary Supplements: Probiotics fact sheet for health professionals · Source	Reference database n/a			Methods, limits and funding Read: not-read
van Zanten 2014 Synbiotic Lactobacillus acidophilus NCFM and cellobiose does not affect human gut bacterial diversity but increases abundance of lactobacilli, bifidobacteria and branched-chain fatty acids: a randomized, double-blinded cross-over trial. FEMS Microbiol Ecol · PMID 25098489 · DOI	Randomised crossover trial	18 Healthy volunteers	L. acidophilus NCFM plus cellobiose (a fibre) together 10^9 colony-forming units and 5 g cellobiose a day 3 weeks per period · vs Placebo	The mix raised lactobacilli and some other gut bacteria and raised branched-chain fatty acids, but overall variety of gut bacteria did not change. Changes in gut bacteria abundance (p < 0.05); no overall diversity effect. (Not given in the abstract.) Methods, limits and funding Outcomes: Gut bacteria types and numbers; stool fatty acids Limitations: Healthy people, 18 volunteers; the fibre was given with the bacteria, so the effect cannot be credited to NCFM alone; measures are lab markers. Funding and conflicts: Funding and conflicts are not stated in the record read. Read: abstract

What we do not know yet

No trial was read showing the species name alone helps.
Food and capsule forms were not compared.
No head-to-head comparison of acidophilus strains was found.
Safety in pregnancy and breastfeeding was not found.
Vaginal and preterm-infant uses were not researched here.
The ODS fact sheet and the FDA preterm warning could not be read.

How new research is added

New studies are found by a saved PubMed search and placed in a review queue before the page changes.

Lab markers

What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".

Other 7

●

Antibiotic-associated diarrhoea (share of people affected)

Lower in trials of named mixtures in trials

The percentage of people on antibiotics who get diarrhoea linked to the antibiotic.

Low certainty

Results and what it means

Why it was measured

To see whether the product lowers the chance of getting diarrhoea during antibiotic treatment.

Statistical vs. clinical meaning

Lower rates in trials, but low certainty and tied to specific products.

Safety implication

Adverse events were probably no more common with probiotics (Cochrane 2025, moderate certainty).

Study	Result	People	Product
⁵	15.5% (higher dose) and 28.2% (lower dose) vs 44.1% placebo	255 hospital adults	Live L. acidophilus CL1285 + L. casei LBC80R
⁴	23% vs 27.4%, RR 0.67 (0.57 to 0.78)	40 trials, 13,419 people	All probiotics pooled

^{5 4}

●

C. difficile diarrhoea (share of people affected)

Lower in trials of named mixtures (low certainty) in trials

The percentage of people on antibiotics who develop diarrhoea caused by Clostridioides difficile.

Low certainty

Results and what it means

Why it was measured

C. difficile infection can be severe and hard to treat.

Statistical vs. clinical meaning

A real signal for named products, with low certainty; the very high placebo rate in the main trial may overstate the benefit.

Safety implication

Not for very ill or immune-weak people without a doctor.

Study	Result	People	Product
⁵	1.2% and 9.4% vs 23.8% placebo	255 hospital adults	Live L. acidophilus CL1285 + L. casei LBC80R
¹²	RR 0.22 (95% CI 0.11 to 0.42), low certainty	Pooled trials of the same two-strain mixture	Live L. acidophilus CL1285 + L. casei LBC80R
⁴	1.6% vs 3.2%, RR 0.50 (0.38 to 0.64)	38 trials, 13,179 people	All probiotics pooled

^{5 12 4}

●

IBS abdominal pain score

Lower in single trials of DDS-1 in trials

A 0 to 10 rating of how bad belly pain is.

Low certainty

Results and what it means

Why it was measured

Pain is the main complaint in IBS.

Statistical vs. clinical meaning

One trial of one strain; AGA graded overall IBS evidence low.

Safety implication

No safety concern reported in the abstract.

Study	Result	People	Product
¹⁰	-2.59 +/- 2.07 on the pain scale (p = 0.001 vs placebo); 52.3% responders	330 adults with IBS	Live L. acidophilus DDS-1, 6 weeks

^{10 12}

●

IBS Symptom Severity Scale

Lower in trials of DDS-1 and LA-5 + BB-12 in trials

A questionnaire score covering pain, bloating, bowel habit and effect on life.

Low certainty

Results and what it means

Why it was measured

Gives an overall picture of IBS symptoms.

Statistical vs. clinical meaning

Consistent direction across two designs, but one strain and company links.

Safety implication

Mild digestive side effects, similar to placebo.

Study	Result	People	Product
¹⁰	-133.4 +/- 95.19 (p < 0.001 vs placebo)	330 adults with IBS	Live L. acidophilus DDS-1
¹⁸	DDS-1 ranked first of the strains compared (92.9%)	81 trials, 9,253 people	Network comparison of many strains

^{10 18 6}

●

How long children's diarrhoea lasts

Shorter in hospitalised children (very low certainty) in trials

Hours or days of diarrhoea in a child with acute gastroenteritis.

Very low certainty

Results and what it means

Why it was measured

Shorter illness means less risk of dehydration.

Statistical vs. clinical meaning

Limited evidence for a heat-killed product.

Safety implication

Dehydration is the main danger in children's diarrhoea.

Study	Result	People	Product
¹⁶	Shorter in hospitalised, not outpatient, children; no numbers in abstract	4 trials, 304 children	Heat-killed L. acidophilus LB

^{16 12}

●

Insulin sensitivity (clamp test)

Preserved vs placebo (not improved) in trials

How well the body responds to insulin, measured in a hospital test.

Very low certainty

Results and what it means

Why it was measured

To see whether the product changes blood sugar handling.

Statistical vs. clinical meaning

Short, small trial.

Safety implication

None reported.

Study	Result	People	Product
¹	Preserved with NCFM, fell with placebo	45 men	Live L. acidophilus NCFM, 4 weeks

●

Lactobacilli counted in stool

Higher with NCFM in trials

How many lactobacilli are found in stool samples.

Low certainty

Results and what it means

Why it was measured

To see whether the added bacteria can be detected.

Statistical vs. clinical meaning

Shows the bacteria pass through the gut; does not show health benefit.

Safety implication

None.

Study	Result	People	Product
²³	Lactobacilli rose (p < 0.05); overall diversity unchanged	18 healthy volunteers	NCFM + cellobiose, 3 weeks
¹	NCFM found in 75% of treated stool samples	45 men	NCFM, 4 weeks

^{23 1}

Safety

What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.

Main points to know 3

Be careful with very ill, immune-weak or premature infants. NCCIH says the risk of harm from probiotics is greater in people with severe illness or weak immune systems, and that severe or fatal infections have been reported in premature infants given probiotics; it says the FDA has warned health care providers about this. A 2023 review found Lactobacillus bloodstream infection is uncommon but deadlier in people with serious disease, weak immunity, intensive care stays or central venous catheters. Anyone in these groups should only use probiotics under a doctor. Authoritative guidance and review ^{20 9 7}
Most healthy adults tolerate probiotics, but long-term safety is poorly known. A US evidence review of 622 studies found no increase in side effects or serious side effects in short-term trials, but harms were poorly reported and long-term effects are largely unknown. NHS says probiotics appear safe for most people with a healthy immune system. Systematic review and authoritative guidance ^{8 21 3}
Product quality: the label may not match the contents. NHS says products may not contain the bacteria stated, enough of them, or bacteria able to survive to the gut. NCCIH says some products contain organisms not on the label, and some of these may be risky. A lab study of marketed products found almost none met the label claim. Authoritative guidance and lab study ^{21 20 2}

Side effects 4

Effect	How often	Severity and recovery	Evidence
Gas, bloating, cramps, nausea and soft stools In the IBS trial 4.0% (probiotic) vs 0.9% (placebo) had mild or moderate adverse events, not significantly different.	In the 2025 Cochrane review these were the commonest events in both probiotic and control groups; pooled adverse events RR 0.86 (0.72 to 1.01).	Usually mild Not specifically stated in the sources read.	Meta-analysis ^{4 6}
Bloodstream infection with Lactobacillus (rare) DNA matching linked three probiotic species (L. rhamnosus GG, L. plantarum, L. paracasei) to blood isolates in the review; no link to L. acidophilus is stated in the abstract.	8 cases in 127,845 children's hospital admissions over 11 years; 3 had used probiotics.	Can be serious; higher risk of death in very ill patients. Not applicable.	Case series and review ^{7 9}
Theoretical risks: harmful metabolic effects, over-stimulation of immunity in susceptible people, gene transfer Described as theoretical or from case reports.	No rates found.	Not stated Not stated	Narrative review ³
Spread of antibiotic-resistance genes NCCIH lists transfer of resistance genes as a possible harm.	Half of 'locally marketed products' in one lab study held antibiotic-resistant strains.	Not stated Not applicable	Lab study and authoritative guidance ^{2 20}

Liver

No liver injury linked to L. acidophilus was found in the sources read. Liver safety was not searched in LiverTox or similar.

How often. No frequency was found.

Monitoring. No agency monitoring advice was found.

This is a safety connection. It is not evidence that Lactobacillus acidophilus and the acidophilus group supports liver health.

Medicines and supplements 4

With	Why it matters	Importance	Evidence	What to do
Medicines that weaken the immune system (steroids, chemotherapy, transplant drugs, biologics) prescription	Weak immunity raises the chance that live bacteria cause infection (NCCIH; Doron 2015).	NCCIH says risk is greater in people with compromised immune systems; the exact risk for acidophilus is not quantified.	Authoritative guidance Low certainty ^{20 3}	Ask your doctor before any live probiotic.
Central venous catheters and intensive-care stays medical-device	Lactobacillus bloodstream infection is linked to catheters and ICU admission (2023 review).	Rare but serious.	Review Low certainty ^{9 7}	Hospital teams decide; do not self-start.
Antibiotics prescription	Trials gave the bacteria alongside antibiotics (starting within 36 hours of the first dose in one trial). A harmful or cancelling interaction between the antibiotic and the live bacteria was not shown in the sources read.	No interaction finding; spacing of doses was not studied in the abstracts.	Trial design only Not enough evidence ⁵	Ask a pharmacist about timing.
Other probiotics and prebiotic fibres supplement	Many products are blends; some trials combined the bacteria with fibre.	Interactions were not studied.	None found Not enough evidence ²³	Check labels for strains and fibres.

Who should check first 5

Situation	Advice	Evidence
Pregnancy and breastfeeding	No source read gave safety information for acidophilus supplements in pregnancy or breastfeeding. Ask a doctor, midwife or pharmacist.	No data found
Premature infants and sick newborns	NCCIH reports severe or fatal infections in premature infants given probiotics and an FDA warning. Only a hospital team should decide.	Authoritative guidance ²⁰
Infants and children	A 2026 trial in 60 colicky infants reported the drops as safe. NCCIH says no serious side effects were seen in otherwise healthy children in antibiotic-diarrhoea reviews. A doctor should advise for children.	Trial and authoritative guidance ^{17 20}
Severe illness, weak immunity, catheters, bowel damage	Higher chance of bloodstream infection; use only with a doctor's agreement.	Authoritative guidance and review ^{20 9}
Milk allergy and lactose	Many acidophilus foods and some products are dairy-based. This is general label information, not a finding in the sources read. Check the label and ask a doctor if you have a milk allergy.	Label note ¹⁵

Overdose, product quality and regulators

Summary. Acidophilus is not a nutrient and no official upper intake level was found in the sources read. Harm is about infection in vulnerable people and product quality, not a dose threshold.

Animal. Not reviewed.

Human doses studied. Trial amounts appear only in the studies table.

High dose or long term signals. Long-term effects are largely unknown (2011 evidence review).

Overdose response. No overdose information was found.

Genotoxicity. Not researched.

Label accuracy is a real concern for probiotics in general.

Label accuracy. NHS: products may not contain the bacteria stated or enough to have an effect. A lab study found almost none of the tested local products met the label claim, 11% had no living cells, and about a quarter had unwanted organisms. ^{21 2}

Other organisms. NCCIH says some probiotic products contain organisms not on the label, which may pose serious health risks. ²⁰

Species name is not the strain. The species name does not tell you which strain is in the product; trial results belong to named strains. ¹¹

Body	Action	Date
NCCIH (US National Center for Complementary and Integrative Health) (United States)	Says probiotics have an extensive history of apparently safe use but few studies looked at safety in detail; risk is greater in severe illness or weak immunity; severe or fatal infections reported in premature infants and an FDA warning; some products contain organisms not on the label; consult a health care provider first. source	2019-08
NHS (UK) (United Kingdom)	Says probiotics appear safe for most people with a healthy immune system; talk to a doctor first if you have a health condition or weak immune system; labels may not match contents. source	2022-11-24

When to get medical help

Fever, chills, fast heartbeat or feeling suddenly very unwell while taking a probiotic, especially with a weak immune system, a central line or a recent operation: get medical help now.
A premature or very young sick baby who has been given a probiotic and becomes unwell: tell the hospital team straight away.
Diarrhoea with blood, severe belly pain or signs of dehydration (very sleepy, dry mouth, no tears, little urine): get medical help; a probiotic is not a substitute.
Swelling of the lips, face or throat, hives or trouble breathing after a dairy-based product: call emergency services.

Stop using the product and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.

General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.

Frequently asked questions

What is Lactobacillus acidophilus?

It is a lactic acid bacterium that lives naturally in the gut, mouth and vagina and is used in yogurt, fermented milk and supplements. It is not an essential nutrient.

^{20 19}

Is acidophilus the same as a probiotic?

Acidophilus is one species used as a probiotic. A probiotic is any live microorganism intended to help health. Effects belong to the exact strain, not to the species name.

^{20 11}

Does acidophilus help with diarrhoea from antibiotics?

One named mixture of L. acidophilus CL1285 and L. casei LBC80R lowered diarrhoea in hospital adults on antibiotics, with low-certainty evidence. This is not shown for other acidophilus products.

^{5 12 4}

Does it help irritable bowel syndrome?

Some strains and blends improved IBS scores in single trials, but overall evidence is low certainty and one mixture did worse than placebo. NCCIH says definite conclusions cannot be drawn.

^{10 6 12 20}

Is acidophilus in yogurt the same as in capsules?

No trial compared them. NHS says there is likely a big difference between trial products and shop yogurts and supplements, and labels may not match contents.

^{21 20}

Can acidophilus help lactose intolerance?

A small old trial of strain BG2FO4 in 18 people found no clear change in lactose digestion, and it had no placebo group.

¹⁴

Is it good for infant colic?

One 2026 trial of NCFM drops in 60 infants did not meet its main goal. Ask a paediatrician before giving any probiotic to a baby.

¹⁷

Does it boost the immune system?

The sources read do not show a proven immune benefit in healthy people. NHS says there is little evidence for many health claims.

^{21 20}

Who should be careful with probiotics?

People with severe illness, weak immune systems, central venous catheters, bowel damage and premature infants. NCCIH reports severe or fatal infections in premature infants. Ask a doctor first.

^{20 9 7}

What are the usual side effects?

Gas, bloating, cramps and soft stools were the commonest events, at similar rates to placebo in the trials read.

^{4 6 8}

Can I trust the label on a probiotic?

Not always. NHS says products may not contain the bacteria stated, and a lab study found almost none of the tested local products met label claims. Look for the full strain name.

^{21 2}

Is it safe in pregnancy or for children?

No source read gave safety information for acidophilus supplements in pregnancy or breastfeeding. For children, ask a doctor.

^{20 17}

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Editorial transparency

Written by: AlternativeMed editorial team. Research compiled with AI assistance, then checked against the sources listed.
Medical review: None. This page has not been reviewed by a physician or pharmacist.
First published: 2026-10-26
Last substantive update: 2026-10-26
How we research: We started from our existing probiotic summary, read NCCIH and NHS pages and the AGA technical review text, and re-read PubMed abstracts for the trials and reviews. Only abstracts were read for most studies. The NIH Office of Dietary Supplements page was blocked and is marked unread.
How we rate evidence: See "How we rate evidence" in the Evidence tab.
Independence: No product is promoted on this page. No affiliate links are shown. Several trials of named products have company links, which are flagged in the studies table where the abstract states them.

Sources 23

Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.

Andreasen AS, Larsen N, Pedersen-Skovsgaard T, Berg RM, Moller K, Svendsen KD, et al.. Effects of Lactobacillus acidophilus NCFM on insulin sensitivity and the systemic inflammatory response in human subjects.. Br J Nutr. 2010. PMID 20815975. DOI 10.1017/S0007114510002874. (abstract)
Aziz G, Zaidi A, Tariq M. Compositional Quality and Possible Gastrointestinal Performance of Marketed Probiotic Supplements.. Probiotics Antimicrob Proteins. 2022. PMID 35199309. DOI 10.1007/s12602-022-09931-7. (abstract)
Doron S, Snydman DR. Risk and safety of probiotics.. Clin Infect Dis. 2015. PMID 25922398. DOI 10.1093/cid/civ085. (abstract)
Esmaeilinezhad Z, Ghosh NR, Walsh CM, Steen JP, Burgman AM, Mertz D, Johnston BC. Probiotics for the prevention of Clostridioides difficile-associated diarrhea in adults and children.. Cochrane Database Syst Rev. 2025. PMID 40931979. DOI 10.1002/14651858.CD006095.pub5. (abstract)
Gao XW, Mubasher M, Fang CY, Reifer C, Miller LE. Dose-response efficacy of a proprietary probiotic formula of Lactobacillus acidophilus CL1285 and Lactobacillus casei LBC80R for antibiotic-associated diarrhea and Clostridium difficile-associated diarrhea prophylaxis in adult patients.. Am J Gastroenterol. 2010. PMID 20145608. DOI 10.1038/ajg.2010.11. (abstract)
Ghoshal UC, Ramakrishna BS, Rathi PM, Shukla A, Panigrahi MK, Jain S, et al.. Probiotic Blend of Lactobacillus acidophilus LA-5 and Bifidobacterium animalis ssp. Lactis BB-12 in Non-constipated Irritable Bowel Syndrome: A Double-Blind Randomized Placebo-Controlled Trial.. J Gastroenterol Hepatol. 2026. PMID 41255078. DOI 10.1111/jgh.70137. (abstract)
Hefter Y, Powell L, Tabulov CE, Sadler ED, Campos J, Hanisch B. An 11-Year Review of Lactobacillus Bacteremia at a Pediatric Tertiary Care Center.. Hosp Pediatr. 2023. PMID 37203378. DOI 10.1542/hpeds.2022-006892. (abstract)
Hempel S, Newberry S, Ruelaz A, Wang Z, Miles JN, Suttorp MJ, et al.. Safety of probiotics used to reduce risk and prevent or treat disease.. Evid Rep Technol Assess (Full Rep). 2011. PMID 23126627. (abstract)
Kullar R, Goldstein EJC, Johnson S, McFarland LV. Lactobacillus Bacteremia and Probiotics: A Review.. Microorganisms. 2023. PMID 37110319. DOI 10.3390/microorganisms11040896. (abstract)
Martoni CJ, Srivastava S, Leyer GJ. Lactobacillus acidophilus DDS-1 and Bifidobacterium lactis UABla-12 Improve Abdominal Pain Severity and Symptomology in Irritable Bowel Syndrome: Randomized Controlled Trial.. Nutrients. 2020. PMID 32019158. DOI 10.3390/nu12020363. (abstract)
McFarland LV, Evans CT, Goldstein EJC. Strain-Specificity and Disease-Specificity of Probiotic Efficacy: A Systematic Review and Meta-Analysis.. Front Med (Lausanne). 2018. PMID 29868585. DOI 10.3389/fmed.2018.00124. (abstract)
Preidis GA, Weizman AV, Kashyap PC, Morgan RL. AGA Technical Review on the Role of Probiotics in the Management of Gastrointestinal Disorders.. Gastroenterology. 2020. PMID 32531292. DOI 10.1053/j.gastro.2020.05.060. (full-text)
Ringel-Kulka T, Goldsmith JR, Carroll IM, Barros SP, Palsson O, Jobin C, et al.. Lactobacillus acidophilus NCFM affects colonic mucosal opioid receptor expression in patients with functional abdominal pain - a randomised clinical study.. Aliment Pharmacol Ther. 2014. PMID 24853043. DOI 10.1111/apt.12800. (abstract)
Saltzman JR, Russell RM, Golner B, Barakat S, Dallal GE, Goldin BR. A randomized trial of Lactobacillus acidophilus BG2FO4 to treat lactose intolerance.. Am J Clin Nutr. 1999. PMID 9925136. DOI 10.1093/ajcn/69.1.140. (abstract)
Sarkawi M, Raja Ali RA, Abdul Wahab N, Abdul Rathi ND, Mokhtar NM. A randomized, double-blinded, placebo-controlled clinical trial on Lactobacillus-containing cultured milk drink as adjuvant therapy for depression in irritable bowel syndrome.. Sci Rep. 2024. PMID 38658619. DOI 10.1038/s41598-024-60029-2. (abstract)
Szajewska H, Ruszczynski M, Kolacek S. Meta-analysis shows limited evidence for using Lactobacillus acidophilus LB to treat acute gastroenteritis in children.. Acta Paediatr. 2014. PMID 24175943. DOI 10.1111/apa.12487. (abstract)
Vaz SR, Tofoli MHC, Avelino MAG, Mota JF, de Araujo Filho HB, da Costa PS. Lactobacillus acidophilus for infant colic and microbiota modulation: a randomized clinical trial.. BMC Pediatr. 2026. PMID 41998618. DOI 10.1186/s12887-026-06883-7. (abstract)
Xie P, Luo M, Deng X, Fan J, Xiong L. Outcome-Specific Efficacy of Different Probiotic Strains and Mixtures in Irritable Bowel Syndrome: A Systematic Review and Network Meta-Analysis.. Nutrients. 2023. PMID 37686889. DOI 10.3390/nu15173856. (abstract)
Zheng J, Wittouck S, Salvetti E, Franz CMAP, Harris HMB, Mattarelli P, et al.. A taxonomic note on the genus Lactobacillus: Description of 23 novel genera, emended description of the genus Lactobacillus Beijerinck 1901, and union of Lactobacillaceae and Leuconostocaceae.. Int J Syst Evol Microbiol. 2020. PMID 32293557. DOI 10.1099/ijsem.0.004107. (abstract)
. NCCIH: Probiotics: Usefulness and Safety (page footer: Last Updated August 2019). . . (full-text)
. NHS: Probiotics (page last reviewed 24 November 2022). . . (full-text)
. NIH Office of Dietary Supplements: Probiotics fact sheet for health professionals. . . (not-read)
van Zanten GC, Krych L, Roytio H, Forssten S, Lahtinen SJ, Abu Al-Soud W, et al.. Synbiotic Lactobacillus acidophilus NCFM and cellobiose does not affect human gut bacterial diversity but increases abundance of lactobacilli, bifidobacteria and branched-chain fatty acids: a randomized, double-blinded cross-over trial.. FEMS Microbiol Ecol. 2014. PMID 25098489. DOI 10.1111/1574-6941.12397. (abstract)

Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.