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Probiotic strains: what have they been studied for?

By Published 10 min read

Probiotic packs carry names such as Lacticaseibacillus rhamnosus GG or Bifidobacterium longum BB536. But what have those strains actually been studied for, and what was found?

Here we go through each strain in the NDS products we write about. For each strain we describe the most important human trials, including the ones that found no difference, and how strong the research is overall.

Before you read

  • The research was done with the strain, not with the product. We have not found a single published trial of an NDS product. NDS does not state how many bacteria there are of each strain either, so the doses cannot be compared with the trials.
  • Results apply to the strain and the condition that was studied. A large review of 228 trials found that some strains of a species showed an effect while others did not [1]. So a result from one strain cannot be carried over to another.
  • No health claims are authorised. Not a single health claim for probiotic bacteria has been authorised in the EU. This is a description of research, not a promise of what a product does.
  • Many trials are paid for by the producers. That goes for most trials of IFF's strains (formerly Danisco) and Morinaga's strains. It does not make them wrong, but it is worth knowing.

How we rate the research: several meta-analyses (many trials pooled), some RCTs (several randomised trials with placebo), a few small trials, laboratory data only or no research found.

Overview

Strain Mostly studied for The research
L. rhamnosus GG (LGG) Diarrhoea with antibiotics and stomach infections Several meta-analyses
L. rhamnosus HN001 Eczema in infants Some RCTs
L. acidophilus NCFM Colds in children, IBS Some RCTs, mostly in mixtures
L. salivarius Ls-33 Inflammation markers in obesity A few small trials
L. brevis Lbr-35 No human trials Laboratory data only
Lc. lactis Ll-23 Only in a five-strain mix A few small trials
B. lactis B420 Body fat, gestational diabetes Some RCTs
B. lactis Bi-07 Colds, together with NCFM Some RCTs, mostly in mixtures
B. lactis Bl-04 Colds Some RCTs with mixed results
B. longum BB536 Respiratory infections, constipation Some RCTs, all small
B. infantis Bi-26 Weight in underweight infants A few small trials
B. longum Bi-05 Nothing found No research found
B. bifidum Bb-06 Only in a five-strain mix A few small trials
B. breve M-16V Preterm infants Some RCTs, very low quality

Lactobacilli and lactococci

Lacticaseibacillus rhamnosus GG (LGG)

LGG is one of the most studied strains. A meta-analysis of 12 trials with 1,499 participants found diarrhoea during antibiotic treatment in 12% with LGG and 22% without. The difference was clear only in children [2]. A meta-analysis of 18 trials in children with gastroenteritis found diarrhoea almost one day shorter [3], but the largest single trial, with 971 children, found no difference [4]. In 2,653 intensive-care patients there was no effect, and the bacterium was found in blood or other normally sterile samples in 15 versus 1 [5].

The research: several meta-analyses of low to moderate quality.

Lacticaseibacillus rhamnosus HN001

HN001 has mainly been studied in pregnant women and infants in New Zealand. In a trial of 474 children from allergic families, where both mother and child took HN001, half as many children had eczema by age 2 [6], and the difference was still there at age 11 [7]. In a later trial of 423 pregnant women, where only the mother took the strain, there was no difference in eczema [8]. Trials on exam stress in 483 students and on blood sugar in 153 adults found no difference either [9][10].

The research: some RCTs, no meta-analysis.

Lactobacillus acidophilus NCFM

NCFM has mostly been studied together with other strains. In a trial of 326 children aged 3-5, over six months there were 53% fewer cases of fever with NCFM alone and 73% fewer with NCFM plus B. lactis Bi-07 [11]. The first author worked for the producer. In the largest trial of NCFM alone, 391 adults with IBS for 12 weeks, there was no difference from placebo [12]. A trial of 60 infants with colic found no difference either [13].

The research: some RCTs, no meta-analysis.

Ligilactobacillus salivarius Ls-33

Ls-33 has been tested alone in only one small human trial. In a Danish trial, 50 adolescents with severe obesity took Ls-33 or placebo every day for 12 weeks. There was no difference in inflammation markers, blood sugar, cholesterol, blood pressure or weight [14], but some bacterial groups in the stool changed [15]. Ls-33 was also part of a nine-strain mix tested in 87 infants with colic, but without a placebo group [16]. The rest is laboratory and animal work.

The research: a few small trials.

Levilactobacillus brevis Lbr-35

Lbr-35 is a strain from IFF (formerly Danisco). We found no human trials, neither of the strain alone nor in a mix. The only article on Lbr-35 is a laboratory study by the producer, in which Lbr-35 made clearly less of the signalling substance GABA than another L. brevis strain [17]. Research on other L. brevis strains says nothing about Lbr-35.

The research: laboratory data only.

Lactococcus lactis Ll-23

Ll-23 has not been tested alone in humans. It is part of a five-strain mix with L. acidophilus La-14, L. casei Lc-11, B. lactis Bl-04 and B. bifidum Bb-06. The mix was tested in two small Brazilian trials. In 42 people with rheumatoid arthritis, some inflammation markers were lower, but disease activity did not differ [18]. In 32 women with overweight, only the gut bacteria were measured [19]. It is not possible to tell which strain in the mix did what.

The research: a few small trials, only of a mix.

Bifidobacteria

Bifidobacterium animalis subsp. lactis B420

B420 has mainly been studied for body weight and body fat. In a trial of 225 adults with overweight who took 10 billion CFU a day for six months, there was no difference in fat mass in the main analysis. Among those who completed the trial as planned, there was a difference with B420 plus fibre, but not with B420 alone [20]. In a trial of 439 pregnant women with overweight, where B420 was given together with L. rhamnosus HN001, there was no difference in gestational diabetes [21].

The research: some RCTs, where the main results mostly showed no difference.

Bifidobacterium animalis subsp. lactis Bi-07

Bi-07 has mostly been studied together with L. acidophilus NCFM. In the trial of 326 children aged 3-5, there were fewer cases of fever and cough with the combination than with placebo [11]. In a trial of 465 physically active adults, the combination made no difference to colds [22]. On its own, Bi-07 has been tested in small lactose trials at a very high dose. In 2020 the European Food Safety Authority, EFSA, concluded that it has not been shown that the strain increases lactose digestion [23].

The research: some RCTs, mostly of mixtures.

Bifidobacterium animalis subsp. lactis Bl-04

Bl-04 has mainly been studied for colds. In a trial of 465 physically active adults who took 2 billion CFU a day for about five months, there were fewer upper respiratory infections than with placebo [22]. In a later trial, 334 healthy adults took Bl-04 or placebo for 28 days and were then infected with a cold virus. There was no difference in how many became ill: 56 versus 50% [24].

The research: some RCTs with mixed results.

Bifidobacterium longum BB536

BB536 has been tested in many small trials, mostly in Japan. In a trial of 520 preschool children in Malaysia, of whom 219 were analysed, sore throats were shorter, but there was no difference in diarrhoea [25]. In a trial of 80 older adults with constipation, there was no difference in the main outcome, but there was a difference in the number of bowel movements [26]. In a trial of 56 people with ulcerative colitis, 63% reached remission with BB536 versus 52% with placebo, a difference that was not statistically significant [27].

The research: some RCTs, all small, no meta-analysis.

Bifidobacterium longum subsp. infantis Bi-26

Bi-26 has been tested alone in only one small trial. Forty underweight infants in Pakistan took Bi-26 or placebo for 28 days. The trial was stopped early, and there was no difference in weight [28]. Otherwise the strain has mostly been studied in the laboratory, in animals and in a mix that many UK neonatal units give to preterm infants [29].

The research: a few small trials.

Bifidobacterium longum Bi-05

For Bi-05 we found no published studies, whether in humans, animals or the laboratory. We could not confirm who makes the strain either. IFF has a strain with a similar name, B. longum Bl-05, but we cannot tell whether it is the same, and we found no human trials of that one either.

The research: no research found.

Bifidobacterium bifidum Bb-06

As far as we could find, Bb-06 has not been tested alone in humans. It is part of the same five-strain mix as Ll-23. In 42 people with rheumatoid arthritis, some inflammation markers were lower, but disease activity did not differ [18]. In 32 women with overweight, only the gut bacteria were measured [19].

The research: a few small trials, only of a mix.

Bifidobacterium breve M-16V

M-16V has mostly been studied in preterm infants and in infant formula. A systematic review of 5 randomised trials with 482 preterm infants found no clear difference in the serious bowel disease NEC, in infections or in deaths, and rated the quality of the evidence as very low [30]. In a trial of 90 infants with eczema who received M-16V in formula with prebiotics, there was no difference in eczema severity [31].

The research: some RCTs, rated as very low quality overall.

Strains without a strain code

Some NDS packs name only the species, such as Lactobacillus paracasei, L. plantarum, L. acidophilus, L. casei, Bifidobacterium bifidum or B. animalis subsp. lactis, with no strain code. Then the research cannot be looked up. The review of 228 trials found that results apply to the specific strain and the specific condition [1]. A trial of one L. plantarum strain therefore says nothing about an unnamed L. plantarum in a product. Read more about how to read the strain code on the pack.

Sources

  1. McFarland LV et al. Strain-Specificity and Disease-Specificity of Probiotic Efficacy: A Systematic Review and Meta-Analysis. Front Med. 2018. PMID 29868585
  2. Szajewska H, Kołodziej M. Systematic review with meta-analysis: Lactobacillus rhamnosus GG in the prevention of antibiotic-associated diarrhoea in children and adults. Aliment Pharmacol Ther. 2015. PMID 26365389
  3. Szajewska H et al. Systematic review with meta-analysis: Lactobacillus rhamnosus GG for treating acute gastroenteritis in children, a 2019 update. Aliment Pharmacol Ther. 2019. PMID 31025399
  4. Schnadower D et al. Lactobacillus rhamnosus GG versus Placebo for Acute Gastroenteritis in Children. N Engl J Med. 2018. PMID 30462938
  5. Johnstone J et al. Effect of Probiotics on Incident Ventilator-Associated Pneumonia in Critically Ill Patients: A Randomized Clinical Trial. JAMA. 2021. PMID 34546300
  6. Wickens K et al. A differential effect of 2 probiotics in the prevention of eczema and atopy: a double-blind, randomized, placebo-controlled trial. J Allergy Clin Immunol. 2008. PMID 18762327
  7. Wickens K et al. Effects of Lactobacillus rhamnosus HN001 in early life on the cumulative prevalence of allergic disease to 11 years. Pediatr Allergy Immunol. 2018. PMID 30430649
  8. Wickens K et al. Maternal supplementation alone with Lactobacillus rhamnosus HN001 during pregnancy and breastfeeding does not reduce infant eczema. Pediatr Allergy Immunol. 2018. PMID 29415330
  9. Slykerman RF et al. Probiotics for Reduction of Examination Stress in Students (PRESS) study. PLoS One. 2022. PMID 35675229
  10. Barthow C et al. A randomised controlled trial of a probiotic and a prebiotic examining metabolic and mental health outcomes in adults with pre-diabetes. BMJ Open. 2022. PMID 35332040
  11. Leyer GJ et al. Probiotic effects on cold and influenza-like symptom incidence and duration in children. Pediatrics. 2009. PMID 19651563
  12. Lyra A et al. Irritable bowel syndrome symptom severity improves equally with probiotic and placebo. World J Gastroenterol. 2016. PMID 28082816
  13. Vaz SR et al. Lactobacillus acidophilus for infant colic and microbiota modulation: a randomized clinical trial. BMC Pediatr. 2026. PMID 41998618
  14. Gøbel RJ et al. Probiotics to adolescents with obesity: effects on inflammation and metabolic syndrome. J Pediatr Gastroenterol Nutr. 2012. PMID 22695039
  15. Larsen N et al. Effect of Lactobacillus salivarius Ls-33 on fecal microbiota in obese adolescents. Clin Nutr. 2013. PMID 23510724
  16. Piątek J et al. Effects of a nine-strain bacterial synbiotic compared to simethicone in colicky babies, an open-label randomised study. Benef Microbes. 2021. PMID 33765904
  17. Banerjee S et al. Transcriptomics reveal different metabolic strategies for acid resistance and gamma-aminobutyric acid (GABA) production in select Levilactobacillus brevis strains. Microb Cell Fact. 2021. PMID 34488774
  18. Cannarella LAT et al. Mixture of probiotics reduces inflammatory biomarkers and improves the oxidative/nitrosative profile in people with rheumatoid arthritis. Nutrition. 2021. PMID 34111674
  19. Gomes AC et al. Gut microbiota is associated with adiposity markers and probiotics may impact specific genera. Eur J Nutr. 2020. PMID 31250099
  20. Stenman LK et al. Probiotic With or Without Fiber Controls Body Fat Mass, Associated With Serum Zonulin, in Overweight and Obese Adults. EBioMedicine. 2016. PMID 27810310
  21. Pellonperä O et al. Efficacy of Fish Oil and/or Probiotic Intervention on the Incidence of Gestational Diabetes Mellitus in an At-Risk Group of Overweight and Obese Women. Diabetes Care. 2019. PMID 30967436
  22. West NP et al. Probiotic supplementation for respiratory and gastrointestinal illness symptoms in healthy physically active individuals. Clin Nutr. 2014. PMID 24268677
  23. EFSA NDA Panel. Bifidobacterium animalis subsp. lactis Bi-07 contributes to increasing lactose digestion: evaluation of a health claim pursuant to Article 13(5) of Regulation (EC) No 1924/2006. EFSA J. 2020. PMID 32742434
  24. Turner RB et al. Effect of Bifidobacterium animalis spp. lactis Bl-04 on Rhinovirus-Induced Colds. EClinicalMedicine. 2022. PMID 34927036
  25. Lau AS et al. Bifidobacterium longum BB536 alleviated upper respiratory illnesses and modulated gut microbiota profiles in Malaysian pre-school children. Benef Microbes. 2018. PMID 29065707
  26. Takeda T et al. Usefulness of Bifidobacterium longum BB536 in Elderly Individuals With Chronic Constipation: A Randomized Controlled Trial. Am J Gastroenterol. 2023. PMID 36216361
  27. Tamaki H et al. Efficacy of probiotic treatment with Bifidobacterium longum 536 for induction of remission in active ulcerative colitis. Dig Endosc. 2016. PMID 26418574
  28. Parrino J et al. Impact of Bifidobacterium infantis supplementation on growth, health outcomes, and gut microbiome features in underweight infants from Pakistan. Front Nutr. 2026. PMID 42137872
  29. Patel N et al. How frequent is routine use of probiotics in UK neonatal units? BMJ Paediatr Open. 2023. PMID 37451704
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  31. van der Aa LB et al. Effect of a new synbiotic mixture on atopic dermatitis in infants: a randomized-controlled trial. Clin Exp Allergy. 2010. PMID 20184604