Lactobacillus acidophilus
What's this?
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Its ID gene: the stretch scientists read to tell microbes apart. Each bar is one letter of its DNA. Every species has its own order of letters, so the pattern works like a fingerprint. Close relatives share most of it.
16S rRNA gene, V4 region: the 253 letters between the standard primers (515F/806R), which are the same in every species. One reference sequence; strains can differ by a letter or two. NCBI NR_117062.1
Formerly Bacillus acidophilus.
Small for a gut microbe: longer than 11% of the 2,354 we have genomes for.
35% G+C, higher than 10% of gut microbes.
To scale: if its ID gene were 1 cm long, its genome would stretch 13 meters. Yours would stretch 21 kilometers. One reference genome; strains vary. NCBI GCF_034298135.1
What it can do
- Can make lactic acid What yogurt bacteria make; other microbes turn it into butyrate.
- Can make B vitamins Folate, B12, riboflavin and others.
- Can ferment fiber Breaks down dietary fiber that our own enzymes can't.
- Can eat inulin A fiber in onions, garlic, leeks, chicory and bananas (also sold as FOS).
- Can use lactose The sugar in milk and dairy.
- Can change bile acids Modifies the bile acids the liver makes to digest fat.
Not seen in its genomes: make butyrate, make propionate, eat resistant starch, eat pectin, feed on gut mucus, make hydrogen sulfide, make methane.
All 13 capabilities and their evidence
| Capability | Verdict | Genome analysis | Lab tests | Published research |
|---|---|---|---|---|
| Can make butyrate | Not seen | 0 of 4 genomes | — | No papers |
| Can make propionate | Not seen | 0 of 4 genomes | — | No papers |
| Can make lactic acid | Can | 4 of 4 genomes | — | No papers |
| Can ferment fiber | Can | 3 of 4 genomes | 8 of 24 strains · strip test Strip tests often miss fiber-eaters, so this doesn't override the genomes. | Papers say yes |
| Can eat inulin | Can | 3 of 4 genomes | 1 of 24 strains · strip test Strip tests often miss fiber-eaters, so this doesn't override the genomes. | Papers say yes |
| Can eat resistant starch | Not seen | 0 of 4 genomes | — | No papers |
| Can eat pectin | Not seen | 0 of 4 genomes | — | No papers |
| Can use lactose | Can | 3 of 4 genomes | 16 of 21 strains | Papers say yes |
| Can feed on gut mucus | Not seen | 0 of 4 genomes | — | No papers |
| Can change bile acids | Can | 2 of 4 genomes | — | Papers say yes |
| Can make B vitamins | Can | 4 of 4 genomes | — | Papers say yes |
| Can make hydrogen sulfide | Not seen | 0 of 4 genomes | — | No papers |
| Can make methane | Not seen | 0 of 4 genomes | — | No papers |
AGORA2 (Heinken et al. 2023) via VMH, CC BY 4.0 · BacDive (DSMZ), CC BY 4.0 · NJC19 (Lim et al., Scientific Data 2020), CC0
In healthy guts
Found in 2.0% of healthy people.
- largest Segatella copri 6.2%
- 2nd largest Phocaeicola vulgatus 5.0%
- 3rd largest Faecalibacterium prausnitzii 4.7%
- 4th largest Bacteroides uniformis 3.2%
- 5th largest Agathobacter rectalis 2.5%
- 6th largest Alistipes putredinis 2.3%
- 7th largest Bifidobacterium longum 2.1%
- 8th largest Ruminococcus bromii 1.8%
- Lactobacillus acidophilus under 0.01%
- 2,169 other microbes, each a sliver 56.7%
- 15.6%
On average, a sliver, under 0.01% of the microbes in a healthy gut.
Every group, drawn the same way. Only some samples record age or sex, so each group says how many people it comes from. Tap one to see it above.
In conditions
Compared with healthy people in the same studies, it’s less common in none and more common in 1 condition. Only studies that had both are counted.
A difference is an association: it doesn’t mean this microbe causes, prevents or treats any of these.
Strongest first, then the biggest gap · Each figure is 10 peopleIn studies of how people live
Higher in vegetarians than vegans
Fackelmann 2025 · 21,561 people Landmark study
Higher in 3 of 3 cohorts
“Higher” is the study’s measure: on average, a bigger share of gut bacteria across everyone in the group, carriers or not. It isn’t how many people carry it. An association the authors report, measured once per person. It doesn’t mean a diet changes this microbe, or that the microbe affects health.
Recent research
Strains studied
How much each strain has been studied in people, not whether it works. Many trials test a strain inside a blend, so those are counted apart, and reviews are summaries of trials, so they're never counted as more trials.
47 strains of L. acidophilus are named on product labels. 0 have human trials; 47 have none found yet, including La-14, which is in 445 products.
L. acidophilus La-14
In 445 products →No human trials found yet
L. acidophilus NCFM
In 157 products →No human trials found yet
L. acidophilus DDS-1
In 143 products →No human trials found yet
L. acidophilus CUL-60
In 128 products →No human trials found yet
L. acidophilus CUL-21
In 86 products →No human trials found yet
L. acidophilus HA-122
In 55 products →No human trials found yet
L. acidophilus SD-5212
In 35 products →No human trials found yet
L. acidophilus UALa-01
In 32 products →No human trials found yet
L. acidophilus LA02
In 27 products →No human trials found yet
L. acidophilus LA-5
In 13 products →No human trials found yet
L. acidophilus L61A
In 12 products →No human trials found yet
L. acidophilus 16axg
In 11 products →No human trials found yet
L. acidophilus R0418
In 11 products →No human trials found yet
L. acidophilus VPLA-4
In 11 products →No human trials found yet
L. acidophilus VP-35
In 10 products →No human trials found yet
L. acidophilus VP-96
In 10 products →No human trials found yet
L. acidophilus VP-97
In 10 products →No human trials found yet
L. acidophilus SD-5221
In 8 products →No human trials found yet
L. acidophilus LA-2
In 7 products →No human trials found yet
L. acidophilus NCIMB 30156
In 6 products →No human trials found yet
L. acidophilus NCIMB 30157
In 6 products →No human trials found yet
L. acidophilus PXN 35
In 6 products →No human trials found yet
L. acidophilus ATCC SD5212
In 5 products →No human trials found yet
L. acidophilus DSM 21717
In 4 products →No human trials found yet
L. acidophilus L-92
In 4 products →No human trials found yet
L. acidophilus LA85
In 4 products →No human trials found yet
L. acidophilus VK3
In 4 products →No human trials found yet
L. acidophilus La-140
In 3 products →No human trials found yet
L. acidophilus Rosell 418
In 3 products →No human trials found yet
L. acidophilus W22
In 3 products →No human trials found yet
L. acidophilus W37
In 3 products →No human trials found yet
L. acidophilus A118
In 2 products →No human trials found yet
L. acidophilus ATCC SD6865
In 2 products →No human trials found yet
L. acidophilus ATCC SD6866
In 2 products →No human trials found yet
L. acidophilus DSM 24735
In 2 products →No human trials found yet
L. acidophilus KB-27
In 2 products →No human trials found yet
L. acidophilus La-1
In 2 products →No human trials found yet
L. acidophilus Vpro 80
In 2 products →No human trials found yet
L. acidophilus DDS1-25
In 1 product →No human trials found yet
L. acidophilus LA-11
In 1 product →No human trials found yet
L. acidophilus LA-3
In 1 product →No human trials found yet
L. acidophilus LN19
In 1 product →No human trials found yet
L. acidophilus MAK32L61A
In 1 product →No human trials found yet
L. acidophilus NI317
In 1 product →No human trials found yet
L. acidophilus Rosell-52
In 1 product →No human trials found yet
L. acidophilus RSB12
In 1 product →No human trials found yet
L. acidophilus VP-61
In 1 product →No human trials found yet
Human trials, meta-analyses and systematic reviews naming the strain · animal and lab studies not counted · Data sources