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Food, herbs & supplements · health · Emerging
Lab Study Finds Two Popular Probiotic Strains Produce Distinct Chemical Byproducts
Lab analysis, not human trialTwo probiotic strains comparedDistinct metabolite profilesSize not reported
A laboratory analysis published October 2, 2026 in Food & Function found that two widely used probiotic strains release distinctly different sets of bioactive compounds, a finding the authors say is the first of its kind for these species.
Researchers used untargeted metabolomic analysis, a method that profiles all the small molecules present in a sample, to study the secretomes, meaning the cell-free mix of molecules a bacterium releases into its surroundings, of two probiotic strains: Lacticaseibacillus rhamnosus R0011 and Bifidobacterium longum R0175. Sample size was not reported in the abstract. The L. rhamnosus secretome contained higher relative amounts of branched-chain hydroxy acids, aromatic lactic acids, the sugar alcohols mannitol and sorbitol, mevalonate, and flavin mononucleotide, a form of vitamin B2 involved in cell energy production. The B. longum secretome was marked instead by higher relative amounts of indolelactate, a gamma-glutamyl amino acid, niacin-related compounds, and organic acids from the citric acid cycle, the core chemical pathway cells use to generate energy. The authors describe this as the first study to show that these two specific, widely used probiotic strains have distinct chemical signatures.
Probiotic secretomes are the cocktail of byproducts a bacterium leaves behind as it grows, separate from the live bacteria themselves. The authors note these byproducts have antioxidant and anti-inflammatory activity and help bacteria communicate with each other and with the host's own cells. Because the two strains produced different dominant compounds, such as B vitamin derivatives from one strain versus citric acid cycle intermediates from the other, the authors suggest each strain may support health in its own distinct way rather than functioning interchangeably with other probiotics.
This study is the first to reveal distinct metabolomic signatures of two widely used probiotic species
Data Panel
- Who
- Lab analysis of bacterial secretomes; sample size not reported
- Design
- Untargeted metabolomic analysis comparing cell-free secretomes from two probiotic strains
- Dose
- Not applicable; strains compared were L. rhamnosus R0011 and B. longum R0175
- Primary result
- The two strains showed distinct metabolomic profiles with different dominant compound classes
- Secondary
- L. rhamnosus secretome higher in branched-chain hydroxy acids, aromatic lactic acids, mannitol/sorbitol, mevalonate and flavin mononucleotide; B. longum secretome higher in indolelactate, gamma-glutamyl amino acid, niacin-related metabolites and citric acid cycle organic acids
- Funding / conflicts
- Not reported
This is a lab analysis of bacterial secretions in isolation, not a study of what happens when these strains are consumed by animals or people, and no sample size was reported in the available abstract. Funding and conflicts of interest were not reported in the retrieved text.
Dr. Axe's Take
This kind of chemistry mapping backs up something worth remembering: not all probiotics behave alike, and lumping them together by genus ignores real biological differences. Seeing Lacticaseibacillus rhamnosus produce more B2-related compounds while Bifidobacterium longum leans toward citric acid cycle metabolites tells me these strains are doing different metabolic work before we even ask what that does in a human gut. This is lab chemistry, not a human outcome study, so I would not change a supplement routine on it alone. What I would do is keep rotating fermented foods like kefir, sauerkraut and kimchi rather than relying on one strain, since variety naturally exposes you to a broader range of these bacterial byproducts.
— Dr. Axe