Heat-treated Lactiplantibacillus plantarum LM1004 and immune function
What it found
In a randomised trial in healthy adults, 8 weeks of a heat-treated Lactiplantibacillus plantarum LM1004 supplement increased natural killer cell activity and white blood cell counts compared with a placebo.
In a lab model of the human gut, the same ingredient changed gut bacteria and their metabolic products.
What they found
Studies in people
Natural killer cell activity
After 8 weeks, natural killer cell activity increased in the supplement group compared with the placebo group at all tested ratios. The authors report the increase ranged from 12.4% to 19.2% depending on the ratio.
White blood cell counts
White blood cell counts also rose significantly in the supplement group compared with the placebo group. The authors say this stayed within the normal range.
Cytokine levels
Levels of IL-12 dropped more in the supplement group than in the placebo group. Other cytokines such as IFN-γ and TNF-α showed no significant changes.
Safety and side effects
Mild cold-like symptoms were the only adverse events reported, in 8.47% of the supplement group and 6.67% of the placebo group. No moderate or severe events occurred, and blood tests, vital signs and lipid profiles stayed stable.
Animal and lab studies
Gut bacteria diversity
In the lab model, the ingredient increased species diversity in the ascending colon and richness in the transverse and descending colon. It enriched low-abundance bacteria that are often linked to health.
Metabolites and bile acids
The lab model showed compartment-specific changes in metabolites, especially in bile acid pathways. Secondary bile acids increased in the transverse and descending colon, while primary bile acids rose in the ascending colon.
What the authors conclude
“Collectively, these results indicate that L. plantarum LM1004 boosts NK cell activity in humans by enriching low-abundance beneficial bacteria and modulating their metabolic products, underscoring its promise as a microbiome-based functional food and preventative option to support immune health.”
Also in their conclusions
- They conclude that Lactiplantibacillus plantarum LM1004 boosts natural killer cell activity in humans by enriching low-abundance beneficial bacteria and modulating their metabolic products.
- They say the ingredient shows promise as a microbiome-based functional food and preventative option to support immune health.
- They advise that future studies using immune cell profiling and gene activity analysis could confirm the proposed mechanism.
How it was done
The authors wanted to test whether this heat-treated probiotic strain improves immune function in healthy adults, and to understand how it might work through the gut microbiome.
They gave 120 healthy adults aged 19 to 75 either a 500 mg daily capsule of heat-treated Lactiplantibacillus plantarum LM1004 or a placebo for 8 weeks. They also ran a lab model of the human colon with three compartments, adding the ingredient for 4 weeks and measuring bacteria and metabolites.
What it can’t tell you
- The lab model uses donated gut bacteria, not a living human gut, so it cannot show exactly what happens inside people.
- The trial was in healthy adults under stress, so the results may not apply to other groups.
- The study cannot prove that the changes in gut bacteria directly caused the immune changes.
Who paid
- Conflicts
- Conflict of Interest . The authors have no financial conflicts of interest to declare.
- Authors work at
- Soonchunhyang University, Republic of Korea; Yonsei University, Republic of Korea; Korea University, Republic of Korea
The paper
- Title
- Microbiome-Modulating Effects of Heat-Treated Lactiplantibacillus plantarum LM1004 and Its Enhancement of NK Cell Activity: Evidence from a Clinical Trial and a Simulated Human Intestinal Microbiome Ecosystem
- Type
- Randomised controlled trial
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Kim S, Seo H, Kim TR, et al (2026). Microbiome-Modulating Effects of Heat-Treated Lactiplantibacillus plantarum LM1004 and Its Enhancement of NK Cell Activity: Evidence from a Clinical Trial and a Simulated Human Intestinal Microbiome Ecosystem. Journal of microbiology and biotechnology. doi:10.4014/jmb.2604.04046Free full textPubMed 42487409DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error