Metabolic & Cardiometabolic · Gut & Microbiome
Lactobacillus paracasei W8 increases GLP-1
In plain terms: Does the probiotic L. paracasei boost the appetite-and-blood-sugar hormone GLP-1?
Unclear — evidence is mixed; the main trial found no effect on the hormone, appetite, or blood sugar.
📅 Last reviewed: 2026-07-15 ⓘ
Evidence ladder
How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."
Top evidence so far: Human trials (RCT / n-of-1)
How the studies fall
What the evidence shows
L. paracasei W8 had NO effect on GLP-1, glucose, insulin, appetite or energy intake in a 4-wk RCT (n=64) — a Lactobacillus is not automatically a GLP-1 booster; strain-specificity is real.
The evidence (12)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Potrykus 2025 · Nutr | RCT | tested-null | low | 12-wk preoperative probiotic vs placebo: no clear benefit on gastrointestinal peptides (incl. incretins) 6 mo post-bariatric surgery. |
| NabizadehAsl L, Sendur SN, Ozer B, Lay I, Erbas T, Buyuktuncer Z 2022 · Appetite | RCT | tested-null | high | DB crossover: L. paracasei subsp. paracasei 431 +/- inulin did not robustly raise satiety hormones; effects on GLP-1 not significant. |
| Xu W, Guan Y, Tian L, Fu Y, Zhang Y, Liu Y, Hu Y, Zhao B, Wu C 2025 · Curr Microbiol | animal | mixed | low | L. paracasei Glu-07 characterized as anti-T2DM candidate via microbiota/metabolic pathways; GLP-1 stimulation inferred mechanistically, not measured in humans. |
| Bjerg AT, Sørensen MB, Krych L, Hansen LH, Astrup A, Kristensen M, Nielsen DS 2015 · Benef Microbes | RCT | tested-null | moderate | W8 lowered triacylglycerol independent of colonisation; no GLP-1 benefit |
| Li S, Liu Z, Zhang Q, Su D, Wang P, Li Y, Shi W, Zhang Q 2024 · Nutrients | observational | mixed | low | Review of antidiabetic probiotics: some Lactobacillus strains improve incretin/insulin signaling, but GLP-1 elevation is strain- and host-dependent. |
| Zeng Y, Wu Y, Zhang Q, Xiao X 2024 · mBio | observational | mixed | low | Review of microbiota-GLP-1 crosstalk: SCFA/bile-acid/TGR5 routes can modulate GLP-1, but specific Lactobacillus strains give inconsistent human GLP-1 effects. |
| Nilsson A, Johansson-Boll E, Sandberg J, Björck I 2016 · Clin Nutr ESPEN | RCT | tested-null | high | Co-ingesting commercial probiotics with barley did not enhance gut-hormone (GLP-1) or appetite responses beyond fiber fermentation alone. |
| Xiang M, Sa X, Tuo Z, Bian J, Wang P, Zhang X 2025 · Front Nutr | meta-analysis | tested-null | low | SR/MA: probiotic supplementation improved islet beta-cell function/glycemia in glucose-metabolism disorders; direct GLP-1 elevation not consistently shown. |
| Bjerg AT, Kristensen M, Ritz C, Stark KD, Holst JJ, Leser TD, Wellejus A, Astrup A 2015 · Benef Microbes | RCT | contradicts | moderate | Double-blind placebo RCT, 64 healthy young adults, L. casei W8 10^10 cfu/d x 4 wk, meal test: 'Compared to placebo, L. casei W8 did not affect appetite, ad libitum energy intake, GLP-1, glucose and insulin response'. Null on the directional claim -> contradicts; no GLP-1 estimate or CI in the abstract. Off-object: fasting TAG fell vs placebo (P=0.03). Two authors from the strain manufacturer (Chr. Hansen). |
| Simon MC, Strassburger K, Nowotny B, Kolb H, Nowotny P, Burkart V, Zivehe F, Hwang JH, Stehle P, Pacini G, Hartmann B, Holst JJ, MacKenzie C, Bindels LB, Martinez I, Walter J, Henrich B, Schloot NC, Roden M 2015 · Diabetes Care | RCT | supports | high | Proof-of-concept RCT: L. reuteri (not paracasei) increased GLP-1/GLP-2 and insulin secretion in glucose-tolerant humans - strain-specific, not W8. |
| Bjerg AT, Kristensen M, Ritz C, Holst JJ, Rasmussen C, Leser TD, Wellejus A, Astrup A 2014 · Appetite | RCT | tested-null | moderate | L. paracasei W8 suppressed energy intake but no significant GLP-1 effect; single network |
| Chowdhury S, Reeds DN, Crimmins DL, Patterson BW, Laciny E, Wang S, Tran HD, Griest TA, Rometo DA, Dunai J, Wallendorf MJ, Ladenson JH, Polonsky KS, Wice BM 2014 · Am J Physiol Gastrointest Liver Physiol | RCT | contradicts | high | Endogenous GLP-1 may not be a major insulin-secretion enhancer under physiological human conditions - tempers GLP-1-centric probiotic claims. |
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Educational only, not medical advice. Grades and scores reflect published evidence weighted by study design and quality; see the methodology.