Key Takeaways
- In a randomized, double-blind trial of 72 adults with stage 3 or 4 chronic kidney disease, six months of Lactobacillus plantarum supplementation improved creatinine-based measures of kidney function compared with placebo.
- Median estimated glomerular filtration rate, or eGFR, increased by 4.85 mL/min/1.73 m² in the probiotic group and declined by 1.5 mL/min/1.73 m² in the placebo group.
- A post hoc analysis adjusting for baseline eGFR also favored the probiotic, but the trial was small, conducted at one center, and did not confirm kidney function using cystatin C or directly measured GFR.
- The study does not establish that probiotics prevent chronic kidney disease progression, and it does not justify starting an over-the-counter probiotic as a CKD treatment.
Introduction
A randomized trial investigated whether six months of Lactobacillus plantarum supplementation could improve kidney-function measures in adults with stage 3 or 4 chronic kidney disease.
A specific probiotic was associated with improved creatinine-based measures of kidney function compared with placebo in people with moderate-to-severe chronic kidney disease in a small randomized clinical trial published September 4, 2026, in Scientific Reports.
Researchers at Mansoura University in Egypt randomly assigned 72 adults with stage 3 or 4 chronic kidney disease, or CKD, to receive either Lactobacillus plantarum or placebo daily for six months. Estimated kidney function improved in the probiotic group while declining in the placebo group (Saleh et al., 2026).
The result is potentially important because previous trials and evidence reviews of probiotics, prebiotics and synbiotics in CKD have produced inconsistent findings. A 2023 Cochrane review concluded that it remained uncertain whether these interventions improve kidney function because the available evidence was generally low or very low certainty (Cooper et al., 2023).
The new trial provides a notable signal, but its size, single-center setting and reliance on creatinine-based kidney measurements mean that larger studies are needed before the findings should influence routine treatment.
What the Study Examined
Saleh et al. (2026) conducted a double-blind, randomized, placebo-controlled trial at the Urology and Nephrology Center at Mansoura University in Egypt between May and November 2025.
Participants were adults with stage 3 or 4 CKD, defined in the study as an eGFR of 15 to 59 mL/min/1.73 m². Their median age was approximately 60. More than 80% were men, most had hypertension, and about 40% had diabetes.
Thirty-seven participants were assigned to take one capsule containing 10¹⁰ colony-forming units of Lactobacillus plantarum each day. Thirty-five received an identical-looking placebo containing microcrystalline cellulose.
Both groups continued standard CKD management and received dietary counseling. Among participants with hypertension, treatment with an ACE inhibitor or angiotensin-receptor blocker remained stable during follow-up.
The trial used computer-generated randomization and concealed allocation with sequentially numbered, sealed opaque envelopes. Participants and research personnel were blinded to treatment assignment. All 72 participants completed the six-month study (Saleh et al., 2026).
The prespecified primary outcome was the change in eGFR from baseline to six months. The researchers also assessed serum creatinine, 24-hour proteinuria, urinary indoxyl sulfate and several other laboratory measures.
What Researchers Found
The primary kidney-function result favored the probiotic.
Median eGFR increased by 4.85 mL/min/1.73 m² in the probiotic group, with an interquartile range of 2.86 to 7.78. In the placebo group, median eGFR declined by 1.5 mL/min/1.73 m², with an interquartile range of -6.26 to 0. The difference in changes between the groups was statistically significant (Saleh et al., 2026).
Serum creatinine showed a consistent pattern. Median creatinine decreased by 0.3 mg/dL in the probiotic group and increased by 0.1 mg/dL in the placebo group.
Measured 24-hour creatinine clearance also moved in the same direction. It increased by a median of 7.80 mL/min among probiotic recipients and declined by 4.90 mL/min among placebo recipients (Saleh et al., 2026).
The investigators subsequently performed a baseline-adjusted analysis that was not prespecified before the trial. In that post hoc ANCOVA, adjusted mean eGFR at six months was 38.90 mL/min/1.73 m² in the probiotic group and 31.18 mL/min/1.73 m² in the placebo group.
That corresponded to an adjusted difference of 7.72 mL/min/1.73 m², with a 95% confidence interval of 5.63 to 9.82. Because this analysis was added after the trial began, it should be considered supportive rather than a replacement for the prespecified primary analysis (Saleh et al., 2026).
Not every kidney-related outcome favored the probiotic.
Twenty-four-hour proteinuria increased in both groups. The median increase was 0.42 g/24 h in the probiotic group and 0.54 g/24 h in the placebo group, with no statistically significant difference in the amount of change between groups.
The researchers also examined a CKD-progression endpoint defined as at least a 25% decline in eGFR or a doubling of serum creatinine. None of the 37 probiotic recipients met that definition, compared with three of 35 placebo recipients, or 8.6%.
However, that difference was not statistically significant, with a p value of 0.11. The trial therefore does not demonstrate that the probiotic prevented CKD progression (Saleh et al., 2026).
No adverse events, side effects or unintended harms were reported in either group during the six-month study.
How It Compares With Earlier Research
The idea that altering gut bacteria could affect kidney disease has attracted growing research interest, but clinical results have not been consistent.
A 2022 network meta-analysis by Tan et al. evaluated 28 randomized trials involving 1,373 people with CKD. Probiotics were associated with lower serum creatinine overall. However, the researchers did not find a statistically significant overall improvement in eGFR with probiotics, prebiotics or synbiotics (Tan et al., 2022).
Other analyses have been less favorable. Liu et al. (2023) combined 12 randomized controlled trials involving 652 non-dialysis participants and found that prebiotic, probiotic or synbiotic supplementation did not significantly reduce serum creatinine compared with placebo.
That analysis was not limited exclusively to people with CKD. Seven of the 12 included trials involved non-dialysis kidney disease, while the remainder involved other populations, including people with diabetes and hypertension. In the kidney-disease subgroup, the pooled analysis likewise found no significant difference in serum creatinine between biotic interventions and placebo (Liu et al., 2023).
The evidence was also cautious in a subsequent Cochrane review.
Cooper et al. (2023) examined 45 randomized studies involving 2,266 participants with CKD. The review included people receiving dialysis as well as those not receiving dialysis and concluded that there was insufficient reliable evidence to determine whether probiotics, prebiotics or synbiotics improve kidney function, gastrointestinal symptoms, quality of life or levels of uremic toxins.
The reviewers rated much of the evidence as low or very low certainty because studies were generally small and had methodological limitations (Cooper et al., 2023).
Taken together, the conflicting results across individual trials and evidence reviews mean the apparent kidney-function improvement in the new study deserves further investigation, but does not settle whether microbiome-targeted supplements meaningfully preserve kidney function in CKD.
What the Results May Mean
Researchers have proposed that gut bacteria could influence CKD partly through the production of uremic toxins.
One toxin investigated in the new trial was indoxyl sulfate, which originates from bacterial metabolism in the intestine and accumulates as kidney function declines.
The researchers expected that L. plantarum might improve kidney function partly by reducing indoxyl sulfate. That explanation was not supported by the results.
Urinary indoxyl sulfate concentrations did not differ significantly between the probiotic and placebo groups after six months. Changes in urinary indoxyl sulfate were also not correlated with changes in eGFR (Saleh et al., 2026).
Other biological pathways could theoretically be involved, including changes in intestinal-barrier function, inflammation or microbial metabolites. However, the trial did not measure gut microbiome composition, inflammatory biomarkers or short-chain fatty acids.
The study therefore shows a difference in kidney-function measurements but does not establish how the probiotic produced that difference.
It is also important that the intervention cannot be generalized to probiotics as a category. The trial tested a particular L. plantarum product at a dose of 10¹⁰ colony-forming units daily. Different probiotic organisms, strains, formulations and doses may not have the same effects.
Limitations
The trial has several limitations that materially affect its interpretation.
First, only 72 people participated, and all were recruited at a single center in Egypt. Small trials can produce treatment-effect estimates that change substantially when the intervention is tested in larger populations.
The participants were also predominantly male. Only 13 women were included, limiting confidence about how well the results apply to women.
Second, the primary outcome depended on serum creatinine. The researchers calculated eGFR using the 2021 CKD-EPI creatinine equation. Creatinine is useful in clinical practice, but its level can be influenced by factors other than filtration, including muscle mass and creatinine production.
The 24-hour creatinine-clearance findings pointed in the same direction, and body weight and BMI did not decrease in the probiotic group. Those observations make a simple explanation based solely on loss of body mass less likely. Still, creatinine clearance also depends on creatinine and can be affected by tubular secretion and the accuracy of urine collection (Saleh et al., 2026).
The researchers did not measure cystatin C and did not directly measure GFR using an exogenous filtration marker. Independent confirmation of the apparent kidney-function improvement is therefore particularly important.
Third, proteinuria increased in both groups. Although the increase was not significantly different between groups, the finding means the probiotic did not produce consistent improvement across all kidney-related measures.
Fourth, follow-up lasted only six months. CKD is a long-term condition, and the trial cannot determine whether the observed eGFR difference would persist or translate into a lower risk of kidney failure, dialysis or other major clinical outcomes.
Finally, the trial did not establish a biological mechanism for the effect.
The study was funded by the Urology and Nephrology Center at Mansoura University as part of an MD research program. The authors reported no external commercial or industry funding and declared no competing financial or non-financial interests (Saleh et al., 2026).
Final Thoughts
Six months of daily Lactobacillus plantarum supplementation produced better creatinine-based kidney-function measures than placebo in this randomized trial of adults with stage 3 or 4 CKD.
The randomized, double-blind design, complete follow-up and consistent direction of the eGFR, serum-creatinine and creatinine-clearance results make the finding worth taking seriously.
But it is not yet evidence that probiotics should become part of standard CKD treatment.
The trial involved only 72 participants, did not independently confirm the apparent improvement with cystatin C or directly measured GFR, found no advantage for proteinuria, and did not demonstrate a statistically significant reduction in its CKD-progression endpoint. Previous randomized-trial evidence and systematic reviews have also produced inconsistent or low-certainty results.
The appropriate next step is replication in a larger, multicenter trial with longer follow-up and independent measures of kidney filtration. Such research would help determine whether the laboratory changes represent a durable improvement in kidney function and, ultimately, whether they lead to better outcomes for patients.
People with chronic kidney disease should not start, stop or replace treatment with a probiotic based on this study alone. Supplement decisions should be discussed with a clinician who can consider kidney function, medications and individual health risks.
References
Cooper, T. E., Khalid, R., Chan, S., Craig, J. C., Hawley, C. M., Howell, M., Johnson, D. W., Jaure, A., Teixeira-Pinto, A., & Wong, G. (2023). Synbiotics, prebiotics and probiotics for people with chronic kidney disease. Cochrane Database of Systematic Reviews, 2023(10), CD013631. https://doi.org/10.1002/14651858.CD013631.pub2
Liu, F., Liu, Y., Lv, X., & Lun, H. (2023). Effects of prebiotics, probiotics and synbiotics on serum creatinine in non-dialysis patients: A meta-analysis of randomized controlled trials. Renal Failure, 45(1), 2152693. https://doi.org/10.1080/0886022X.2022.2152693
Saleh, S. E., Elnagar, S. S. E., Fouda, M. A., & Sayed-Ahmed, N. (2026). Effects of probiotic supplementation on disease progression in patients with moderate to severe chronic kidney disease: A randomized controlled trial. Scientific Reports, 16, 27799. https://doi.org/10.1038/s41598-026-67044-5
Tan, J., Zhou, H., Deng, J., Sun, J., Zhou, X., Tang, Y., & Qin, W. (2022). Effectiveness of microecological preparations for improving renal function and metabolic profiles in patients with chronic kidney disease. Frontiers in Nutrition, 9, 850014. https://doi.org/10.3389/fnut.2022.850014
