Probiotic supplementation also significantly increased Lactobacillus and Bifidobacterium levels, which researchers said could have mediated these changes.
Writing in npj Science of Food, researchers from Sun Yat-sen University and Zhongshan City People’s Hospital said the probiotic could have improved adiposity-related outcomes, partly through gut microbiota remodeling.
A total of 110 middle-aged individuals aged 40 to 65 with metabolic syndrome took part in the 12-week randomized, double-blind, placebo-controlled trial, where they were randomized to take a capsule containing either 5 bn CFU of Lactiplantibacillus plantarum J26 or placebo after a meal daily.
Lactiplantibacillus plantarum J26 is a probiotic isolated from traditional fermented yogurt, which has shown promising metabolic benefits in preclinical studies.
All study materials were both provided by Shanghai-based BioGrowing Co., Ltd.
Findings showed that probiotic supplementation could significantly lower body weight.
By the end of the study, the probiotic group reported a 0.97kg reduction in body weight, down from the baseline of 71.51 ± 12.03 kg to 70.55 ± 11.98 kg.
The placebo group showed a non-significant reduction, which was down from 69.65 ± 11.00 kg to 69.43 ± 11.09 kg, with a mean change of 0.22 kg.
The net difference in body weight between the two groups was 0.75kg.
Other parameters, including BMI, waist circumference and body fat, also saw a significant reduction.
Waist circumference, for example, was reduced by 1.92cm. Body fat decreased by 0.87% and BMI by 0.29kg/m².
While probiotic supplementation lowered triglycerides, total cholesterol and LDL-cholesterol relative to placebo, none of the between-group differences reached statistical significance.
No significant between-group differences were also seen for glycemic and blood pressure outcomes, including fasting plasma glucose, HbA1c, insulin, HOMA-IR, systolic blood pressure and diastolic blood pressure.
Researchers said this might be because of mild baseline metabolic abnormalities, and a longer intervention period may be needed to see significant differences.
“These findings suggest that J26 supplementation may preferentially improve adiposity-related traits, whereas broader metabolic effects may require longer intervention periods, higher doses, or populations with greater metabolic impairment,” the researchers wrote.
Enrichment in Lactobacillus and Bifidobacterium
Probiotic supplementation also increased Lactobacillus and Bifidobacterium compared to placebo by the end of the 12-week intervention.
The increase in Lactobacillus also significantly mediated the effects of probiotic intervention on reductions in body weight, BMI, and body fat, accounting for 67.3%, 67.3%, and 46.4% of the total effects, respectively.
On the other hand, the change in Bifidobacterium levels accounted for 60.4% of the association between probiotic supplementation and BMI reduction, with no significant mediation effects in body weight, waist circumference, or body fat.
“Mechanistically, Lactobacillus may act via microbiota-derived metabolites that enhance energy expenditure and adipose remodeling, whereas Bifidobacterium may influence bile acid–associated activation of oxidative and thermogenic pathways in adipose tissue,” the researchers explained.
The role of host-specific factors
The researchers also suggested that host-specific factors, such as dietary quality, protein and fiber intake, might have contributed to the effectiveness of probiotic supplementation.
“Notably, responders were characterized by higher baseline dietary quality, including higher CHEI (Chinese Healthy Eating Index) scores, greater dietary protein and fiber intake, and less fat intake, suggesting that higher baseline dietary quality may provide a more favorable ecological context for probiotic colonization and microbial cross-feeding,” the researchers wrote.
Individuals who responded to probiotic supplementation also exhibited more pronounced gut microbiota remodeling, with greater enrichment of Lactobacillus, Bacteroides, and Anaerobutyricum.
Although these associations remain inferential, the researchers suggested that baseline dietary quality and intervention-related microbial remodeling may partly explain the observed heterogeneity in metabolic responses to probiotic supplementation.
Source: npj Sci Food. doi: 10.1038/s41538-026-01114-w. “Lactiplantibacillus plantarum J26 supplementation improves adiposity-related outcomes in adults with metabolic syndrome via remodeling the gut microbiota.” Authors: Zheng, J. et al.
