Effects of Lactobacillus curvatus HY7601 and Lactobacillus plantarum KY1032 on Overweight and the Gut Microbiota in Humans: Randomized, Double-Blinded, Placebo-Controlled Clinical Trial

Randomized, double-blind, placebo-controlled trial in healthy Korean adults who were overweight or obese. The active intervention arm included 30 participants, with eligibility criteria of age >19 to ≤65 years and BMI ≥23.0 to <35.0 kg/m2.

Participants in the active arm took 1 oral probiotic capsule daily after breakfast for 12 weeks. Each capsule contained Lactobacillus curvatus HY7601 250 mg and Lactobacillus plantarum KY1032 250 mg, providing 5 × 10^9 cfu of each strain (1 × 10^10 cfu total per capsule).

The probiotic intervention produced modest but significant reductions in adiposity over 12 weeks. In the active arm, body weight decreased by -0.47 ± 0.29 kg (p = 0.001), BMI by -0.15 ± 0.1 kg/m2 (p < 0.001), waist circumference by -0.41 ± 0.37 cm (p = 0.007), body fat mass by -0.28 ± 0.24 kg (p = 0.043), lean body mass by -0.18 ± 0.25 kg (p = 0.032), and visceral fat area by -1.67 ± 1.44 cm2 (p = 0.025). Adiponectin increased by 133.33 ± 150.47 ng/mL (p = 0.046), while hip circumference, leptin, insulin, hs-CRP, and the reported lipid measures did not show clear significant benefit. The authors concluded that HY7601 and KY1032 may have anti-obesity effects, potentially mediated by beneficial shifts in gut microbiota.

The active arm was small (n = 30) and the intervention lasted only 12 weeks, limiting precision and durability assessment. Participants were healthy overweight/obese Korean adults, so generalizability to other populations is uncertain. Some clinically relevant outcomes were not significant, including hip circumference, leptin, insulin, and hs-CRP.