Effects of Bovine Lactoferrin on Vaginal Microbiota in Healthy Postmenopausal Women: A Randomized, Double-Blind, Placebo-Controlled Trial

Background/Objectives: This study investigated the effects of bovine lactoferrin (LF) on vaginal microbiota in healthy postmenopausal women. Methods: A randomized, double-blind, placebo-controlled trial was conducted. Healthy Japanese postmenopausal women were administered a placebo or bovine LF (300 mg/day) for 12 weeks. The primary endpoint was the Nugent score and the secondary endpoints were the Nugent sub-scores. The exploratory outcomes included vaginal immunoglobulin and urinary deoxypyridinoline levels. Results: Eighty participants were randomized (placebo, n = 40; LF, n = 40), of whom 8 were excluded. The remaining 72 participants (placebo group: n = 36; LF group: n = 36) were included in the per-protocol set. Although the Nugent score was lower in the LF group, the difference was not significant. The Gardnerella/Bacteroides Nugent sub-score was significantly lower in the LF group than in the placebo group. The vaginal immunoglobulin G1 levels were significantly higher in the LF group than in the placebo group. In addition, the urinary deoxypyridinoline levels were significantly lower in the LF group than in the placebo group. Adverse events were comparable between the groups and no adverse drug reactions were observed. Conclusions: Although oral LF supplementation did not significantly affect the primary endpoint (overall Nugent score), a lower Gardnerella/Bacteroides morphotype score and higher vaginal IgG1 levels were observed. As these findings were derived from secondary and exploratory analyses, respectively, they are considered hypothesis-generating and require confirmation in future studies.