Entry 8
Probiotic science page
Produces biosurfactants that inhibit vaginal pathogens to restore and maintain healthy vaginal flora, with RCT evidence.
Overview
L. reuteri RC-14 is a urogenital probiotic strain. It was originally isolated from the distal urethra of a healthy woman. It was first identified as L. fermentum [1][5]. It is used almost exclusively in combination with L. rhamnosus GR-1. The two strains are given as oral supplements for vaginal and urinary tract health [1][5]. The strain has been reclassified to Limosilactobacillus reuteri [7].
Mechanism
RC-14 sticks to vaginal and uroepithelial cells. This forms a colonization barrier that blocks uropathogens by taking up space. Blocked pathogens include Escherichia coli and Candida species [1][5]. The strain produces biosurfactants. These compounds stop pathogens from sticking and reduce biofilm formation on epithelial surfaces [5]. RC-14 tunes local immune responses. This includes turning down pro-inflammatory signals from epithelial cells (in vitro) [5]. When taken by mouth, RC-14 and GR-1 travel through the gastrointestinal tract. They then ascend to colonize the vaginal area. This measurably changes vaginal flora composition [1].
Health Benefits
A randomized, placebo-controlled trial in 64 healthy women showed that oral RC-14/GR-1 capsules restored normal vaginal lactobacilli-dominated flora. The restoration rate was 37% with probiotics versus 13% with placebo (P=0.02). The trial also found reductions in coliform and yeast colonization (RCT) [1]. An RCT in 65 HIV-positive women found no improved BV cure rate when probiotics were added to metronidazole. The results suggested preventive benefit for intermediate flora (Nugent 4–6; OR 2.4, P=0.1). The trial also found a beneficial effect on vaginal pH (OR 3.8, P=0.02) (RCT) [2]. A Chinese RCT found no additional BV cure rate when RC-14/GR-1 was combined with metronidazole (RCT) [3]. A pilot RCT in pregnant women showed no reduction in Group B Streptococcus colonization (RCT) [4]. Evidence supports vaginal flora modulation in healthy women. Efficacy for treating established BV is inconsistent across populations.
Biology
RC-14 was originally described as L. fermentum. It was later reclassified as L. reuteri [1]. In 2020, Zheng et al. transferred the species from Lactobacillus reuteri (old name) to Limosilactobacillus reuteri (new name) [7]. It is a Gram-positive, rod-shaped bacterium. It produces lactic acid plus other byproducts from sugar fermentation. The strain was isolated from the human distal urethra [5]. L. reuteri naturally lives in the gastrointestinal and urogenital tracts of humans [7].
Bibliography
Reid G, et al. (2003). Oral use of Lactobacillus rhamnosus GR-1 and L. fermentum RC-14 significantly alters vaginal flora: randomized, placebo-controlled trial in 64 healthy women. FEMS Immunol Med Microbiol. 35(2):131-134. PMID: 12628548
Hummelen R, Changalucha J, Butamanya NL, Cook A, Habbema JD, Reid G. (2010). Lactobacillus rhamnosus GR-1 and L. reuteri RC-14 to prevent or cure bacterial vaginosis among women with HIV. Int J Gynaecol Obstet. 111(3):245-248. PMID: 20801446
Zhang Y, et al. (2021). Probiotic Lacticaseibacillus rhamnosus GR-1 and Limosilactobacillus reuteri RC-14 as an Adjunctive Treatment for Bacterial Vaginosis Do Not Increase the Cure Rate in a Chinese Cohort: A Prospective, Parallel-Group, Randomized, Controlled Study. Front Cell Infect Microbiol. 11:669901. PMID: 34295831
Sharpe M, et al. (2021). Effectiveness of oral intake of Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 on Group B Streptococcus colonization during pregnancy: a midwifery-led double-blind randomized controlled pilot trial. J Matern Fetal Neonatal Med. 34(11):1814-1821. PMID: 31362572
Reid G. (2008). Probiotic Lactobacilli for urogenital health in women. J Clin Gastroenterol. 42 Suppl 3 Pt 2:S234-S236. PMID: 18685506
Reid G, Bruce AW. (2006). “Probiotics to prevent urinary tract infections: the rationale and evidence.” World J Urol. 24(1):28-32. PMID: 16389539
Zheng J, et al. (2020). A taxonomic note on the genus Lactobacillus: Description of 23 novel genera, emended description of the genus Lactobacillus Beijerinck 1901, and union of Lactobacillaceae and Leuconostocaceae. Int J Syst Evol Microbiol. 70(4):2782-2858. PMID: 32293557
Available Products
RC-14 is formulated with L. rhamnosus GR-1 in oral capsules. The combination was developed through the Urex Biotech platform. It was later added to the Chr. Hansen portfolio [1][5]. The combination is marketed under multiple brand names internationally for women’s urogenital health [6].