Entry 9
Probiotic science page
Stimulates immune components in breast milk to reduce infant infections, with RCT support.
Overview
L. fermentum CECT5716 is a probiotic strain isolated from human breast milk [1]. It has been studied mainly for infant health applications. These include reducing gastrointestinal and respiratory infections in formula-fed infants who cannot be exclusively breastfed [1][4]. In 2020, L. fermentum was reclassified to the genus Limosilactobacillus [6].
Mechanism
CECT5716 fights pathogens through production of lactic acid and bacteriocin-like substances (bacteria-killing compounds). These compounds inhibit enteropathogens including Salmonella and E. coli (in vitro) [1]. The strain activates Toll-like receptor 9 (TLR9) signaling in cells lining the gut. It changes cytokine profiles. It reduces interleukin-6 production (in vitro) [1]. In animal models, CECT5716 calms intestinal inflammation and dysbiosis. It does this by changing gut microbiota composition and immune cell populations (animal) [1]. The strain strengthens the intestinal barrier. It also blocks pathogens from sticking to epithelial binding sites [1].
Health Benefits
A randomized controlled trial showed that synbiotic infant formula with CECT5716 reduced gastrointestinal and upper respiratory tract infections in infants. This was compared to standard formula (RCT) [2]. A separate RCT showed beneficial effects on gut microbiota and immune markers in infants delivered by cesarean section. The strain partially restored the microbiota deficit linked to surgical delivery (RCT) [3]. A systematic review and meta-analysis (pools results from multiple trials) concluded that CECT5716 reduces gastrointestinal infections in infants (systematic review/meta-analysis) [4]. An RCT in premature infants assessed outcomes including necrotizing enterocolitis and late-onset sepsis (RCT) [5]. Evidence is strongest for infection reduction in term infants. Data in preterm populations are still emerging.
Biology
L. fermentum (old name: Lactobacillus fermentum; new name: Limosilactobacillus fermentum) is a Gram-positive, rod-shaped bacterium. It produces lactic acid plus other byproducts from sugar fermentation. It ferments hexoses and pentoses to lactic acid, acetic acid, ethanol, and CO₂. CECT5716 was isolated from human breast milk. This reflects the species’ presence in the human milk microbiota [1]. Zheng et al. (2020) reclassified L. fermentum from Lactobacillus to Limosilactobacillus based on genomic phylogeny [6].
Bibliography
Ozen M, Piloquet H, Schaubeck M. (2023). Limosilactobacillus fermentum CECT5716: Clinical Potential of a Probiotic Strain Isolated from Human Milk. Nutrients. 15(9):2207. PMID: 37432320
Piloquet H, et al. (2024). Efficacy and safety of a synbiotic infant formula for the prevention of respiratory and gastrointestinal infections: a randomized controlled trial. Am J Clin Nutr. 119(5):1259-1269. PMID: 38462218
Blanco-Rojo R, et al. (2022). Beneficial Effects of Limosilactobacillus fermentum CECT 5716 Administration to Infants Delivered by Cesarean Section. Front Pediatr. 10:906924. PMID: 35874592
Pastor-Villaescusa B, Blanco-Rojo R, Olivares M. (2021). Evaluation of the Effect of Limosilactobacillus fermentum CECT5716 on Gastrointestinal Infections in Infants: A Systematic Review and Meta-Analysis. Microorganisms. 9(7). PMID: 34208893
Hurtado Suazo JA, et al. (2025). L. Fermentum CECT5716 and B. Breve CECT7263 on premature infants morbidities: a randomized clinical trial. Pediatr Res. PMID: 41310220
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
CECT5716 is sold by Biosearch Life (Granada, Spain). It is added to infant formula products including those from HiPP and Hero Baby product lines [1][2]. The strain is also used in follow-on formula and growing-up milk products in European markets [1].