Human milk oligosaccharides (HMOs) are the third most abundant solid component in human milk after lactose and lipids. Preclinical research has demonstrated that HMOs and specifically 2'-fucosyllactose (2'-FL) are more than a prebiotic and have multiple functions, including immune, gut, and cognition benefits. Previously, human milk has been the only source for significant levels of HMOs. The most abundant HMO in most mothers' breast milk is 2'-FL. Recently, 2'-FL has been synthesized and shown to be structurally identical to the 2'-FL found in human milk. 2'-FL HMO is now available in some commercial infant formulas. The purpose of this narrative review was to summarize the clinical experiences of feeding infant formula supplemented with the HMO, 2'-FL. Most of these studies investigated standard intact milk protein-based infant formulas containing 2'-FL, and one evaluated a partially hydrolyzed whey-based formula. Collectively, these clinical experiences demonstrated that 2'-FL being added to infant formula was safe, well-tolerated, and absorbed and excreted with similar efficiency to 2'-FL in human milk. Further, infants that were fed formula with 2'-FL had immune benefits, fewer parent-reported respiratory infections, and improved symptoms of formula intolerance. Ultimately, infant formula with 2'-FL supports immune and gut health and is closer compositionally and functionally to human milk.
Keywords: 2′-FL; 2′-fucosyllactose; HMO; gastrointestinal tolerance; human milk oligosaccharide; infant; infant formula; infant growth; partially hydrolyzed formula; respiratory infection.