Fructooligosaccharides: From Breast Milk Components to Potential Supplements. A Systematic Review

Breast milk is the optimal food choice for infant growth and development. Among breast milk components, fructooligosaccharides (FOSs) are being actively studied because of their role in microbiota development. In particular, 2'-fucosyllactose is being proposed as a potential supplement/nutraceutical or component of infant formula. In this systematic review, we critically summarize the available information on FOSs and we discuss their future use in infant nutrition. We searched the main electronic databases (PubMed, Embase, and Scopus), with a final check in May 2021. Search terms were inserted individually and using the Boolean tools AND and OR. Relevant articles were identified using the following words: ("fructooligosaccharides" OR "FOS") AND ("human milk" OR "breast milk" OR "donor milk" OR "bank milk"). The search retrieved 1814 articles. After removal of duplicates, we screened 1591 articles based on title, abstract, and exclusive use of the English language. We included articles describing the concentration of FOSs in human milk and assessed the relevant ones. We excluded reviews, studies on animals, and studies exclusively carried out on adults. Also, we excluded studies that have not reported evidence either on FOSs or on galactooligosaccharides from human milk. The resulting publications were reviewed, and 10 studies were included in the systematic review. We conclude that human milk FOSs are, indeed, crucial to infant gut development and their addition to infant formula is safe, well-tolerated, and might provide immune benefits to newborns. However, we would like to underscore the scantiness of human data and the need to avoid the immediate translation of infant research to the commercialization of supplements marketed to adults.