2´-Fucosyllactose (2´-FL) – HMO in Breast Milk

What is 2´-Fucosyllactose?

2´-Fucosyllactose (2´-FL) is a complex carbohydrate belonging to the group of human milk oligosaccharides (HMOs). It is the most abundant oligosaccharide found in human breast milk, making up a significant proportion of the total HMO fraction. Chemically, it is a trisaccharide composed of fucose, galactose, and glucose, with fucose attached at the 2-position of galactose – hence the name.

Biological Functions

2´-FL performs several important biological roles in infants:

• Prebiotic effect: 2´-FL serves as a food source for beneficial gut bacteria, particularly Bifidobacterium longum subsp. infantis, thereby promoting the development of a healthy gut microbiome.
• Protection against pathogens: 2´-FL acts as a so-called decoy receptor. Pathogens such as Helicobacter pylori, noroviruses, and enterotoxigenic Escherichia coli preferentially bind to free 2´-FL molecules rather than to the intestinal mucosa, thereby preventing infections.
• Immune modulation: 2´-FL directly influences immune cells and can dampen pro-inflammatory processes, contributing to the maturation of the immune system.
• Brain development: Fucosylated oligosaccharides may support cognitive development and the maturation of the nervous system.

Occurrence and Sources

2´-FL occurs naturally and exclusively in human breast milk, with particularly high concentrations in colostrum (the first milk produced after birth). The amount varies depending on the genetic background of the mother – so-called secretor mothers (approximately 70–80% of all mothers) produce significantly more 2´-FL than non-secretor mothers. Animal milk contains no or only negligible amounts of 2´-FL.

Through modern biotechnological processes – primarily microbial fermentation – 2´-FL can now be produced on a large scale and added to infant formula.

Application in Infant Nutrition

Since breastfed infants naturally benefit from HMOs, 2´-FL is now an approved additive in infant formula and follow-on formula. The European Food Safety Authority (EFSA) has assessed 2´-FL as safe for use in infant formula. The goal is to mimic the composition of breast milk as closely as possible.

Scientific Evidence and Health Benefits

Clinical studies show that infants fed 2´-FL-supplemented formula demonstrated similar growth and safety profiles to breastfed infants. Additional observed effects include:

• Reduction of respiratory infections and diarrheal diseases
• Favorable influence on the composition of the gut microbiome
• Possible reduction of the risk of necrotizing enterocolitis (NEC) in premature infants
• Support of immune tolerance and reduction of allergic reactions

Research into 2´-FL is ongoing; many of the positive effects have been demonstrated in animal and in vitro studies and need to be confirmed in further clinical trials in humans.

Safety and Tolerability

2´-FL is considered very well tolerated in both infants and adults. Adverse effects are rare and, at high doses, may occasionally include mild gastrointestinal complaints such as bloating. Both EFSA and the US Food and Drug Administration (FDA) have recognized 2´-FL as safe.

References

1. Bode, L. (2012). Human milk oligosaccharides: Every baby needs a sugar mama. Glycobiology, 22(9), 1147-1162. doi:10.1093/glycob/cws074
2. EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) (2015). Safety of 2'-fucosyllactose as a novel food ingredient. EFSA Journal, 13(7), 4184.
3. Vandenplas, Y. et al. (2018). Human Milk Oligosaccharides: 2'-Fucosyllactose (2'-FL) and Lacto-N-Neotetraose (LNnT) in Infant Formula. Nutrients, 10(9), 1161. doi:10.3390/nu10091161