Safety evaluation of the human-identical milk monosaccharide, l-fucose.

l-Fucose is a natural monosaccharide present in mammals where it is found predominantly as an O-glycosidically linked component of glycoproteins, glycolipids, and oligosaccharides. It is also present in its free form in human breast milk (human milk monosaccharide). l-Fucose plays important roles in the development of the immune and nervous systems and is involved in cognitive function and memory formation. The human-identical milk monosaccharide l-fucose is therefore proposed for use in infant formulas to better simulate the free saccharides present in human breast milk. As part of the safety evaluation of l-fucose, a subchronic dietary toxicity study preceded by an in utero phase was conducted in Sprague-Dawley rats. l-Fucose was without maternal toxicity or compound-related adverse effects on female reproduction and general growth and development of offspring at a maternal dietary level up to 1%, equivalent to a dose of 1655 mg/kg body weight (bw)/day. During the subchronic phase, no compound-related adverse effects were observed in first generation rats at dietary levels of up to 1% (highest level tested), corresponding to doses of 516 and 665 mg/kg bw/day in males and females, respectively. l-Fucose was non-genotoxic in a series of in vitro genotoxicity/mutagenicity tests. These results support the safe use of l-fucose in infant formula and as a food ingredient at levels equivalent to those present in human breast milk.