The level of galactose in fermented milk products depends
on growth conditions of the different organisms and fermentation
time, and for example after 24 h fermentation,the concentration of galactose has been reported to about 20 g/litre . A study in rats showed that administration
of galactose in the form of lactose seemed to be less toxic than when galactose was fed. High levels of galactose as well as glucose may cause glycation of proteins,
form advanced glycation end products, and the activation of polyol metabolism. This may accelerate generation of reactive oxygen species (ROS) and increases
in oxidative chemical modification of lipids, DNA, and proteins in various tissues.