LACTOSE

LACTOSE--> GAL + GLU
GAL 1P+ UDP GLU-->
GLU 1P-->
GLU 6P-->
KREBS

UDP GAL-->UDP GLU
TRANS-FER-ase
\-->GALACTOS-EMIA

Related reading:

The Tyrolean Iceman, a 5,300-year-old Copper age individual had complete genome sequenced - he was lactose intolerant. Nature, 2012.