Some are intolerant to this disaccharide present in milk
Some cell biology questions (cancer & lactose intolerance) ... the enzyme 
necessary to hydrolyze lactose, the disaccharide present in milk" [DOC] [TLE] Lactose intolerance - Wikipedia [PAR] Lactose intolerance is a condition in which people have symptoms due to the 
decreased ability to digest lactose, a sugar found in milk products.