This is intended for those with a lactose intolerance — meaning their bodies lack the digestive enzyme lactase, which breaks lactose down into glucose. (thelittlepine.com)
Lactose (milk sugar) intolerance, a deficiency of the intestinal enzyme lactase, is seen in some adult cats which is why the traditional saucer of milk is not necessarily the best treat for a cat. (petpeoplesplace.com)
These include intestinal inflammation; deficiency of the digestive enzyme lactase, associated with lactose intolerance; and increased intestinal permeability, sometimes called «leaky gut.» (sciencedaily.com)