Immediately after being placed on it, most children experience several reactions, including eczema, rashes, constipation, ear infections and colds. Most of us simply adjust to the discomfort and go through life permanently gassy. After all, none of the smiling, beautiful stars with milk mustaches on billboards and the back of Time are quoted as receiving stomach cramps from drinking milk. However, there are those that join the ranks of Derek Hoyme, Leslie Wilcox, Chris Holstrom and Robyn Wyatt and come out as officially allergic to milk. Our milk intolerance really isn't all that curious.
Humans are the only species that consumes milk after infancy, especially that of another species.
Cow milk is perfectly designed to properly nourish a calf. I assume that I need not mention that the nutritional needs of a calf are not the same those of a human. Calcium comes from green, leafy vegetables, nuts and some grains. A diet that includes calcium in addition to weight training can successfully prevent osteoporosis. All this without mentioning the nasty hormones injected into cattle to produce more milk or the environmental degradation caused by billions of cow farts.