+1 to that. Among all the people I've ever known (in India) only 2 people are lactose intolerant. Indian society has, historically, placed a lot of importance on the cow and milk. Indian mythology has rich references to milk and other dairy products for eg. Samudra Manthan [1], Krishna the cowherd [2]. If we were to consider the level of medicine practiced in India (see [3] and [4], for eg.), one would imagine that any real problem of such widespread nature would be heavily studied and discussed about.
[1] http://en.wikipedia.org/wiki/Samudra_manthan
[2] http://en.wikipedia.org/wiki/File:Krishna_with_flute.jpg