Frank Oski, MD, Former Director of the Department of Pediatrics at Johns Hopkins University, wrote in his 1996 book Don't Drink Your Milk!:

“Studies have suggested that some of the nutritional benefits of milk may be lost when a lactase-deficient [lactose intolerant] individual consumes milk. Not only does this person fail to receive the calories normally supplied by the undigested carbohydrates; resultant diarrhea may lead to loss of protein as well.

Two studies were conducted in groups of children with ‘recurrent abdominal pain of childhood,’ one study preformed in Boston and the other in San Francisco, came to a similar conclusion. The conclusion was that about one-third of such children had their symptoms on the basis of lactose intolerance. The simple solution was to remove all milk and milk-containing foods from the diet.”