That's probably because people commonly refer to it as lactose intolerance, which is very much is not. Moms whose babies have this cut all dairy -- sometimes they can still have small bits but sometimes they can't have even the trace amounts you don't even realize are in things. Babies usually but not always outgrow it by the time they're a year or two old. When a baby can handle soy formula, this is probably what they have -- but SOME very unlucky babies react to both cow's milk proteins and soy, and their poor moms end up eating a very restricted diet. There are special formulas for such babies, but they cost a fortune and taste so bad it's hard to get babies to drink them, so many moms end up living on difficult diets for a while. I am thankful that I could eat anything I wanted while nursing.