I was interested in Jon Ahrendsen's letter about baby and toddler who got ear infects. when their nursing mother consumed lots of cow milk. He brought up some provocative points on this kind of sensitivity. My youngest -- who did some nursing until she was 5-5 1/2 -- never had an ear infection until she totally weaned. At that point she developed a pattern which continues to date (she's now 10) of an annual ear infection during rag weed season. My understanding of food (and other) intolerances is that there is a concept called "body burden" which visualizes the immune system as a kind of weight lifter who can heft a certain amount of immune insult. However, if the " load" becomes too great, the ability of the immune system to carry it falters, everything crashes, and the body then becomes ill with whatever opportunistic stuff is around. Thats why people with intolerances to foods can handle a certain amount of these foods in rotation diets etc. Insults which cause the "weight lifter" to stagger under the load it may be able to normally bear are loads of extra allergens in an environment, bacterial or viral infections, stress, fatigue, etc. What I've noticed with Lydia is that when the ragweed is high, she cannot tolerate any dairy products. If I have my wits about me, I pull it out of her diet totally, or limit it severely. If I forget and she gets lots of pizza or ice cream or breakfast cereal, sure enough, she gets a raging ear infection. The little bit of human milk she got during the last few yrs of nursing was enough to keep her " weight lifter" bolstered with a bit of extra strength. Dairy during those yrs did not exceed her body's immune burden capability. Without that bolster, I have to be very careful. She has, interestingly, the same problem with cigarette and wood smoke. We used to be able to use our fire place in the winter when I was nursing, but not now. I speculate that there are people who have all kinds of sensitivities to stuff in their diets and environments and that reactions to these things are sometimes more complicated than simple cause and effect. Human milk protects the immume system, and when individual kids have reactions to proteins migrating through milk I think we should remove the food (or whatever) and protect the breastfeeding, and I agree with Jon that we should be following those kids to ensure that they aren't unwittingly being made sick by something which could be substituted for in their diets. I know this is getting long, but I have presented before on a severely allergic baby I saw at 4 mo pp covered with weeping eczema. Mom was subsisting on a diet of lamb and rice and baby still wasn't any better. He refused formula, and she (wisely) resisted all the people pushing her to wean who blamed nursing for the whole thing. At 14 mo pp he finally was referred to an environmental allergist who dx an allergy to carpet fumes. When all carpets were removed from his home and the family car, the child quickly got better, and mom was able to eat a normal diet while nursing with none of the ill effects she'd previously seen. Baby was able to begin to really eat solids. His body was no long so burdened trying to combate the toxic insult, and he could consume foods he'd seemed intolerant to . Barbara Wilson-Clay, BSE, IBCLC priv. pract. Austin, Tx