Counter-intuitive allergy experience of the day: it is safer for me to eat butter than to eat margarine, even though butter is 100% made from milk (OK, water and salt, too). Butter is milk fat only and does not appear to have any significant amounts of milk protein left in it. Not enough to trigger allergic symptoms in Adrian, at least. Margarine on the other hand is an unpredictable mixture of stuff, often including skimmed milk powder or whey powder, both of which do contain milk protein. So when a restaurant serves margarine with their bread, I skip it; when they serve butter, I eat it.