Similarly, if butters or margarines are used to make a purchasable product, they’ll have to list these ingredients on their food labels. Butter is curdled and processed milk. 1  Some nutritionists claim that butters are the least harmful form of dairy to those with dairy allergies or lactose processing problems.imilarly, if butters or margarines are used to make a purchasable product, they’ll have to list these ingredients on their food labels. Butter is curdled and processed milk. 1  Some nutritionists claim that butters are the least harmful form of dairy to those with dairy allergies or lactose processing problems.