we fed our baby with soy based formula when his ped said we could try that because of his eczema. It worked better than cow milk based formula at first but after several days his eczema came back, which means he is allergic to both. But i feel that soy based formula make him easier to constipate, so now we mixed soy based and cow milk based, works pretty fine so far :) However, I personally recommend cow milk based formula, which i think is added with something that helps immune system develop w