I think the whole point is that commercial food is fine but their little tums are only used to liquid so you want to introduce foods home cooked or otherwise, slowly incase there is a reaction to a food. my baby was quite sick on potato!! who would have thought?? the idea of slow introduction over 3-5 days is that you start with a teaspoon of the new food with a portion of already tolerated food incase there is a reaction. if the offending food was limited then obvioulsy the potential reaction will be minor.
if you have bought a heinz combo of sweet potato and pumpkin mixed for example keep that for whenever but first introduce those two foods individually cooked by you at home over 3-5 days first so you know the baby tolerates them and then you can assume the same for the commercial mix. if you gave yours a lamb and vege casserole first up and your baby got a reaction how would you know what was the problem food? I suggest getting your baby onto a few key basics individually first like sweet potato, pumpkin, potato, rice cereal, apple, banana and pear individually and then you'll know, if these are in the commercial food you have bought, that they can tolerate it fine.
By the way I tried the "only organic" brand wild rice and pumpkin and my baby was up all night with terrible colic. he's had pumpkin and rice ceral so i assumed it would be OK but perhaps not. another friend had the same problem with that same brand but the pumpkin and sweetcorn combo.
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