The American Academy of Pediatrics, who I alternately loathe and rejoice, have recently changed some of their guidelines for avoiding childhood allergies, again, to now say (paraphrase) "exclusively breastfeed for at least three months, nothing else seems to really make a difference." Of course BF4Dads recommends at least six months of exclusive breastfeeding, avoiding formula entirely (pump & freeze some if you need to store up for emergencies) and start off on regular food, skip that over-processed special baby food crap.