What Parents Should Know About Baby Food Allergies? Baby food allergies are not as common as food allergies in older children and adults. However, these kinds of baby food allergies do sometimes occur. In order to recognize the symptoms in their baby, it is a must that parents should understand how allergies affect the body of their baby. If a substance is ingested that the immune system deems a threat, antibodies are produced to attack the offending substance. The attack is what causes the symptoms of an allergic reaction. These symptoms may be mild, moderate or severe.