The new health study show that blueberry have antioxidant that are thought to help protect the body against the damaging effects of free radicals and the chronic diseases associated with the aging process. But if you have asthma, you might be allergic to blueberries, like one of the kid in our neighbor, after he ate blueberry muffins he feels so itchy all over his body. Allergic reaction signs include swelling of the tongue, lips and face, a rash on the skin, wheezing, diarrhea or vomiting.