There is a large correlation between a peanut allergy and a nut allergy. Although most people discussing food allergies tend to combine peanuts and tree nuts into one, on a basic biological level, the two are quite different. Peanuts are actually legumes and they grow in the ground. Tree nuts, which are truly nuts, grow in trees and include cashews, almonds, pecans, walnuts, pistachios, pine nuts, hazel nuts, Brazil nuts, macadamia nuts, and hickory nuts.
Despite the botanical differences between a peanut and a tree nut, there are some remarkable similarities for those suffering from nut allergies. First, both peanuts and tree nuts can cause extreme allergic reactions. Second, a person with a nut allergy can have a severe reaction with only the smallest exposure to the offending nut – just like the peanut. Third, typically, where one finds peanuts, there will also be tree nuts – common places for hidden nuts are in baked goods, candy, ice cream, and ethnic food. Fourth, both peanut oil and extract and tree nut oils and extracts have proteins that cause allergies.
Usually thirty to forty percent of the people with a peanut allergy also have a tree nut allergy. Basic research holds that both peanuts and tree nuts are potent allergens; consequently, they remain the highest among the foods that cause fatal reactions. Other research holds that there some structural similarities between the protein of the peanut and that of the tree nut. In general, a person who has a peanut allergy should also avoid tree nuts for fear of developing a tree nut allergy – and visa versa.
Typically, a reaction to peanuts has a greater chance of turning into anaphylaxis than a reaction to tree nuts. Anaphylaxis can appear within a few seconds of consuming a peanut or in rarer cases, a tree nut. The symptoms can last up to a few hours. It affects the skin, intestines, blood vessels, heart, and breathing passages of a person who has a peanut or a nut allergy. Itching, hives, vomiting, cramps, difficulty breathing due to swollen passages, and fainting may occur. In the worst cases, it could cause a deep, deadly shock.
In addition, both peanuts - to a greater degree - and tree nuts – to a lesser degree – can cause exercised-induced anaphylaxis. In those cases, a person who does not even know he has a food allergy eats the food, and then exercises. The same symptoms seen in normal food-induced anaphylaxis is seen; however, it can be hours after eating a peanut or tree nut. Consequently, an allergy exists; but, the person may have a hard time determining that he has a peanut or nut allergy because of the duration between the consumption of the food and the symptoms of the attack.