Peanuts are among the most common allergy-causing foods, and
they often find their way into things you wouldn't imagine. Take
chili, for example: It may be thickened with ground peanuts.
Peanuts aren't actually a true nut; they're a legume (in the
same family as peas and lentils). But the proteins in peanuts
are similar in structure to those in tree nuts. For this reason,
people who are allergic to peanuts can also be allergic to tree
nuts, such as almonds, Brazil nuts, walnuts, hazelnuts,
macadamias, pistachios, pecans, and cashews. What Happens With a
Nut or Peanut Allergy? The body's immune system normally fights
infection. But, when someone is allergic to tree nuts or
peanuts, the immune system overreacts to proteins in these
foods. Every time the person eats (or, in some cases, handles or
breathes in) a peanut or tree nut, the body thinks the proteins
are harmful invaders. The immune system responds by kicking into
high gear to fend off the "invader." This causes an allergic
reaction, in which chemicals