Shea butter can be found in a huge number of materials, ranging from diaper cream to types of paper. The U.S. Food and Drug Administration considers shea nuts (from which the butter is made) to be tree nuts- potential allergens.

The proteins in peanuts and other tree nuts are what cause the allergic reaction. In people who are allergic, the immune system considers the proteins to be dangerous and launches an attack, resulting in an allergic reaction. These can be both mild and severe, the latter often resulting in the failure of airways. Around two million Americans are allergic to some type of tree nut, but the number of allergy-linked deaths is small; around twelve each year.

The issue of shea butter arose when a pediatrician named Dr. Kanwaljit K. Chawla questioned the safety of most baby products. “I was looking up baby products and realized that many of the ‘natural’ or ‘organic’ products contained shea butter, including wipes, diaper creams, baby lotion and nipple cream for breastfeeding mothers. I saw that the FDA listed shea nut as something to avoid if you are allergic to tree nuts, but shea is in everything. How is it possible to avoid it?” She explained.

The nuts are mostly fat, but the doctor and her colleagues decided to run a few tests. They extracted the miniscule amount of protein found in shea nuts, and added it to blood samples taken from a number of people with known tree-nut allergies. The immune system did not respond, implying that although shea nuts should in theory trigger an allergic reaction, the immune system does not recognize it as a nut protein.