Scientists do not know what causes a peanut allergy (or any allergy for that matter). Food allergies in general are often inherited. According to the University of Michigan, "The tendency to be allergic is inherited. If one parent has allergies, each child has about a 40% chance of developing allergies. If both parents have allergies, the chance of food allergy rises to about 75% for each child. Sometimes a child is allergic to the same food(s) as the parent."
The Anaphylaxis Campaign states that if there is allergy in a family, a sibling of a child with allergies will also be prone to allergies. There is only a seven percent risk of this second child developing peanut allergy, compared with a 1-2 percent risk in a child from a non-allergic family.
Scientists and doctors understand the causes of an allergic reaction to peanuts, or more specifically, an allergic reaction to at least seven of the proteins found in peanuts, and this understanding may lead to treatment advances in the future. Allergic people come into contact with these proteins through one of three general means: direct contact, cross-contact, and through inhalation of airborne particles.
Direct Contact with peanuts
This includes any direct exposure with peanuts, whether by ingestion, through the skin, the lips or any direct manner which puts the body in contact with peanut proteins. Direct contact is not only the most common cause of an allergic reaction, it is also the most preventable, provided the patient is diligent.
Cross-Contact with peanuts
Cross-contact causes of allergic reactions are somewhat insidious. For example, a company that processes peanuts might use the same machinery to process a non-peanut food product and if the machinery isn't thoroughly cleaned, traces of peanut can get into the other processed foods. Cross-contact is unintentional but for the patient it is not preventable. In an effort to prevent cross-contact, the Food Allergen Labeling and Consumer Protection Act (FALCPA), passed in 2006, requires manufacturers to label foods that may contain peanuts.
Airborne inhalation of peanuts
Some aerosols contain peanuts, for a variety of reasons, along with peanut flour or peanut oil cooking spray. When trace amounts are inhaled by someone with a peanut allergy, they can trigger an allergic response. Like direct contact, inhaling peanut proteins through the air is preventable.
Dive Deeper
References
- Interesting causes of peanut allergy identified, Cincinnati Children's Hospital
- Lack, G. et al, "Factors Associated with the Development of Peanut Allergy in Children" NEJM, March 13, 2003
- Tan, BM et al, Severe food allergies by skin contact," Annals of Allergy Asthma Immunol 2001 May;86(5):583-6
- "Food allergy in adolescents and adults," Internal Medicine Journal, April, 2009
