Peanut allergy

Peanut allergy is a type of food allergy, distinct from nut allergies. It is a hypersensitivity to dietary substances from peanuts causing an overreaction of the immune system which may lead to severe physical symptoms for millions of people^[1]. The Asthma and Allergy Foundation of America estimates that the majority of pediatric and adult food allergy patients have a peanut allergy^[2]. Prevalence among adults and children is similar (around 1%) but at least one study shows it to be on the rise in children.^[3] 25% of children with a peanut allergy grow out of it.^[4] It is usually treated with an exclusion diet and vigilant avoidance of foods that may be contaminated with whole peanuts or peanut particles and/or oils. The most severe peanut allergies can result in anaphylaxis^[5] and is an emergency situation requiring immediate attention and treatment with epinephrine.

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Symptoms

Symptoms of peanut allergy are related to the action of IgE and other anaphylatoxins, which act to release histamine and other mediator substances from mast cells (degranulation). In addition to other effects, histamine induces vasodilation of arterioles and constriction of bronchioles in the lungs, also known as bronchospasm (constriction of the airways).

Symptoms can include the following:^[6]

• vomiting
• diarrhoea
• urticaria (hives)
• angioedema (swelling of the lips, face, throat and skin)
• acute abdominal pain
• exacerbation of atopic eczema
• asthma
• anaphylactic shock

The British Dietetic Association warns that: "If untreated, anaphylactic shock can result in death due to obstruction of the upper or lower airway (bronchospasm) or hypotension and heart failure. This happens within minutes to hours of eating the peanuts. The first symptoms may include sneezing and a tingling sensation on the lips, tongue and throat followed by pallor, feeling unwell, warm and light headed. Severe reactions may return after an apparent resolution of 1-6 hours. Asthmatics with peanut sensitivity are more likely to develop life threatening reactions."^[6]

As with most allergies, avoidance is the key. All labels for foods, medicines, cosmetics, creams, and ointments should be read. A history of allergic reactions after consuming a peanut may suggest an allergy.

While several companies have developed promising drugs to counteract peanut allergies, trials have been mired in legal battles.^[7]

Deaths from peanut allergy

Approximately 125 people die in the United States each year from food allergies.^[8][9] Peanut allergy is the most common cause of death from food allergies. ^[10]

The dangers of peanut allergy are real, even if sometimes misrepresented in the popular press. The 2005 death of Christina Desforges, which was initially reported as a result of exposure to peanuts, spurred many parents to speak out about the dangers from such seemingly mundane matters as peanut butter and jam sandwiches at schools or peanut shells on the floors of restaurants.^[11] According to a coroner's statement in March 2006 however, Ms. Desforges did not die of anaphylactic shock caused by a kiss from her boyfriend after he ate a peanut butter snack, but in fact died as a result of asthma-linked respiratory failure, which was triggered by tobacco smoke at a party. Research by Jennifer Maloney suggests that peanut allergens normally leave the saliva after about an hour.[1]

See also

• Allergy
• Nut allergy
• Anaphylaxis
• Food allergy
• Asthma

References