Have you wondered where all the complimentary peanuts on plane trips have gone? Although the economy has forced airlines to cut expenses, it would seem peanuts are no longer in vogue. But why is that?

One reason why peanuts have been eliminated is the rise in gastrointestinal food allergies, such as peanut allergies, and their potential fatality. A prominent example featured in the November 2005 news was of a Canadian teenager who died after kissing her boyfriend, who had eaten a peanut butter sandwich earlier that day. Examples like this have led peanut allergies to be considered the most terrifying of the gastrointestinal food allergies because they account for nearly half of all food allergy-related deaths.

Although peanut allergy-associated fatalities are currently low, there are trends and data that are alarming for immunologists and clinicians. Peanut and/or tree nut allergies were identified in the 1980’s to be one of the top three causes of food-induced allergic reactions in children. To date, approximately 12 million Americans suffer from food allergies, a fourth of which (3 million) are attributed to peanut allergies. In addition to the 1.1% of the American population that currently have peanut allergies, there are another approximately 8.6% that are sensitized to peanuts and therefore on there way to developing peanut allergies. Furthermore, the incidence of peanut allergies doubled from four in 1,000 to eight in 1,000 people between 1997-2002, suggesting that peanut allergies may become more prevalent with time. Inexplicably, children are having allergic reactions at younger ages, which may in part be due to improved diagnosis and recognition of symptoms.

What are gastrointestinal food allergies?

For some people, the ingestion of otherwise benign foods induce allergic reactions originating from the esophagus, stomach or colon. Potential sources of allergic reactions are wheat, corn, milk, egg, as well as numerous other commonly eaten foods. Allergic reactions to these various foods can induce a variety of symptoms including abdominal pain, cramping, diarrhea, vomiting, skin rashes/dermatitis, ocular symptoms, blood pressure loss, or respiratory distress. More severe responses to trigger foods can lead to anaphylaxis, a rapid onset of potentially fatal multi-organ reactions.

Peanut allergies are the result of undesired and uncontrolled immune response. Normally, our immune system can discriminate between two classes of proteins: those made within our own body and those made from foreign sources. Foreign protein may come from bacteria or viruses, or they can be from plants or other dietary sources. Ordinarily, our body is tolerant of foreign protein that enters our body through the gastrointestinal tract. Curiously, individuals who suffer from peanut allergies elicit a strong immune response against the peanut proteins. These immuno-reactive proteins are called allergens.

The immune system makes proteins that are called immunoglobulins (Ig). Specifically, immunoglobulin E (IgE) can detect foreign allergens. IgE binding of allergens leads to activation of immune cells, which in turn release pro-inflammatory molecules that are responsible for the wide range of physical symptoms exhibited by patients suffering from allergic reactions. The theory is that initial allergen exposures leave the immune system in a “primed” or hyper-sensitive state, which means that future exposures require less allergen to elicit the same IgE-mediated immune response.

Is there hope for nut allergy sufferers?

To date, there is no treatment for peanut allergies. Therefore, the best strategy for people who suffer from peanut allergies is avoidance of peanuts and products contaminated with peanuts. In the case of an accidental peanut ingestion, the hormone epinephrine is administered as a bronchodilator to counter the flood of histamines released as the body ramps up its allergic response. The histamines are responsible for constriction of the respiratory passageways within the lungs. In addition, epinephrine cues certain neurons in the brain to increase blood pressure through increasing heart muscle contraction and thus heart rate.

Recently, encouraging clinical research studies conducted by Dr. Wesley Burks were reported at the annual meeting of the American Academy of Asthma and Immunology. The study involved 33 children who had a history of peanut allergy. During the study, the children were given increasing amounts of peanut protein over 8-10 months and they exhibited an increased tolerance to peanuts. Such a strategy to promote desensitization to an allergen is called oral immuno-therapy (OIT) and has been used previously with success to promote tolerance in the case of egg related food allergies. Although Burks’ study is promising, more work needs to be done before there is a FDA-licensed OIT regime that may be employed safely under close supervision by a doctor.

Are we being hypersensitive about peanut allergies?

Some would argue that the measures that airlines, for example, are employing to eliminate peanut consumption is overkill. A recent TIME article raises the question about whether the public’s response to peanut allergy is a measured one. In particular, the author describes the recent hype about the establishment of peanut-free zones within public schools and the push for peanut warnings on manufacturer labels despite the relatively low fatality rates associated with peanut allergies. Massachusetts has been a pioneer in the creation of new laws that mandate training to ensure safe food preparation in commercial restaurant kitchens in order to minimize the level of peanut contamination.

Unfortunately, no genetic factors have been determined to be associated with the development of peanut allergies. Therefore, individuals often become aware of their allergy only after suffering from the frightening adverse reaction. Also, doctors remain uncertain about the cause of the rise in peanut allergies and the observed earlier onset of allergic reactions within children. Some speculate that the more recent introduction of soy into the American diet or that peanut consumption during pregnancy and/or lactation may be contributing factors. However, these theories have not been substantiated yet by data.

Therefore, while some may argue that we are becoming hypersensitive to this relatively rare disease, the nearly 3 million American families whose lives are affected by peanut allergies will undoubtedly benefit from our increased understanding and assistance. While so much of the disease remains illusive, what is certain is that allergen avoidance works 100% of the time. Thus, the increased awareness can only help ensure allergen exposure is prevented in public places for the protection and health of everyone.

–Maria LC Powell, Harvard Medical School

For More Information:

Article from the BBC:
< http://news.bbc.co.uk/2/hi/americas/4481546.stm >

Article from Time Magazine:
< http://www.time.com/time/magazine/article/0,9171,1881985,00.html >

Article from WebMD:
< http://www.webmd.com/allergies/news/20090316/new-therapy-may-knock-out-peanut-allergy >

Primary Literature:

Lee, LA and Burks, AW. New insights into diagnosis and treatment of peanut food allergy. Frontiers in Bioscience. (14) 3361-3371 (2009).