An allergic reaction is caused by a dysfunction in the immune system, whether it is an allergic reaction to food, a bee sting, or to latex. With food allergy, a naturally occurring protein in the food is considered an invader by the immune system and the body reacts like it is fighting to remove it. About four percent of adults and four percent of children 18 years of age or under have food allergies, with a slightly higher percentage in children under 5 years old. As indicated by the reduced incidence in adults, some of these allergies may, fortunately, be outgrown over time.
The Centers for Disease Control and Prevention (CDC) reports that children with food allergy are more likely to have asthma or other allergic conditions. Nearly 90 percent of food allergies are caused by these common foods: tree nuts (almonds, walnuts, pecans, cashews, pistachios, etc.), peanuts, milk, eggs, fish, crustacean shellfish, wheat, and soy.
Most allergic reactions are not life threatening, but some can lead to a more severe reaction known as “anaphylaxis”, where blood pressure drops abruptly and the airways and throat swell, which lead to breathing difficulties. When this is not controlled, unconsciousness and death can occur, so it is important to know how to manage severe allergies, whether they are food or non-food related.
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With increasing news coverage on peanut allergy in the past few years, there may be a misperception that there is a high incidence of peanut allergy in the U.S. and worldwide. However, the numbers show that only 0.6 - 1.0% of people have a mild to more severe peanut allergy, and studies show that about 20% of peanut allergies can be outgrown. By comparison, about four times as many adults are allergic to seafood. As with all allergies, those with a family history of allergy, asthma, or eczema, may be at increased risk.
The National Institute of Allergy and Infectious Disease (NIAID) has reported that approximately one in 90 people in the United States, or 1.1%, have a tree nut and/or peanut allergy and the Food Allergy and Anaphylaxis Network (FAAN) has stated that it is about 0.6% each. People who are allergic to peanuts are also often allergic to one or more tree nuts (almonds, walnuts, pecans, cashews, pistachios, etc.).
In those who are severely allergic, reactions to peanuts can occur from ingesting just a trace amount. This can cause anxiety, especially with the parents of peanut allergic children. But did you know that touching, smelling, or inhaling airborne particles from peanuts does not cause a severe reaction. ( Simonte SJ, et al. Relevance of casual contact with peanut butter in children with peanut allergy. J Allergy Clin Immunol.. 2003 Jul:112 (1): 180-2.
Smelling the aroma of peanuts is not the same as inhaling peanut particles that could potentially contain the allergenic protein. The aroma of peanuts comes from different compounds that cannot cause an allergic reaction.
In one controlled study that looked at this, 30 children with significant peanut allergy were exposed to peanut butter, which was either pressed on the skin for one minute, or the aroma was inhaled. Reddening or flaring of the skin occurred in about one third of the children, but none of the children in the study experienced a reaction either in their lungs or throughout their bodies!
To prevent an allergic reaction, the best recommendation to those with peanut allergy is to avoid intake. To minimize the risk of being exposed to allergens, which may occur by accident, there are also important strategies that can be taken.
- Read labels - which highlight allergens on the ingredient list
- Plan ahead - when dining out or attending a party. Call ahead to notify friends, talk with retaurant staff, or use a “chef card,” which lists ingredients to avoid and can be found at the Food Allergy Anaphylaxis Network (FAAN) website at www.foodallergy.org/downloads.html.
- Practice proper sanitation - with common cleaning agents, such as hot, soapy water to remove cross contamination
- Carry medicine - such as epinephrine injector pens, which are also referred to as “EpiPens. They must be used within 10 minutes but can provide the time necessary to seek medical attention. Epinephrine is a hormone that is released during stress. It boosts the supply of oxygen and glucose to the brain and muscles, while suppressing other non-emergency bodily processes, such as digestion. Make sure to fill your prescription as one study showed that almost 50 percent of allergic children did not carry prescribed medication!
- Control asthma - with proper medical care since asthma is a main risk factor for death due to anaphylaxis
- Let people know – by wearing a bracelet or necklace identifying the allergy and its severity
Evidence does not support the effectiveness of allergen bans. In fact, many experts feel that bans, except in situations that involve very young children such as in daycare centers, give a false sense of security. Peanut bans, for example, ignore other potentially serious foo0d allergies. School-aged children need to be prepared to understand real-world environments. Education of faculty, school foodservice personnel, parents and students on how to manage food allergies is thought to be the most effective approach.
The allergens in peanuts have been identified as proteins called Ara h 1, Ara h 2, and Ara h 3. A number of therapeutic interventions to reduce or eliminate peanut allergy are currently are being investigated. Among these are Chinese herbal medicine, anti-IgE therapy, oral immunotherapy, and vaccine strategies that utilize genes from peanut proteins.
“Food Allergy Herbal Formula-2” is a Chinese herbal therapy that is being tested and shows promise. When this formula was used in mice for seven weeks it prevented anaphylactic reactions for six months following the treatment. The formula is currently being tested at FDA as a new botanical drug in patients with food and peanut allergy.
Another therapy that has shown some success in increasing the threshold of sensitivity to peanut allergens is called anti-IgE therapy. Immunoglobulin E (IgE) is a type of protein found in our immune system that identifies foreign objects, such as bacteria. This protein is also involved in anaphylaxis that can occur in some who are allergic to peanuts. Injecting other proteins that bind IgE in our blood, helps calm the immune reaction.
Recently, it was shown that the blocking of the certain hormones involved in causing anaphylaxis resulted in significant reductions in the severity of peanut-induced anaphylaxis in mice. In all but one mouse, the reactions were mild.
The most promising emerging strategy is called oral immunotherapy. It uses peanut protein to increase tolerance to peanuts. A 2009 study gave small daily doses of peanut flour, which contains high levels of peanut protein, to peanut allergic children over a number of weeks. All of the allergic children were ‘desensitized’ to the peanut allergen, including one that was highly allergic. The levels of peanut protein were increased two times each week and ultimately the children could eat up to 10 peanuts without a reaction -- more than someone would encounter during accidental ingestion.
Although oral immunotherapy remains experimental, it could be extremely valuable to children with severe peanut allergy and to those who have reactions when exposed to very small amounts. Researchers recommend that at this time, it only be carried out in a clinical setting under trained medical supervision.
What Causes Peanut Allergy?
The science is not clear as to what causes peanut allergy. Both genetic and environmental factors appear to be involved. Family history, occurrence of eczema-type skin rashes, and exposure to soy protein were associated with the development of peanut allergy in childhood in one study. The most current data does not support the theory that if peanuts are eaten during pregnancy or infancy there is a greater chance that the child will end up with the allergy.