Reviewer: S. Randhawa, M.D., Allergist/Immunologist and Assistant Professor at LSU (Shreveport) Department of Allergy and Immunology
The word cloud of food allergen avoidance shows the frequency of term use in this article.
What is the primary treatment in food allergy?
Avoidance of the allergen.
Allergen avoidance is easy in theory but difficult in practice.
Methods:
1. read labels on packaged foods
2. prepare safe meals at home
3. avoid food allergens in restaurants
Despite best efforts, most patients will not be successful at all times to eliminate a certain food from their diet. Therefore, patients must always be prepared to treat an unexpected anaphylactic reaction.
Eight top allergens account for 90 percent of all food allergies. The 8 top allergens can be remembered by the mnemonic TEMPS WFS.
8 top allergens account for 90 percent of food allergies. Specific IgE levels (sIgE) that predict the likelihood of passing an oral food challenge are shown in the figure. (click to enlarge the image). Read more in Food Challenges for Diagnosis of Food Allergy.
How strict must the avoidance be? What is the threshold?
Less than a milligram (mg) of milk, egg, or peanut, can cause symptoms.
Skin contact and inhalation
Allergic reactions occur after ingestion. Skin contact or inhalation are unlikely to cause systemic reactions in food-allergic patients.
Contact urticaria to peanut is not uncommon but systemic reactions secondary to skin exposure are unlikely.
There is a difference between smelling a food and inhaling an aerosolized food.
In inhalation of aerosolized food, there is a contact between actual food matter and the respiratory mucosa in the nose and lungs.
Aerosolization of food can occur in boiling, frying, grating, shredding, grinding.
Inhalation of aerosolized food can induce wheezing in sensitive individuals.
Food Labels
Several studies have demonstrated inaccuracies in both food labeling and label interpretation
FDA surveyed food recalls in one year and found 25% of the products had labeling errors in regard to egg, milk, or peanut
Source: Recalls of foods containing undeclared allergens reported to the US Food and Drug Administration, fiscal year 1999. Vierk K; Falci K; Wolyniak C; Klontz KC. J Allergy Clin Immunol. 2002 Jun;109(6):1022-6.
Parents of food-allergic children often make mistakes identifying allergens from food labels: only 10% correctly identified all of the labels indicating milk, 25% identified soy, 50% peanu.
Legislation in the U.S.
The Food Allergen Labeling and Consumer Protection Act (FALCPA) went into effect in 2006 and requires that the 8 major food (milk, egg, fish, shellfish, tree nuts, wheat, peanut and soy) be listed on labels using plain English.
Previously, foods could be labeled with scientific or nonspecific terms (casein or "natural flavor" for milk).
FALCPA only applies to the 8 major food allergens listed here. Other allergens, for example, garlic or sesame, may be listed simply as "spice."
In 2005, the European Union enacted legislation requiring the following food allergens must be listed on the labels: milk, egg, fish, crustacean shellfish, peanuts, soybeans, tree nuts, cereals containing gluten (wheat, rye, barley, oats, spelt, and their hybridized strains), celery, mustard, and sesame seeds. The EU list is more comprehensive than the U.S. FALCA.
Home meal preparation
- Avoid cross-contact
- Cleaning of utensils
- Cleaning tabletops with standard cleansers removes peanut allergen.
- Soap removes peanut allergen from hands but alcohol-based antibacterial gels do not.
Restaurant meals
High risk places:
- Asian restaurants
- ice cream shops
- bakeries
The issue is often cross-contamination and unexpected ingredients in desserts and Asian food.
Source: Peanut and tree nut allergic reactions in restaurants and other food establishments. Furlong TJ; DeSimone J; Sicherer SH. J Allergy Clin Immunol. 2001 Nov;108(5):867-70.
Use common sense - it would be difficult for person with a seafood allergy to have a safe meal in a restaurant that specializes in seafood.
Buffet services should be avoided due to cross-contact risk.
Restaurants employees have poor understanding of food allergy issues.
In a simple telephone survey (5 true/false questions about food allergy) of 100 restaurants employees (managers, servers, chefs) in the New York City:
- only 22% answered all 5 correctly
- 50% felt "very comfortable" they could provide a safe meal to a food-allergic customer
- 24% indicated that consuming a small amount of allergen would be safe
- 54% considered a buffet safe if kept "clean"
- 25% thought that removing an allergen from a finished meal (eg, taking off nuts) makes it safe
Conclusion: Patients should not assume that restaurant personnel understand food allergy.
Source: Food-allergy management from the perspective of restaurant and food establishment personnel. Ahuja R; Sicherer SH. Ann Allergy Asthma Immunol. 2007 Apr;98(4):344-8.
Tips:
- identify that you have an allergy to the the cook, rather than the waiter/waitress
- carry pre-printed cards about which foods cannot be eaten
- deep fryers (oil is reused for different foods) should be avoided
Allergenicity of refined vegetable oils is extremely low (http://goo.gl/EzUgp).
Non-food items and food allergy
Non-food items (medications, vaccines, cosmetics) may contain food ingredients.
Vaccines
Vaccines can contain food allergens (egg and gelatin proteins).
Dry powder asthma inhalers
Dry powder asthma inhalers may contain lactose (carbohydrate) derived from milk.
Pharmaceutical-grade lactose is unlikely to contain any milk protein but possible reactions in children with severe milk allergy have been reported.
Certain inhalers contain soy lecithin (fatty derivative of soy) with a trace amount of soy protein. Those inhalers should not be used in patients allergic to soybean or peanut.
Person-to-person contact
Saliva
Food allergen exposure through saliva may occur through:
- kissing
- sharing straws, glasses, or utensils
Kissing is the most common route of exposure: 5-12% of food allergy patients report reactions after kissing.
Source: The hazards of kissing when you are food allergic. A survey on the occurrence of kiss-induced allergic reactions among 1139 patients with self-reported food hypersensitivity. Eriksson NE; Moller C; Werner S; Magnusson J; Bengtsson U. J Investig Allergol Clin Immunol. 2003;13(3):149-54.
How long does food protein stay in saliva? "When is it safe to kiss after a meal?"
Time course of peanut protein (Ara h 1) in saliva after a meal of peanut butter:
- 87% had undetectable levels after 1 hour
- 100% had undetectable levels several hours later following a subsequent peanut-free lunch
Immediate brushing, prolonged rinsing, chewing gum did not produce a statisally significant difference.
Best option: wait several hours, then eat a peanut-free meal
Source: Peanut allergen exposure through saliva: assessment and interventions to reduce exposure. Maloney JM; Chapman MD; Sicherer SH. J Allergy Clin Immunol. 2006 Sep;118(3):719-24.
Other bodily fluids
First case of a sexually transmitted allergic reaction:
A 20-year-old female with documented Brazil nut allergy developed urticaria and dyspnea after unprotected intercourse with her boyfriend who had earlier consumed Brazil nuts. Skin prick testing with the boyfriend's semen after Brazil nut consumption confirmed significant reactivity. A sample before nut consumption was negative.
Source: Dangerous Liaison: Sexually Transmitted Allergic Reaction to Brazil Nuts. J Investig Allergol Clin Immunol 2007; Vol. 17(3): 189-191.
References
Food Allergen Avoidance. UpToDate, 16.2.
Non-food items and food allergy
Non-food items (medications, vaccines, cosmetics) may contain food ingredients.
Vaccines
Vaccines can contain food allergens (egg and gelatin proteins).
Dry powder asthma inhalers
Dry powder asthma inhalers may contain lactose (carbohydrate) derived from milk.
Pharmaceutical-grade lactose is unlikely to contain any milk protein but possible reactions in children with severe milk allergy have been reported.
Certain inhalers contain soy lecithin (fatty derivative of soy) with a trace amount of soy protein. Those inhalers should not be used in patients allergic to soybean or peanut.
Person-to-person contact
Saliva
Food allergen exposure through saliva may occur through:
- kissing
- sharing straws, glasses, or utensils
Kissing is the most common route of exposure: 5-12% of food allergy patients report reactions after kissing.
Source: The hazards of kissing when you are food allergic. A survey on the occurrence of kiss-induced allergic reactions among 1139 patients with self-reported food hypersensitivity. Eriksson NE; Moller C; Werner S; Magnusson J; Bengtsson U. J Investig Allergol Clin Immunol. 2003;13(3):149-54.
How long does food protein stay in saliva? "When is it safe to kiss after a meal?"
Time course of peanut protein (Ara h 1) in saliva after a meal of peanut butter:
- 87% had undetectable levels after 1 hour
- 100% had undetectable levels several hours later following a subsequent peanut-free lunch
Immediate brushing, prolonged rinsing, chewing gum did not produce a statisally significant difference.
Best option: wait several hours, then eat a peanut-free meal
Source: Peanut allergen exposure through saliva: assessment and interventions to reduce exposure. Maloney JM; Chapman MD; Sicherer SH. J Allergy Clin Immunol. 2006 Sep;118(3):719-24.
Other bodily fluids
First case of a sexually transmitted allergic reaction:
A 20-year-old female with documented Brazil nut allergy developed urticaria and dyspnea after unprotected intercourse with her boyfriend who had earlier consumed Brazil nuts. Skin prick testing with the boyfriend's semen after Brazil nut consumption confirmed significant reactivity. A sample before nut consumption was negative.
Source: Dangerous Liaison: Sexually Transmitted Allergic Reaction to Brazil Nuts. J Investig Allergol Clin Immunol 2007; Vol. 17(3): 189-191.
References
Food Allergen Avoidance. UpToDate, 16.2.
Food Challenges for Diagnosis of Food Allergy
Should Avoidance of Foods be Strict in Prevention and Treatment of Food Allergy? Medscape, 2010 http://goo.gl/Buwu
PowerPoint Presentations
Related reading
Understanding Deadly Food Allergies - This Post Could Save A Life. Michael Natkin, 2009.
Putting a face on food allergies - USA Today readers share their stories about dining out with food allergies, 2010.
PowerPoint Presentations
Related reading
Understanding Deadly Food Allergies - This Post Could Save A Life. Michael Natkin, 2009.
Putting a face on food allergies - USA Today readers share their stories about dining out with food allergies, 2010.
5% of foods with warning labels ("made in a facility that processes") had traces of allergens, compared to 2% of foods without labels. Reuters, 2010. http://bit.ly/91a9ls
Published: 11/01/2008
Updated: 06/06/2011
Updated: 06/06/2011
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