Outline 1.What is the link between food allergy and asthma development? 2. What routes of exposure to food should be considered in evaluating suspected food-related respiratory tract symptoms? 3.What is the role of food additives in provoking asthmatic reactions? 4. Can asthma be induced by food allergy? 5.What is the role of food allergy as a risk factor for severe asthma?

Q1:What is the link between food allergy and asthma development?

There has been an apparent increase in the overall prevalence of food allergy and asthma over the past 30 years.

WHAT ARE THE CAUSES OF THIS INCREASE ?

Since both of food allergy and asthma are atopic diseases they may coexist, but asthma alone as a manifestation of a food allergy is rare and atypical.

Respiratory tract symptoms may be observed with allergic reactions to foods. These symptoms are: Nasal congestion Rhinorrhea Sneezing Pruritus of the nose and throat Coughing Wheezing

Food allergy in early childhood appears to be a good predictive marker for later respiratory allergy, especially asthma.

In a cohort of 1218 consecutive births followed until 4 years of age, 29 (2.4%) developed egg allergy. Increased respiratory allergy (e.g. asthma) was associated with egg allergy (odds ration OR: 5.0). The addition of the diagnosis of eczema to egg allergy increased the positive predictive value to 80%. Tariq SM. PAI 2000; 11:162

Another prospective cohort study of 100 infants at risk for asthma and atopy found that skin sensitivity to hen’s egg, cow’s milk, or both in the first 5 years of life was predictive of asthma (OR: 10.7). Rhodes HL, et al. JACI 2001;108:720

In an American study, the degree of food allergen sensitization to six common foods was assessed (milk,egg, soy, peanut, wheat, and fish) in 504 children 4 to 9 years of age. Forty-five percent of the children were sensitized to at least one food. Children sensitized to foods had higher rates of hospitalization for asthma exacerbations and required more treatment with systemic glucocorticoids. Wang J, JACI 2005; 115:1076–80.

In a 10-year follow-up of the Prevention and Incidence of Asthma and Mite Allergy (PIAMA) birth cohort that included 565 children of mothers with allergies: Hen's egg sensitization at one year of age was a better predictor of developing asthma in later years than sensitization to cow's milk. Bekkers MB. JACI  2013;132:1427-8

Asthma Predictive Index(API) Guilbert TW. JACI 2004;114:1282-7.

What about adults?

In an Australian cross-sectional epidemiologic study including 1141 randomly selected young adults (aged 20–45 years), those with probable IgE-mediated peanut allergy were more likely to have current asthma, wheeze, and a history of eczema; Those with probable IgE-mediated shrimp allergy were also more likely to have current asthma and nasal allergies. Woods RK. Ann Allergy Asthma Immunol 2002; 88:183.

Q2:What routes of exposure to food should be considered in evaluating suspected food-related respiratory tract symptoms?

Oral Ingestion of Food Allergens Oral ingestion of a food allergen is the primary route of exposure that can cause or exacerbate respiratory symptoms. A survey of 51 anaphylactic reactions to foods demonstrated that … 78% of these reactions occurred after ingestion, 16% occurred following exclusive skin contact 6% occurred after inhalation of the food allergen. Eigenmann PA. Allergy 2002;57:449–53.

Inhalation of Food Allergens and Occupational Exposure This type of exposure is usually more obvious and more substantial in occupational environments but can also occur in non-occupational settings, such as private homes, schools, restaurants, and commercial airline flights. Prolonged and persistent exposure to high levels of food allergens increase the risk of sensitization. Occupational exposures to airborne food allergens can result in chronic asthma. James JM. Curr Allergy Asthma Rep 2007; 7:167

A CASE: A 30-year-old man was sitting at a shopping mall’s food court area. There were several different types of food being served, including fish and shellfish . There was a strong aroma of all of foods in the court. He had a past history of anaphylactic reactions following the ingestion of fish. While he was eating a salad without any seafood, he noticed itching in his mouth and throat, a swelling sensation in his throat and repetitive coughing and wheezing.

This clinical case is an example of how some foodallergic individuals may react when exposed to airborne allergens in a restaurant when fish or shellfish are cooked in a confined area. Seafood allergens aerosolized during food preparation are a source of potential respiratory and contact allergens.

An internet-based survey of 51 anaphylactic reactions to foods showed that whereas most reactions (40–78%) occurred after ingestion, eight (16%) reactions occurred following exclusive skin contact and three (6%) after inhalation. Eigenmann PA, et al. Allergy 2002;57:449–53.

Sensitized children can develop asthma following inhalation exposure to other aerosolized food allergens during the cooking process. In one study, 12 food allergic children reportedly developed asthma after inhalation of food allergens including fish, chickpea, milk, egg, and buckwheat. In follow-up to verify the self-reports, 5 of 9 bronchial challenges were positive with acute asthmatic reactions and 2 of these children experienced late-phase asthmatic reactions. Sicherer SH, JACI 1999;104:186-9 .

Q3:What is the role of food additives in provoking asthmatic reactions?

A high percentage of patients with asthma perceive that food additives contribute to worsening of their respiratory symptoms. Monosodium glutamate, sulfites, and aspartame have been implicated in adverse respiratory reactions, but well-controlled investigations have reported a prevalence rate of less than 5%. Weber RW. Ann Allergy 1993; 70:183

Q4.Can asthma be induced by food allergy?

There were positive food challenges in 60% of these. In a study, 410 children with a history of asthma, 279 (68%) had a history of food-induced asthma. There were positive food challenges in 60% of these. Twenty-four percent of the 279 children with a history of food-induced asthma had a positive blinded food challenge that included wheezing. Bock SA. Pediatr Allergy Immunol 1992; 3:188.

The most common foods that were responsible for these reactions included peanut, cow’s milk, egg, and tree nuts. But, only 2% of these patients had wheezing as their only objective adverse symptom. Finally, 10 of the 188 children without a history of asthma had wheezing provoked by the food challenge, demonstrating a tendency for a bronchial response in the absence of accompanying asthma. Bock SA. Pediatr Allergy Immunol 1992; 3:188.

Q5.What is the role of food allergy as a risk factor for severe asthma?

To answer to this question, an investigation was undertaken of 19 children with exacerbations of asthma requiring intensive care unit management and assisted ventilation. When compared to controls, these patients had an increased risk of food allergy, multiple allergic diagnoses and frequent asthma admissions. The authors concluded that food allergy and frequent asthma admissions appear to be significant, independent risk factors for life-threatening asthmatic events. Roberts G. JACI 2003:112:168

Conclusion and Clinical Points • Allergic reactions to food are rarely a cause of asthma • Inhalation of aerosolized food allergen(s) can lead to respiratory symptoms. • Family history of atopy and sensitization to specific food allergens in early infancy increase the risk of future allergic respiratory disease. • Consider food allergy evaluation in patients with unexplained, acute asthma exacerbations. • Allergic sensitization to foods is a marker for increased asthma severity/ morbidity. • Having asthma is a risk factor for fatal and near-fatal food-induced anaphylaxis.