Oral allergy symptoms and Anaphylaxis
Food allergy symptoms, such as OAS, urticaria, and anaphylaxis, following consumption of maize, have been reported in some countries, especially in Italy, where polenta (cooked maize flour) is popularly consumed (10).
In a study conducted on 22 patients (age range: 12 to 50 years), 100% of patients suffered from severe systemic reactions, such as anaphylaxis, after consuming maize in different forms (e.g. popcorn, polenta, crisps, etc.). Nine of these 22 patients (41%) presented with OAS (including 5 with localized OAS), before the onset of systemic symptoms, such as laryngeal edema anaphylaxis, and shock. Further, 3 of the 22 patients (13.6%) presented with food-dependent, exercise-induced anaphylaxis (FDEIA) (18).
In a study conducted on 661 Mexican patients with a history of allergy, 56 (8.4%) patients reported maize allergy. Among them, two patients reported to develop urticaria or even angioedema, upon consumption of maize, in forms such as corn-on-the-cob or popcorn. (11).
A double-blind, placebo-controlled food challenge (DBPCFC) was conducted on 16 corn-allergic patients with positive SPT. It was reported that 37.5% of patients (6 out of 16) showed symptoms of itching and urticaria, upon ingestion of cooked corn (19).
In another DBPCFC study involving 27 suspected maize-allergic patients, OAS was found to be the most frequent symptom observed in 53.8% of patients (7 out of 13) with positive findings to maize. Other symptoms included generalized and persistent erythema (23%; 3 out of 13), abdominal pain or diarrhea (23%; 3 out of 13), generalized pruritus (15.3%; 2 out of 13), angioedema (15.3%; 2 out of 13), and one case (7.6%; 1 out of 13) each of generalized urticaria, persistent cough, nausea or vomiting, and eczema flare (10).
A study was conducted on 82 Italian patients (age range: 9 to 47 years) with a history of at least one episode of FDEIA linked with physical exercise (done within 4 hours after a meal), to assess the actual allergenic molecules responsible for FDEIA. Maize and peanut were found to be the most common positive foods (n= 70), followed by apple, peach, onion, lentil and fennel (20).
Two case studies have been identified that reported allergic reactions, such as OAS and anaphylaxis, after ingestion of corn, in different forms. The first case was of a 44-year-old woman, who had a history of anaphylactic reaction (tingling sensation) post ingestion of corn (licking the cornmeal from fingers). It was further reported that, on subsequent exposure to corn, the women developed urticaria, pruritus, diarrhea, vomiting, and breathlessness. In a two phase, DBPCFC conducted with corn flour, the woman presented with anaphylaxis (21). In the second case, studied on a 34-year-old male, ingestion of baby cereal formula, containing nongluten rice and corn, led to severe reactions, such as sudden respiratory and gastrointestinal (GI) symptoms, reduced consciousness, and paleness. The patient’s history showed that, although he well-tolerated bread and other cereal-derived products, he experienced OAS after taking beer and mustard. Further, it was reported that the patient suffered from occupational asthma, after coming in contact with the rye flour, that was added in the wood boards. The SPT was found to be positive for mustard and several other food allergens. According to DBPCFC conducted with cereal baby food in lime juice, positive reactions, such as pharyngeal itching, cough, and GI symptoms were noted (22).
Allergic rhinitis, rhino-conjunctivitis, and asthma
Respiratory symptoms, such as allergic rhinitis (AR), rhino-conjunctivitis and asthma/occupational asthma have commonly been reported in individuals, who either ingest or come in contact with maize. (6).
In a study conducted on 661 adult patients in Mexico, 8.4% (n=56) of patients presented with a history of maize allergy. Of these 56 individuals, 89.3% (n=50) individuals, who worked with the cereal, experienced AR and/or asthma, after coming in contact with maize. The rest of the 10.7% (n=6) individuals, who reported no history of working with the cereal, presented with asthma and/or AR, upon ingestion of maize (popcorn or corn-on-the- cob) (11).
In a case study of a 40-year-old non-smoker male, occupational exposure to maize while working on a maize extrusion process led to rhino-conjunctivitis and asthma. These allergic reactions lasted for around 6 months while at work, however the symptoms reduced, when off-work. The SPT results was found to be positive for maize flour, wheat flour, and beer. Moreover, the specific IgE determinations showed positive result for maize flour extracts, however it was reported negative for other cereal flours (6).
Two more case studies documented about corn-induced occupational asthma (6). The first case was of a 24-year-old, non-smoker male who reported a history of rhinorrhea, sneezing, and chest tightness, as a result of handling corn dust for making stock feed. The male informed that he did not experience these symptoms in the past, however, his symptoms got worsened on handling the corn dust. The bronchoprovocation test and Enzyme Linked Immunosorbent Assay (ELISA) suggested that corn dust can lead to IgE-mediated bronchoconstriction in an exposed individual (23). In the second case,a 19-year-old girl, with no prior history of seasonal or perennial allergies, developed erythematous itching rash, on both hands as well as face, along with dyspnea. She worked in a pharmaceutical company that manufactured tablets. Every day, after about 2 hours of working on tablets (containing maize starch, microcrystalline cellulose and lactose), she developed allergic symptoms. A strong positive reaction (including sneezing, conjunctival reaction, and pruritus in nose and eye) was elicited within 6 minutes of nasal provocation test with maize bran. The study revealed that the patient developed allergy to maize through inhalation and cutaneous contact to the allergen, while at work. (9).
Maize has also been reported as a causative agent in baker’s asthma. These patients, however, have never reported problems after consumption of this cereal grain (10)
Atopic dermatitis
A 33-year-old nurse with a history of asthma and seasonal AR, presented with hand dermatitis, since the time she started nursing. She complained of having intermittent, itchy blisters on her hands, which improved when she was off work. She also experienced ‘itchy throat’, when she ate bananas, kiwi, avocado, and cantaloupe. The SPT showed positive response for corn, and the nurse was advised to avoid wearing gloves that contain corn-starch powder. It was reported that her symptoms started improving, after she used a non-cornstarch-based gloves (24).
