Sensitivity to Ingested Sulfites

Sulfiting agents, including sodium and potassium bisulfite, sodium and potassium metabisulfite, sodium sulfite, and sulfur dioxide, have enjoyed widespread use as food and drug ingredients. The oral ingestion of these sulfiting agents is now known to trigger asthma in a small subset of the asthmatic population. The best evidence suggests that perhaps 150,000 to 200,000 individuals in the United States may be sulfite sensitive. Although the mechanism of sulfite-induced asthma remains unknown, several possibilities have been considered, including inhalation of sulfur dioxide (SO2) while swallowing, an IgE-mediated reaction, and a deficiency of sulfite oxidase leading to impaired sulfite metabolism and excretion. The only treatment for sulfite sensitivity is avoidance of sulfites in foods and drugs

Sulfite Residues in Maraschino Cherries

A survey of 53 samples of maraschino cherries from 14 different processors revealed that total sulfite residues averaged 52.3 ± 44.7 ppm. However, 58.5% of the samples had less than 40 ppm total SO2, while only 7.6% had greater than 120 ppm total SO2 indicating that the distribution was skewed in the direction of lower residue levels. Free sulfite residues in the 53 samples were considerably lower, averaging 14.2 ± 7.1 ppm. With free SO2 levels, 35.8% of the samples had less than 10 ppm free SO2, while only 5.7% had greater than 30 ppm free SO2. With an average serving size of one cherry (3–7 g), maraschino cherries would contribute only 0.16–0.37 mg per serving of total sulfites as SO2

Allergenic Foods

Virtually all food allergens are proteins, although only a small percentage of the many proteins in foods are allergens. Any food that contains protein has the potential to cause allergic reactions in some individuals. However, a few foods or food groups are known to cause allergies on a more frequent basis than other foods. At a 1995 consultation on food allergies sponsored by the Food and Agriculture Organization, a group of international experts confirmed that peanuts, soybeans, crustacea, fish, cow’s milk, eggs, tree nuts, and wheat are the most common allergenic foods. These foods are responsible for more than 90% of serious allergic reactions to foods. Allergies to certain fresh fruits and vegetables are also rather common, but the allergens tend to be labile to processing and cooking and the symptoms are mild and confined primarily to the oropharyngeal area. The prevalence of allergic sensitivities to specific foods varies from one country to another depending on the frequency with which the food is eaten in that country and the typical age at its introduction into the diet. For example, peanuts are a much more frequent cause of food allergies in the United States than in most other countries. Americans eat peanuts more often and introduce peanut butter into the diet of children at an early age. The Japanese probably experience more soybean and rice allergies than some other cultures because of the frequency of these two foods in the Japanese diet. Scandinavians have a high incidence of codfish allergy for similar reasons. Table 1 provides a listing of the most common allergenic foods and food groups compiled from a thorough search of the medical literature. Table 2 provides a listing of the less common allergenic foods. Only some of the foods listed in this table have been documented to cause severe, life-threatening allergic reactions. Citations are provided to studies and/or case reports that document the allergenicity of those particular foods. The absence of a particular food on this list may not mean that it is nonallergenic but may indicate that its allergenicity has not been documented. Conversely, the presence of a specific food on the list merely indicates that it has been listed in one or more reports as a cause of food allergy and does not indicate the prevalence or potential as an allergenic food

Sulfites

Key Concepts Sulfites are frequently used food and drug additives. Ingestion of sulfite residues has been documented to trigger asthmatic reactions in sensitive individuals. Sulfite-induced asthma occurs in less than 5% of asthmatic individuals, and those with severe, persistent asthma are at greatest risk. The diagnosis of sulfite-induced asthma is best made by blinded oral challenge with assessment of lung function. Labeling regulations in the United States alert sulfite-sensitive individuals to the presence of sulfites in foods, which must then be avoided

Evaluation of a Handheld Gluten Detection Device

A portable, handheld gluten detection device, the Nima sensor, is now available for consumers wishing to determine if gluten is present in food. By U.S. regulation, gluten-free foods should contain \u3c 20 ppm of gluten. Thirteen gluten-free foods (muffins, three different types of bread, three different types of pasta, puffed corn snack, ice cream, meatballs, vinegar and oil salad dressing, oatmeal, and dark chocolate) were prepared; each food was spiked on a weight-to-weight basis with gluten levels of 0, 5, 10, 20, 30, 40, and 100 ppm before processing or preparation. Unprocessed and processed foods were tested with the handheld gluten sensor and by two gluten-specific enzyme-linked immunosorbent assays (ELISAs) on the basis of the R5 and G12 monoclonal antibodies, respectively. The portable gluten detection device detected gluten in all food types at the 30-ppm addition level, failing to detect gluten in only 5 (6.4%) of 78 subsamples. At the 20-ppm addition level, the portable gluten detection device failed to detect gluten in one type of pasta but detected gluten residues in 63 (87.5%) of 72 other subsamples. The device was able to detect gluten at the 10-ppm addition level in 9 of the 13 food matrices (41 of 54 subsamples, 75.9%) but not in the three types of pasta and the puffed corn snack. The gluten-sensing device did not perform reliably at the 5-ppm addition level in 11 of 13 food matrices (exceptions: ice cream and muffins). In contrast, the ELISA methods were highly reliable at gluten addition levels of ≥ 10 ppm in all food matrices. The portable gluten detection device yielded a low percentage of false-positive results (4 of 111, 3.6%) in these food matrices. Thus, this handheld portable gluten sensor performed reliably in the detection of gluten in foods having ≥ 20 ppm of added gluten with only 18 (5.9%) of 306 failures, if results of the one type of pasta are excluded. The device worked with greater reliability as the gluten levels in the foods increased

Soybean Oil Is Not Allergenic to Soybean-Sensitive Individuals

We have previously demonstrated that peanut oil is not allergenic to peanut-sensitive individuals. Seven soybean-sensitive patients were enrolled in a double-blind crossover study to determine whether ingestion of soybean oil can induce adverse reactions in such patients. All subjects had histories of systemic allergic reactions (urticaria, angioedema, wheezing, dyspnea, and/or vomiting) after soybean ingestion and had positive puncture skin tests with a 1:20 w/v glycerinated-saline whole soybean extract. Sera from six of the seven subjects were tested by RAST assay for the presence of specific IgE antibodies to soybean allergens. All patients had elevated levels of serum IgE antibodies to the crude soybean extract; binding values ranged from 2.3 to 28.1 times that of a negative control serum. Before the oral challenges, all patients demonstrated negative puncture skin tests to three commercially available soybean oils and to olive oil (control). On four separate days, patients were challenged with the individual soybean oils and to olive oil in random sequence. At 30-minute intervals, under constant observation, patients ingested 2, 5, and 8 ml of one of the soybean oils or olive oil contained in 1 ml capsules. No untoward reactions were observed with either the commercially available soybean oils or olive oil. Soybean oil ingestion does not appear to pose a risk to soybean-sensitive individuals

Allergenicity of Various Peanut Products as Determined by RAST Inhibition

Extracts of 19 different peanut products and peanut oil were tested for their allergenicity by the radioallergosorbent test inhibition assay using a crude peanut extract from raw peanuts as the standard for comparison. Seventeen of the extracts were able to competitively inhibit the binding of serum IgE from peanut-sensitive patients with the solid-phase raw peanut extract. Peanut oil and the extract from hydrolyzed peanut protein did not inhibit binding, which suggests that these products are not allergenic. The peanut hull flour extract showed a slight ability to inhibit binding, suggesting that this product contains minor amounts of the peanut allergen

Identification of a Brazil-Nut Allergen in Transgenic Soybeans

Background: The nutritional quality of soybeans (Glycine max) is compromised by a relative deficiency of methionine in the protein fraction of the seeds. To improve the nutritional quality, methionine-rich 2S albumin from the Brazil nut (Bertholletia excelsa) has been introduced into transgenic soybeans. Since the Brazil nut is a known allergenic food, we assessed the allergenicity of the 2S albumin. Methods: The ability of proteins in transgenic and nontransgenic soybeans, Brazil nuts, and purified 2S albumin to bind to IgE in serum from subjects allergic to Brazil nuts was determined by radioallergosorbent tests (four subjects) and sodium dodecyl sulfate–polyacrylamidegel electrophoresis (nine subjects) with immunoblotting and autoradiography. Three subjects also underwent skin-prick testing with extracts of soybean, transgenic soybean, and Brazil nut. Results: On radioallergosorbent testing of pooled serum from four subjects allergic to Brazil nuts, protein extracts of transgenic soybean inhibited binding of IgE to Brazil-nut proteins. On immunoblotting, serum IgE from eight of nine subjects bound to purified 2S albumin from the Brazil nut and to proteins of similar molecular weight in the Brazil nut and the transgenic soybean. On skin-prick testing, three subjects had positive reactions to extracts of Brazil nut and transgenic soybean and negative reactions to soybean extract. Conclusions: The 2S albumin is probably a major Brazil-nut allergen, and the transgenic soybeans analyzed in this study contain this protein. Our study shows that an allergen from a food known to be allergenic can be transferred into another food by genetic engineering

Wild Buckwheat Is Unlikely to Pose a Risk to Buckwheat-Allergic Individuals

Buckwheat (Fagopyrum esculentum) is a commonly allergenic food especially in Asia where buckwheat is more commonly consumed. Wild buckwheat (Polygonum convolvulus, recently changed to Fallopia convolvulus) is an annual weed prevalent in grain-growing areas of the United States. Wild buckwheat is not closely related to edible buckwheat although the seeds do have some physical resemblance. A large shipment of wheat into Japan was halted by the discovery of the adventitious presence of wild buckwheat seeds over possible concerns for buckwheat-allergic consumers. However, IgE-binding was not observed to an extract of wild buckwheat using sera from 3 buckwheat-allergic individuals either by radio-allergosorbent test inhibition or by immunoblotting after protein separation by sodium dodecyl sulfate–polyacrylamide gel electrophoresis. Furthermore, the extract of wild buckwheat was not detected in a buckwheat enzyme-linked immunosorbent assay developed with antisera against common buckwheat. Thus, wild buckwheat is highly unlikely to pose any risk to buckwheat-allergic individuals. The common names of plants should not be a factor in the risk assessment for possible cross-allergenicity

Prevalence of Sensitivity to Sulfiting Agents in Asthmatic Patients

Ingestion of sulfiting agents can induce wheezing in some asthmatic patients. However, neither the prevalence of sulfite sensitivity nor the clinical characteristics of the affected asthmatic population are known. In a prospective single-blind screening study, 120 non-steroid-dependent and 83 steroid-dependent asthmatic patients underwent challenge with oral capsules of potassium metabisulfite. Five non-steroid-dependent and 16 steroid-dependent asthmatic patients experienced a greater than 20 percent reduction in their one-second forced expiratory volume within 30 minutes following the oral challenge. Twelve of these sulfite reactors were rechallenged with metabisulfite capsules in a double-blind protocol. Under these conditions, only three of seven steroid-dependent patients had a positive response. Moreover, only one of five non-steroid-dependent patients had a response to double-blind challenge. On the basis of this challenge study, the best estimate of the prevalence of sulfite sensitivity in the asthmatic patients studied is 3.9 percent. This population, however, contained a larger number of steroid-dependent asthmatic patients than would be found in the general asthmatic population. It is concluded, therefore, that the prevalence of sulfite sensitivity in the asthmatic population as a whole would be less than 3.9 percent and that steroid-dependent asthmatic patients are most at risk