Allergies have been around for what it seems like forever. Most of our patients suffer from environmental or seasonal allergy. Most of the patients with on-going gastrointestinal symptoms self-diagnose with a food allergy, and they start avoiding the food in the matter. Therefore, the exact number of people with a food allergy is unknown, but it’s estimated that the prevalence rate is 3% and less than 10% of adults worldwide.
Several adverse gastrointestinal symptoms, reproducible or not reproducible, can be caused by the ingestion of different foods. Adverse food reactions can be immune derived or non-immune conditions. Food allergy is considered an immune-derived reaction.
Institute of Allergy and Infectious Diseases defined as food allergy
as ‘‘an adverse health effect arising from a specific immune
response that occurs reproducibly on exposure to a given food’’
Food allergies are adverse immunologic IgE-mediated reactions related to food hypersensitivity. Â The risk factors can be varied:
| Sex (male sex children) | Timing in the exposure to food (weaning) |
| Race/ ethnicity (Asian and black children) | Environmental sensitization |
| Genetics | Obesity |
| Atopy | Inflammatory state |
| Vitamin D deficiency | Probiotics |
| Omega 3 PUFA’s deficiency | |
| Antioxidant deficient diet | |
| Increased hygiene |
The reproducible adverse food reaction called food allergy is associated with the ingestion of different foods, and these can vary depending on the patient’s life stage:
| Childhood (can be resolved) | Adult (persistent) |
| Milk | Peanut |
| Egg | Tree nuts |
| Wheat | Fish |
| Soy | Shellfish |
Testing for food allergy can be tricky; false positives or cross-reactions between foods can easily take place. The best approaches are currently regulated by the Expert Panel Guidelines and should be accompanied by a physical examination.
Considered the gold standard.
It can be easily reproduced, but cross-reactions to different foods can appear if the test is not properly prepared.
Not appropriate for patients that have a high risk of anaphylaxis or using steroids, antihistamines, dermatitis.
Useful but not diagnostic
The adverse food reaction should appear within minutes or 2-4 hours after the test. Is considered to be time consuming and risky.
THE CROSS REACTORS |
|||||
| Environmental allergen | Fruits | Vegetables | Nuts | Spices | Other foods |
| Pollen | Apple, cherry, fig, kiwi, lychee, nectarine, pear, plum, peach, apricot. | Beans, carrot, celery, potato, tomato, peas. | Almond, hazelnut, walnut. | Anise, basil, dill, chicory. | Lentils, peanuts, soybean, sunflower. |
| Grass | Date, kiwi, melons, orange, tomato, watermelon. | Peas, potato. | Peanut | ||
| Ragweed | Banana, melons, watermelon. | Cucumbers, Zucchini | |||
An allergy is considered a systemic disease and may be presented with diverse manifestations. Food allergy can have the following adverse reactions.
FOOD ALLERGY MANIFESTATIONS |
|
| DIGESTIVE | NON-DIGESTIVE |
| Immediate gastrointestinal hypersensitivity: IgE mediated reaction, often accompanied by effects in the skin and the lungs. Symptoms:
·      pyloric spams ·      hypotonia ·      vomiting ·      diarrhea |
Cutaneous manifestations:
·      atopic dermatitis ·      urticaria ·      exercise-induced urticaria ·      contact urticaria |
| Oral allergy syndrome: the presence of itching and swelling of oral tissues. | Respiratory:
·    asthma ·      Heiner syndrome ·      coughing or rhinitis |
| Eosinophilic esophagitis and gastritis: IgE mediated and non-IgE mediated, the first involves dysphagia, vomiting, abdominal pain, and irritability. Eosinophilic gastritis is associated with vomiting, abdominal pain, hematemesis, and poor weight gain. | Systemic manifestations: anaphylaxis. |
| Dietary protein enterocolitis: In the first months of life, babies may present vomiting and diarrhea, leading to dehydration. | |
| Celiac disease: an increased transglutaminase activity is found in this disease. | |
| Irritable bowel syndrome and food allergy. | |
Sicherer, Scott H., and Hugh A. Sampson. “Food allergy: epidemiology, pathogenesis, diagnosis, and treatment.” Journal of Allergy and Clinical Immunology 133.2 (2014): 291-307.
Olivier, C. E. “Food allergy.” J Aller Ther S 3 (2013): 2.
Flores Kim, J., et al. “Diagnostic accuracy, risk assessment, and costâ€effectiveness of componentâ€resolved diagnostics for food allergy: a systematic review.” Allergy 73.8 (2018): 1609-1621.
Allergic Living,  Charts, Food Allergy, Fruit & Vegetable  August 30, 2010. https://www.allergicliving.com/2010/08/30/the-cross-reactors/