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.

Food allergies: Recent studies had reported that the incidence of food allergy has risen around the globe, but there is no exact number to report. Children’s food allergy prevalence is estimated to be 4% to 7% and 3% to 6% in adults, but the heterogeneity of rates and methodology between studies differs in a large amount. These epidemiological reports are consistent because the proper diagnosis and definition of food allergy are imprecise.

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.  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

Diagnose screening:

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.

• Elimination Diet

Considered the gold standard.

• Skin Prick Tests

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.

• S IgE measurements

Useful but not diagnostic

• Oral Food Challenges (OFC)

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 cost‐effectiveness of component‐resolved diagnostics for food allergy: a systematic review.” Allergy 73.8 (2018): 1609-1621.

Allergic Living

Allergic Living,  Charts, Food Allergy, Fruit & Vegetable  August 30, 2010. www.allergicliving.com/2010/08/30/the-cross-reactors/