Many different chemicals and compounds in food can trigger allergic reactions. Protein, especially from dairy products, shellfish and nuts, is a very common allergy trigger in children and adults. Children often outgrow their allergies to foreign protein, but “leaky gut syndrome” during adulthood triggers a type of protein allergy that’s often misdiagnosed as auto-immune disease.
An allergic reaction is a quick defense response by your immune system to a potentially harmful “foreign invader.” Foreign invaders can be animal protein, plant protein, dust, preservatives, food coloring or essentially any chemical that your body identifies or tags as a dangerous allergen or antigen. Sometimes your body overreacts or gets confused if your immune system isn’t working properly, but usually an allergic reaction is an indication that something is somewhere it shouldn’t be. Nasal congestion, watery eyes, puffy face, swollen throat, difficulty breathing, skin rash, upset stomach, diarrhea and inflamed joints are all common symptoms of an allergic reaction.
Proteins in cow’s milk are the most frequent trigger of allergies in infants and a relatively common cause of allergic reactions in adults. The proteins in dairy products that cause the most difficulty are lactoglobulin and casein. These proteins resist digestion and can be absorbed through the intestines mainly intact, which triggers an immune response and the release of antibodies and histamine. In later childhood, egg albumin protein intolerance and allergy is more common than negative reactions to cow’s protein. In adults, allergic reactions to protein-rich shellfish such as shrimp and lobster are potentially the most deadly because they frequently lead to anaphylactic shock if left untreated. Allergic reactions to meats are very unusual, although beef contains a blood protein called bovine serum albumin that acts as an allergen.
Soybean protein, a common additive in baby formula, is the second-most common allergen for infants. Soy protein is also relatively difficult to break down into smaller amino acids, which are building blocks that don’t trigger allergic reactions. Instead, soy protein is sometimes absorbed intact, which your body perceives as foreign and dangerous. Allergies to nuts such as peanuts are very common and potentially deadly too, although it’s often the fungi and aflatoxins that cause the extreme reactions from the body instead of the protein.
Leaky Gut Syndrome
Leaky gut syndrome occurs because damage to and inflammation of the small intestine make it unable to prevent undigested protein and other compounds in food from being absorbed into the bloodstream. Consequently, proteins can become deposited within joints and other tissues, which trigger localized immune responses such as inflammation. Gluten protein intolerance and allergy is a common cause of leaky gut syndrome, which is often misdiagnosed as an auto-immune condition because the body appears to be attacking itself. Thus, protein from any source is capable of causing allergic reactions in people with leaky gut syndrome.
- Textbook of Functional Medicine; David S. Jones
- Public Health Nutrition: From Principles to Practice; Mark Lawrence and Tony Worsley
- Human Biochemistry; Charles Dreiling
- Harrison's Principles of Internal Medicine; A. Fauci et al.
Sirah Dubois is currently a PhD student in food science after having completed her master's degree in nutrition at the University of Alberta. She has worked in private practice as a dietitian in Edmonton, Canada and her nutrition-related articles have appeared in The Edmonton Journal newspaper.