Protein intolerance results from the inability to digest or effectively break down amino acids
. When food proteins are not digested well, they can act as antigens that cause
food protein allergies. Most often, cow's milk proteins are the cause of food intolerance in infancy. Food protein induced enterocolitis syndrome is also commonly attributed to intolerance to cow's milk proteins. Affected individuals present with diarrhea, edema, and
hypoalbuminemia. With increasing age and the introduction of different foods
, egg protein intolerance, soy and peanut allergy becomes more common.
Protein intolerance can be seen in the following conditions.
Immunological food protein intolerance : May or may not be IgE-mediated. IgE-mediated reactions occur within minutes to an hour after food protein ingestion and
symptoms range from skin rashes, urticaria, angioedema, wheezing to anaphylaxis, while non-IgE-mediated reactions occur within hours to days.
IgE-mediated conditions include:
- Cow's milk allergy
- Oral allergy syndrome
- Immediate GI hypersensitivity
- eosinophilic esophagitis
- Eosinophilic gastritis
- Eosinophilic gastroenteritis
IgE non-mediated conditions include:
- Food protein-induced enterocolitis
- Food protein-induced enteropathy
- Food protein-induced allergic proctocolitis
Autoimmune reaction: Autoimmune reaction to gluten proteins is found in celiac disease, non-celiac
gluten sensitivity, wheat allergy, gluten ataxia and dermatitis herpetiformis.
Enzyme deficiency: Enterokinase (enteropeptidase) deficiency
Metabolic disorders:
- Phenylketonuria (PKU)
- Maple syrup urine disease (MSUD)
- Tyrosinemia
- Homocystinuria
Genetic/hereditary disorder: Urea cycle disorders, lysinuric protein intolerance
Pharmacological: Chronic use of drugs to suppress stomach acid production use [4]
Toxic reactions to biogenic amines:
- Tyramine in aged cheeses
- Histamine
Unspecified: Irritable Bowel Syndrome
Protein intolerance
can occur due to any abnormality in the digestive or metabolic process. Food proteins, when completely denatured by stomach acid, have been found to cause
protein sensitization and food allergies in the gut. As seen in patients on long-term treatment for dyspeptic disorders, hypoacidic states have often been found to develop
food protein allergies.
Review
In IgE-mediated food allergies, positive skin prick test responses to
food proteins are usually evident, with detection of food-specific IgE antibodies. However, most food
protein intolerances are not IgE-mediated.
When food protein intolerance is suspected, the following measures and tests are helpful in diagnosis
1. Food diary: Keeping a food diary is important as it helps clinicians
map symptoms and find the relationship of food to patient symptoms.
2. Skin prick test: This test screens for IgE-mediated food protein allergies. Although a positive test
result may indicate the presence of IgE antibodies, it has a low predictive value
while a negative test result has high predictive accuracy.
3. Atopic patch test: Test against food proteins Used to screen for delayed intolerances (
cell-mediated reactions). If food protein intolerance or allergy is suspected, the
patient should consume a
a diet free from the suspected protein for 2 to 4 weeks. If symptoms improve, an oral food challenge test
may be performed as a diagnostic test.
6. Oral food challenge test: It is the gold standard test under medical
to diagnose or rule out food allergy. Diagnosis of food protein intolerance, dietary elimination of the relevant
food It can be put in place when symptoms subside after treatment and
when symptoms reappear after administration of the same food.
Treatment and Management
Mothers should be advised to stay away from cow's milk and milk products in breastfed babies
. Intense hydrolyzed formula with documented hypoallergenicity can be preferred for the treatment of cow's milk allergy, especially in infants and young children who are not breastfed. Amino acid formulas may also be recommended for patients with more
severe symptoms.
Steroids are a treatment for IgE-mediated immunological
food protein intolerance, including eosinophilic gastrointestinal disorders.
If acute allergic reactions or anaphylaxis are suspected, possible offending
foods should be avoided and emergency medical care should be sought. A prescription for a self-injectable epinephrine device may be given and instruction
for their proper use.
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