Food Allergies & Intolerances: Causes, Symptoms, and Management
Understanding Food Allergies
General Features of Food Allergens
- Proteins or low molecular weight glycoproteins
- Water-soluble
- Resistant to heat, denaturation, degradation by proteases, or acidification
- Molecular weight generally <70 kDa
Modifications due to chemical processes or food processing (ultrafiltration, high temperature, irradiation) can generate new antigenic sites or reduce digestibility.
Common Food Allergens
- In Children: Egg, fish, milk, peanuts, and soybeans
- In Adults: Fish, tree nuts, peanuts, shellfish, and wheat
Food antigens are usually water-soluble glycoproteins of large size; only a few are allergenic. Cross-reactions can occur between antigens, especially among foods of the same biological family. For example, an infant allergic to cow’s milk may also be allergic to goat’s milk.
Specific Food Allergies
Latex-Food Syndrome
Patients allergic to latex may also be allergic to certain foods, especially:
- Bananas
- Avocados
- Kiwi
- Melon
- Nuts
Cow’s Milk Allergy
- Prevalence: Sensitivity in children from 2% to 2.5%.
- Development: Usually appears early with initial dietary incorporation.
- Resolution: Children often outgrow this allergy between 3 to 5 years of age.
- Proteins: Divided into Casein (80%) and Whey (20%).
The multiplicity and diversity of cow’s milk allergens and epitopes are significant. Hypoallergenic formulas, including those based on soy, can also contain antigens that may trigger symptoms.
Chicken Egg Allergy
One of the most common food allergies, chicken egg can appear as an ingredient with various functions. It is used in the manufacture of cosmetics, shampoo, and other products. Certain components, like lysozyme, may be used individually as a food preservative.
Peanut Allergy: Severity & Risks
Peanut allergy is the most common cause of death from food allergy in the U.S. Approximately one-third of those allergic to peanuts experience severe reactions. Peanuts can be “de-flavored” and “re-flavored” to resemble almonds or walnuts, but they retain their antigenicity, and allergenicity may even increase with warming.
Soy Allergy: Widespread Use & Risks
Due to its virtually unlimited use in industry, many foods and items contain soy antigens. Soy can be consumed as grain, flour, or oil. It is used as a texturizer, emulsifier, and protein filler, often mixed with other flours in baking.
Understanding Food Intolerances
Enzymatic Intolerances
- Disaccharidase Deficiencies: Lactase, Sucrase
- Galactosemia: Deficiency of galactose-1-phosphate uridyltransferase, uridine diphosphate-4 epimerase
- Phenylketonuria: Deficiency of phenylalanine hydroxylase
- Alcohol Intolerance: Deficiency of aldehyde dehydrogenase
- Favism: Deficiency of G6PD (Glucose-6-phosphate dehydrogenase)
Pharmacological Intolerances
- Vasoactive Amines: Tyramine (found in cheese and red wine)
- Histamine: (found in strawberries)
- Nonspecific histamine release additives
Celiac Disease: Permanent Gluten Intolerance
Celiac disease is a chronic intestinal condition characterized by permanent gluten intolerance. It causes atrophy of the intestinal villi, leading to poor absorption of nutrients. It is one of the most common chronic intestinal diseases in many countries (e.g., 1 in 380). It is often underdiagnosed, with atypical forms of the disease (e.g., 1 in 150). Its origin is debated, possibly involving a hypersensitivity reaction or a hereditary mucosal defect.
Gluten Intolerance & Prolamins
Gluten is composed of storage proteins called prolamins and glutenins. Specific prolamins from certain grains cause gluten intolerance:
- Gliadin: Wheat
- Secalins: Rye
- Hordein: Barley
- Avenin: Oats
Non-toxic prolamins include:
- Oryzenin: Rice
- Zein: Maize (Corn)