Allergies are the hypersensitive response of the body to foreign substances. These foreign substances are called antigens, which stimulate the body to produce antibodies, whose normal function is to combat antigens by destroying them or otherwise making them harmless. In allergic individuals, for poorly understood reasons, the body's antibody defense mechanism goes awry and injures the body instead of protecting it. The most familiar allergies are hay fever and asthma, which are caused by a wide variety of inhaled pollens, dusts, and other agents. However, food can also be a cause of allergic reactions.
Food does not often cause allergic reactions. Food allergies are more common in infants than in older children and adults, probably because the infant's immature digestive tract permits more ready absorption of offending food molecules.
Manifestations of food allergies in adults are usually of the immediate kind, including hives, angioderma, eczema, gastrointestinal disorders, and general systemic reactions of the anaphylactic type. Systemic reactions occur quickly after eating.
They are most frequently caused by legumes, nuts, seafoods (especially shellfish), and berries, but carbohydrates, fats, food additives, and contamination by drugs may be implicated.
In infants and children, eczema is the prominent manifestation, and the most frequent causative agents include milk, wheat, eggs, fish, and soybean products.
