Definition and Types of Food Allergy

Food allergy is an abnormal reaction of the body's immune system against food components (proteins) and cause adverse symptoms of the body. All substances which cause immunological reactions are called allergens. When an allergen enters the body, then the body will produce antibodies which then attack the allergens that trigger allergic reactions (hives, swelling of the tongue or lips, dizziness, fainting, and in severe cases, death). Allergy symptoms take place quickly after consuming the allergen. In people who are very sensitive, very little consumption of food allergens can trigger allergies.

Food allergy is a collection of symptoms that affect many organs and body systems caused by food allergies. In some food allergy literature used to express a reaction to a food that is essentially a type I hypersensitivity reactions and hypersensitivity to food is essentially a hypersensitivity reaction type III and IV. Food allergy is an immunological reaction (immune system) that deviate because the influx of allergy-causing substances in the body. Most of these reactions through a type 1 hypersensitivity reaction.

The potential occurrence of food allergies in a person is often a descent. Some foods that often cause allergies in children are milk, nuts and eggs while in adults are shellfish. Allergies can be lost with age. For example, milk protein allergy in children can disappear when the child is an adult.

Food intolerance is an adverse reaction to food and cause few symptoms (likely related to digestion, such as cramps, diarrhea, gas and bloating), but does not involve the immune system. Cause of food intolerance is due to the gastrointestinal tract of patients lack the enzyme needed to digest certain substances in food. Examples of intolerance is lactose intolerance and celiac disease. Lactose intolerance occurs in people who lack the enzyme lactase in the channel cernanya so can not drink milk (unless the lactose has been removed), while patients with celiac disease can not consume products containing wheat because people can not digest gluten contained in wheat.

Food intolerance is a non-immunologic reaction and the food is mostly cause unwanted reactions to food. This reaction can be caused by substances contained in food because of toxic contamination (eg toxins secreted by Salmonella, Campylobacter and Shigella, histamine fish poisoning), pharmacologic substances contained in foods, for example tyramine in cheese, caffeine in coffee or abnormalities in the host's own such as deficiency of lactase, maltase or idiosyncratic responses in the host.

According to the rapid onset of the allergic reaction to food is divided into two kinds, namely:
1. Rapid reaction (Immediate Hipersensitivity / rapid onset of reaction): This reaction occurs by a certain type of immune reaction. Occurred a few minutes to a few hours after eating or inhalation exposure to allergy.
2. The reaction is slow (delayed onset reaction): This reaction occurs more than 8 hours after eating allergy-causing substances.

Adverse food reactions is a general term for unwanted reactions to food are ingested. This reaction may be a secondary reaction to food allergies or food intolerance.

Not all adverse reactions to food is a pure allergic reactions, but many doctors or lay people use the term food allergy to all unwanted reaction from food, either immunological or non-immunological.

Adverse reactions to food are often occurs in everyday life. The reaction can be mediated by a mechanism that is both immunology, pharmacology, toxins, infections, idiosyncrasy, metabolism and neuropsychological to food. Of all adverse reactions to foods and food additives approximately 20% due to food allergies.