An allergy is an inappropriate response to a stimulus and it is mediated by immunoglobulins E (IgE). It can be triggered by food, medications, environmental allergens, but also by things like the fabric we wear, the washing powder we use to clean. The brain perceives the item as a threat and tells the body to react against it, creating an immune response.
The effects of an allergen on an individual may be physical, physiological, and/ or psychological, and can be caused by something the person has eaten, inhaled, or made contact with the skin. The reaction is immediate.
A Type III Hypersensibility is another reaction involving the immune system, but this time immunoglobulins G (IgG) are involved. Reactions are delayed, as symptoms can appear up to 72 h after ingestion of the food. Very often, there is no reaction at all, but it contributes to low grade inflammation.
An intolerance to food is a difficulty or incapacity to metabolise it properly, and generally comes from a lack of enzymes or other digestive products (HcL, bile…). The most famous is intolerance to lactose, which is a lack of production of the enzymes lactase, which degrades lactose.
In current language people, including practitioners, use the word intolerance to speak about enzyme deficiency and Type III Hypersensibilities.
