First of all, what is the difference between a food allergy and a food intolerance?
With a food allergy, the immune system is involved and the response is usually immediate and dramatic.
Typical symptoms include: coughing, sneezing, vomiting, migraines, watering eyes, rashes, swelling tissue, hives. In severe cases, there can be anaphylactic shock which requires emergency medical intervention. With symptoms involving the digestive system, such as nausea, vomiting and diarrhoea, the response can be delayed for hours or even days.
A food intolerance tends to have a slow onset (hours, days or even weeks).
It happens when a person is unable to break down and digest a particular food, often because of a lack of appropriate enzymes. The food therefore passes through the digestive tract unprocessed, or lingers in the gut fermenting and producing excess ‘gas’.
Although food intolerances may involve the immune system, they aren’t life threatening, although over time can prevent the absorption of nutrients, and create inflammation and immunity issues.