A food intolerance is not the same as a food allergy, even though the symptoms can be the same. There are several common types of intolerance, including gluten intolerance, food poisoning, and histamine toxicity. Other types include gluten intolerance and reactions to food additives (such as MSG and sulfites).
If you go to your healthcare provider and say, "I think I have a food allergy," your healthcare provider has to consider other possibilities that may cause symptoms and could be confused with food allergy, such as food intolerance. To find out the difference between food allergy and food intolerance, your healthcare provider will go through a list of possible causes for your symptoms. This is called a "differential diagnosis." This type of diagnosis helps confirm that you do indeed have a food allergy rather than a food intolerance or other illness.
There are several common types of food intolerance, including:
- Food poisoning
- Histamine toxicity
- Lactose intolerance
- Food additives
- Gluten intolerance
- Psychological causes.
One possible cause of symptoms like those of food allergy is foods contaminated with microbes, such as bacteria, and bacterial products, such as toxins. Contaminated meat and dairy products sometimes cause symptoms, including GI discomfort, that resemble a food allergy when it is really a type of food poisoning.
Another type of food intolerance is histamine toxicity. There are substances -- such as histamine present in certain foods -- that cause a reaction like an allergic reaction. For example, histamine can reach high levels in cheese, some wines, and certain kinds of fish such as tuna and mackerel.
In fish, histamine is believed to come from contamination by bacteria, particularly in fish that are not refrigerated properly. If you eat one of these foods with a high level of histamine, you could have a reaction that strongly resembles an allergic reaction to food. This reaction is called "histamine toxicity."