A food intolerance is difficulty digesting certain foods and having an unpleasant physical reaction to them.
It causes symptoms, such as bloating and stomach pain, which usually come on a few hours after consuming the food.
The number of people who believe they have a food intolerance has risen dramatically over recent years, but it's hard to know how many people are truly affected. Many people assume they have a food intolerance when the true cause of their symptoms is something else.
This page covers:
In general, people who have a food intolerance tend to experience:
These symptoms usually come on a few hours after eating the food.
It can be difficult to know for sure whether you have a food intolerance as these are very general symptoms, typical of many other conditions too.
There are no tests for food intolerances. The only way to know if you have one is to monitor your symptoms and the food you eat. See what happens when you cut out the suspected food for a while, and then reintroduce it back into your diet.
Try keeping a food diary, noting:
Once you have a good idea which foods may be causing your symptoms, you can try excluding them from your diet one at a time and observing the effect this has.
Consider seeing a dietitian to make sure you're receiving all your recommended daily nutrients while you do this trial. Find a registered dietitian.
Never restrict your child's diet unless this has been advised by a dietitian or your doctor.
If you regularly have diarrhoea, bloating, tummy pain or skin rashes but you're not certain of the cause, see your GP.
Your GP may be able to diagnose the cause from your symptoms and medical history. If necessary, they'll carry out tests, such as blood tests.
You can also do some research yourself. It may help to read up on other conditions that cause similar symptoms. For example, learn about:
Bowels are sensitive organs, and it's common to have bowel symptoms when you have been ill or feel run down or stressed.
A food intolerance is not the same as a food allergy. Here's how you can tell the difference:
A food allergy:
A food intolerance:
Read about the diagnosis of food allergies.
It is often unclear why a person is sensitive to certain foods.
If your symptoms come on after having dairy products, it's possible you may have lactose intolerance. This means your body can't digest lactose, a sugar found in milk, yoghurts and soft cheeses. Your GP can usually diagnose lactose intolerance by looking at your symptoms and medical history.
Some people have trouble digesting wheat and experience bloating, wind, diarrhoea, vomiting and stomach pain after eating bread. Read more about wheat intolerance (also known as wheat sensitivity).
Otherwise, the culprit may be a food additive, chemical or contaminant, such as:
Many people cut gluten from their diet thinking that they are intolerant to it, because they have symptoms that come on after eating wheat.
But it's hard to know whether these symptoms are because of a genuine intolerance to gluten, an intolerance to something else in wheat, or nothing to do with wheat at all. It may help to read Should you cut bread from your diet?
In reality very few people need to cut out gluten from their diet, although it's important to do so if you have coeliac disease (which is neither an intolerance nor an allergy).
If you're confident you are intolerant to a particular food, the only way you can manage this is to:
By checking food labels, you'll learn which sorts of foods to avoid.
If you think your child may have a food intolerance, check with your GP or a dietitian before eliminating foods from their diet, as a restricted diet could affect their growth and development. Cows' milk, for example, is an important source of calcium, vitamin D and protein.
Your GP may want to refer you to a specialist if they're not sure what's causing your symptoms and further tests are needed.
You may also be referred if your child has digestive symptoms (such as tummy pain and diarrhoea) and: