Ask Dr Trisha: How to manage food intolerance

Ask Dr Trisha: How to manage food intolerance

Food allergy and intolerance seem to be more common these days, with many people associating their health problems to the food they eat. This probably just reflects more widespread information about food intolerance thanks to the internet. Food intolerances can persist into later life, and may even appear for the first time in people over 50. You may not realise that food is to blame for your health issues, or feel confused about the difference between an allergy and an intolerance.

Food intolerance is more common – as many as one in ten of the population get symptoms related to eating one or more foods. But very few of these people actually have a food allergy, in which the immune system reacts against certain proteins in the food, resulting in a release of chemicals and sometimes white blood cells. Most food allergies are mild, causing symptoms such as an itchy red rash, or itching inside the mouth and throat with swelling of the face. Some, however, lead to a life-threatening reaction, such as an anaphylactic allergic reaction to peanuts. Symptoms tend to come on fast, often after eating just a tiny amount of the food.

In an intolerance, the person is unable to digest a food properly and develops symptoms which result from this altered digestion. Symptoms usually occur several hours after eating the food and are often related to your gut, such as bloating, diarrhoea and abdominal pain.

Lactose intolerance can develop in adult life when the lining of the gut becomes gradually damaged by disease or less quick to heal after episodes of gastroenteritis. This means you don’t produce the enzymes necessary to digest the milk sugar, lactose.

It’s quite easy to diagnose a food intolerance yourself with an exclusion diet. Leave out the foods that you think are causing problems one at a time for a few weeks. Then gradually reintroduce them individually and see if the symptoms return. Allergies may be more difficult to diagnose and are best discussed with your doctor.

Once you have identified what may be causing your symptoms, avoiding this food can be another big challenge. Lactose, for example, is used in products as diverse as crisps and medicines, so you will need to do some solid detective work and read labels very carefully. If you get it wrong, you may unnecessarily cut out nutritionally valuable foods and find yourself on a severely restricted diet which risks deficiencies of vitamins and minerals. Ask your doctor for help if you are worried.


  • Dr Trisha writes a column every fortnight in Yours magazine. Ask Dr Trisha about your health problems by emailing