Got a bellyache? A food intolerance may be the culprit

Written by: Dr Aathavan Loganayagam
Edited by: Conor Lynch

Top Doctors recently spoke to highly revered London-based consultant gastroenterologist, Dr Aathavan Loganayagam, to find out how common food intolerance is, and what the main associated symptoms of food intolerance are.

How common is food intolerance?

Digestive problems can range from mildly annoying to incredibly uncomfortable, and they are often caused by food intolerances. For some people, it can be bloating. For others, it is a headache or hives.


Food intolerance is quite common. A recent UK study showed food intolerance affects up to 15 to 20 per cent of the population. It is important to bear in mind, here, however, that before jumping to the conclusion that your symptoms are being caused by food intolerance, it’s a good idea to get an expert opinion.


Rather than self-diagnosing a food intolerance and deciding to cut something out of your diet, it’s really important to seek medical advice and work towards getting an official diagnosis. For starters, you don’t want to eliminate a core food group unnecessarily, which could cause nutritional deficiencies.


It’s also important to make sure you haven’t missed a diagnosis of another condition that causes similar symptoms, but that needs to be treated quite differently.


How will I know if I have a food intolerance or a food allergy?

A food allergy is an immune system response where the body mistakes a protein in a food as harmful and releases antibodies to fight it. A food intolerance, meanwhile, is a digestive system response, and occurs when someone isn’t able to properly digest or break down the food or when the food irritates the digestive system.


One big difference between a food allergy and a food intolerance is that, with the exception of a reaction to one of two food preservatives, food intolerances don’t cause anaphylaxis, the severe allergic reactions that can be life-threatening.


What are the main symptoms of food intolerance?

Symptoms of food intolerances can be quite broad, but they’re often digestive related, causing symptoms such as bloating or a change in bowel motions. Food intolerance can also cause rashes and hives, headaches, wheezing, a runny nose, and just generally feeling a bit under the weather.


How is a food intolerance diagnosed?

Unfortunately, unlike food allergies, fail-safe clinical tests to diagnose food intolerances are lacking. Breath tests designed to help pinpoint a lactose or fructose intolerance are available, but results need to be interpreted carefully.


It’s also really important to be wary of advertised testing methods for food intolerances that lack credible evidence. The challenging thing with food intolerances is that it can be quite difficult to work out which food is causing the problem. With this in mind, visiting an experienced gastroenterologist is highly recommended.


With that done, we would then look at doing a strict elimination diet, which removes the higher-risk foods, with the goal being to have a few symptom-free weeks before gradually reintroducing those foods to try to identify which you might be intolerant to.


How are food intolerances treated?

Just like a food allergy, the main treatment for a food intolerance (once diagnosed) is avoiding that food. Once you have identified which food or foods that you’re intolerant to, it’s a matter of working out what your threshold is so you can hopefully still eat and enjoy a certain amount of it, rather than having to remove it from your diet completely.


What are the most common food intolerances?

A wide variety of foods and ingredients can trigger reactions, including food additives, eggs, and even citrus fruits. Below are three of the most commonly reported food intolerances.


  1. Lactose intolerance: This occurs when the body doesn’t produce enough lactase, a gut enzyme that is required to break down lactose, a type of sugar found in milk and other dairy products. Symptoms are typically digestive related, and most people who are lactose intolerant can and should continue to enjoy dairy foods, given some contain no or very little lactose.


  1. Wheat intolerance: This causes gastrointestinal symptoms when wheat-containing foods are eaten and where coeliac disease has been ruled out. Research shows it may be the gluten or a wheat-based protein called amylase trypsin inhibitors or the fructans in wheat that people react to.


  1. FODMAP intolerance: FODMAPs are a group of sugars that are not completely digested or absorbed in our intestines. They are found in a wide variety of healthy foods. Different foods contain different FODMAPs, and while they are certainly an important food source for good gut bacteria, they trigger symptoms in people with irritable bowel syndrome.


Schedule an appointment with Dr Aathavan Loganayagam today via his Top Doctors profile if you feel like you might be suffering from a food intolerance.

By Dr Aathavan Loganayagam

Dr Aathavan Loganayagam trained in medicine at Guy’s, King's and St. Thomas’ medical schools. He then underwent rigorous structured specialty training in gastroenterology and general internal medicine in the well respected South London training programme.

He then spent two years during postgraduate training as a research and endoscopy fellow at Guy’s and St Thomas’ Hospitals, London. His research was in the fields of pharmacogenetics, inflammatory bowel disease and gastrointestinal malignancy. He has received awards and grants for outstanding research work, including the prestigious NHS Innovation London Award.

Dr Loganayagam has numerous publications in peer reviewed journals on all aspects of gastroenterology. He is actively involved in clinical research. He has particular local expertise in the practice of personalised medicine and the utilisation of novel therapeutic agents in the treatment of complex inflammatory bowel disease. He is currently the lead clinician for endoscopy at Queen Elizabeth Hospital, Woolwich.

Diagnostic and advanced therapeutic endoscopy remains a major part of his clinical expertise, including assessment and treatment of inflammatory bowel disease, strictures, polyps and cancers.

Dr Loganayagam is an approachable doctor who takes pride in his communication skills with patients. He is keen to ensure that patients are fully informed and involved in all aspects of their care.

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