Food Intolerance


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Reactions to foods that are not food allergies include food intolerances, such as lactose or milk intolerance. Food intolerance is an abnormal response to food which affects the gut and not the immune system. The symptoms can easily resemble those of food allergy and correct diagnosis is essential in order to get the right treatment. Food intolerance is far more prevalent, occurs in a variety of diseases, and is triggered by several different mechanisms that are distinct from the immunological reaction responsible for food allergy. Some other common food intolerances are due to gluten, eggs, fish, shellfish, nuts and soya additives.

Intolerance to food is actually fairly common. Most individuals suffer at some point in their lives with an unpleasant reaction to something they have eaten. Symptoms of food intolerance include; nausea, stomach pain, gas, cramps, bloating, vomiting, heartburn, diarrhoea, headaches and irritability or nervousness. Some food intolerances can lead to the onset of migraine headaches. These headaches, when triggered, cause the temporal artery to enlarge. This in turn puts pressure on the nerve cells that encircle the artery causing a release of chemicals. These chemicals cause the artery to swell even further, which leads to pain, inflammation and the onset of the migraine.

Drugs & Food Intolerance

Two of the most common drugs associated with symptoms of food intolerance are aspirin and Ibuprofen. Both are members of a family of drugs known as NSAIDS (non steroidal anti-inflammatory). This family of drugs is known to increase the flow of molecules through the gut wall. This means that bigger particles, such as food molecules, can get through the gut wall and into the blood. For many people, the side effects of NSAID’s is partly due to an already deteriorated gut lining. A proper healthy diet and exercise not only increases health and well being, but allows the gut to recover.

Food intolerance is not the same as a food allergy. Food intolerance is an abnormal reaction to a type of food or a chemical contained within that food. It produces unpleasant symptoms, much like a food allergy to which it is usually mistaken for. However, food intolerance is a gradual reaction that happens over time (sometimes hours after the offending food is eaten) and involves the digestive system rather than the immune system. Whereas, a food allergy produces a rapid onset of symptoms due to the body’s immune response to that particular food. Such responses are triggered by the culprit food no matter how small the amount is, but in food intolerance you can usually withstand some exposure to the food. The severity of the reaction to the offending food normally increases with increased amount of that particular food, the symptoms typically surface at these larger amounts as the body can’t break down the food as fast as required.

What are the symptoms of food intolerance?

Food intolerance is not usually harmful; it is more the issue of the unpleasant symptoms that accompany it. Although, persistent symptoms can sometimes trigger more chronic conditions. Generally symptoms associated with food intolerance include:

  • Bloating
  • Nausea
  • Rashers
  • Fatigue
  • Joint pains
  • Eczema
  • Migraine
  • Arthritis

These symptoms are just those that commonly develop in a number of different food intolerances. Food intolerance is associated with other chronic conditions, so you may see symptoms linked to these conditions as well as just the food intolerance. However, sometimes it can be difficult to identify whether the food intolerance is causing the chronic condition or as a result of it. For example: lactose intolerance can cause symptoms very similar to irritable bowel syndrome.

Problems in diagnosis may arise if the food intolerance is due to a single chemical present in many different types of foods rather than a specific food type. This could mean symptoms present in a variety of foods causing confusion as to the exact cause of the food intolerance. The symptoms may be indicative of a number of different food intolerances making it difficult for a single food intolerance to be identified. Hence recognition of the generic symptoms is usually followed by a food diary in order to pin point which food intolerance you are suffering from.

The severity of these symptoms is usually dependent upon; the amount of the offending food that was consumed and the amount of enzyme/chemical that breaks down that particular food the person has.

What are the different types of food intolerance?

  • Lactose Intolerance
  • Casein Intolerance
  • Alcohol  Intolerance
  • Wheat Intolerance
  • Gluten Intolerance
  • Histamine Intolerance
  • Yeast Intolerance
  • Food Additive  - sulphites
  • Flavour enhancers - MSG
  • Salicylates in foods
  • Chocolate
  • Wine (in particular red wine)
  • IgG ANTIBODIES IN FOODS
  • Caffeine

How do I know if I have food intolerance?

If you think you may have any of the listed symptoms of food intolerance then you should go and see your GP for further advice. If you seem to get symptoms when you eat a specific food, this could be a sign of intolerance to something contained within that food type.

When you visit the GP, take a food dairy with you. This food dairy should include what you have eaten and any symptoms that occur along with foods. The food diary should be kept for at least 2 weeks. With this information your GP may ask you to have further tests that are specific for certain food intolerances, in order to attain what is the offending food. They may also ask you to eliminate the suspected offending food and keep another food diary to see whether symptoms improve.

Food diary

A food diary is the most successful day to identify the offending food. A food diary should be kept for at least 2 weeks while you are following your normal diet, in order to get accurate representation of which foods are causing the problem. This food diary should then be analysed by a health professional; a doctor, registered dietician and/or nutritionist.

The food diary should give details of your diet every day over the 2 week period. Each time you eat something you should include:

  • Date of food eaten
  • Time of food eaten
  • Food eaten
  • Amount of food eaten
  • Any symptoms
  • Date of symptoms
  • Time of symptoms
  • Duration of symptoms

It is also really useful if you include your ideas and opinions of what food you think is causing the problem.

Elimination Diets

Elimination diets are an effective method of identifying the foods being consumed that cause food intolerance and eliminating them. Although it can be time consuming taking weeks or even months, once the suspected cause of the intolerance is removed, the symptoms then cease.

Private Care Options

There are a variety of food intolerance test advertised online. Tests for specific food intolerances aren’t usually seen as reliable. They may include; blood tests, skin prick tests, stool samples, IgG testing and vega testing. Although, recent guidelines suggest no test can be definitive, and it is best to seek advice form you GP on such tests; many of the more beneficial informative tests are available on the NHS.

Infant Intolerance

Babies can sometimes suffer from a range of different food intolerances as they grow. More often than not, lactose is the culprit. This is due to the insufficient production of enzymes in the digestive system to break down the lactose. However, there are many different types including fruit, carbohydrates and gluten. Although some infants are unlucky enough not to, most grow out of their intolerance as they move into childhood.


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Guide to Food Allergies