Food intolerance symptoms

Food intolerance symptoms can range from nausea to constipation


Alison Cullen
Nutritional Practitioner, BA (Hons), DN, DNT (Distinction)
@AVogelUK
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An introduction to the symptoms of food intolerance

Food intolerances are surprisingly common and should not be confused with food allergies such as a peanut allergy.

In general, food allergies give rise to sudden reactions involving inflammation whereas food intolerances lead to a variety of symptoms which develop over time. In addition, if you are intolerant to a particular food, you may still be able to consume small amounts of it without symptoms arising.

Symptoms of a food intolerance

A food intolerance is a sign that your digestive system is unable to cope with or break down certain components or types of food. Eating the problem food will result in a range of unpleasant symptoms, and these may vary from person to person.

The first thing to note is when symptoms occur. Food intolerance will, in general, lead to the appearance of symptoms several hours after eating. This is because it takes some time for food to work its way through your digestive system, and in some people it is only after eating large quantities of the problem food that the symptoms become noticeable.

Intolerance symptoms are not normally serious; however they can be persistent, making you feel generally miserable and lethargic. You will usually experience some form of stomach discomfort, such as abdominal pain, bloating, loose stools or diarrhoea.

As symptoms are similar to those associated with many long term digestive disorders, such as irritable bowel syndrome, it can be difficult to find a diagnosis. However, if you can recognise the onset of symptoms after eating certain foods, you can try removing them one-by-one from your diet to see if it clears your symptoms.

Symptoms of food allergy

The symptoms of a food allergy can be more serious than those of intolerance. These arise not as a reaction of the digestive system, but of the immune system. The onset of symptoms is usually immediately after eating the food which triggers the allergy, sometimes as soon as the problem food touches the skin. In severe allergies, only a trace of the problem food needs to be consumed to trigger a reaction.

As well as causing digestive symptoms such as nausea, diarrhoea or a swollen abdomen, symptoms of an allergy can also include a rash, wheezing and itching. In severe cases, known as anaphylaxis, this can cause swelling of the airways and difficulty breathing,and requires immediate treatment.

Complications of a food intolerance

In itself, a food intolerance should not result in any complications. However, the necessity to remove certain foods from your diet may have a knock-on effect on your health. For example, dairy products contain high levels of calcium and protein and if these products must be removed from your diet, you may be at greater risk of developing malnutrition or problems with bone density, such as osteoporosis.

Monitoring your diet, and ensuring you are consuming enough vital nutrients and vitamins is important. You may find that you benefit from certain food supplements if you struggle to include a healthy balance of minerals purely through diet.

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