+44(0)808 101 0337
fee
Allergies

Food Intolerance

In food allergy, an abnormal immune system response results in the body making antibodies to 'fight off' a food. Food allergy, either IgE antibody mediated or delayed non-IgE mediated allergy are reactions caused by the immune system, which affects approximately 1% of adults and 5-9% of children in the UK.

However, some people suffer symptoms after eating certain foods even when they are not producing antibodies against them. A variety of different mechanisms can cause foods to affect people in this way. These non-immune reactions are known as food intolerances.

Food intolerances may be toxic, irritant, pharmacologic or metabolic reactions to food. These reactions are not immunologically mediated, that is they are not due to the formation of a specific IgE to a particular food, hence are not allergic reactions. An individual can be intolerant to different types of food:

Tyramine sensitivity

Tyramine rich foods such as chocolate, red wine, cheese, yeast extracts, nuts, soy, pickled herring, smoked fish, bananas, fava beans etc, can cause vasodilatation of the cerebral blood vessels in susceptible individuals and trigger migraine. In young children it can cause abdominal migraine.

Sulphite sensitivity

Sulfites are preservatives used in some drinks, foods and occasionally medication. Sulfites can cause allergy like reactions (intolerances), most commonly asthma symptoms in those with underlying asthma, sometimes allergic rhinitis (hay fever) like reactions, occasionally urticaria (hives) and very rarely, anaphylaxis (severe allergic reaction). Wheezing is the most common reaction.

Glutamates - (MSG, additive numbers 620 and 621) was originally isolated from seaweed in 1908 by a Japanese chemist. Glutamates also occur naturally in such foods as camembert cheese, Parmesan cheese, tomatoes, soy sauce and mushrooms. 

Vasoactive Amines - such as tyramine, serotonin and histamine are well known triggers of migraines in some patients and are present naturally in pineapples, bananas, baked meat, vegetables, red wine, wood-matured white wine, avocados, chocolate, citrus fruits and mature cheese. Amines can act directly on small blood vessels to expand their capacity, perhaps accounting for their effect on flushing, migraines and nasal congestion in some patients.

Salicylate Sensitivity

Salicylates are natural aspirin like compounds (aspirin was originally isolated from willow tree bark) present in a wide variety of herbs, spices as well as fruit and vegetables. Reactions to these may be even more common than reactions to artificial colours and preservatives. Aspirin can trigger hives (urticaria) by acting directly on skin mast cells. Natural and structurally similar salicylates can also worsen hives in some patients.

Gluten intolerance/coeliac disease

This is not a true ‘intolerance’ but an immunologically mediated condition. Blood tests are available for screening this condition. In order for the test to be reliable, it is essential to remain on a normal, gluten-containing diet for al least 6 weeks. 

Non Coeliac Gluten Sensitivity ( NCGS) / Non Coeliac Wheat Sensitivity (NCWS) 

This is an ‘intolerance’  and one may get symptoms similat to Coeliac dieseae but  do not have the antibodies. 

Irritable bowel symptoms

In some individuals symptoms of irritable bowel can be provoked by the fermentation products of unabsorbed food residues which lead to the release of gases which cause bloating, colic, nausea and intestinal hurry. In these cases, milk and wheat are often triggers.

Lactose intolerance

Lactose intolerance is a common digestive problem where the body is unable to digest lactose, a type of sugar mainly found in milk and dairy products. Symptoms of lactose intolerance usually develop within a few hours of consuming food or drink that contains lactose.

The severity of symptoms and when they appear depends on the amount of lactose  consumed. Some people may still be able to drink a small glass of milk without triggering any symptoms, while others may not even be able to have milk in their tea or coffee.

The body digests lactose using a substance called lactase. This breaks down lactose into two sugars called glucose and galactose, which can be easily absorbed into the bloodstream. People with lactose intolerance don't produce enough lactase, so lactose stays in the digestive system where it's fermented by bacteria. This leads to the production of various gases, which cause the symptoms associated with lactose intolerance.milk and dairy products can cause excessive mucous production from the nose, sinuses or chest.

Scombroid poisoning

Badly stored or old fish, such as mackerel, can release histamine which can cause facial flushing, dizziness, nausea, headache, urticaria, abdominal cramps and diarrhoea.

Tests

Since IgE mediated mechanisms are not involved in these reactions it is not possible to determine the cause of intolerance by allergy testing (skin prick test or blood test for specific IgE).

Treatment

The mainstay of treatment involves identifying, by trial and error, the foods which trigger symptoms and avoiding them from the diet. Some food intolerance will resolve spontaneously and therefore it is worthwhile attempting to re-introduce the foods into the diet say, after 6 weeks. Patients with intolerance to several foods should seek advice from their dietician to ensure that they are receiving a balanced diet.

© 2016 -  Manchester Allergy Clinic, All Rights Reserved Site Hosted by Veriton