Many people who have an adverse reaction to dairy products think they are
allergic to milk this is not always the case. A food allergy is defined as any
adverse reaction to an otherwise harmless food or food component that involves
the body's immune system. Therefore when talking about a food allergy it only
involves the body's immune system.
A food intolerance is when you develop symptoms after eating a food product that your body can't deal with adequately. With milk products this is because the digestive system does not produce enough of or any lactase (an enzyme found in the stomach), which breaks down lactose ( the sugar found in dairy products), to a simpler sugar which can be digested. The symptoms include stomach cramps, bloating etc. (see Symptoms and diagnosis).
A range of tests can be taken to find out what you are allergic to or have
an intolerance the most common is the RAST Test (RadioAllergoSorbent
Test). This test is used to see if you have any antibodies, particularly
the antibody IgE, against a specific allergen in your blood. Basically a sample
of blood is taken added to the food that might be the cause, a radioactive
marker is added aimed at the antibody IgE. The sample is then measured to see
how much IgE is present in the blood. The test however is not perfect as a
positive result can be obtained if the food contains anything that will
specifically bind to IgE that is already in the blood sample.
The other test is a Skin Prick Test. Here a few drops of a highly diluted solution of the allergen is put on the skin, the skin is then scratched and the weak substance leaks under the skin. After 15 minutes the allergist examines the test area for a zone of redness. This zone is measured to give a level of reaction, depending on the severity of the the large the zone the more severe the allergy. This procedure is carried out by a doctor or qualified nurse.
(Please bear in mind that these test are mainly for allergies rather than intolerances and you should speak to your doctor or health professional before undertaking these test.)
Nice - The National Institute of Health and Clinical Excellence has produce some guidance in February 2011 for Allergy and Intolerance test for children. Click here for the guidance material.
If however you think you or a member of your family are intolerant to dairy products rather than allergic there are three types of tests available to measure lactose absorption in the digestive system. The first is the Lactose Tolerance Test. The test begins with a fast for 24 hours and blood is taken and the glucose level tested. Then a drink of lactose is given and for the next 2-3 hours blood samples are taken to see how much glucose is in your blood, and this will determine if lactase is present in your digestive system. This test is not used on young children.
The second test is the Hydrogen Breath Test. Normally no hydrogen is produced in a normal gut, however undigested lactose produces various gases including hydrogen. The test can be affected by certain foods and drugs, and smoking so may not be very accurate. This test is not normally used on young children, however the test is being used more recently.
The final test is the Acid Stool Test. This measures the amount of acid in stools. Undigested lactose is fermented in the lower bowel and creates lactic acid which can be simply measured. This test is used for young children and gives some idea if the child is lactose intolerant.
Another test available is the Enzyme-Linked Immunosorbent Assay (ELISA). This is a food sensitivity test that measures the amount of the antibody IgG your immune system produces in response to a specific food group you are sensitive. The test is carried out by taking a tiny sample of blood (a pin prick). The sample is then tested for the antibody against each food group and any raised levels of antibody show you have a sensitivity to that food group. This is the test used by most of the home testing companies (see below for some companies that offer this type of test).
The following tests are also available however they are usually carried out by unqualified people and often give false readings.
This is an electrical test where the machine measures the conductivity between electrodes either held in the patient's hand or to acupuncture points. Different solutions are then placed in a metallic tray . Then the machine is calibrate by place a vial containing a toxic substance in the tray, the vial causes a reduction in electrical conductivity. Other substances are then placed in the try and if similar readings are seen they are reported as an allergic or sensitive reaction. These tests are usually carried out in health food store by unqualified people who advise the patient to eliminate various foods, sometime to the detriment of the patient. Elimination diets should only be prescribed by a qualified dietician or nutritionist. The BMA recommends that Vega testing should be avoided.
In this test the patient's white blood cells are mixed with extracts of specific foods and the cells are measured for evidence of some form of change. Various false positive and false negative results are seen and although various tests have been carried out they have been shown to be unscientific.
Here a sample of hair is tested for toxic metals. However hair analysis as a means for diagnosing an allergy has never been validated. The test will only tell you if you have been exposed to heavy metals.
Patients are asked to hold samples of food either under their tongue or in a glass container in their hand. The patient is then asked to press their free arm against the examiner. An allergic response is detected if the patient does push as hard as prior to holding the food (a reduction in muscle response). It has been difficult to find any scientific evidence for this test and in fact the test failed a double blind study.
Most of the material above has come from The non dairy, organisation (now closed)and Gastroenterology group of Naples (USA) see links.
A number of private test facilities are available, most have been shown to be a waste of money ( see articles by The Sunday Times and Which? Consumer Association magazine). Please speak to your GP, allergist of dietician first before embarking on these expensive tests.
However if you wish to try one of the postal test then visit York Test Laboratory Site. York Test Laboratory have a range of tests for food allergies and sensitivities. These tests examine the amount of food specific IgG antibody your body produces against the food type you are sensitive to, by using the Enzyme-Linked Immunosorbent Assay (ELISA) method. York Test Laboratory Site will supply more information and the cost for the test (dependant on the number of foods tested. The company supply and sample kit for you to use and return to the laboratory. They also will carry out tests for vegetarian food sensitivity, Helicobacter pylori (the ulcer bacteria) and a hair mineral analysis. You can write to Genesis 3 at York Science Park,York,YO10 5DQ, Tel: Freephone 0800 074 6185 (UK only) or +44 (0) 1904 410 410, Fax: 01904 422000 or email email@example.com and of course by visiting their site by clicking the heart logo. York currently offer milk intolerance tests not lactose intolerance.
Another company you can try is Cambridge Nutritional Sciences Ltd. The company provides a special blood collection kit which allows collection and safe transport of the sample to their laboratory for analysis. The cost of the test is similar to the other companies. Their address is Cambridge Nutritional Sciences Ltd, Eden Research Park, Henry Crabb Road, Littleport, Ely, Cambridgeshire CB6 1SE Tel: 01353 863279 Fax : 01353 863330.
This page has been around since 3 March 1998. Thanks for the support.This page was last updated Wednesday, 31-Aug-2005 20:30:35 GMT