Food intolerance IgG testing, Digi Mart USA News (United Kingdom): Cooking for a group of friends can be complicated these days. Some may have allergies, and a growing number of people say they cannot tolerate certain foods, often wheat, dairy, or in one friend’s case, a seemingly random list of vegetables.
An intolerance typically means a food triggers symptoms such as wind, bloating, abdominal pain, diarrhoea or constipation. Some people who say they have a food intolerance are likely correct, but others may be mistaken.
A major cause of such errors, according to Kirsten Jackson, a dietitian and spokesperson for the British Dietetic Association, is flawed intolerance tests that check for IgG antibodies.
True food allergies have risen in recent decades. With these, even a crumb of the food can trigger mouth tingling, rash and throat swelling, and adrenaline injections may be needed to avoid potentially deadly anaphylactic shock.
Food intolerances and sensitivities, which are more common, typically cause gut problems because certain food components are difficult to digest in the upper bowel and reach the large bowel, which houses most gut bacteria.
When this happens, the food draws water into the large bowel, which can cause diarrhoea. Bacteria then digest the food and produce gas, leading to bloating, pain and flatulence.
Common examples include lactose in dairy, where some people stop producing the enzyme needed to break it down as they age, and gluten in wheat, barley and rye, which triggers an immune reaction in coeliac disease.
Fodmaps, a group of sugars and carbohydrates that some people digest poorly, are found in wheat, milk and certain vegetables such as onion, asparagus and cauliflower. Wheat intolerance, in which sugars from wheat starch cannot be digested, may be confused with coeliac disease.
This has contributed to the growth of food intolerance or sensitivity tests, often sold online, that check for IgG antibodies to specific foods through a finger-prick blood test. One company, YorkTest, whose products are sold in Boots, says its IgG tests can help people find out whether they have an intolerance to 200 food and drink ingredients.
Several other online brands make similar claims.
Professor George Du Toit, an immunologist at London Allergy Consultants, says a positive IgG test does not show that someone is allergic, intolerant or sensitive to a food. These antibodies signal that the immune system should not react to the food, so a positive test is a sign of tolerance.
The NHS uses a different antibody, IgE, to test for food allergies.
Many medical bodies and patient groups reject IgG testing for food intolerances, including the British Dietetic Association, Guts UK and the British Society for Allergy and Clinical Immunology. Jackson said there is evidence showing the tests do not work and that they can create eating disorders.
She regularly sees patients with irritable bowel syndrome who have been wrongly convinced they have food intolerances because of such tests.
Jackson said stress can also trigger symptoms, explaining that chronic stress increases pain signalling and that some people’s nervous systems may read discomfort when gas levels rise only slightly. Cutting out many food groups can also lead to malnutrition, such as a shortage of fibre from avoiding wheat and pulses, or vitamin and mineral deficiencies from avoiding dairy.
Professor Helen Brough, a paediatric allergist and Director of Children’s Allergy Doctors, said the tests are especially harmful for children, as they can lead parents to unnecessarily eliminate important foods such as milk, wheat and eggs. Jackson and a colleague have started a parliamentary petition seeking a ban on IgG testing for food intolerances, along with a separate hair-sample analysis technique they consider invalid.
YorkTest did not reply to a request for comment. A Boots spokesperson said the company checks that third-party products it sells comply with applicable legislation and regulatory requirements, and that its pharmacy teams can advise customers on whether testing is appropriate or whether further advice from their GP may help.
Jackson said the tests may gain trust because they are sold by a well-known British brand.
Jackson advises anyone who believes they have an intolerance to see their GP or a dietitian before cutting out food groups. People can usually be helped by structured elimination diets with step-by-step reintroduction of individual foods.
