How to Eat Well: Intolerances put to the test
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Few things divide the nutrition professionals as much as the subject of food intolerances. Over the last decade I have heard of innumerable therapists all too glad to “diagnose” their clients with some food intolerance that is causing any number of symptoms. Many use software that the programmers claim was developed for NASA, although why a space agency would be interested in an astronaut feeling mildly bloated after eating wheat is beyond me.
The immune system is highly complex. Responses to food involve many different kinds of cells, most notably the immunoglobulins, of which there are a number of types. Food allergies — ie a swift and dramatic response to a particular food — involve immunoglobulin E, or IgE. If you have raised levels of these antibodies in the blood as a result of eating a food, then an allergic reaction is possible.
Intolerances, as distinct from allergies, involve another Ig, known as IgG. Measuring levels supposedly allows a diagnosis to be made. But there is disagreement about IgG. Many professionals believe that raised levels of IgG simply denote that the body has been exposed to the food, and do not signal an intolerance.
But the problem goes further than doubts over what the tests tell us. It is my belief that we have become obsessed with food intolerances. As your GP is unlikely to diagnose them, we set off on a journey to find out what might be causing whatever condition we might be suffering from. Intolerance testing is cleverly marketed and implies that everything from fatigue to headaches, as well as weight gain, could be linked to intolerances. Compelling stuff, isn’t it? Who wouldn’t want more energy and weight loss, and even better, something to blame? It wasn’t your poor diet or lack of exercise, it was the wheat/herring/noodles what done it.
My opinion is that intolerance tests rarely show that the individual doesn’t have an intolerance, not because we all have them, but because the tests are flawed. The main problem is that misplaced and inaccurate diagnoses don’t help the people who do have genuine immune responses to food. Crying wolf doesn’t help anyone.
Ian Marber is one of the UK’s most highly regarded nutrition experts and the author of 11 books. www.ianmarber.com