So this week’s news is that NICE has published the first evidence-based guidelines for the diagnosis and assessment of food allergy in young people and children. Here’s a link.
Not surprisingly the media has chosen to run with the angle that NICE are recommending alternative food allergy tests should be avoided. To say this is not a new idea is an understatement. As Twitter user Andy Lewis of The Quackometer put it: “In other news, Elvis is dead.”
Again we’re faced with the question of semantics and definitions and the difference between food allergy and food intolerance. The former is well defined medically but the latter – other than lactose intolerance and a few others – is less clear cut. If it’s not a type I (IgE) or IV food allergic reaction, and it is not a lactose intolerance (or other sugar intolerance), and it is not coeliac disease – what else can it be? This is where the nebulous concept of food intolerances lies on the food hypersensitivity map. Many suspect they exist but what they actually are medically remains a puzzle.
Allergy UK’s Food Intolerance Awareness site warns readers of the lack of evidence for the effectiveness of some of the alternative tests available, and acknowledges that the evidence for IgG antibodies’ involvement in food intolerance is “not clear”.
Elimination/exclusion diets and keeping a food diary, all under the supervision of a dietitian, are the way to go for suspected food intolerances, but Allergy UK add: “We recognise, however, that for many people it is quite simply not possible to keep a food diary. In cases where the person concerned wishes to take a test we refer people to Yorktest.”
YorkTest is a private testing laboratory offering IgG testing. Remember, the evidence base for the IgG test in relation to food intolerance is “not clear” and NICE have just today warned it should not be used for food allergy. In fact, NICE felt IgG testing should be singled out for a particular mention, “given the science-based marketing of the test”.
If it shouldn’t be used for allergy or intolerance, why do Allergy UK refer people to YorkTest?
I understand that the charity represents the people, and I understand that an awful lot of people are struggling with health problems they attribute to food. With a poor allergy healthcare service, and doctors sometimes sceptical about food hypersensitivities – and not always that aware of them – they play an important role in supporting those suffering.
But it seems to me that they somehow feel obliged to refer their members to a private test – even when the evidence base is not sturdy. The reasons are given on their site here, and basically boil down to the mildly positive Whorwell study of 2004. But this is just one study, and this study only looked at IBS, and the authors themselves stated that IgG antibodies may only be relevant in a subset of IBS patients, and “they may not be relevant in food intolerance in general”.
Yes, there are positive stories too, from people who have taken an IgG test, acted on it, and felt better. But as I have said before “it worked for me” reports are virtually useless, and prove as little as “it didn’t work for me” reports. I addressed this in a previous post, The Lottery of Food Sensitivity Testing. We need good scientific trials, blinded, and placebo-controlled.
My view: Allergy UK should not refer their members to a test they appear to admit is unproven and which the NICE guidelines they claim to welcome declare should be avoided.