I want to reproduce a summary section from the Wheat Hypersensitivity Report here, in full:
What are the gaps in our knowledge?
It is clear from a recent survey that a number of people consider themselves to be intolerant or allergic to wheat and subsequently avoid wheat or wheat containing foods. Research suggests that wheat allergy or intolerance may not be that prevalent, with slightly more people having coeliac disease. However, more research is needed.
However, the above data clearly indicates the following gaps in our knowledge:
• It is unclear what the general public understand about food allergy and food intolerance.
• It is unclear how many adults have a wheat allergy or intolerance, although we do know that:
o Only 1.4‐1.8% of adults have an allergy or intolerance to any food.
o Wheat allergy is less prevalent than allergies to peanuts, tree nuts, egg and milk.
o It is however, unclear in particular, how many adults have food or wheat intolerances.
• It is unclear what effect the avoidance of wheat, either supervised or unsupervised, has on the nutritional content of the diet and the quality of life of the person.
• It is unclear how many of those diagnosed with wheat allergy or intolerance may outgrow their allergy/intolerance.
Not a lot is clear, then, according to the researchers. In fact, only two things.
The first is that wheat allergy is less prevalent than allergies to nuts, egg and milk. This is correct. Wheat rarely causes immediate, IgE-mediated food allergies which are characterised by rapid inappropriate reactions such as hives, wheezing and worse. This is hardly a revelation.
And the second thing that is clear is that 1.4-1.8% have an allergy or intolerance to any food.
Or is it? Those figures are almost 20 years old. The authors of the report from which these figures are taken said something telling in 1994:
“Our results give prevalence of intolerance for eight test foods studied of 1.4% with stringent criteria and 1.8% with less stringent criteria. These eight foods accounted for 49.3% of reported reactions but we also identified other foods causing symptoms. Our prevalences are, therefore, an underestimate.”
So, they were considered an underestimate then, and surely are now. Why? Because:
a/ coeliac disease, an autoimmune disease caused by a specific form of gluten intolerance, twenty years ago was thought to affect around 1 in 1,000 or fewer. We now know it’s 1 in 100.
b/ oral allergy syndrome (OAS), virtually unheard of twenty years ago, may now affect 3-5% of the population.
c/ lactose intolerance affects 70% of the world’s population, but in the UK, various estimates range from 3% to 15%.
And then there are the regularly reported rises to childhood nut (and other) allergies, for instance, over recent years to take into account too.
So how many people have one or more food hypersensitivity in 2010? It is difficult to come to a single reliable figure, for a number of reasons. For instance, some sensitivities may coexist (coeliac disease patients are often lactose intolerant, for example), but given the above I doubt whether it can possibly be less than 5%.
You may be interested to know where OAS’s 3-5% prevalence comes from, by the way. It’s described as a ‘likely’ figure by OAS researcher and dietitian Isabel Skypala in a superb book, called Food Hypersensitivity, published last year, which I reviewed here. You will notice Skypala’s co-editor is Carina Venter. It is a brilliantly referenced book and there are many studies quoted – well worth investigating, and I admire the book hugely.
I’ve asked to speak with Carina Venter via the press office at the University of Portsmouth a few times over the last weeks, and it hasn’t happened yet. I’ve also offered her a response on this blog – and she of course is free to comment like anyone else. What I most want to ask her is why she used 1994 data in the Wheat Hypersensitivity Report on which to base her key finding – and seemed to exclude the many more recent figures quoted in Food Hypersensitivity? Why maintain 1.4-1.8% of the population has food hypersensitivity when the combined evidence collated in the book suggests it may well now be considerably higher?
I do hope for a response and clarification.
So. Where does this leave us?
In summary, we have a report, funded by a body representing the interests of the flour industry, using 1994 data of debatable current relevance to support the notion that food hypersensitivity – and wheat hypersensitivity in particular – is largely a British delusion. A strong PR campaign and a seemingly unquestioning media ensures publicity in several major newspapers and elsewhere, as reported in my previous posts. Some of this coverage effectively portrayed people as hypochondriacs, which surely only serves to drive them towards discredited and expensive alternative tests (e.g. Vega) and away from their GPs – especially, I suspect, if they feel they may run the risk of encountering the attitudes expressed such as those of the Telegraph’s Dr Max Pemberton here.
Bit rubbish, isn’t it?