The Rise in Food Allergy Self Diagnosis

The Rise in Food Allergy Self Diagnosis and its Impact on Other Statistical Information

This article from BBC sparked my interest http://www.bbc.co.uk/news/health-17373904

In summery it explains that there is a rise in self diagnosis when it comes to food allergies and other life-changing diets like gluten free. I was interested in this because I seem to be surrounded by friends and family members trying out new diets, insisting that there is something wrong or that they're intolerant to something that they're eating. I've seen many people change their diet dramatically, fall ill, and then refuse to attribute it to the diet change because of some sort of 'detoxing' side effects they claim to be having. All the while, they fail to consult a doctor on whether or not they even have this 'disease' or not. So, I have a couple questions, naturally.

1. How much of the existing statistics is self-diagnosis?

2. How many people who 'self-diagnose' aren't really sick at all?

In this article BBC pokes at the issue, saying that "while 20% of the population believe they have a problem 'the reality is much smaller than that'. He says the numbers actually suffering from a food allergy are probably closer to between 1-2% of adults, and 4-6% of children".

Now, in the articles I read often, there is never really a link back to where they get their data from so its a bit hard to trace. But assuming that these statistics are true, and assuming that 20% of the population diagnosing themselves with gluten intolerance or another food allergy is significant in someway, I wonder what impact these numbers have on other statistics in other articles. For instance, on the Celiac Disease website, (http://www.celiac.com/articles/1164/1/Celiac-Disease-Statistics/Page1.html) they state that "Celiac disease is one of the most common chronic health disorders in western countries", and that:

"Up until ten years ago, medical schools taught that celiac disease was relatively rare and only affected about 1 in 2,500 people. It was also thought to be a disease that primarily affected children and young people. Recent studies and advances in diagnosis show that at least 3 million Americans, or about 1 in 133 people have celiac disease, but only 1-in-4,700 is ever diagnosed."

Now, how can you get a '1 in 133' Americans have celiac disease, but only '1 in 4,700' are actually diagnosed with celiac disease? This leads me to believe that the rise in self-diagnoses is mucking up the statistics. Are these diagnoses statistics self proclaimed or doctor prescribed? I can easily see a medical survey being sent out asking if you have the following diseases: A, B, and C. People who go gluten-free might want to self proclaim that they must have celiac disease because going gluten-free helped them (for whatever reason - placebo or not). So, in this article BBC did a good job of pointing out a potential problem in how people are behaving. This behavior can very easily affect existing statistical studies. Makes you think.

If any of you have any other insights into this, please feel free to comment and critique. These are just my observations and I'm curious to see if I am missing something here.