Thursday, August 9, 2012

How Common Is Celiac Disease?

Following a gluten-free diet is suddenly mainstream – there’s even a Prius ad that mentions ‘gluten-free alternatives’. Unfortunately, determining how common celiac disease – a severe immune intolerance to wheat gluten – is has proven a difficult task.

Part of the problem is that celiac disease has proven notoriously hard to diagnose in a simple, affordable manner. A disease like hypertension is easy enough to diagnose, and anyone with a blood pressure cuff can do it, but celiac is a complex interplay of symptoms, blood tests and tissue damage. We’ve all learned that an intestinal tissue biopsy is the gold standard for diagnosing celiac disease, but obtaining a biopsy is invasive and expensive, to say the least. There are a variety of blood tests that can be run, but combining them to achieve perfect sensitivity and specificity hasn’t been fully agreed upon, and genetic testing, while theoretically perfect, can also be prohibitively expensive. The combination of imperfect testing and high costs means that very frequently, celiac and gluten-sensitive enteropathy (a fancy word that includes a spectrum of gluten-sensitive intestinal syndromes) are diagnosed clinically, based on symptoms and clinical picture.

While lab testing still leaves a little bit to be desired, one thing that is clear is that celiac disease itself is far more common than we thought it was even a few years ago.

A recently published article in the American Journal of Gastroenterology found that celiac disease (as measured by a combination of the more established blood tests) had a prevalence of 0.71% among Americans a whole, but was higher among non-Hispanic white Americans, at 1.01%. This is in stark contrast to previous data on celiac disease, which in the distant past put its prevalence at around 0.02% of the population, but also more recent data, which put prevalence at around 0.33-0.70% of the population.

Sometimes, when diseases become ‘more common’, it’s because testing methods improve and awareness increases – the disease itself doesn’t become more common, but our ability to detect it and patients' likelihood of asking their doctor about it means that the amount of cases increases. This, however, does not appear to be the case with celiac disease – yes, our methods of detection are improving, and awareness of the disease is also increasing, but the disease itself seems to be increasing in prevalence. A population study that analyzed blood samples drawn from adults between 1948 and 1954, and compared them to blood samples of matched subjects drawn in the mid-2000s found that contemporary adults were 4.5 times more likely to have celiac disease than their counterparts 50 years ago. Why the disease is apparently more common is unclear, but what is clear is that the disease is rapidly on the rise.

What is also clear, especially based on this last study, is that we need to continue to improve diagnostic methods around celiac disease, so that we can screen for the disease, and institute treatment for patients. Among the findings of this study was an indication that all-cause mortality for persons with undiagnosed (and therefore untreated) celiac disease was 4 times higher than people without celiac disease – even though the percent of the population with celiac disease is much smaller than the percent of the population with, for example, high blood pressure or high cholesterol, this greatly increased risk of mortality is enough to make us pay attention to this population. There was no further discussion of the increased mortality, but because celiac disease results in chronic immune activation, inflammation, and poor nutrient assimilation, there are any number of potential causes for increased mortality.

Of course, this doesn’t really address the growing population of people who follow gluten-free diets, but who haven’t been formally diagnosed with celiac disease – the study mentioned previously, in addition to finding that celiac disease was more common than expected, also found that more people follow gluten-free diets than have been formally diagnosed with celiac disease. While we are improving our ability to diagnose celiac disease itself, there will probably remain a set of people who have some degree of gluten sensitivity – this is a grey area, and one which lab testing is unlikely to clarify any time soon. These folks are the ones whose IBS or eczema improve with a gluten-free diet, but who don’t test positive for celiac disease. It’s still advisable to be under the care of a health care provider if you fall into this category, as with any long-term treatment – a naturopathic physician can help assess whether or not it would help to follow such a diet, help determine your progress, and above all help you implement it. While resources do exist for celiac patients, it’s an overwhelming world of information, and almost everyone needs some help in sorting it out – a naturopathic physician can help guide you through the process, pointing out pitfalls, and helping you overcome obstacles.

While celiac disease is indeed on the rise, it is in some ways surprising that gluten-free diets have become popular, because of how restrictive they can be. Unlike vegetarianism, it’s not a diet that I would advise anyone to undertake unless they were working with a healthcare professional, for the reasons listed above. Even so, a gluten-free diet can be extremely helpful for a variety of immune-related conditions – sometimes celiac disease itself is at fault, but in other cases, it’s a gluten-sensitive spectrum syndrome. As always, I urge you to work with a healthcare professional, as they can best determine the cause and solution to your health issues, and provide needed guidance and support in finding resolution.