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This is another one of those videos that I expect many of you to hate. Gluten is surprisingly polarizing. Of course, most of the evidence that many of you will throw at me are anecdotes. And we all know that the plural of "anecdote" is not "data". So let's talk about gluten, and whether a gluten-free diet is for you. "Spoiler" – for the vast majority of you, the answer is "no".

For those of you who want to read more or see references, look here:

John Green -- Executive Producer
Stan Muller -- Director, Producer
Aaron Carroll -- Writer
Mark Olsen -- Graphics

(00:00) This is another one of those videos that I expect many of you to hate. Gluten is surprisingly polarizing.

Of course, most of the evidence that many of you will throw at me are anecdotes. And we all know that the plural of anecdote is not data.

So let's talk about gluten. And whether a gluten-free diet is for you.

Spoiler... For the vast majority of you, the answer is 'no.' This is Healthcare Triage.


(00:27) What is gluten? It's the main structural protein complex of wheat, barley, rye, and triticale (which is a cross between wheat and rye).  That's a problem, because the stuff is in almost everything. Wheat is in bread, soup, pasta, cereal, sauces. and lots of other stuff; barley is in food coloring, malts, and beer! Rye is in a lot of stuff too. Eliminating gluten is not easy.

(00:50) Let's start with the fact that people on gluten-free diets are usually trying to treat one of three things: celiac disease, wheat allergy, or a gluten sensitivity. These are not the same thing.

(01:00) Let's do celiac disease first. It's basically an immune reaction to gluten. When it hits your small intestines, something makes your body go a little nuts; it activates the immune system to try and fix the problem but it does more harm than good. Over time, the lining of the small intestine gets chronically inflamed and you can't absorb all the nutrients you need. Celiac disease can cause weight loss, bloating and diarrhea. As other parts of the body are denied the nutrition they need you can develop other problems too.

(01:30) One of the issues with diagnosing celiac disease, though, is that most people don't have any real symptoms that they notice. About 20% of people with celiac disease have constipation, and 10% are obese. As many as 75% of kids with celiac disease are overweight or obese at the time of diagnosis.

(01:48) Some people are more likely to have it than others. It runs in families, so people related to people with celiac disease are at higher risk. Celiac disease is also more common in people with Type 1 diabetes, Down syndrome, and Turner syndrome. It can also be more common among those with auto-immune thyroid disease, or microscopic colitis.

(02:03) There are blood tests that can help in the diagnosis of celiac disease, but the real gold standard is an endoscopy. Doctors will stick a camera and tube down your throat to look at your small intestine; they'll take a biopsy. That's the most definitive test for celiac disease. The only real treatment for celiac disease is a gluten-free diet. There is no cure. You can start to feel better pretty fast on the diet, but complete healing of the small intestine could take up to years. If you start eating gluten again it could all start over.

(02:31) A recent study estimated that the prevalence of celiac disease in the United States was 0.71%, meaning that about one in a hundred-and-forty people have it. That's similar to the rates of the disease in most European countries. Unfortunately, most cases are under-diagnosed which is why there's been such a rush of publicity lately. We know it's there and too few people are being diagnosed.

(02:52) I'm sympathetic to the problem here. Given the statistics I just mentioned, about three million Americans are likely to have celiac disease and tons of them have no idea. A study published in 2005 in the Journal of General Internal Medicine surveyed more than 2400 patients with celiac disease. Only 11% of them were diagnosed by their primary care providers; the rest were diagnosed by somebody else. They also surveyed primary care physicians, and only 35% of them had ever diagnosed celiac disease.

(03:21) Research has also shown that doctors will often misdiagnose celiac disease as other things. People diagnosed with irritable bowel syndrome are four times as likely to have celiac disease than the general public. Patients diagnosed with iron and folic deficiency are also more likely to have celiac disease. There's even a case of autism that turned out to be celiac disease. When that happens, people start self-diagnosing. They put themselves on a new diet and say that they feel better, then they declare that gluten-free is awesome.

(02:49) That's not how research or medicine works. If you think you have celiac disease, you need to see a doctor; only they can make the diagnosis. And that's celiac disease. Let's be clear, if you've got that you absolutely need a gluten-free diet. Do it. But lots of people who go on gluten-free diets don't have celiac disease; some of them have wheat allergy.

(04:10) Real wheat allergy is pretty rare. In Europe the prevalence is about 0.1%, which makes it rarer than allergies to cow's milk, eggs, soy, peanut, tree nuts, fish, and shellfish. In Asia it's between 0.08% and 0.21%. In the United States it's between 0.4% and 1%.

(04:30) And lots of these numbers are for children, and many of them outgrow the allergy. So wheat allergy is less common than celiac disease, especially in adults. Even then, there are people who believe we are way over-diagnosing allergies. But, if you've been diagnosed by a doctor as having a real allergy to wheat, then yes, you should avoid that too.

(04:50) But the groups I've previously discussed are relatively rare. It's the rest of you who need to pay attention.You're the ones with gluten intolerance. It's not an auto-immune problem like celiac disease or an allergic problem like wheat allergy; it's a different group with some symptoms that have been attributed to gluten. And a couple years ago there was some research to support you.

(05:11) In 2011, a study was published in the American Journal of Gastroenterology. They randomized 34 patients who claimed gluten-intolerance to receive either a gluten or gluten-free diet, in the form of two bread slices. They found a significant difference in symptoms, pain, bloating, tiredness, and satisfaction with stool consistency. Their conclusion was, and I quote, "non-celiac gluten intolerance may exist, but no clues to the mechanism were elucidated."

(05:38) This set off a firestorm. Tons of people started blaming things wrong with their life or health or stool consistency on gluten. Millions gave it up and billions of dollars were made on new diets and fads. "Gluten-free" became huge, and even lots of my friends began buying into the idea that gluten was horrible. You have to remember that this was a really small study of 34 people. The results were not a slam dunk in terms of absolute improvements, so lots of people argued against its findings.

(06:06) Rather than rest on his laurels though, Peter Gibson, one of the main researchers involved, continued to study this. He set up a better study to confirm his findings. This time he used a much more sophisticated study design. He included cross-overs of various levels of gluten. His findings this time, and I quote, "in a placebo-controlled cross-over rechallenge study, we found no evidence of specific or dose-dependent effects of gluten in patients with non-celiac gluten sensitivity placed on diets low in FODMAPs."

(06:39) In other words, the gluten-free diet made no difference. He went further. In another study just recently published, he and others studied people who claimed that they had gluten-sensitivity. Of the 147 patients they looked at, 72% didn't meet the criteria for gluten-sensitivity, despite having made the self-diagnosis or been given it, most often by non-physicians. In 25% of these people, their symptoms were poorly controlled even with a gluten-free diet.

(07:08) Look, I can't prove gluten-sensitivity doesn't exist; it probably does but it's likely pretty darn rare, nowhere near the one quarter of consumers who are demanding gluten-free products. Why?! It's not going to do almost all of you any good at all. If you're avoiding gluten because it leads you to eat fewer processed foods, fine. If you do it to eat fewer carbs and more proteins and vegetables, fine. But if you're substituting gluten-free products for similar gluten-containing products then the joke may be on you.

(07:36) A recent article in the Wall Street Journal showed that gluten-free products sometimes are higher in carbs and sodium, and lower in fiber and protein than some gluten-containing products. Gluten-free cereals can have significantly fewer vitamins and minerals as gluten-containing cereals.

(07:52) And they're making some people a ton of money. Sales of products containing a gluten-free label in the United States have gone from $11.5 billion in 2010 to $23 billion last year. $23 billion! Worldwide, companies sold $2.1 billion of gluten-free dog food last year!

(08:10) If you have celiac disease you need to be on a gluten-free diet. If you have a proven wheat allergy you need to avoid wheat. But everyone else: there's almost no evidence that a gluten-free diet will do you any good at all. It will, however, make some of the food companies a ton of money. If that's your goal then well done, I guess.

(08:30) As always it's best to discuss your individual case with your physician. If he or she recommends a gluten-free diet, ask for the evidence behind the decision. I bet there won't really be any.