Non-celiac gluten sensitivity is not the same as food intolerance: gluten sensitivity may turn out to be a type of immune system reaction, while food intolerance is a non-allergic sensitivity to food chemicals. They do share one thing, though: the only proper way to diagnose them is through an elimination diet and food challenges.
Elimination diets and food challenges are not rocket science, but they do need to be done right. Here, I’d like to give you an example of how to do them WRONG. This comes from an episode of The Dr. Oz Show, in a segment titled “The New Warning Signs for Gluten Sensitivity.” Let’s look at why Dr. Oz’s advice is not a good way to go about investigating your diet.
“The New Warning Signs for Gluten Sensitivity”
In this episode, Dr. Oz warns that anyone who experiences migraine, brain fog, depression, joint pain, arthritis, or skin rashes could actually be suffering from gluten sensitivity (1). His guest, Dr. Amy Myers, agrees.
Dr. Myers is introduced as a specialist in functional medicine, which means that she is a licensed MD who practices alternative medicine. This is far from the first time that “America’s doctor” has promoted alternative medicine on his show; there are many good articles out there on his mixture of scientific and non-scientific beliefs – search on his name at Science-Based Medicine for more than a few – so I’m not going to get into that here. But I will say that much of what is said on his show should be taken with a grain of salt, including Dr. Myers’ thoughts on the prevalence of gluten sensitivity.
Dr. Myers first states that gluten sensitivity affects 18 million people in the US. She doesn’t explain this, but this figure corresponds to 6% of the US population, which is what some quote as the maximum possible prevalence for non-celiac gluten sensitivity (2). She then states that her personal suspicion is that 1 out of 2 people have gluten sensitivity, but this goes directly against what the researchers who originated the disorder think. She and Dr. Oz then tell us that people who suspect gluten sensitivity can do a gluten-free trial at home.
What’s wrong here?
The first problem with Dr. Oz’s advice is a matter of motivation. How likely is it that someone has gluten sensitivity? If the prevalence is 6%, then gluten sensitivity is a problem of similar size to food intolerance, but it’s not that likely for people who suffer from migraine, brain fog, depression, joint pain, or rashes – which are fairly common problems – to have gluten sensitivity. If the prevalence is 50%, as is presented on the show, then it’s quite a different story – you’d be crazy not to go gluten-free, right? And you might think, “Well, it’s only a two week diet. It won’t hurt and it might help.” But it could hurt, and it’s important to get it right.
Even for people who do have a deep suspicion that their symptoms are related to food, it is hard to know exactly which food or foods are causing the problem because we don’t eat single ingredients all day long. This leads me to the second problem with Dr. Oz’s advice – he doesn’t explain that an elimination diet and food challenges must be done in a systematic way.
Theoretically, you could just remove one food from your diet and keep the rest of your diet entirely the same. But this is difficult, if not impossible, to do in reality, especially with a foundation food like wheat. For example, if you stop eating pasta, you will probably also stop eating tomato sauce, and if you stop eating bread, you might also stop eating jam. You might still eat tomatoes and you might eat fruit, but tomato sauce and jam are concentrated versions of these foods and more likely to cause food intolerance. (3) Or you might inadvertently cut down on sugar and carbs or dairy or some other common trigger. (In fact, there is an idea floating around that high-sugar diets can lead to the same health effects as described by Dr. Oz.) So, if you started a two week gluten-free diet and felt better, could you really blame gluten for your symptoms? No.
All you can conclude from a poorly-done elimination diet is that your symptoms might be caused by something in your usual diet. Food challenges are the necessary second step to determine whether a specific food is causing your symptoms. After your symptoms subside, you must try eating that food again (the ‘challenge’) – if your symptoms return, then you can blame that food. But the food challenge is not as simple as it sounds, and you should be working with a doctor or dietitian on this. First, you should challenge with every food or trigger chemical that you excluded during the elimination diet phase – which, as I said, will probably include more substances than just gluten. Second, you should not only test yourself with the foods in question but also with a placebo. In an informal setting, a placebo could be any meal for which you do not know the ingredients (of course, you need to be working with someone else to pull this off). As you can see, coming up with the right foods or meals to challenge with does take some research and planning.
The placebo test is important to make sure that you find the truth and not just what you expect to find. In some cases, a doctor or dietitian might omit this step, especially in open challenges where it is obvious which food is being tested; however, the placebo effect could be significant for someone who goes into the process believing that they have a 50/50 chance of being sensitive to gluten. On top of this, specialists think that for patients with subjective symptoms (symptoms that can’t be measured by a third-party, like headache, brain fog, etc.), the food challenge and placebo tests should be repeated three times each, with a sufficient ‘wash out’ or break period in between, in order to get the best results.
So far I have been talking about avoiding results that are false positives – that is, thinking that you have gluten sensitivity when you don’t. It is also conceivable that you could get a false negative result, where you really are sensitive to gluten but your symptoms didn’t go away during the elimination diet. One way this could happen is if you also have a food intolerance – either you kept eating other foods that contributed to your symptoms or you added more of them to your diet through gluten substitutes. For example, sweet potato flour, sesame seeds, coconut flour, fava bean flour (and ‘garfava flour’), and almond flour are reported to be high in salicylate and/or amines. Most other grains and substitutes are not. Something similar could happen if you also suffer from a food allergy that you don’t know about (many gluten sensitive people also report food allergies). In order to avoid false negatives, the elimination diet should remove as many possible allergens or trigger chemicals as possible.
The price for getting it wrong
Those who suffer from celiac disease must to be extremely careful to avoid even trace amounts of gluten or else risk serious complications. This is a hard life to lead, to say the least, and not something to get into unnecessarily just because we are in the middle of a gluten-free fad. People on gluten-free diets also have problems meeting certain nutritional requirements, such as for folate and fiber. Doctors do not yet know whether gluten-sensitive people would need to follow the same level of adherence to a gluten-free diet as celiac suffers do.
Health problems should be approached more carefully than a 10 minute TV segment can convey. Doctors diagnose people with gluten sensitivity by ruling out all other causes and by looking at several different gastrointestinal test results that are easiest to interpret before you go gluten free. Self-diagnosis is dangerous because you can miss a serious medical problem; you also do yourself a disservice if you do have gluten sensitivity, because a doctor could provide you with ongoing advice as new risk factors, diagnostics, and treatments are discovered in this active area of research. You’ve waited long enough to sort out your symptoms – find a medical professional to help you get it right the first time.
Last updated March 4, 2015
1. The New Warning Signs for Gluten Sensitivity [Internet]. The Dr. Oz Show. 2013 [cited 2013 Dec 27]. Available from: http://www.doctoroz.com/episode/gluten-warning-signs-next-epidemic (Archived by WebCite® at http://www.webcitation.org/6OjaH1MXG).
2. Catassi C, Bai J, Bonaz B, Bouma G, Calabrò A, Carroccio A, et al. Non-Celiac Gluten Sensitivity: The New Frontier of Gluten Related Disorders. Nutrients. 2013 Sep 26;5(10):3839–53.
3. Swain A. The role of natural salicylates in food intolerance [PhD Dissertation]. University of Sydney; 1988. Available from: http://www.sswahs.nsw.gov.au/rpa/allergy/research/students/1988/AnneSwainPhDThesis.pdf