The Symptoms of Gluten Intolerance You Haven’t Heard About
by Chris Kresser
Last updated on April 18, 2019
Brain fog, skin issues, depression, and even anemia are all symptoms of gluten intolerance.
You just don’t feel good. You’re tired and get frequent headaches, have ongoing skin issues, or struggle with depression—or all of the above. Maybe you’ve wondered if gluten could be the culprit, but because you don’t experience gastrointestinal upset, you’ve since put the thought out of your mind and haven’t mentioned anything to your doctor. Or perhaps you’ve shared your suspicion, but conventional testing ruled out celiac disease (CD) and thus, supposedly, any issues with gluten. In either case, your diet has likely stayed the same … and so have these often-overlooked symptoms of gluten intolerance.
Yes, all of the symptoms mentioned here—and many others you may not have heard about—can be signs that you have a significant degree of gluten intolerance. Even if you don’t run to the bathroom right after enjoying a plate of pasta, and even if standard lab work says otherwise, your body (and brain) may be having serious problems with gluten. Let’s explore these lesser-known symptoms and discuss if going gluten free is right for you.
You’ve heard of the havoc gluten can wreak on your digestive tract, but did you know that gluten intolerance can cause skin problems, depression, and frequent headaches? Check out this article for more symptoms of gluten intolerance you’ve never heard of.
Undiagnosed Intolerance Is More Common Than You May Think
First off, I want you to know that if you eat gluten and you feel lousy but you don’t have digestive issues—and you have tested negative for CD and been told it’s all in your head—you are not alone. In fact, undiagnosed cases of gluten intolerance are incredibly widespread. Here’s why.
As I’ve written before, wheat contains several different classes of proteins: gliadins (of which there are four different types, including one called alpha-gliadin); glutenins; agglutinins; and prodynorphins. Once wheat is consumed, enzymes in the digestive tract called tissue transglutaminases (or tTGs) help break down the wheat compound. During this process, additional proteins are formed, such as deamidated gliadins and gliadorphins (also called gluteomorphins). Stick with me here—these terms are worth knowing so that you can understand the pitfalls of conventional testing for CD.
CD is a serious form of gluten intolerance, one that can do real damage to the tissues in the small intestine (though its symptoms aren’t merely gut related). CD is characterized by an immune response to one specific gliadin (the aforementioned alpha-gliadin) and one specific type of transglutaminase (tTG-2). But people can—and very much do—react to several other components of wheat and gluten.
Therein lies the problem, because conventional lab testing for CD and gluten intolerance only screens for antibodies to alpha-gliadin and tTG-2.
If your body reacts to any other wheat protein or type of transglutaminase, even severely, you’ll still test negative for CD and intolerance.
Statistics suggest that for every one case of CD that is diagnosed, 6.4 cases remain undiagnosed—the majority of which are atypical forms without gastrointestinal symptoms; even many patients who are eventually diagnosed don’t experience an upset stomach after consuming gluten. (1)
What’s more, the distinct autoimmune response to wheat proteins and transglutaminase enzymes in the gut that defines CD is just one possible expression of gluten intolerance. The many other ways a sensitivity to gluten can affect the body are collectively referred to as non-celiac gluten sensitivity, or NCGS. Cases of gluten intolerance classified as NCGS involve both intestinal and non-digestive reactions to gluten that are not autoimmune or allergic in nature and that resolve when gluten is eliminated from the diet.
There is no definitive diagnostic test for NCGS, making it difficult to put a number on its prevalence. By some estimates, it may occur in as many as one in 20 Americans. (2) And although your doctor and plenty of others out there might still insist that NCGS doesn’t truly exist, several studies have validated it as a distinct clinical condition. (3) As I’ve explained previously, gluten sensitivity is very real. Stories painting NCGS as a collective delusion have gotten it wrong.
Decoding Your (Real) Symptoms
Gluten intolerance can affect nearly every tissue in the body, including the brain, skin, endocrine system, liver, blood vessels, smooth muscles (found in hollow organs such as the intestines), and, yes, stomach.
That’s why it can manifest either in the classic presentation of digestive distress—abdominal pain, bloating, gas, and diarrhea or constipation—or in any of the following, likely surprising, non-digestive symptoms.
Although it’s discussed infrequently in popular articles, iron-deficiency anemia is well documented as a symptom of gluten intolerance in scientific studies. (4, 5) In fact, research suggests that it may often be the first noticeable symptom of CD and that up to 75 percent of those with an anemia diagnosis may be gluten intolerant. (6, 7) Gluten intolerance can interfere with the uptake of iron from food, causing malabsorption of this important nutrient. (8) What’s more, because anemia generally saps one’s energy, it can trigger or worsen the next non-digestive sign of gluten intolerance on this list.
Many gluten-intolerant individuals report feeling tired and fatigued, especially right after eating, you guessed it, gluten. (9) Research has linked NCGS to chronic fatigue symptoms in some people. (10) As with chronic fatigue syndrome, symptoms of gluten intolerance can also include muscle fatigue and muscle and joint pain.
This type of cognitive dysfunction can be a sign of gluten sensitivity. Those affected often describe experiencing “foggy mind” symptoms such as an inability to focus and concentrate; some also describe feeling mentally fatigued. (11, 12)
Headache is a frequent finding in NCGS, with one recent study reporting the symptom in more than half of its participants. (13, 14, 15) Migraine in particular is an associated symptom. (16, 17)
Eczema and Other Skin Disorders
As with fatigue, brain fog, and headaches, people with NCGS may notice a worsening of skin symptoms such as eczema, rash, and undefined dermatitis after ingesting gluten-containing foods. The most commonly reported skin lesions include those similar to subacute eczema, as well as the bumps and blisters indicative of dermatitis herpetiformis, or Duhring’s disease—to which CD is closely linked. Those who are gluten intolerant may also experience scaly patches resembling psoriasis. Lesions are typically found on the muscles of the upper limbs. (18, 19, 20)
Depression and Anxiety
One of the main reasons gluten sensitivity often goes unrecognized and untreated, researchers theorize, is because mental health issues can be a hallmark of this condition. Data suggests that up to 22 percent of patients with CD develop such dysfunctions, with anxiety and depression occurring most commonly. One study found that CD patients were more likely than others to feel anxious in the face of threatening situations, while additional research has linked conditions such as panic disorder and social phobia to gluten response. Depression and related mood disorders appear to occur with both NCGS and CD. (21, 22)
Here’s the good news: The majority of studies cited here not only investigated whether or not these symptoms are signs of gluten intolerance, but also whether or not they can be addressed by going gluten free. And it turns out, these problems improved or completely resolved with adherence to a gluten-free diet.
But more on that in a minute.
Beware These Surprising Consequences of Intolerance
While the symptoms mentioned above are what will most likely clue you in to your body’s negative response to gluten, they aren’t the only effects of intolerance to be aware of. In fact, a variety of chronic diseases may develop due to long-term CD or NCGS, including: (23, 24)
Attention-deficit hyperactivity disorder, or ADHD
Autism spectrum disorders
Type 1 diabetes
Amyotrophic lateral sclerosis, or ALS
In one study, researchers found a strong link between gluten sensitivity and neurological complications—especially those in which the cause was unknown. (25) Research has even shown that, for some people with gluten sensitivity, the primary symptom they experience is a neurological dysfunction. (26) The data suggests that nearly 60 percent of people with neurological dysfunction of unknown origin test positive for anti-gliadin antibodies. (27)
Challenge Yourself: Do You Feel Better on a Gluten-Free Diet?
If you’re currently experiencing any of the symptoms of gluten intolerance I shared in this article and can’t seem to find relief, or if you have received a diagnosis of any of the above linked diseases or disorders and you and your doctor have not found a probable cause or resolution, gluten could very well be a trigger for you.
Because of the limitations of current testing for CD and the lack of diagnostic options for NCGS, the most reliable test for gluten intolerance is a “gluten challenge.”
This involves removing gluten from your diet completely for a period of at least 30 days—60 days is best—then adding it back in after that time has elapsed. If your symptoms and/or diagnosis improve during the elimination period and return when gluten is reintroduced, let your healthcare provider know. You have NCGS or atypical CD.
Though I consider this to be the gold-standard test for gluten intolerance, Cyrex Laboratories does offer a comprehensive blood panel that screens for all of the wheat and gluten proteins and transglutaminase enzymes discussed earlier. It can be a helpful diagnostic tool, but it shouldn’t replace a gluten challenge. (Note: It must be ordered by your physician or another healthcare provider.)
How Will You Deal with Your Symptoms of Gluten Intolerance?
If you experience improvement on a gluten-free diet and plan to continue eating this way, you can feel confident that there is no risk in terms of nutrient deficiencies to removing gluten from your diet. (28) If anything, my experience has shown me that people who eat gluten-free are more likely to increase their intake of essential nutrients, especially if they replace breads and other flour products with whole foods.
Have you experienced any of these symptoms? Are you planning a gluten challenge to determine once and for all if gluten is the culprit? Let me know below in the comments!
My comments: My anaemia, post wheat meal fatigue and brain fog, irritable bowel, and mouth ulcers all went away when I stopped wheat. And they recurred after four days of eating wheat after a long period of abstinence. We discuss how you can meal plan and bake without wheat on this blog site and in our book.