What Is Gluten? Why It's Harmful for Some People

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By Check Gluten Team โ˜…โ˜…โ˜…โ˜…โ˜… Published Feb 18, 2026 ยท Last reviewed Apr 2026

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Gluten is a protein in wheat, barley, and rye. For millions of people, it triggers an immune response that damages the gut. Here's the science.

What Is Gluten? Why It's Harmful for Some People

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What Is Gluten?


Gluten is a family of proteins found in wheat, barley, and rye. The two main proteins are glutenin and gliadin โ€” gliadin is the one that causes problems for sensitive individuals.


Gluten gives bread its chewy texture and helps dough rise. It's the "glue" that holds baked goods together (the name literally comes from the Latin word for "glue").


Where Is Gluten Found?


Gluten is in three grains:


  • โ–บWheat โ€” (and all wheat varieties: durum, spelt, kamut, farro, einkorn, semolina)
  • โ–บBarley โ€” (and malt, which comes from barley)
  • โ–บRye

  • Plus any food made FROM these grains: bread, pasta, beer, soy sauce, cereals, cookies, cakes, and hundreds of processed foods.


    Why Is Gluten Harmful?


    Gluten is NOT harmful for most people. About 93% of the population can eat gluten without any issues.


    But for the remaining 7%, gluten triggers real health problems:


    Celiac Disease (~1% of people)


    An autoimmune disease where gluten triggers the immune system to attack the small intestine lining. This damages the villi (nutrient-absorbing structures) and leads to:


  • โ–บMalnutrition and weight loss
  • โ–บAnemia (iron deficiency)
  • โ–บOsteoporosis (calcium malabsorption)
  • โ–บInfertility
  • โ–บNeurological issues
  • โ–บIncreased cancer risk (if untreated)

  • The only treatment is a strict, lifelong gluten-free diet.


    Non-Celiac Gluten Sensitivity (~6% of people)


    Causes similar symptoms to celiac but WITHOUT the autoimmune response or intestinal damage:


  • โ–บBloating, gas, diarrhea
  • โ–บFatigue and brain fog
  • โ–บHeadaches
  • โ–บJoint pain

  • Wheat Allergy (<1%)


    An allergic reaction specifically to wheat proteins (not just gluten). Can cause hives, breathing difficulty, and anaphylaxis.


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    Should YOU Avoid Gluten?


  • โ–บIf you have celiac disease โ€” : Yes, strictly. Even trace amounts cause damage.
  • โ–บIf you have gluten sensitivity โ€” : Yes, as much as possible for symptom relief.
  • โ–บIf you have no symptoms โ€” : No medical reason to avoid gluten. It's a nutritious protein for most people.

  • How to Know If You're Sensitive


  • Don't go gluten-free yet (it interferes with testing)
  • See your doctor for a celiac blood test (tTG-IgA)
  • If negative, try an elimination diet for 3-4 weeks
  • Track symptoms when you reintroduce gluten

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    About the Author

    SM

    Sarah Mitchell

    Lead Content Writer & Nutritionist, B.S. Nutrition Science

    Sarah was diagnosed with celiac disease in 2018 and writes evidence-based guides combining clinical nutrition knowledge with 6+ years of personal gluten-free living experience. All health content is medically reviewed by our advisory team.

    Meet our full team โ†’

    Medical Disclaimer: This article is for informational purposes only and is not a substitute for professional medical advice. Always consult your physician or a registered dietitian before making dietary changes related to celiac disease or gluten sensitivity. Read full disclaimer.