Food intolerance and FODMAPs

Gluten

Also called: wheat protein, gliadin, glutenin

Gluten is a family of proteins (mainly gliadin and glutenin) found in wheat, barley and rye. It gives bread its stretch and chew. About 1 percent of people have coeliac disease and must avoid it strictly. A larger group has non-coeliac gluten or wheat sensitivity, where the cause may be the carbohydrates rather than the protein. Most healthy people do not need to avoid gluten and lose more than they gain by doing so.

What gluten actually is

Gluten is a stretchy, elastic protein network that forms when water is mixed with wheat flour. The two main parts, gliadin and glutenin, also exist in slightly different forms in barley (hordein) and rye (secalin). Oats are technically gluten-free but are usually contaminated by shared milling lines, which is why coeliacs need certified gluten-free oats.

Three different things people mean by 'reacting to gluten'

  • Coeliac disease: a serious autoimmune condition affecting around 1 in 100 people. The immune system attacks the small intestine when gluten is eaten, damaging the lining over time. Diagnosed by blood antibody test (tTG-IgA) and a biopsy.
  • Wheat allergy: a true IgE-mediated allergy. Rare. Symptoms appear within minutes (hives, swelling, breathing trouble). Most common in children and often outgrown.
  • Non-coeliac gluten or wheat sensitivity: the diagnosis when coeliac and allergy are both ruled out but symptoms still improve on a wheat-free diet. Affects perhaps 5 to 10 percent of people. The cause is debated. Recent evidence points strongly at the FODMAP fructans in wheat, not the gluten itself.

How to know which one you have

  1. If you suspect coeliac, do not cut gluten before testing. The blood test only works while you are still eating gluten. Eat at least 1 to 2 slices of wheat bread daily for 6 weeks, then ask the GP for a tTG-IgA test.
  2. If the test is positive, expect a referral for a small bowel biopsy to confirm.
  3. If the test is negative but symptoms persist on gluten, ask about a structured wheat or FODMAP elimination trial under a registered dietitian.
  4. Reintroduce specific components one at a time. If you tolerate sourdough or spelt but not standard bread, the culprit is more likely fructans than gluten.

Why gluten-free is a bad default for healthy people

  • Many gluten-free packaged products are higher in salt and lower in fibre and protein than their gluten-containing equivalents, and gluten-free breads in particular tend to be higher in fat.
  • Whole-wheat foods are a major source of fibre, B vitamins and iron. Cutting them lowers fibre intake on average.
  • Coeliac patients on long-term strict gluten-free diets often have lower levels of beneficial gut bacteria such as Bifidobacterium than the general population.
  • Restaurant gluten-free options are usually the most ultra-processed dish on the menu.
  • Spending more on gluten-free for an unproven reason is a textbook health-tax.

When trying gluten-free is reasonable

After ruling out coeliac, a structured 4-week wheat or gluten elimination is reasonable for chronic bloating, fatigue or skin issues that have not responded to other changes. Track symptoms in a daily log. Reintroduce systematically. Most people find their tolerance is for moderate amounts of well-prepared wheat (sourdough, properly fermented bread) rather than zero. Working with a registered dietitian beats Reddit.

Common questions

Is sourdough bread gluten-free?
No. Sourdough still contains gluten. Long fermentation does break down some of the FODMAP fructans, which is why people with non-coeliac wheat sensitivity often tolerate sourdough better than standard bread. Coeliacs cannot have sourdough.
Can you develop coeliac disease later in life?
Yes. Coeliac disease can present at any age, though peak diagnoses are in children, in the 30s, and again after 60. Triggers can include pregnancy, severe gut infection, or surgery. If symptoms started recently, do not assume you would have known by now.
Are oats safe?
Pure oats are naturally gluten-free, but most commercial oats are processed alongside wheat and contain enough cross-contamination to cause symptoms in coeliacs. Look for certified gluten-free oats. A small minority of coeliacs also react to a protein in oats called avenin.
Why does pasta in Italy not bother me?
A few possible reasons. Italian durum pasta wheat differs from the bread wheat used in many packaged products, though gluten content of wheat overall has not meaningfully increased over the last century. Traditional preparation includes longer fermentation. Portion sizes and meal patterns are different. The placebo of being on holiday and not stressed is also genuinely effective for gut symptoms.

Sources

The Book of Suna is general information, not medical advice. It is not a substitute for talking to a qualified healthcare professional about your own situation.