Gluten

Gluten

Gluten — from the Latin gluten, “glue” — is the name of a protein network that forms when wheat, rye or barley flour meets water. It is this network that turns a mix of flour and water into a dough that can be stretched, it traps the carbon dioxide bubbles that yeast produces, and it is what gives bread an airy texture instead of a crumbly one. (In Hebrew it is “גלוטן”; two grain names that trip up Hebrew speakers in particular, “כוסמין” (spelt) and “כוסמת” (buckwheat), are covered below.)

Gluten is also one of the most controversial components in nutrition: a small, well-defined part of the population must avoid it completely for medical reasons, and alongside them millions of people avoid it even though it does nothing to them. This page separates the two groups and explains what the research really shows.

What gluten is — and why it isn’t in dry flour

A bag of dry flour does not yet contain a gluten network — it contains its two components, which sit separately in the endosperm cells of the grain:

• Gliadin — a monomeric protein that dissolves in alcohol. It is viscous and fluid, and is responsible for the extensibility of dough and its ability to flow.
• Glutenin — a large polymeric protein made of long chains. It is responsible for strength and elasticity — the dough’s ability to spring back after stretching.

Only when water is added and mechanical force applied (kneading) do the chains bind to each other with disulfide bonds and hydrogen bonds, forming a continuous three-dimensional network — gluten. Together they make up about 80-85% of all the protein in the wheat grain.

Biochemically, the medically problematic part is the prolamins — the alcohol-soluble protein fraction, rich in the amino acids proline and glutamine. This combination is especially resistant to human digestive enzymes, so remnants of it reach the small intestine as long, intact peptides instead of as single amino acids. Each grain has its own prolamin:

When people talk about a “gluten-free diet,” they actually mean avoiding only the first three.

Which foods contain gluten and which don’t

This is a table worth remembering, especially because of two names that confuse people:

Two name traps:

• Spelt is wheat. Despite its “healthy” and ancient image, spelt (Triticum spelta) is a species of wheat and contains gluten in full. It is completely off-limits for people with celiac disease.
• Spelt is not buckwheat. Buckwheat is the seed of a plant in the knotweed family, with no relation to wheat at all (despite the “wheat” in its English name), and it is gluten-free. In Hebrew the two names are nearly identical and confusing them is very common — including on restaurant labels.

Its role in baking — and why gluten is added to processed food

Gluten is the reason wheat, and not rice or corn, became the world’s bread grain. When yeast produces carbon dioxide, the elastic network traps it in bubbles and lets the dough rise without the gas escaping. The higher the protein content of the flour, the stronger the network:

This is also where an industrial product called vital wheat gluten comes from — a powder that is gluten itself after the starch has been washed out and it has been dried. Industry adds it to strengthen weak flours, shorten kneading and rising times and stabilize mass-produced baked goods. This is an important point: even if the gluten content of wheat varieties themselves has not changed substantially over the last hundred years, the total amount of gluten in the Western diet has gone up — because of added vital wheat gluten and because of greater consumption of flour products in general.

The same powder is also the basis of seitan — a long-standing meat substitute from Buddhist cuisine, which is nothing more than gluten that has been soaked, kneaded and cooked.

Nutrition facts

Gluten itself is hardly ever eaten in isolation, except in seitan and vital wheat gluten powder. The figures are estimates and vary between manufacturers:

Protein quality is the important point here. Despite the impressive protein percentages, gluten is an incomplete protein: it is very low in lysine, its limiting amino acid, so its PDCAAS score is low — only about a quarter of that of whey protein or egg. Anyone relying on seitan as a main protein source should combine it with legumes, soy or dairy, which are rich in lysine — just as is customary with other grains.

Who really needs to avoid it — four completely different conditions

This is where most of the public confusion arises. “Gluten sensitivity” is not one diagnosis but at least four, with entirely different mechanisms, severity and implications:

Celiac disease

This is neither an allergy nor a sensitivity but a true autoimmune disease. In genetically predisposed people (carriers of the HLA-DQ2 or HLA-DQ8 genes), gliadin peptides cross the intestinal wall, are chemically modified by the enzyme tissue transglutaminase, and trigger an immune response that attacks the lining of the small intestine itself. The result is flattening of the villi (villous atrophy) — the tiny projections through which most nutrients are absorbed, and whose flattening dramatically reduces the absorptive surface.

• Prevalence: global meta-analyses find a prevalence of about 1.4% by blood tests and about 0.7% by biopsy-confirmed diagnosis. In Israel, estimates hover around 1%.
• Genetics is not destiny: about 30-40% of the population carry the genes, but only a tiny fraction of them will develop the disease. The value of the genetic test is mainly negative — a negative result almost completely rules out the diagnosis.
• The symptoms aren’t only in the gut: alongside diarrhea, bloating and abdominal pain, the disease often presents with symptoms outside the gut: iron-deficiency anemia that does not respond to treatment, chronic fatigue, osteoporosis, stunted growth in children, recurrent mouth ulcers, fertility problems and neurological symptoms.
• Dermatitis herpetiformis: a skin presentation of the same disease — a very itchy, blistering rash, mainly on the elbows, knees and buttocks. It appears in about 10-15% of people with celiac disease and also responds to avoiding gluten.
• The risk of neglecting it: untreated celiac disease raises the risk of osteoporosis, ongoing nutritional deficiencies, and — slightly but significantly — small-intestine lymphoma.

An important practical warning: do not stop eating gluten before you get tested. Blood tests (tTG-IgA antibodies alongside total IgA) and biopsy detect the response to gluten, so in someone who has already stopped eating it the results may come back negative even though the disease is present. Anyone who suspects celiac disease should be tested while still eating gluten regularly — guidelines range from two to six weeks of intake before the test.

Wheat allergy

A classic IgE-mediated allergy to wheat proteins — not necessarily to gluten. The reaction is fast (minutes to two hours) and includes hives, swelling, shortness of breath, vomiting and, in severe cases, anaphylaxis. It is most common in childhood, and many people develop tolerance with age. People with this allergy can usually eat rye and barley — unlike people with celiac disease.

It also has a variant that is especially relevant to athletes: WDEIA (wheat-dependent exercise-induced anaphylaxis), in which the reaction occurs only when eating wheat is followed by strenuous physical activity in the hours afterward. A hard workout after a carbohydrate-rich meal is no reason to suspect this in most people, but a repeated, unexplained reaction during exercise warrants an allergy workup.

Non-celiac gluten sensitivity (NCGS)

People who report bloating, gas, abdominal pain, fatigue or “brain fog” after eating wheat products, but whose celiac and allergy tests are negative. The phenomenon is real — but research in recent years suggests that in most cases gluten is not the main culprit:

• Fructans: wheat is one of the main sources of fructans — carbohydrates from the FODMAP family that are fermented in the large intestine and produce gas. In an important trial published in Gastroenterology, people who described themselves as gluten-sensitive received gluten, fructans or placebo in a crossover design: the fructans caused significantly more symptoms, and gluten was no different from placebo.
• ATIs — amylase/trypsin inhibitors: a group of natural defense proteins in wheat that has been shown to activate an innate immune response through the TLR4 receptor. They are another leading candidate.
• The nocebo effect: in double-blind studies, a substantial share of participants report symptoms even when they received placebo. Expecting a symptom produces it.

The practical meaning: if you feel better on a wheat-free diet — the improvement is real and there is no reason to doubt it. But it is worth knowing that the avoidance you need may be more moderate and more targeted than it seems: sometimes it is enough to cut down on fructans, choose long-fermented sourdough bread, or reduce the portion — without having to avoid every last crumb. In any case, celiac disease should be ruled out before you start.

How much gluten is too much

For a person with celiac disease, “no gluten” is not a figure of speech. A classic dosing study showed that eating 50 mg of gluten a day for three months already caused measurable damage to the intestinal lining, whereas 10 mg a day did not — which established the practical threshold of less than 10 mg a day.

The “gluten-free” label is derived from this too: the international Codex Alimentarius standard and regulations in the US and the European Union define it as less than 20 parts per million (ppm), i.e. 20 mg of gluten per kg of food. The math is simple: someone who eats half a kilo a day of a food sitting exactly at the threshold would consume 10 mg — exactly the safety limit.

To put this in perspective:

In other words: a crumb the size of one-hundredth of a slice contains about 25 mg of gluten — more than twice the entire daily threshold. That is why cross-contamination in the kitchen is not excessive fussiness but a medical matter.

Hidden sources of gluten

This list accounts for most “accidental exposures” in people with celiac disease:

• Soy sauce: traditional Japanese soy sauce is fermented with wheat. Tamari is usually wheat-free, and coconut aminos is completely gluten-free — but always check the label.
• Beer and malt drinks: made from malted barley. “Gluten-reduced” beer undergoes enzymatic treatment whose measurement reliability is disputed, and it is not recommended for people with celiac disease.
• Malt vinegar and malt extracts in breakfast cereals, candy and drinks.
• Processed meat and meat substitutes: sausages, schnitzels, patties and kebabs often contain breadcrumbs or flour as a binder. Many plant-based meat substitutes are built on actual wheat gluten.
• Thickeners and additives: ready-made sauces and salad dressings, soup powders, seasoning blends, and “food starch” whose source is not specified.
• Medicines and dietary supplements: fillers in tablets may contain wheat starch. It is worth checking with the pharmacist.
• Matzah and “kosher for Passover”: this is an especially common mistake in Israel. Matzah is made from wheat flour and contains plenty of gluten; a “kosher for Passover” label has nothing to do with gluten. Products based on potatoes or legumes may indeed be gluten-free, but only an explicit label is decisive.
• Cross-contamination in the kitchen: a shared toaster, pasta colander, frying oil used for flour products, wooden spoons, cutting boards, and a butter dish or spread touched by a knife that touched bread.

Is a gluten-free diet healthier for everyone?

For people without celiac disease, an allergy or a proven sensitivity — the answer, based on current knowledge, is no. There is no evidence that removing gluten from a healthy person’s diet benefits their health, weight or energy levels. On the other hand, there are several measurable downsides:

• An inferior nutritional profile in processed products: reviews of commercial “gluten-free” products consistently find less fiber and less protein, and often more fat, sugar and salt — to make up for the texture gluten was supposed to provide.
• Less iron and B vitamins: in many countries wheat flour is fortified with iron and folic acid. Rice, potato and tapioca flours are usually not fortified, which creates a gap.
• A higher glycemic index: most “gluten-free” products are built on rice, corn and tapioca starches — refined starches that are absorbed quickly.
• Less fiber and harm to the microbiome: cutting down on whole grains lowers intake of fiber and fructans, both of which feed beneficial gut bacteria.
• Arsenic: a gluten-free diet relies heavily on rice. An American study found higher urinary arsenic levels among people avoiding gluten.
• Price: market studies in various countries find that gluten-free products cost on average 2-3 times as much as their counterparts.

And in sports? This is one of the most common myths in athletics: in a survey of more than 900 non-celiac athletes, about 41% reported avoiding gluten at least half the time, mainly out of a belief that it reduces inflammation and improves performance. A double-blind crossover trial that tested the claim among competitive cyclists found no difference at all in performance, digestive symptoms, inflammatory markers or overall well-being between a week with gluten and a week without it. For endurance athletes, available carbohydrates are an asset — and cutting out major carbohydrate sources without a medical reason may actually make it harder to fill glycogen stores.

Myths versus evidence

• “Today’s wheat contains more gluten than it used to”: analyses of American wheat varieties across the 20th century found no significant increase in the gluten content of the grain itself. What did go up is total gluten intake, mainly because of vital wheat gluten added to processed food. At the same time, studies comparing historical blood samples with current ones found a real rise in the prevalence of celiac disease — so the trend exists, but the explanation is more complex than “engineered wheat.”
• “Gluten causes leaky gut in everyone”: gliadin does increase release of the protein zonulin, which loosens the tight junctions between intestinal cells. This is an established lab finding, but its clinical significance in healthy people is not established, and the reliability of commercial zonulin test kits has also been questioned. There is currently no evidence that it causes disease in a healthy person.
• “Sourdough is safe for people with celiac disease”: no. Long fermentation does break down some of the gluten, and it may explain why sourdough bread is better tolerated by people with non-celiac sensitivity — also because some of the fructans are broken down. But ordinary sourdough bread contains gluten in amounts orders of magnitude above the 20 ppm threshold.
• “A gluten enzyme solves the problem”: preparations containing an AN-PEP-type enzyme can break down gluten in the stomach in controlled studies, but there is no evidence that they protect a person with celiac disease from damage. They are not a substitute for avoidance and not a “free pass” for a plate of pasta.

Practical use

If you suspect celiac disease: don’t stop eating gluten. See a doctor for a tTG-IgA test alongside total IgA while you are still eating gluten. A definite diagnosis changes much more than diet — it requires monitoring bone density, iron and vitamins, and testing first-degree relatives.

If you have been diagnosed: avoidance is absolute and lifelong. Look for an explicit “gluten-free” label or the crossed-grain symbol, not just the absence of wheat in the ingredient list. In a shared kitchen — a separate toaster, a separate colander, and spreads in a personal jar. In Israel, it is worth checking with your health fund (kupat holim) whether it contributes toward the cost of gluten-free food.

If you feel unwell after bread but don’t have celiac disease: before giving up a whole category, try to isolate the cause. Switching to long-fermented sourdough bread, to rye bread, or reducing the portion solves the problem for many people — a good sign that fructans, not gluten, were to blame.

If you avoid gluten by choice: build your menu around naturally gluten-free foods — quinoa, buckwheat, brown rice, legumes, potatoes, vegetables and fruit — and not around processed “gluten-free” products, which are usually processed food with less fiber and more sugar.

For vegetarians and vegans: seitan is a dense, convenient protein source, but its protein is low in lysine. Combine it in the same meal with legumes or soy to complete the amino acid profile.

Summary

Gluten is a protein network formed from gliadin and glutenin when they meet water, and it is the technical reason wheat became the world’s bread grain. For about 1% of the population — people with celiac disease — it causes a true autoimmune disease, and avoiding it must be absolute and precise down to the crumb. For another, less well-defined group, eating wheat causes real discomfort — but research increasingly points to fructans and ATI proteins as the main culprits, not gluten itself. And for the rest of the population, there is no evidence that avoiding gluten is beneficial — and there are several measurable reasons to think that switching to processed “gluten-free” products actually lowers diet quality. The practical rule is simple: get tested before you stop, and if there is no diagnosis — choose whole grains and whole foods, not a whole shelf of substitutes.