Gut Health

Should You Be Eating Wheat? Here's The Science...

Should You Be Eating Wheat? Here's The Science...

Wheat has been a staple of the human diet for around 9000 years. Yet many people these days are choosing to avoid wheat claiming they experience health improvements by so-doing. What is it about wheat that causes problems and why do these problems appear to have increased?

What’s wrong with wheat?

Wheat (and other grains such as barley and rye), contains several plant chemicals that can cause us problems, namely:

  • Wheat-germ agglutinin
  • Amylase trypsin inhibitors
  • Phytic acid
  • Fructans1,2
  • Let’s have a look at how each of these chemicals can cause problems:


Gluten can damage the lining of the gut. This happens through it triggering the release of a chemical (called zonulin) from the gut lining. Studies have shown that in people with coeliac disease, very large amounts of zonulin are triggered by gluten.5 This damage allows fluid and incompletely digested food particles to cross between the body and the gut. Which in turn causes problems.

Zonulin instructs the cells that line the gut to separate from their neighbours3. This situation is sometimes called “leaky gut”. Separation of the cells that line the gut allows fluid to pass straight from the body into the gut. This can lead to diarrhoea.

At the same time the separation allows gluten or or food components in the gut to pass straight into the bloodstream before they have been completely digested.4 When gluten and other incompletely digested elements penetrate through the gut, they can trigger an immune response from the vigilant immune system that patrols the gut for foreign invaders.4

Many food components have similarities in the shapes of their proteins to proteins that occur naturally in the human body. If these food components pass through into the bloodstream, and this in turn triggers and immune reaction, it is possible that the immune system may also attack any organs that contain similarly shaped proteins.7 As a prime example, part of the gluten molecule mimics the shape of proteins found in the thyroid gland. Therefore, it’s no surprise that gluten plays a role in thyroid disease.8

The Gutology Podcast

Want more help to find the right diet for you? Grab Episode 7 of The Gutology Podcast.


Wheat Germ Agglutinin (WGA) 

WGA is a small chemical found in the bran part of the wheat grain. It can pass through the gut lining into the bloodstream relatively easily, large amounts of zonulin do not need to be released for this to happen.9,10 Thus, WGA can enter the bloodstream of wheat-eaters who don’t have coeliac disease. WGA has been shown to:

  • Bind to sugars found in cells lining the gut and our immune cells9,10
  • Provoke an inflammatory response in the lining of the gut, worsening leaky gut.9,10
  • Interfere with digestion of protein,11 increasing the chances of improperly digested food being able to pass through the leaky gut
  • Inhibit production of digestive enzymes from the pancreas12
  • Mimic the effect of insulin in encouraging storage of fat13 (this fattening property made wheat a desirable part of the diet for much of human history as famine rather than excess food was the biggest problem for our species)
  • Amylase Trypsin Inhibitors (ATIs)
  • ATIs are found in wheat, barley and rye, can inhibit the enzymes in the gut that digest the protein and starchy components14. This means that poorly digested food is instead fermented by our gut bacteria which can cause bloating and discomfort.

By inhibiting digestion in this way, it makes it more likely that undigested food components will be available to pass through the leaky gut and trigger immune reactions to other foods.

ATIs are produced by the wheat plant to act as pest resistance molecules, they directly target certain pro-inflammatory receptors in the gut to increase gut inflammation.15,16

Phytic Acid

This is found in wheat and other grains, as well as legumes and nut. It binds to minerals, such as calcium, magnesium, zinc and iron so that we are unable to absorb them.17,18


Wheat also contains fructans, which are long chains of sugars that are rapidly fermented by our gut bacteria. This can be good as it helps to increase the growth of beneficial microbes. However, for those with a sensitive gut, it can lead to uncomfortable abdominal cramping and gas.19

Why is wheat a problem now?

As wheat has been in the human diet for so long, you would be right to ask, why if wheat is such a problem for our health, have we been eating it for thousands of years? Did something change? Yes! Several things have changed over the centuries since wheat entered our diet:

  • Higher amounts of Gluten, Amylase-trypsin Inhibitors and Fructans
  • Lower amounts of nutrients
  • Different processing
  • More wheat is consumed
  • Higher Gluten, Amylase-trypsin Inhibitors and Fructans

The gluten content of wheat is what gives baked goods their structure and allows bread to be soft and springy. Over centuries, and particularly since the 1950s, farmers have selected strains of wheat that contain higher amounts of gluten and, inadvertently, have also selected strains which have a particular form of gluten that appears to have a greater propensity to trigger an immune response.2,20 Gluten is actually not a single protein, it is a family of different proteins and one of the gluten proteins that seems to be is significantly higher in modern wheat.21

Similarly, amounts of amylase-trypsin inhibitors and fructans in wheat can vary and may be lower in some ancient varieties of wheat.2

Lower Amount of Nutrients

Modern wheat is lower in nutrients, such as zinc, copper, selenium, iron and magnesium, nearly a third lower in some cases.22,23 Almost all of the wheat eaten today is high-yield dwarf wheat. This wheat grows very quickly which may explain why it accumulates less minerals.

Different Processing

Modern wheat is also processed very differently. Whereas previously wheat was milled using grinding stones which produced a fairly coarse flour, now we use roller mills which grind the wheat so fine that it breaks open the individual starch-containing cells. This makes a very fine flour but one which releases the starches in our digestive system very quickly.24

This can cause big rises in our blood sugar,24,25 which is undesirable for several reasons. Blood sugar peaks trigger the body to react quickly to bring these levels down as high blood sugar damages our cells and the body reacts to prevent this. Unfortunately, this rapid release of the hormone, insulin, which lowers blood sugar, results in blood sugar coming down so fast it may dip below normal blood sugar levels. This causes us to feel hungry, light-headed and unwell. Even with this rapid reaction by the body, high blood sugar levels will start to damage our cells. Finally, high insulin levels tend to stimulate weight gain.

Higher Consumption

Although wheat has long been a staple in our diet, it may be that we are consuming more wheat than in the past: wheat-based cereals for breakfast, muffins with coffee mid-morning, a sandwich at lunchtime, biscuits with tea in the afternoon, pasta for our evening meal perhaps followed by more biscuits? That’s a lot of wheat! Further, today’s world has other challenges which might make us more susceptible to becoming sensitive to wheat: increased stress affecting our gut, exposure to toxins, loss of gut bacteria diversity, might contribute.

Is eating bread always a bad idea?

Some people who have problems with wheat find they can tolerate bread that has undergone a prolonged fermentation as in authentic sour-dough. Supermarket bread is only fermented for an hour or so, compared with up to 3 days for genuine sour-dough. Longer fermentation affects several aspects:

  • The amount of gluten is lower in longer-fermented breads26,27
  • The wild yeast and lactobacillus in the sourdough starter neutralise the phytic acid as the bread proves through the acidification of the dough.28
  • The action of yeast and bacteria (in sourdough) can increase the vitamin content of the bread.27
  • As some ancient varieties of wheat may be lower in gluten and other unwanted components. In particular, bread (or other wheat containing foods) made from spelt, einkorn or emmer may also be better tolerated.2

Choose authentic, white sourdough

Bread sold as sourdough may not be true sourdough with long fermentation and presence of the wild yeasts and lactic acid bacteria which help to make wheat more tolerable. Often, sourdough breads available in supermarkets is made with sourdough flavouring and actually goes through the same fast fermentation as standard supermarket breads.

White flour contains no wheat germ agglutin (see above for why wheat germ agglutinin is a problem), so choosing white sourdough will minimise the harmful elements of standard bread. If you are sensitive to wheat and choose to eat sourdough, it is still wise to eat it in moderation. It does still contain some gluten and is a source of carbohydrate that may feed unwanted gut bacteria you might be harbouring.

If you struggle with wheat could things change?

Many of the problems arising from wheat stem from problems with the gut: an inflamed, leaky gut is more likely to result in food intolerances of all kinds. Healing the gut and restoring your internal barriers could well mean that in future you will be able to tolerate wheat again, particularly authentic sourdough and ancient grains…although perhaps not at every meal! Read our article on having a Leaky Gut here.


Wheat can have harmful effects on your body through the reactions caused by:

  • Gluten
  • Wheat-germ agglutinin
  • Amylase trypsin inhibitors
  • Phytic acid
  • Fructans1,2

Even though we’ve been eating it for thousands of years, we could be experiencing more problems because of key differences today:

  • Higher amounts of gluten, amylase-trypsin Inhibitors and fructans
  • Lower amounts of nutrients
  • Different processing
  • More wheat is consumed

If you do choose to eat bread, eat authentic white sourdough, in moderation. Maybe buy a loaf for your household at the weekend as a treat!

    GI Biome+
    GI Biome+
    Regular price From $262.15
    Regular price Sale price From $262.15

    Take the gut health quiz!

    Get articles, product recommendations & information based on your symptoms.

    Start now


    1. Aziz I, Dwivedi K, Sanders DS. From coeliac disease to noncoeliac gluten sensitivity; should everyone be gluten free? Curr Opin Gastroenterol. 2016;32(2):120-127. doi:10.1097/MOG.0000000000000248
    2. Kucek LK, Veenstra LD, Amnuaycheewa P, Sorrells ME. A Grounded Guide to Gluten: How Modern Genotypes and Processing Impact Wheat Sensitivity. Compr Rev Food Sci Food Saf. 2015;14(3):285-302. doi:10.1111/1541-4337.12129
    3. Lammers KM, Lu R, Brownley J, et al. Gliadin Induces an Increase in Intestinal Permeability and Zonulin Release by Binding to the Chemokine Receptor CXCR3. Gastroenterology. 2008;135(1):194-204.e3. doi:10.1053/j.gastro.2008.03.023
    4. Fasano A. Zonulin, regulation of tight junctions, and autoimmune diseases. Ann N Y Acad Sci. 2012. doi:10.1111/j.1749-6632.2012.06538.
    5. Fasano A, Not T, Wang W, et al. Zonulin, a newly discovered modulator of intestinal permeability, and its expression in coeliac disease. Lancet. 2000. doi:10.1016/S0140-6736(00)02169-3
    6. Drago S, El Asmar R, Di Pierro M, et al. Gliadin, zonulin and gut permeability: Effects on celiac and non-celiac intestinal mucosa and intestinal cell lines. Scand J Gastroenterol. 2006. doi:10.1080/00365520500235334
    7. Fasano A. Leaky gut and autoimmune diseases. Clin Rev Allergy Immunol. 2012. doi:10.1007/s12016-011-8291-
    8. Vojdani A, O’Bryan T, Kellermann GHH. The immunology of gluten sensitivity beyond the intestinal tract. Eur J Inflamm. 2008;6(2):1721-1727. doi:10.1177/1721727X0800600201
    9. Punder K, Pruimboom L. The dietary intake of wheat and other cereal grains and their role in inflammation. Nutrients. 2013;5(3):771-787. doi:10.3390/nu5030771
    10. Pellegrina CD, Perbellini O, Scupoli MT, et al. Effects of wheat germ agglutinin on human gastrointestinal epithelium: Insights from an experimental model of immune/epithelial cell interaction. Toxicol Appl Pharmacol. 2009;237(2):146-153. doi:10.1016/j.taap.2009.03.012
    11. Pusztai A, Ewen SW, Grant G, et al. Antinutritive effects of wheat-germ agglutinin and other N-acetylglucosamine-specific lectins. Br J Nutr. 1993;70(1):313-321.
    12. Mikkat U, Damm I, Schröder G, et al. Effect of the lectins wheat germ agglutinin (WGA) and Ulex europaeus agglutinin (UEA-I) on the alpha-amylase secretion of rat pancreas in vitro and in vivo. Pancreas. 1998;16(4):529-538.
    13. Livingston JN, Purvis BJ. The effects of wheat germ agglutinin on the adipocyte insulin receptor. Biochim Biophys Acta. 1981;678(2):194-201.
    14. Cuccioloni M, Mozzicafreddo M, Ali I, et al. Interaction between wheat alpha-amylase/trypsin bi-functional inhibitor and mammalian digestive enzymes: Kinetic, equilibrium and structural characterization of binding. Food Chem. 2016;213:571-578. doi:10.1016/J.FOODCHEM.2016.07.020
    15. Zevallos VF, Raker V, Tenzer S, et al. Nutritional Wheat Amylase-Trypsin Inhibitors Promote Intestinal Inflammation via Activation of Myeloid Cells. Gastroenterology. 2017;152(5):1100-1113.e12. doi:10.1053/j.gastro.2016.12.006
    16. Junker Y, Zeissig S, Kim S-J, et al. Wheat amylase trypsin inhibitors drive intestinal inflammation via activation of toll-like receptor 4. J Exp Med. 2012;209(13):2395-2408. doi:10.1084/jem.20102660
    17. Hurrell RF. Influence of Vegetable Protein Sources on Trace Element and Mineral Bioavailability. J Nutr. 2018. doi:10.1093/jn/133.9.2973s
    18. Lopez HW, Leenhardt F, Coudray C, Remesy C. Minerals and phytic acid interactions: Is it a real problem for human nutrition? Int J Food Sci Technol. 2002. doi:10.1046/j.1365-2621.2002.00618.x
    19. Wilson B, Whelan K. Prebiotic inulin-type fructans and galacto-oligosaccharides: definition, specificity, function, and application in gastrointestinal disorders. J Gastroenterol Hepatol. 2017;32:64-68. doi:10.1111/jgh.13700
    20. De Santis MA, Giuliani MM, Giuzio L, et al. Differences in gluten protein composition between old and modern durum wheat genotypes in relation to 20th century breeding in Italy. Eur J Agron. 2017;87:19-29. doi:10.1016/J.EJA.2017.04.003
    21. Broeck HC van den, Jong HC de, Salentijn EMJ, et al. Presence of celiac disease epitopes in modern and old hexaploid wheat varieties: wheat breeding may have contributed to increased prevalence of celiac disease. Theor Appl Genet. 2010;121(8):1527. doi:10.1007/S00122-010-1408-4
    22. Fan M-S, Zhao F-J, Fairweather-Tait SJ, Poulton PR, Dunham SJ, McGrath SP. Evidence of decreasing mineral density in wheat grain over the last 160 years. J Trace Elem Med Biol. 2008;22(4):315-324. doi:10.1016/j.jtemb.2008.07.002
    23. Zhao FJ, Su YH, Dunham SJ, et al. Variation in mineral micronutrient concentrations in grain of wheat lines of diverse origin. J Cereal Sci. 2009;49(2):290-295. doi:10.1016/J.JCS.2008.11.007
    24. Mandalari G, Merali Z, Ryden P, et al. Durum wheat particle size affects starch and protein digestion in vitro. Eur J Nutr. 2018;57(1):319-325. doi:10.1007/s00394-016-1321-y
    25. Heaton KW, Marcus SN, Emmett PM, Bolton CH. Particle size of wheat, maize, and oat test meals: effects on plasma glucose and insulin responses and on the rate of starch digestion in vitro. Am J Clin Nutr. 1988;47(4):675-682. doi:10.1093/ajcn/47.4.675
    26. Rizzello CG, De Angelis M, Di Cagno R, et al. Highly efficient gluten degradation by lactobacilli and fungal proteases during food processing: New perspectives for celiac disease. Appl Environ Microbiol. 2007. doi:10.1128/AEM.00260-07
    27. Poutanen K, Flander L, Katina K. Sourdough and cereal fermentation in a nutritional perspective. Food Microbiol. 2009. doi:10.1016/ Lopez HW, Krespine V, Guy G, Messager A, Demigne C, Remesy C. Prolonged fermentation of whole wheat sourdough reduces phytate level and increases soluble magnesium. J Agric Food Chem. 2001. doi:10.1021/jf001255z