The per capita consumption of wheat and its contribution to the total intake of calories have declined with increased prosperity in most developed countries over the past century. In addition, there has been a marked decrease in consumption of wheat over the past decade in some countries, particularly in Europe and North America, due to perceived negative effects of wheat or gluten on health.
Gooding & Shewry, Wheat, Environment, & Health, Wiley 2022
Over the last century as some developed countries have enjoyed an increasing prosperity there has been a drop in per capita consumption of wheat. Prosperity has brought an increasing range of foodstuffs to be coupled to a more mixed diet in which wheat has lost its prominence. More recently, particularly in this new century, there has been in Europe, the UK, and in North America a further drop in consumption of wheat as loud voices proclaim that wheat and its gluten are harmful to health. Underpinning these concerns is a general rise in the community’s interest in the influence of diet on maintaining good health as well as an unease about industrial processes affecting so much of our food. The state of unease and suspicion concerning gluten has led to misconceptions that wheat consumption has led to obesity and diet-related chronic diseases. While it is indisputable that white flour lacks fibre and other nutrients found in wholemeal, scientists point out that the main problem with the so-called “Western diet” is its general reliance on fats and sugar with rapidly digested carbohydrates. Gooding & Shewry remark that the peer-reviewed scientists have concluded that wheat, and even white bread, does not contribute directly to these diseases and can be considered as worthy of consumption as part of a balanced diet.
Having cleared up some of the fall-out from anti-wheat prejudice, it is still necessary to survey some of the harmful effects of wheat and examine several types of adverse reactions to it in susceptible people.
There are two main categories in which the adverse reactions are labelled: allergies and intolerance.
While wheat is listed among the main eight allergens that must be placed on food labels (milk, eggs, crustaceans, shellfish, tree nuts, peanuts, soybean), it has actually a very low prevalence, and it is fair to say that wheat products cause adverse reactions in only a small group of humans. Symptoms include dermatitis, hives, gastro-intestinal and respiratory problems. Science has implicated a range of wheat proteins as the likely cause, mainly the gluten-forming proteins, but lately much research attention has been given to a protein type known as ATI which would amount to only 3% of wheat protein. These ATI’s inhibit hydrolytic enzymes, hence they can cause disruption in the human gut. It is interesting to note that their most likely purpose is to protect the wheat seed since it has been found that they mostly inhibit enzymes in pests and pathogens of wheat. While no conclusions are drawn yet it is thought that the protein substance causing the discomfort has stimulated the innate immune system. For the intestinal symptoms the allergic reaction is associated with a range of discomfort from mild bloating to intense pain. Some medical researchers today say that sufferers could be as high as 10% of the population.
There is some overlap with IBS (irritable bowel syndrome). Among the sugars in wheat that were listed under the heading of Sugars in the previous chapter two are relevant when we look at IBS: trisaccharide raffinose and the polymers of fructose known as fructans. For foodstuffs in general there is a name used in science for small fermentable carbohydrates. They are called FODMAPS and in wheat it is raffinose and fructans that are the main ones. Their impact on IBS sufferers is pronounced since their fermentation and resulting gas causes discomfort in the colon. Sufferers of IBS, Crohn’s Disease, and ulcerative colitis can be assisted in selecting a diet which is low in FODMAPS.
Probably the most devastating form of allergy is one that is triggered when exercise follows the ingestion of a wheat-based food. Again gliadin is thought to be the culprit. Its grandly hyphenated name in English is “wheat-dependent exercise-induced anaphylaxis”, yet it occurs most in Japan where it possibly affects 0.2% of the population.
Regarding respiratory trouble, often labelled “bakers’ asthma”, it is the very fine particles of airborne flour that lodge in the lungs. It is classed as an occupational disease. Modern laws ensure that when the workplace is of a certain size employers must provide powerful extraction systems. Bakers and mill workers should be encouraged to wear a mask. The craftsman, often working alone or in a small group without extraction systems, must be careful since dough making machinery puffs flour into the atmosphere, and bench work can involve clouds of “dusting” flour as bakers hurry to throw flour across large surfaces that are about to be covered with dough. When I had been twenty-odd years as a hands-on baker I was diagnosed with asthma. At one place where I worked some colleagues – young men who were either lazy or more probably uninterested in wearing a mask – had to go off work with respiratory problems brought on by working for a few days in a row with rye flour, which has a noticeably finer particle, enabling it to become more airborne than wheat. I am always mindful of that story when I pour rye flour into a machine or a bin, and I don my mask.
Another occupational disorder for bakers is dermatitis, affecting hands and arms. Among the group of allergies ascribed to the effect of wheat proteins it seems under-rated, but it is certainly an irritant for some.
The Coeliac Problem
At the high end of the allergy scale is the severe illness called coeliac disease. Knowledge of coeliac disease has been with us since both the Greeks and the Romans, but scientific certainty of it being associated with grain proteins (wheat, rye, barley, and oats) only stems from the 1950’s when it was also pronounced that it occurs m
In wheat, gluten proteins are made up of gliadins and glutenins, which are present in approximately equal amounts and form 80% of the total storage protein content in the wheat kernel, next to albumins (12%) and globulins (8%).
Both gliadins and glutenins are large families of molecule with many different forms. In the last two decades a deeper understanding has occurred with researchers announcing that in wheat it is the gliadins, not the glutenins, that are more closely associated with difficulties in the human digestive system, and it is by studying the gliadins that progress has been made about understanding the coeliac problem. These findings together with contingent publicity has led to a public perception that the coeliac condition is increasing, but that is not really the case, and for some time it has been around 1% of the population.
It is a serious illness, being an auto-immune condition where gluten causes the body’s immune system to attack itself. The tiniest consumption of gluten results in an inflammatory disorder of the small intestine causing a flattening of the villi leading to malabsorption of food with consequent weight loss and fatigue. There is a wide variety of chronic symptoms, including diarrhoea, bowel pain, headache, osteoporosis, infertility, and lymphoma. While more research is needed, many in the scientific community take the view that modern wheat breeding practices may have contributed to this phenomenon.
Bread wheat (Triticum aestivum) is an allohexaploid species resulting from natural hybridization between a type of emmer, tetraploid T.turgidum (dicoccum), carrying the AB-genome and a wild grass called “goat grass” – Aegilops tauschii – adiploid species carrying the D-genome. The introduction of the D-genome improved the breadmaking properties by changing the gluten molecules. Although this occurred some 10,000 years ago (see Chapter…..) it was the origin of what is confusingly called modern bread wheat. It is regarded as modern because it was free-threshing as well as having properties to make it suitable for bread.
In the pursuit of a better understanding of coeliac disease, by examining varieties of the last 100 years scientists are of course reviewing truly modern wheats, including the dwarf varieties and wheats bred after World War II. These modern varieties of the 20th century moved us away from the ancient long straw varieties including the covered wheats, and the land races which humans had developed over the centuries. (The “covered” wheats are those with a very tough hull, the glume, that must be removed before milling. They include einkorn, emmer, and spelt).
To create these modern wheats of the twentieth century breeders started to systematically cross and select bread wheat varieties for higher yields, climatic adaption, better bread-making characteristics, and improved disease resistance. Before this scientific activity, little information on these many aspects of wheat was available from the breeding history of all the landraces that comprised the world’s known breeds of wheat. Breeding has resulted in many thousands of different wheat varieties that are stored in genetic resource centres and breeding company stocks around the world. The lack of information about landraces and early wheats makes it difficult to draw conclusions, but it is possible that changes at the genetic level due to crossing and selection have caused the wheat grain’s physiology to aggravate digestive intolerances. Some scientists remain unconvinced about this outlook, saying that the changes in gluten composition brought about in modern wheats are not leading to increased coeliac toxicity for the simple reason that the wheat breeding programmes involving selection for breadmaking attributes have led to more elastic dough (being the measure of “strength”) and dough elasticity is associated with glutenin polymers rather than the gliadins.
In the endeavour to overcome coeliac disease the botanists now want to examine the tall wheats and nineteenth century landraces that were the norm before the twentieth century breeding got underway. Current and future breeding programmes may be able to decrease those forms of the gliadin molecules which aggravate digestive intolerances, contributing to a reduction in the incidence of coeliac disease. Breeding programmes can incorporate varieties from different origins to maximise the genetic diversity available to them, and sometimes can even make use of tetraploid (durum) and diploid (einkorn) wheat species. In the last two decades there has also been a revived interest in the covered grains by people who, while not being extreme sufferers like coeliacs, still find wheat difficult to digest and thus claim an intolerance to wheat, manifested in digestion discomfort and perhaps bloating as women often report. The ancient grains do indeed have a different gluten structure, in particular different gliadin, which may account for easier digestion of them claimed by many consumers. A strict science approach would point out that none of this is fully proved yet and may be based on hopeful speculation.
There is a link here to the fermentation method of sourdough. It is reported that sourdough can reduce coeliac toxicity by its action of breaking down the gluten proteins during its long period of fermentation. The powerful acids in the sourdough break down the peptide bonds that hold the protein together. It is thought that something like 20 hours may be required for this, and while that length of time would seem unsuitable for many types of bread fermentation, in the world of sourdough it is not uncommon where the baker imposes refrigeration on the process. I expect we shall hear more about this in the future, with coeliac sufferers being urged to eat properly crafted sourdough bread, although it is no surprise that today medical science is being slow to endorse it.