Extensive farming or extensive agriculture (as opposed to intensive farming ) is an agricultural production system that uses small inputs of labour , fertilizers, and capital , relative to the land area being farmed.
120-576: Extensive farming most commonly means raising sheep and cattle in areas with low agricultural productivity, but includes large-scale growing of wheat , barley , cooking oils and other grain crops in areas like the Murray-Darling Basin in Australia . Here, owing to the extreme age and poverty of the soils, yields per hectare are very low, but the flat terrain and very large farm sizes mean yields per unit of labour are high. Nomadic herding
240-552: A DQ2 isoform . This peptide, when altered by intestinal transglutaminase, has a high density of overlapping T-cell epitopes. This increases the likelihood that the DQ2 isoform will bind, and stay bound to, peptide when recognised by T-cells. Gliadin in wheat is the best-understood member of this family, but other prolamins exist, and hordein (from barley), secalin (from rye), and avenin (from oats) may contribute to coeliac disease. Avenin's toxicity in people with coeliac disease depends on
360-652: A broad area of Europe and the US. The prevalence of coeliac disease genotypes in the modern population is not completely understood. Given the characteristics of the disease and its apparent strong heritability, it would normally be expected that the genotypes would undergo negative selection and to be absent in societies where agriculture has been practised the longest (compare with a similar condition, lactose intolerance , which has been negatively selected so strongly that its prevalence went from ~100% in ancestral populations to less than 5% in some European countries). This expectation
480-476: A coeliac disease diagnosis. However, a 2006 study showed that EMA-negative people with coeliac tend to be older males with more severe abdominal symptoms and a lower frequency of "atypical" symptoms, including autoimmune disease. In this study, the anti-tTG antibody deposits did not correlate with the severity of villous destruction. These findings, coupled with work showing that gliadin has an innate response component, suggest that gliadin may be more responsible for
600-438: A combination of artificial and natural selection . This complexity and diversity of status has led to much confusion in the naming of wheats. Hexaploid species (6N) Tetraploid species (4N) Diploid species (2N) The wild species of wheat, along with the domesticated varieties einkorn , emmer and spelt , have hulls. This more primitive morphology (in evolutionary terms) consists of toughened glumes that tightly enclose
720-535: A decline in climate resilience of wheat has been observed. Hunter-gatherers in West Asia harvested wild wheats for thousands of years before they were domesticated , perhaps as early as 21,000 BC, but they formed a minor component of their diets. In this phase of pre-domestication cultivation, early cultivars were spread around the region and slowly developed the traits that came to characterise their domesticated forms. Repeated harvesting and sowing of
840-412: A diagnosis is achieved. As a result of screening , the diagnosis is increasingly being made in people who have no symptoms . Evidence regarding the effects of screening, however, is not sufficient to determine its usefulness. While the disease is caused by a permanent intolerance to gluten proteins, it is distinct from wheat allergy , which is much more rare. The only known effective treatment
960-404: A genetically susceptible individual will go on to develop coeliac disease. Major theories include surgery, pregnancy, infection and emotional stress. The eating of gluten early in a baby's life does not appear to increase the risk of coeliac disease but later introduction after six months may increase it. There is uncertainty whether being breastfed reduces risk. Prolonging breastfeeding until
1080-409: A good crop of grain. The farmer may intervene while the crop is growing to add fertilizer , water by irrigation , or pesticides such as herbicides to kill broad-leaved weeds or insecticides to kill insect pests. The farmer may assess soil minerals, soil water, weed growth, or the arrival of pests to decide timely and cost-effective corrective actions, and crop ripeness and water content to select
1200-858: A human recombinant protein as an antigen . tTG testing should be done first as it is an easier test to perform. An equivocal result on tTG testing should be followed by anti-endomysial antibodies. Guidelines recommend that a total serum IgA level is checked in parallel, as people with coeliac with IgA deficiency may be unable to produce the antibodies on which these tests depend ("false negative"). In those people, IgG antibodies against transglutaminase (IgG-tTG) may be diagnostic. If all these antibodies are negative, then anti-DGP antibodies (antibodies against deamidated gliadin peptides) should be determined. IgG class anti-DGP antibodies may be useful in people with IgA deficiency. In children younger than two years, anti-DGP antibodies perform better than anti-endomysial and anti-transglutaminase antibodies tests. Because of
1320-470: A less reliable method based on grain size. Einkorn and emmer are considered two of the founder crops cultivated by the first farming societies in Neolithic West Asia. These communities also cultivated naked wheats ( T. aestivum and T. durum ) and a now-extinct domesticated form of Zanduri wheat ( T. timopheevii ), as well as a wide variety of other cereal and non-cereal crops. Wheat
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#17327905086481440-681: A low quality for human nutrition, according to the DIAAS protein quality evaluation method. Though they contain adequate amounts of the other essential amino acids, at least for adults, wheat proteins are deficient in the essential amino acid lysine . Because the proteins present in the wheat endosperm (gluten proteins) are particularly poor in lysine, white flours are more deficient in lysine compared with whole grains. Significant efforts in plant breeding are made to develop lysine-rich wheat varieties, without success, as of 2017 . Supplementation with proteins from other food sources (mainly legumes )
1560-450: A major contribution to the nutritional welfare of the poor. Some wheat species are diploid , with two sets of chromosomes , but many are stable polyploids , with four sets of chromosomes ( tetraploid ) or six ( hexaploid ). Einkorn wheat ( Triticum monococcum ) is diploid (AA, two complements of seven chromosomes, 2n=14). Most tetraploid wheats (e.g. emmer and durum wheat) are derived from wild emmer , T. dicoccoides . Wild emmer
1680-475: A major contributor to increased grain output. More widely over the last 40 years, a massive increase in fertilizer use together with the increased availability of semi-dwarf varieties in developing countries, has greatly increased yields per hectare. In developing countries, use of (mainly nitrogenous) fertilizer increased 25-fold in this period. However, farming systems rely on much more than fertilizer and breeding to improve productivity. A good illustration of this
1800-551: A number of advantages over intensive farming: Extensive farming can have the following problems: Extensive farming was once thought to produce more methane and nitrous oxide per kg of milk than intensive farming. One study estimated that the carbon "footprint" per billion kg (2.2 billion lb.) of milk produced in 2007 was 37 percent that of equivalent milk production in 1944. However, a more recent study by Centre de coopération internationale en recherche agronomique pour le développement found that extensive livestock systems impact
1920-440: A region that stimulates lymphocytes and results in the release of interleukin-15 . This innate response to gliadin results in immune-system signalling that attracts inflammatory cells and increases the release of inflammatory chemicals. The strongest and most common adaptive response to gliadin is directed toward an α2-gliadin fragment of 33 amino acids in length. The response to the 33mer occurs in most coeliacs who have
2040-470: A source of straw , which could be used for fuel, wicker-making , or wattle and daub construction. Domestic wheat was quickly spread to regions where its wild ancestors did not grow naturally. Emmer was introduced to Cyprus as early as 8600 BC and einkorn c. 7500 BC ; emmer reached Greece by 6500 BC, Egypt shortly after 6000 BC, and Germany and Spain by 5000 BC. "The early Egyptians were developers of bread and
2160-433: A specialist setting, for example, in children who are not having a biopsy, or in patients who already have limited gluten ingestion and opt not to have a gluten challenge. An upper endoscopy with biopsy of the duodenum (beyond the duodenal bulb ) or jejunum is performed to obtain multiple samples (four to eight) from the duodenum. Not all areas may be equally affected; if biopsies are taken from healthy bowel tissue,
2280-489: A state of chronically compromised health. Indeed, after starting a gluten-free diet and subsequent improvement becomes evident, such individuals are often able to retrospectively recall and recognise prior symptoms of their untreated disease that they had mistakenly ignored. Diarrhoea that is characteristic of coeliac disease is chronic, sometimes pale, of large volume, and abnormally foul in odor. Abdominal pain , cramping, bloating with abdominal distension (thought to be
2400-426: A viable crop. When the use of seed drills replaced broadcasting sowing of seed in the 18th century, another great increase in productivity occurred. Yields of pure wheat per unit area increased as methods of crop rotation were applied to land that had long been in cultivation, and the use of fertilizers became widespread. Improved agricultural husbandry has more recently included pervasive automation , starting with
2520-439: A wheat grain or berry; botanically a fruit , it is often called a seed. The grains ripen to a golden yellow; a head of grain is called an ear. Leaves emerge from the shoot apical meristem in a telescoping fashion until the transition to reproduction i.e. flowering. The last leaf produced by a wheat plant is known as the flag leaf. It is denser and has a higher photosynthetic rate than other leaves, to supply carbohydrate to
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#17327905086482640-611: A wide number of symptoms involving any part of the body , or no obvious symptoms. Coeliac disease was first described in childhood; however, it may develop at any age. It is associated with other autoimmune diseases , such as Type 1 diabetes mellitus and Hashimoto's thyroiditis , among others. Coeliac disease is caused by a reaction to gluten, a group of various proteins found in wheat and in other grains such as barley and rye . Moderate quantities of oats , free of contamination with other gluten-containing grains, are usually tolerated. The occurrence of problems may depend on
2760-506: A year's supply. Wheat grain was stored after threshing , with the chaff removed. It was then processed into flour using ground stone mortars . Bread made from ground einkorn and the tubers of a form of club rush ( Bolboschoenus glaucus ) was made as early as 12,400 BC. At Çatalhöyük ( c. 7100–6000 BC ), both wholegrain wheat and flour was used to prepare bread, porridge and gruel . Apart from food, wheat may also have been important to Neolithic societies as
2880-452: Is Australian wheat growing in the southern winter cropping zone, where, despite low rainfall (300 mm), wheat cropping is successful even with relatively little use of nitrogenous fertilizer. This is achieved by crop rotation with leguminous pastures. The inclusion of a canola crop in the rotations has boosted wheat yields by a further 25%. In these low rainfall areas, better use of available soil-water (and better control of soil erosion)
3000-516: Is a long-term autoimmune disorder , primarily affecting the small intestine , where individuals develop intolerance to gluten , present in foods such as wheat , rye and barley . Classic symptoms include gastrointestinal problems such as chronic diarrhoea , abdominal distention , malabsorption , loss of appetite , and among children failure to grow normally . Non-classic symptoms are more common, especially in people older than two years. There may be mild or absent gastrointestinal symptoms,
3120-574: Is a rich source (20% or more of the Daily Value , DV) of multiple dietary minerals , such as manganese , phosphorus , magnesium , zinc , and iron (table). The B vitamins , niacin (36% DV), thiamine (33% DV), and vitamin B6 (23% DV), are present in significant amounts (table). Wheat is a significant source of vegetable proteins in human food, having a relatively high protein content compared to other major cereals. However, wheat proteins have
3240-473: Is a strict lifelong gluten-free diet , which leads to recovery of the intestinal lining ( mucous membrane ), improves symptoms, and reduces the risk of developing complications in most people. If untreated, it may result in cancers such as intestinal lymphoma , and a slightly increased risk of early death. Rates vary between different regions of the world, from as few as 1 in 300 to as many as 1 in 40, with an average of between 1 in 100 and 1 in 170 people. It
3360-400: Is achieved by retaining the stubble after harvesting and by minimizing tillage. Pests and diseases consume 21.47% of the world's wheat crop annually. There are many wheat diseases, mainly caused by fungi, bacteria, and viruses . Plant breeding to develop new disease-resistant varieties, and sound crop management practices are important for preventing disease. Fungicides, used to prevent
3480-460: Is also higher in first-degree relatives such as siblings, parents and children. Whether a gluten-free diet brings this risk back to baseline is not clear. Long-standing and untreated disease may lead to other complications, such as ulcerative jejunitis (ulcer formation of the small bowel) and stricturing (narrowing as a result of scarring with obstruction of the bowel). The changes in the bowel reduce its ability to absorb nutrients, minerals, and
3600-459: Is also important to identify periods of higher risk from the climate. Farmers benefit from knowing when the 'flag leaf' (last leaf) appears, as this leaf represents about 75% of photosynthesis reactions during the grain filling period, and so should be preserved from disease or insect attacks to ensure a good yield. Several systems exist to identify crop stages, with the Feekes and Zadoks scales being
3720-400: Is an extreme example of extensive farming, where herders move their animals to use feed from occasional rainfalls. Extensive farming is found in the mid-latitude sections of most continents, as well as in desert regions where water for cropping is not available. The nature of extensive farming means it requires less rainfall than intensive farming. The farm is usually large in comparison with
Extensive farming - Misplaced Pages Continue
3840-405: Is an important source of carbohydrates . Globally, it is the leading source of vegetable proteins in human food, having a protein content of about 13%, which is relatively high compared to other major cereals but relatively low in protein quality (supplying essential amino acids ). When eaten as the whole grain , wheat is a source of multiple nutrients and dietary fiber . In a small part of
3960-521: Is caused by an inflammatory reaction to gliadins and glutenins ( gluten proteins) found in wheat and to similar proteins found in the crops of the tribe Triticeae (which includes other common grains such as barley and rye ) and to the tribe Aveneae ( oats ). Wheat subspecies (such as spelt , durum , and Kamut ) and wheat hybrids (such as triticale ) also cause symptoms of coeliac disease. A small number of people with coeliac disease react to oats. Oat toxicity in coeliac people depends on
4080-402: Is commonly used to compensate for this deficiency, since the limitation of a single essential amino acid causes the others to break down and become excreted, which is especially important during growth. Consumed worldwide by billions of people, wheat is a significant food for human nutrition, particularly in the least developed countries where wheat products are primary foods. When eaten as
4200-473: Is estimated that 80% of cases remain undiagnosed, usually because of minimal or absent gastrointestinal complaints and lack of knowledge of symptoms and diagnostic criteria. Coeliac disease is slightly more common in women than in men. The classic symptoms of untreated coeliac disease include diarrhea , steatorrhoea , iron-deficiency anemia , and weight loss or failure to gain weight. Other common symptoms may be subtle or primarily occur in organs other than
4320-418: Is greater than for all other crops combined. Global demand for wheat is increasing due to the unique viscoelastic and adhesive properties of gluten proteins, which facilitate the production of processed foods, whose consumption is increasing as a result of the worldwide industrialization process and westernization of diets . Wheat became a central agriculture endeavor in the worldwide British Empire in
4440-473: Is itself the result of a hybridization between two diploid wild grasses, T. urartu and a wild goatgrass such as Ae. speltoides . The hybridization that formed wild emmer (AABB, four complements of seven chromosomes in two groups, 4n=28) occurred in the wild, long before domestication, and was driven by natural selection . Hexaploid wheats evolved in farmers' fields as wild emmer hybridized with another goatgrass, Ae. squarrosa or Ae. tauschii , to make
4560-629: Is likely to be prioritised in drought-adapted crops, while stem non-structural carbohydrate is prioritised in varieties developed for countries where disease is a bigger issue. Depending on variety, wheat may be awned or not awned. Producing awns incurs a cost in grain number, but wheat awns photosynthesise more efficiently than their leaves with regards to water usage, so awns are much more frequent in varieties of wheat grown in hot drought-prone countries than those generally seen in temperate countries. For this reason, awned varieties could become more widely grown due to climate change . In Europe, however,
4680-458: Is more diverse, with domesticated varieties falling into two major groups: hulled or non-shattering, in which threshing separates the whole spikelet ; and free-threshing, where the individual grains are separated. Both varieties probably existed in prehistory, but over time free-threshing cultivars became more common. Wild emmer was first cultivated in the southern Levant , as early as 9600 BC. Genetic studies have found that, like einkorn, it
4800-567: Is necessary but not sufficient to develop coeliac disease. Furthermore, around 5% of those people who do develop coeliac disease do not have typical HLA-DQ2 or HLA-DQ8 alleles (see below). The vast majority of people with coeliac have one of two types (out of seven) of the HLA-DQ protein. HLA-DQ is part of the MHC class II antigen-presenting receptor (also called the human leukocyte antigen ) system and distinguishes cells between self and non-self for
4920-468: Is necessary for the disease to manifest in a person. Almost all people (95%) with coeliac disease have either the variant HLA-DQ2 allele or (less commonly) the HLA-DQ8 allele . However, about 20–30% of people without coeliac disease have also inherited either of these alleles. This suggests that additional factors are needed for coeliac disease to develop; that is, the predisposing HLA risk allele
Extensive farming - Misplaced Pages Continue
5040-399: Is normally planted after tilling the soil by ploughing and then harrowing to kill weeds and create an even surface. The seeds are then scattered on the surface, or drilled into the soil in rows. Winter wheat lies dormant during a winter freeze. It needs to develop to a height of 10 to 15 cm before the cold intervenes, so as to be able to survive the winter; it requires a period with
5160-592: Is not accurate enough for routine diagnostic use. Serology may be unreliable in young children, with anti- gliadin performing somewhat better than other tests in children under five. Serology tests are based on indirect immunofluorescence (reticulin, gliadin and endomysium) or ELISA (gliadin or tissue transglutaminase , tTG). Other antibodies such as anti–Saccharomyces cerevisiae antibodies occur in some people with coeliac disease but also occur in other autoimmune disorders and about 5% of those who donate blood. Antibody testing may be combined with HLA testing if
5280-592: Is not found along portions of the West Pacific rim. DQ8 has a wider global distribution than DQ2.5 and is particularly common in South and Central America; up to 90% of individuals in certain Amerindian populations carry DQ8 and thus may display the coeliac phenotype . Other genetic factors have been repeatedly reported in coeliac disease; however, involvement in disease has variable geographic recognition. Only
5400-511: Is not the same as a wheat allergy . Other diseases triggered by eating wheat are non-coeliac gluten sensitivity (estimated to affect 0.5% to 13% of the general population ), gluten ataxia , and dermatitis herpetiformis . Certain short-chain carbohydrates present in wheat, known as FODMAPs (mainly fructose polymers ), may be the cause of non-coeliac gluten sensitivity. As of 2019 , reviews have concluded that FODMAPs only explain certain gastrointestinal symptoms, such as bloating , but not
5520-681: Is recommended by the National Institute for Health and Clinical Excellence (NICE), the British Society of Gastroenterology and the American College of Gastroenterology , but is of unclear benefit in North America. Coeliac disease leads to an increased risk of both adenocarcinoma and lymphoma of the small bowel ( enteropathy-associated T-cell lymphoma (EATL) or other non-Hodgkin lymphomas ). This risk
5640-431: Is the cross-linking of a glutamine residue from the gliadin peptide to a lysine residue of tTg in a reaction that is catalysed by the transglutaminase. Crosslinking may occur either within or outside the active site of the enzyme. The latter case yields a permanently covalently linked complex between the gliadin and the tTg. This results in the formation of new epitopes believed to trigger the primary immune response by which
5760-493: Is valuable to impart viscoelastic functional qualities in dough , enabling the preparation of diverse processed foods such as breads, noodles, and pasta that facilitate wheat consumption. Raw red winter wheat is 13% water, 71% carbohydrates including 12% dietary fiber , 13% protein , and 2% fat (table). Some 75–80% of the protein content is as gluten . In a reference amount of 100 grams (3.5 oz), wheat provides 1,368 kilojoules (327 kilocalories) of food energy and
5880-436: The extra-digestive symptoms that people with non-coeliac gluten sensitivity may develop. Other wheat proteins, amylase-trypsin inhibitors, have been identified as the possible activator of the innate immune system in coeliac disease and non-coeliac gluten sensitivity. These proteins are part of the plant's natural defense against insects and may cause intestinal inflammation in humans. In 2022, world wheat production
6000-591: The fat-soluble vitamins A, D, E, and K. Coeliac disease has been linked with many conditions. In many cases, it is unclear whether the gluten-induced bowel disease is a causative factor or whether these conditions share a common predisposition. Coeliac disease is associated with several other medical conditions, many of which are autoimmune disorders: diabetes mellitus type 1 , hypothyroidism , primary biliary cholangitis , microscopic colitis , gluten ataxia , psoriasis , vitiligo , autoimmune hepatitis , primary sclerosing cholangitis , and more. Coeliac disease
6120-853: The hexaploid wheats including bread wheat . A 2007 molecular phylogeny of the wheats gives the following not fully-resolved cladogram of major cultivated species; the large amount of hybridisation makes resolution difficult. Markings like "6N" indicate the degree of polyploidy of each species: Barley 2N, rye 2N/4N, and other cereals Triticum monococcum ( einkorn ) 2N × Aegilotriticum hybrids ( Aegilops x Triticum ) 6N Triticum timopheevii (zanduri wheat) and others 4N Triticum aestivum ( common or bread wheat ) 6N Triticum durum/turgidum ( durum wheat) 4N Triticum spelta ( spelt ) 6N Triticum turanicum ( khorasan wheat ) 4N Triticum dicoccum ( emmer ) 4N many other species During 10,000 years of cultivation, numerous forms of wheat, many of them hybrids , have developed under
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#17327905086486240-557: The immunoglobulin A (IgA) type can detect coeliac disease with a sensitivity and specificity of 90% and 99%, respectively. Serology for anti-transglutaminase antibodies (anti-tTG) was initially reported to have a higher sensitivity (99%) and specificity (>90%). However, it is now thought to have similar characteristics to anti-endomysial antibodies. Both anti-transglutaminase and anti-endomysial antibodies have high sensitivity to diagnose people with classic symptoms and complete villous atrophy, but they are only found in 30–89% of
6360-434: The prolamins . These are storage proteins rich in proline ( prol- ) and glutamine ( -amin ) that dissolve in alcohols and are resistant to proteases and peptidases of the gut. Prolamins are found in cereal grains with different grains having different but related prolamins: wheat (gliadin), barley ( hordein ), rye ( secalin ) and oats ( avenin ). One region of α-gliadin stimulates membrane cells, enterocytes , of
6480-424: The variety of oat. It occurs more often in people who are genetically predisposed . Upon exposure to gluten, an abnormal immune response may lead to the production of several different autoantibodies that can affect a number of different organs . In the small bowel, this causes an inflammatory reaction and may produce shortening of the villi lining the small intestine ( villous atrophy ). This affects
6600-427: The whole grain , wheat supplies multiple nutrients and dietary fiber recommended for children and adults. In genetically susceptible people, wheat gluten can trigger coeliac disease . Coeliac disease affects about 1% of the general population in developed countries . The only known effective treatment is a strict lifelong gluten-free diet . While coeliac disease is caused by a reaction to wheat proteins, it
6720-617: The 19th century, and remains of great importance in Australia, Canada and India. In Australia, with vast lands and a limited work force, expanded production depended on technological advances, especially regarding irrigation and machinery. By the 1840s there were 900 growers in South Australia . They used "Ridley's Stripper", a reaper-harvester perfected by John Ridley in 1843, to remove the heads of grain. In Canada, modern farm implements made large scale wheat farming possible from
6840-513: The 20th century, global wheat output expanded by about 5-fold, but until about 1955 most of this reflected increases in wheat crop area, with lesser (about 20%) increases in crop yields per unit area. After 1955 however, there was a ten-fold increase in the rate of wheat yield improvement per year, and this became the major factor allowing global wheat production to increase. Thus technological innovation and scientific crop management with synthetic nitrogen fertilizer , irrigation and wheat breeding were
6960-533: The 6% of European coeliacs that do not have DQ2.5 (cis or trans) or DQ8 (encoded by the haplotype DQA1*03:DQB1*0302), 4% have the DQ2.2 isoform, and the remaining 2% lack DQ2 or DQ8. The frequency of these genes varies geographically. DQ2.5 has high frequency in peoples of North and Western Europe ( Basque Country and Ireland with highest frequencies) and portions of Africa and is associated with disease in India, but it
7080-570: The HLA-DQ loci show a consistent involvement over the global population. Many of the loci detected have been found in association with other autoimmune diseases. One locus, the LPP or lipoma-preferred partner gene, is involved in the adhesion of extracellular matrix to the cell surface, and a minor variant ( SNP =rs1464510) increases the risk of disease by approximately 30%. This gene strongly associates with coeliac disease ( p < 10 ) in samples taken from
7200-473: The absorption of nutrients, frequently leading to anaemia . Diagnosis is typically made by a combination of blood antibody tests and intestinal biopsies , helped by specific genetic testing . Making the diagnosis is not always straightforward. About 10% of the time, the autoantibodies in the blood are negative, and many people have only minor intestinal changes with normal villi. People may have severe symptoms and they may be investigated for years before
7320-555: The autoantibodies against tTg develop. Stored biopsies from people with suspected coeliac disease have revealed that autoantibody deposits in the subclinical coeliacs are detected prior to clinical disease. These deposits are also found in people who present with other autoimmune diseases, anaemia, or malabsorption phenomena at a much increased rate over the normal population. Endomysial components of antibodies (EMA) to tTG are believed to be directed toward cell-surface transglutaminase, and these antibodies are still used in confirming
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#17327905086487440-416: The bowel itself. It is also possible to have coeliac disease without any of the classic symptoms at all. This has been shown to comprise at least 43% of presentations in children. Further, many adults with subtle disease may only present with fatigue, anaemia or low bone mass . Many undiagnosed individuals who consider themselves asymptomatic are in fact not, but rather have become accustomed to living in
7560-446: The cases with minor mucosal lesions. Tissue transglutaminase modifies gluten peptides into a form that may stimulate the immune system more effectively. These peptides are modified by tTG in two ways, deamidation or transamidation . Deamidation is the reaction by which a glutamate residue is formed by cleavage of the epsilon-amino group of a glutamine side chain. Transamidation, which occurs three times more often than deamidation,
7680-414: The cases with partial villous atrophy and in less than 50% of the people who have minor mucosal lesions ( duodenal lymphocytosis ) with normal villi. Tissue transglutaminase (abbreviated as tTG or TG2) modifies gluten peptides into a form that may stimulate the immune system more effectively. These peptides are modified by tTG in two ways, deamidation or transamidation. Modern anti-tTG assays rely on
7800-629: The cultivars used are needed before making final recommendations on their inclusion in a gluten-free diet . Coeliac people who choose to consume oats need a more rigorous lifelong follow-up, possibly including periodic intestinal biopsies . Other cereals such as corn , millet , sorghum , teff , rice , and wild rice are safe for people with coeliac disease to consume, as well as non-cereals such as amaranth , quinoa , and buckwheat . Noncereal carbohydrate-rich foods such as potatoes and bananas do not contain gluten and do not trigger symptoms. There are various theories as to what determines whether
7920-414: The deepest of arable crops, extending as far down as 2 metres (6 ft 7 in). While the roots of a wheat plant are growing, the plant also accumulates an energy store in its stem, in the form of fructans , which helps the plant to yield under drought and disease pressure, but it has been observed that there is a trade-off between root growth and stem non-structural carbohydrate reserves. Root growth
8040-686: The developing ear. In temperate countries the flag leaf, along with the second and third highest leaf on the plant, supply the majority of carbohydrate in the grain and their condition is paramount to yield formation. Wheat is unusual among plants in having more stomata on the upper ( adaxial ) side of the leaf, than on the under ( abaxial ) side. It has been theorised that this might be an effect of it having been domesticated and cultivated longer than any other plant. Winter wheat generally produces up to 15 leaves per shoot and spring wheat up to 9 and winter crops may have up to 35 tillers (shoots) per plant (depending on cultivar). Wheat roots are among
8160-497: The diagnosis is unclear. TGA and EMA testing are the most sensitive serum antibody tests, but as a negative HLA-DQ type excludes the diagnosis of coeliac disease, testing also for HLA-DQ2 or DQ8 maximises sensitivity and negative predictive values. In the United Kingdom, the National Institute for Health and Clinical Excellence (NICE) does not (as of 2015) recommend the use of HLA typing to rule out coeliac disease outside of
8280-533: The diet may require these alternative diagnoses to be considered. Diagnosis is often difficult and as of 2019, there continues to be a lack of awareness among physicians about the variability of presentations of coeliac disease and the diagnostic criteria, such that most cases are diagnosed with great delay. It can take up to 12 years to receive a diagnosis from the onset of symptoms and the majority of those affected in most countries never receive it. Several tests can be used. The level of symptoms may determine
8400-485: The domestic form comes after c. 8800 BC in southern Turkey, at Çayönü , Cafer Höyük , and possibly Nevalı Çori . Genetic evidence indicates that it was domesticated in multiple places independently. Wild emmer wheat ( T. turgidum subsp. dicoccoides ) is less widespread than einkorn, favouring the rocky basaltic and limestone soils found in the hilly flanks of the Fertile Crescent. It
8520-766: The earliest known wheat with sufficient gluten for yeasted breads was found in a granary at Assiros in Macedonia dated to 1350 BC. From the Middle East , wheat continued to spread across Europe and to the Americas in the Columbian exchange . In the British Isles, wheat straw ( thatch ) was used for roofing in the Bronze Age , and remained in common use until the late 19th century. White wheat bread
8640-418: The environment less than intensive systems. Wheat Wheat is a grass widely cultivated for its seed , a cereal grain that is a staple food around the world. The many species of wheat together make up the genus Triticum ( / ˈ t r ɪ t ɪ k ə m / ); the most widely grown is common wheat ( T. aestivum ). The archaeological record suggests that wheat was first cultivated in
8760-567: The farm and because of poor roads, inadequate storage technologies, inefficient supply chains and farmers' inability to bring the produce into retail markets dominated by small shopkeepers. Some 10% of total wheat production is lost at farm level, another 10% is lost because of poor storage and road networks, and additional amounts are lost at the retail level. In the Punjab region of the Indian subcontinent, as well as North China, irrigation has been
8880-456: The farmer have a detailed understanding of each stage of development in the growing plants. In particular, spring fertilizers , herbicides , fungicides , and growth regulators are typically applied only at specific stages of plant development. For example, it is currently recommended that the second application of nitrogen is best done when the ear (not visible at this stage) is about 1 cm in size (Z31 on Zadoks scale ). Knowledge of stages
9000-404: The folds, a mosaic pattern to the mucosa (described as a "cracked-mud" appearance), prominence of the submucosa blood vessels , and a nodular pattern to the mucosa. European guidelines suggest that in children and adolescents with symptoms compatible with coeliac disease, the diagnosis can be made without the need for intestinal biopsy if anti-tTG antibodies titres are very high (10 times
9120-422: The general population, gluten – which comprises most of the protein in wheat – can trigger coeliac disease , noncoeliac gluten sensitivity , gluten ataxia , and dermatitis herpetiformis . Wheat is a stout grass of medium to tall height. Its stem is jointed and usually hollow, forming a straw. There can be many stems on one plant. It has long narrow leaves, their bases sheathing the stem, one above each joint. At
9240-601: The glumes are fragile and the rachis tough. On threshing, the chaff breaks up, releasing the grains. Wheat grain classes are named by colour, season, and hardness. The classes used in the United States are: Wheat is a staple cereal worldwide. Raw wheat berries can be ground into flour or, using hard durum wheat only, can be ground into semolina ; germinated and dried creating malt ; crushed or cut into cracked wheat; parboiled (or steamed), dried, crushed and de-branned into bulgur also known as groats . If
9360-562: The grains of wild grasses led to the creation of domestic strains, as mutant forms ('sports') of wheat were more amenable to cultivation. In domesticated wheat, grains are larger, and the seeds (inside the spikelets ) remain attached to the ear by a toughened rachis during harvesting. In wild strains, a more fragile rachis allows the ear to shatter easily, dispersing the spikelets. Selection for larger grains and non-shattering heads by farmers might not have been deliberately intended, but simply have occurred because these traits made gathering
9480-479: The grains, and (in domesticated wheats) a semi-brittle rachis that breaks easily on threshing. The result is that when threshed, the wheat ear breaks up into spikelets. To obtain the grain, further processing, such as milling or pounding, is needed to remove the hulls or husks. Hulled wheats are often stored as spikelets because the toughened glumes give good protection against pests of stored grain. In free-threshing (or naked) forms, such as durum wheat and common wheat,
9600-504: The gut showed this causes villous atrophy. This suggests that viral proteins may take part in the initial flattening and stimulate self-crossreactive anti-VP7 production. Antibodies to VP7 may also slow healing until the gliadin-mediated tTG presentation provides a second source of crossreactive antibodies. Other intestinal disorders may have biopsy that look like coeliac disease including lesions caused by Candida. The inflammatory process, mediated by T cells , leads to disruption of
9720-536: The haplotype (either DQB1*02 or DQA1*05) from the other parent, increasing risk. Less commonly, some individuals inherit the DQA1*05 allele from one parent and the DQB1*02 from the other parent (DQ2.5trans) (called a trans-haplotype association), and these individuals are at similar risk for coeliac disease as those with a single DQ2.5-bearing chromosome 6, but in this instance, the disease tends not to be familial. Among
9840-410: The intestine to allow larger molecules around the sealant between cells. Disruption of tight junctions allow peptides larger than three amino acids to enter the intestinal lining. Membrane leaking permits peptides of gliadin that stimulate two levels of the immune response: the innate response, and the adaptive (T-helper cell-mediated) response. One protease-resistant peptide from α-gliadin contains
9960-401: The introduction of gluten-containing grains into the diet appears to be associated with a 50% reduced risk of developing coeliac disease in infancy; whether this persists into adulthood is not clear. These factors may just influence the timing of onset. Coeliac disease appears to be multifactorial, both in that more than one genetic factor can cause the disease and in that more than one factor
10080-417: The investigations. Serological blood tests are the first-line investigation required to make a diagnosis of coeliac disease. Its sensitivity correlates with the degree of histological lesions. People who present with minor damage to the small intestine may have seronegative findings so many patients with coeliac disease often are missed. In patients with villous atrophy, anti- endomysial (EMA) antibodies of
10200-519: The late 1840s. By 1879, Saskatchewan was the center, followed by Alberta , Manitoba and Ontario , as the spread of railway lines allowed easy exports to Britain. By 1910, wheat made up 22% of Canada's exports, rising to 25% in 1930 despite the sharp decline in prices during the worldwide Great Depression . Efforts to expand wheat production in South Africa, Kenya and India were stymied by low yields and disease. However, by 2000 India had become
10320-420: The main drivers of wheat output growth in the second half of the century. There were some significant decreases in wheat crop area, for instance in North America. Better seed storage and germination ability (and hence a smaller requirement to retain harvested crop for next year's seed) is another 20th-century technological innovation. In Medieval England, farmers saved one-quarter of their wheat harvest as seed for
10440-487: The major implications of a diagnosis of coeliac disease, professional guidelines recommend that a positive blood test is still followed by an endoscopy / gastroscopy and biopsy . A negative serology test may still be followed by a recommendation for endoscopy and duodenal biopsy if clinical suspicion remains high. Historically three other antibodies were measured: anti- reticulin (ARA), anti- gliadin ( AGA ) and anti-endomysial (EMA) antibodies. ARA testing, however,
10560-568: The most widely used. Each scale is a standard system which describes successive stages reached by the crop during the agricultural season. For example, the stage of pollen formation from the mother cell, and the stages between anthesis and maturity, are susceptible to high temperatures, and this adverse effect is made worse by water stress. Technological advances in soil preparation and seed placement at planting time, use of crop rotation and fertilizers to improve plant growth, and advances in harvesting methods have all combined to promote wheat as
10680-488: The need to systematically remove vegetation or till the soil. They may also have exploited natural wetlands and floodplains to practice décrue farming , sowing seeds in the soil left behind by receding floodwater. It was harvested with stone-bladed sickles . The ease of storing wheat and other cereals led farming households to become gradually more reliant on it over time, especially after they developed individual storage facilities that were large enough to hold more than
10800-473: The next crop, leaving only three-quarters for food and feed consumption. By 1999, the global average seed use of wheat was about 6% of output. In the 21st century, rising temperatures associated with global warming are reducing wheat yield in several locations. Wheat is an annual crop. It can be planted in autumn and harvested in early summer as winter wheat in climates that are not too severe, or planted in spring and harvested in autumn as spring wheat. It
10920-463: The numbers working and money spent on it. In 1957, most parts of Western Australia had pastures so poor that only one sheep to the square mile could be supported. Just as the demand has led to the basic division of cropping and pastoral activities, these areas can also be subdivided depending on the region's rainfall, vegetation type and agricultural activity within the area and the many other parentheses related to this data. Extensive farming has
11040-450: The oat cultivar consumed because the prolamin genes, protein amino acid sequences, and the immunoreactivities of toxic prolamins are different in different oat varieties. Also, oats are frequently cross-contaminated with other grains containing gluten. The term "pure oats" refers to oats uncontaminated with other gluten-containing cereals. The long-term effects of pure oat consumption are still unclear, and further studies identifying
11160-403: The oat cultivar consumed, as prolamin genes, protein amino acid sequences, and the immunoreactivities of toxic prolamins vary among oat varieties. Anti-transglutaminase antibodies to the enzyme tissue transglutaminase (tTG) are found in the blood of the majority of people with classic symptoms and complete villous atrophy, but only in 70% of the cases with partial villous atrophy and 30% of
11280-433: The order of the tests, but all tests lose their usefulness if the person is already eating a gluten-free diet . Intestinal damage begins to heal within weeks of gluten being removed from the diet, and antibody levels decline over months. For those who have already started on a gluten-free diet, it may be necessary to perform a rechallenge with some gluten-containing food in one meal a day over six weeks before repeating
11400-484: The primary manifestations of coeliac disease, whereas tTG is a bigger factor in secondary effects such as allergic responses and secondary autoimmune diseases. In a large percentage of people with coeliac, the anti-tTG antibodies also recognise a rotavirus protein called VP7. These antibodies stimulate monocyte proliferation, and rotavirus infection might explain some early steps in the cascade of immune cell proliferation. Indeed, earlier studies of rotavirus damage in
11520-456: The purposes of the immune system . The two subunits of the HLA-DQ protein are encoded by the HLA-DQA1 and HLA-DQB1 genes, located on the short arm of chromosome 6 . There are seven HLA-DQ variants (DQ2 and DQ4–DQ9). Over 95% of people with coeliac have the isoform of DQ2 or DQ8, which is inherited in families. The reason these genes produce an increase in the risk of coeliac disease is that
11640-461: The raw wheat is broken into parts at the mill, as is usually done, the outer husk or bran can be used in several ways. Wheat is a major ingredient in such foods as bread , porridge , crackers , biscuits , muesli , pancakes , pasta , pies , pastries , pizza , semolina , cakes , cookies , muffins , rolls , doughnuts , gravy , beer , vodka , boza (a fermented beverage ), and breakfast cereals . In manufacturing wheat products, gluten
11760-443: The receptors formed by these genes bind to gliadin peptides more tightly than other forms of the antigen-presenting receptor. Therefore, these forms of the receptor are more likely to activate T lymphocytes and initiate the autoimmune process. Most people with coeliac bear a two-gene HLA-DQ2 haplotype referred to as DQ2.5 haplotype . This haplotype is composed of two adjacent gene alleles , DQA1*0501 and DQB1*0201 , which encode
11880-489: The regions of the Fertile Crescent around 9600 BC. Botanically, the wheat kernel is a caryopsis , a type of fruit . Wheat is grown on a larger area of land than any other food crop (220.7 million hectares or 545 million acres in 2021). World trade in wheat is greater than for all other crops combined. In 2021, world wheat production was 771 million tonnes (850 million short tons), making it
12000-439: The release of interleukin 15 and activation of the innate immune system by a shorter gluten peptide (p31–43/49). This would trigger killing of enterocytes by lymphocytes in the epithelium . The villous atrophy seen on biopsy may also be due to unrelated causes, such as tropical sprue , giardiasis and radiation enteritis . While positive serology and typical biopsy are highly suggestive of coeliac disease, lack of response to
12120-487: The result of fermentative production of bowel gas), and mouth ulcers may be present. As the bowel becomes more damaged, a degree of lactose intolerance may develop. Frequently, the symptoms are ascribed to irritable bowel syndrome (IBS), only later to be recognised as coeliac disease. In populations of people with symptoms of IBS, a diagnosis of coeliac disease can be made in about 3.3% of cases, or four times more likely than in general. Screening them for coeliac disease
12240-399: The result would be a false negative. Even in the same bioptic fragment, different degrees of damage may be present. Most people with coeliac disease have a small intestine that appears to be normal on endoscopy before the biopsies are examined. However, five findings have been associated with high specificity for coeliac disease: scalloping of the small bowel folds ( pictured ), paucity in
12360-452: The right moment to harvest. Harvesting involves reaping , cutting the stems to gather the crop; and threshing , breaking the ears to release the grain; both steps are carried out by a combine harvester . The grain is then dried so that it can be stored safe from mould fungi. Wheat normally needs between 110 and 130 days between sowing and harvest, depending upon climate, seed type, and soil conditions. Optimal crop management requires that
12480-517: The second largest producer of wheat in the world. In the 19th century the American wheat frontier moved rapidly westward. By the 1880s 70% of American exports went to British ports. The first successful grain elevator was built in Buffalo in 1842. The cost of transport fell rapidly. In 1869 it cost 37 cents to transport a bushel of wheat from Chicago to Liverpool . In 1905 it was 10 cents. In
12600-403: The second most-produced cereal after maize (known as corn in North America and Australia; wheat is often called corn in countries including Britain). Since 1960, world production of wheat and other grain crops has tripled and is expected to grow further through the middle of the 21st century. Global demand for wheat is increasing because of the usefulness of gluten to the food industry. Wheat
12720-513: The seeds easier; nevertheless such 'incidental' selection was an important part of crop domestication . As the traits that improve wheat as a food source involve the loss of the plant's natural seed dispersal mechanisms, highly domesticated strains of wheat cannot survive in the wild. Wild einkorn wheat ( T. monococcum subsp. boeoticum ) grows across Southwest Asia in open parkland and steppe environments. It comprises three distinct races , only one of which, native to Southeast Anatolia ,
12840-472: The significant crop losses from fungal disease, can be a significant variable cost in wheat production. Estimates of the amount of wheat production lost owing to plant diseases vary between 10 and 25% in Missouri. A wide range of organisms infect wheat, of which the most important are viruses and fungi. Coeliac disease Coeliac disease ( British English ) or celiac disease ( American English )
12960-442: The structure and function of the small bowel's mucosal lining and causes malabsorption as it impairs the body's ability to absorb nutrients , minerals, and fat-soluble vitamins A, D, E, and K from food. Lactose intolerance may be present due to the decreased bowel surface and reduced production of lactase but typically resolves once the condition is treated. Alternative causes of this tissue damage have been proposed and involve
13080-405: The temperature at or near freezing, its dormancy then being broken by the thaw or rise in temperature. Spring wheat does not undergo dormancy. Wheat requires a deep soil , preferably a loam with organic matter, and available minerals including soil nitrogen, phosphorus, and potassium. An acid and peaty soil is not suitable. Wheat needs some 30 to 38 cm of rain in the growing season to form
13200-514: The top of the stem is the flower head, containing some 20 to 100 flowers. Each flower contains both male and female parts. The flowers are wind-pollinated , with over 99% of pollination events being self-pollinations and the rest cross-pollinations . The flower is housed in a pair of small leaflike glumes . The two (male) stamens and (female) stigmas protrude outside the glumes. The flowers are grouped into spikelets , each with between two and six flowers. Each fertilised carpel develops into
13320-444: The two subunits, DQ α and DQ β . In most individuals, this DQ2.5 isoform is encoded by one of two chromosomes 6 inherited from parents (DQ2.5cis). Most coeliacs inherit only one copy of this DQ2.5 haplotype, while some inherit it from both parents; the latter are especially at risk for coeliac disease as well as being more susceptible to severe complications. Some individuals inherit DQ2.5 from one parent and an additional portion of
13440-597: The upper limit of normal). Until the 1970s, biopsies were obtained using metal capsules attached to a suction device. The capsule was swallowed and allowed to pass into the small intestine. After x-ray verification of its position, suction was applied to collect part of the intestinal wall inside the capsule. Often-utilised capsule systems were the Watson capsule and the Crosby–Kugler capsule . This method has now been largely replaced by fibre-optic endoscopy, which carries
13560-614: The use of threshing machines , and progressing to large and costly machines like the combine harvester which greatly increased productivity. At the same time, better varieties such as Norin 10 wheat , developed in Japan in the 1930s, or the dwarf wheat developed by Norman Borlaug in the Green Revolution , greatly increased yields. In addition to gaps in farming system technology and knowledge, some large wheat grain-producing countries have significant losses after harvest at
13680-542: The use of the oven and developed baking into one of the first large-scale food production industries." By 4000 BC, wheat had reached the British Isles and Scandinavia . Wheat likely appeared in China 's lower Yellow River around 2600 BC. The oldest evidence for hexaploid wheat has been confirmed through DNA analysis of wheat seeds, dating to around 6400–6200 BC, recovered from Çatalhöyük . As of 2023,
13800-486: Was 808.4 million tonnes, led by China, India, and Russia which collectively provided 43.22% of the world total. As of 2019 , the largest exporters were Russia (32 million tonnes), United States (27), Canada (23) and France (20), while the largest importers were Indonesia (11 million tonnes), Egypt (10.4) and Turkey (10.0). In 2021, wheat was grown on 220.7 million hectares or 545 million acres worldwide, more than any other food crop. World trade in wheat
13920-462: Was domesticated in southeastern Anatolia, but only once. The earliest secure archaeological evidence for domestic emmer comes from Çayönü, c. 8300–7600 BC , where distinctive scars on the spikelets indicated that they came from a hulled domestic variety. Slightly earlier finds have been reported from Tell Aswad in Syria, c. 8500–8200 BC , but these were identified using
14040-429: Was domesticated. The main feature that distinguishes domestic einkorn from wild is that its ears do not shatter without pressure, making it dependent on humans for dispersal and reproduction. It also tends to have wider grains. Wild einkorn was collected at sites such as Tell Abu Hureyra ( c. 10,700–9000 BC ) and Mureybet ( c. 9800–9300 BC ), but the earliest archaeological evidence for
14160-399: Was first proposed by Simoons (1981). By now, however, it is apparent that this is not the case; on the contrary, there is evidence of positive selection in coeliac disease genotypes. It is suspected that some of them may have been beneficial by providing protection against bacterial infections. The majority of the proteins in food responsible for the immune reaction in coeliac disease are
14280-601: Was historically a high status food, but during the nineteenth century it became in Britain an item of mass consumption, displacing oats , barley and rye from diets in the North of the country. It became "a sign of a high degree of culture". After 1860, the enormous expansion of wheat production in the United States flooded the world market, lowering prices by 40%, and (along with the expansion of potato growing) made
14400-456: Was relatively uncommon for the first thousand years of the Neolithic (when barley predominated), but became a staple after around 8500 BC. Early wheat cultivation did not demand much labour. Initially, farmers took advantage of wheat's ability to establish itself in annual grasslands by enclosing fields against grazing animals and re-sowing stands after they had been harvested, without
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