Do ancient wheats contain less gluten than modern bread wheat, in favour of better health?

Abstract

Popular media messaging has led to increased public perception that gluten-containing foods are bad for health. In parallel, 'ancient grains' have been promoted with claims that they contain less gluten. There appears to be no clear definition of 'ancient grains' but the term usually includes einkorn, emmer, spelt and Khorasan wheat. Gluten is present in all wheat grains and all can induce coeliac disease (CD) in genetically susceptible individuals. Analyses of 'ancient' and 'modern' wheats show that the protein content of modern bread wheat (Triticum aestivum) has decreased over time while the starch content increased. In addition, it was shown that, compared to bread wheat, ancient wheats contain more protein and gluten and greater contents of many CD-active epitopes. Consequently, no single wheat type can be recommended as better for reducing the risks of or mitigating the severity of CD. An estimated 10% of the population of Western countries suffers from gastrointestinal symptoms that lack a clear organic cause and is often referred to as irritable bowel syndrome (IBS). Many of these patients consider themselves gluten sensitive, but in most cases this is not confirmed when tested in a medical setting. Instead, it may be caused by gas formation due to fermentation of fructans present in wheat or, in some patients, effects of non-gluten proteins. A significant overlap of symptoms with those of CD, IBS and inflammatory bowel disease makes a medical diagnosis a priority. This critical narrative review examines the suggestion that 'ancient' wheat types are preferred for health and better tolerance.

Keywords: FODMAP; ancient grains; coeliac disease; gluten; gluten sensitivity; wheat.

FIGURE 1

Condensed history of wheat. Natural crossing of early diploid wheat ancestors (with the AA and BB genomes) led to the development of tetraploid emmer wheat (AABB genomes), which subsequently became domesticated and diversified into durum wheat. Cultivated bread wheat (AABBDD genomes) arose about 10 000 BC, probably from the crossing of the tetraploid (AABB) emmer with diploid wild goat grass (DD). Recent genetic studies indicate that spelt wheat probably arose from the crossing of bread wheat (AABBDD) with emmer wheat (AABB). Overall, more than a dozen wheat subspecies exists and within each subspecies, thousands of different varieties are available in cultivation and/or gene banks. Furthermore, within each subspecies these varieties vary widely in their age (including land races and old and modern varieties), agronomic properties, and grain composition and food processing quality. Thus, many ‘older’ and more ‘recent’ varieties of bread wheat, spelt, durum and emmer exist. (Arzani & Ashraf, ; Dvorak et al., ; Faris, ; Feuillet et al., ; Honegger & Mertz, ; Matsuoka, ; Pont et al., 2019)

FIGURE 2

Analysis of 150 wheat lines (130 winter wheats and 20 spring wheats), all grown under identical circumstances in Martonvasar in Hungary showed that: (a) over time an increased starch content ‘dilutes’ the protein content in a linear fashion, resulting in (b) a decline in protein content over time. With courtesy of Shewry et al. (2020)

FIGURE 3

Ancient wheats contain more gluten. Total protein (left) and gluten content in bread wheat, spelt, durum wheat, emmer and einkorn (n = 15 cultivars grown at four locations (n = 60) in Germany). Modified with courtesy from Geisslitz et al. (2019)

FIGURE 4

(a) Total gliadin contents of an ‘ancient’ wheat (Khorasan) and a traditional Italian heritage durum wheat (Senatore Cappelli). Figure kindly supplied by A. Gregorini, based on Gregorini et al. (2009). (b) Gliadin content in ‘ancient’ wheats (spelt, emmer and einkorn) compared to modern bread and durum wheat. With courtesy from Geisslitz et al. (2019)

FIGURE 5

(a) Example of a selected gliadin derived peptide (so‐called p. 31–49), which was higher in ‘ancient’ wheat (Khorasan), compared to modern durum wheat (cultivar Cappelli). Figure kindly supplied by A. Gregorini, based on Gregorini et al. (2009). (b) Proportion of 33‐mer peptide based on protein content. Five wheat cultivars per decade of three subsequent harvest years were analysed. Modified from Pronin et al. (2021)

FIGURE 6

From an irritable bowel syndrome sub‐cohort, 392 persons (12.3% of the cohort, 307 females and 85 males), complained of gastrointestinal symptoms after the consumption of gluten‐containing foods. Of these patients 6.63% were diagnosed to suffer from coeliac disease and 0.51% from wheat allergy (WA). The remaining 337 persons were all put on a 6‐months strictly gluten‐free (GF) diet, followed by a reintroduction of gluten‐containing grains in their diet for 1 month. Despite their self‐diagnosis to be gluten sensitive, 85.96% of these individuals showed no specific reaction to gluten. CD, coeliac disease; NCGS, non‐coeliac gluten sensitivity. With permission from Capannolo et al. (2015)