Gluten is a general term describing storage proteins found in cereal grains such as wheat, barley, and rye. Gliadin is the name for the storage protein found in wheat. Gluten is nothing new to our diets; gluten-containing cereal grains have been a component of people’s diets in Western countries for centuries. However, it is becoming increasingly clear that eating cereal grains can have negative effects on human health.[fn value=1][/fn] [fn value=2][/fn] Among these health consequences, celiac disease is probably the best characterized and documented. Whether we have always been this susceptible to celiac disease is an interesting question and a topic of heavy scientific inquiry.

Celiac disease is a life-long gluten-sensitive, immune-mediated disorder that causes significant damage to the small intestine of people with certain genetic backgrounds. In a region of Turkey, archaeological discoveries have given us insight into the transition of humans from hunter-gatherer societies into agrarian societies that took place over 10,000 years ago.[fn value=3][/fn] It was here that it is believed that several wild forms of plant species, such as Einkorn and Emmer wheat and other crops, were first domesticated by humans. Wheat represented a grain that was easily cultivated on a large scale and could be stored after harvest. Archaeological findings show domesticated wheat first appearing in parts of Turkey, Lebanon, Syria, Israel, Egypt and Ethiopia. Cultivated Emmer wheat was then spread from the “Fertile Crescent” to Greece, Cyprus, India, and Egypt around 6500 BC, followed by introductions in Germany and Spain by 5000 BC. Using DNA fingerprinting to compare these ancient plants to modern grains shows significant differences in the genetics between them. These genetic changes may be a contributor to the rise in the incidence of celiac disease. In support of that idea, there is evidence that gluten in Einkorn may not be as toxic to sufferers of celiac disease as modern forms of wheat.[fn value=4][/fn]

The first documented case of celiac disease is thought to have occurred in Italy in about 250 BC in a region of Tuscany where the economy was largely based on wheat and olives. A mummy from this area, buried in a fashion indicative of wealth, appeared to have died from severe malnutrition, despite evidence that her family was quite wealthy. Clinical signs of malnutrition included short stature, signs of anemia, and severe osteoporosis and bone fragility. All these signs together were said to be “strongly suggestive of celiac disease.”[fn value=5][/fn] Damage to the small intestine caused by celiac disease often results in malnutrition, as the damaged intestine cannot absorb nutrients. My point, celiac disease is nothing new!

Nowadays, about 1% of Americans suffer from celiac disease. However the percentage of people with celiac disease is increasing, and not just in the United States. In Scotland, researchers have reported a 6.4-fold increase in the number of children with celiac disease over the last 20 years.[fn value=6][/fn] Similar patterns have been observed in other westernized countries and many cases are thought to remain undiagnosed.[fn value=7][/fn] [fn value=8][/fn] [fn value=9][/fn]Obviously one needs to ingest gluten in order to develop celiac disease, but are there other factors that may be contributing to the rise of this disease around the world?

One point that many skeptics bring up is the suggestion that it is improved testing methods that have caused an increase in the number of people diagnosed with celiac disease rather than an actual increase. To that point, I like to refer to my favorite study addressing this concept. In an eloquent study, Rubio-Tapia et al. tested blood samples taken from military personnel in the late 1940s and early 1950s for celiac disease and compared these samples to samples taken in 2009. They identified a four-fold increase in the frequency of celiac disease in the samples from people living in 2009 compared to samples taken in the 1950s.[fn value=2][/fn]

Some have suggested the increase in celiac disease may have occurred because of changes in wheat due to wheat breeding—mainly an increase in gluten, which is directly proportional to protein content of wheat.[fn value=10][/fn] With the development of leavened bread 2000–5000 years ago (the date is not really known), farmers may have inadvertently begun to select for higher protein because leavened bread requires it. More recently, vital gluten has become a major additive in many foods and is a major contributor to our total gluten intake. Data suggests the average American consumes about 0.9 lb (408 g) of vital gluten annually compared to about 0.3 lb (136 g) in 1977. This increase is important because this is the time frame that fits with the increase in celiac disease.[fn value=10][/fn] It may be noted that whole wheat products, which are recommended for health reasons (in particular, higher fiber content), often have vital gluten added to them because of the negative effects of the ground whole grain on quality factors.[fn value=10][/fn]

There is a genetic predisposition for the development of celiac disease. However, genetic factors are not 100% to blame;[fn value=11][/fn] because of the rapid increase in percentages of people with celiac disease, we must consider environmental factors.[[fn value=11][/fn] In the first 2 years of life, the intestinal microbiota (the bacteria that live in our intestine) are critical for stimulating the development of the immune system.[fn value=11][/fn] In certain conditions, some species of bacteria are capable of causing disease by producing inflammation and infection. The microbiota of celiac disease patients is characterized by increases in numbers or proportions of less-than-beneficial microbes and reductions in certain probiotic bacteria such as Bifidobacterium. Similarly, several intestinal viral infections and bacterial infections have also been associated with development of celiac disease.[fn value=11][/fn]

Also relevant is the age at which we introduce gluten into the diet. As early as the 1970s, it had become clear that the introduction of gluten into the diet after the fourth month of life reduces the incidence of celiac disease. Alternatively, children introduced to gluten at 7 months or older are at a higher risk for celiac disease, possibly due to the larger amounts of gluten intake at the first exposure. Based on this, practical suggestions include avoiding both early (<4 months) and late (≥7 months) introduction of gluten and to gradually introduce small amounts of gluten to the infant while they are still breast-fed in order to reduce the risk for celiac disease later in life.[fn value=11][/fn]

While there is no consensus as to the cause of the rise of celiac disease, there are several hypotheses supported by strong evidence. In all honesty, it is likely a multitude of factors contributing to the increasing number of people with celiac disease. What’s also interesting is the recognition of non-celiac gluten sensitivity as a true health issue,[1] but that’s a whole different blog! Nonetheless, it will be interesting to see where the science takes us over the next several decades and whether the incidence of celiac disease will continue to rise.

From our Nutrition Library:

Gluten Free Substitutions

Celiac Disease and Gluten Sensitivity

Gluten Free Flours

Gluten 101

Possible Sources of Gluten in Packaged Foods

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Taking Gluten Free to the Next Level: For the Holidays

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