Why Are You Allergic To Gluten?

Neither domestic cereals nor milk from hoofed animals is “natural” food in an evolutionary or physiological sense… If there is a single complex of events responsible for the deterioration or human health and ecology, agricultural civilization is it.

-Paul Shepard, Coming Home to the Pleistocene

The reason why celiac disease and gluten sensitivity develops is a topic of great debate:

• My mom had it; it’s got to be genetic
• Wheat these days, it’s not the same
• Pesticide is sprayed on our wheat crops
• That flu I had when I was 12 triggered it
• My last pregnancy made me celiac
• It’s only in North America. The wheat in Europe is fine.

Alas, gluten’s effect on our body is not as simple as any of the above. While we don’t know the exact cause, we do know that it involves a complex interaction between our genes and our environment.

A brief history of gluten consumption

This story takes place in a location called the fertile crescent or, the cradle of civilization. The fertile crescent includes the modern-day countries of Iraq, Syria, Lebanon, Cyprus, Jordan, Lebanon, Israel, and Egypt. This area saw some of the first human civilizations. Likely due to the incredibly fertile land. It is thought that this is where humans transitioned from hunter-gatherers to a more agricultural society. (1) This transition occurred between 8000-12000 years ago. It was at this time that man began to domesticate plants and animals. One of the first plants to be cultivated was wheat.

Preceding man’s settlement of the fertile crescent was the paleolithic era. This era covers roughly 95% of human existence. (2) It extends from 2.6 million years ago up until about 10,000 years before present day. During the Paleolithic period, humans grouped together in small societies such as bands and subsisted by gathering plants and fishing, hunting or scavenging wild animals. (3).

As you can well imagine, the shift from hunters to farmers created large changes in the food supply. Man no longer had to forage in the woods for food. Instead, he could cultivate and breed the foods needed to survive. Crops and animals were selected for their ease of cultivation. One of these crops was wheat.

Wheat and other grains were crops that were not designed to be digested. Our paleolithic ancestors avoided these food sources. Sticking instead to meats, fruits, and vegetables. Grains were avoided because they are nearly impossible to consume in their wild form. It was only through settlement did these cultures devise cooking methods that rendered the grains edible.

As you can see, your ancestors consumed meat, fruits, and vegetables for nearly the entire existence of humanity. In the grand scheme of things, the introduction of grains is an incredibly new addition to our diet. Imagine the entire existence of humans to be the length of a football field. For 99.5 yards of that football field, we consumed meats, fruit, and vegetables. We have consumed grains for only the last half yard of the football field.

This is potentially why the gluten protein is thought to cause so many issues – we have not had the time to adapt our digestive tract to breaking down grains.

Has gluten always affected us? 

Yes.

Even early written history makes note of serious and diverse stomach issues. Of course, these issues were not caused solely by gluten. Infections were very problematic during this era and likely contributed to many stomach issues. It wasn’t until 1888 that celiac disease and gluten sensitivity was first described. And not until 1940 when we first discovered wheat was the problem.

In the 1950’s and 60’s, technology increased to the point where we could see the damage to the intestine common in celiac disease. Still, we hadn’t identified gluten. In 1969, a group of children’s gastroenterologists developed the initial diagnostic criteria used to diagnose celiac disease. (4) They also identified gluten as the causative agent.

If gluten has always caused problems for humans, why do some people seem to be unaffected?

Why isn’t everyone allergic to gluten?

This is the million dollar question. We know that wheat (and, grains in general) are new additions to the human diet. This is likely why there are so many people who react to grains. How many people do you know allergic to meat? As it’s been in the human diet for so long, the vast majority of us have adapted to consume and digest it.

None of us completely digest gluten. Likely because our digestive tract has not had the time to adapt to the prevalence of grains in our diet. Many aspects (peptides) of the wheat and gluten protein remain intact throughout digestion. The enzymes our body produces are not able to break wheat down. (5, 6) It is thought that these partially digested proteins that set off the immune reaction.

Why everyone doesn’t react to gluten is thought to do with genetics. In order to develop celiac disease, you need to have specific genes. However, those with a gluten sensitivity but not celiac disease often don’t have the “celiac genes”. This illustrates there is more to the development of gluten allergies/sensitivities than just genetics. Since we don’t yet know what those other factors are, we will focus on the genetic component we do know about.

95% of celiac patients have a gene called the HLA-DQ2. The other 5% of patients have a gene called HLA-DQ8. (7) HLA stands for human leukocyte antigen. HLA’s are proteins found on the surface of nearly every cell in your body. (8) HLA’s patrol your immune system. They are always identifying cells as “self” (belonging to your body) or “not self” (a foreign substance).

How do HLA antigens trigger celiac disease?

HLA proteins are inherited from our parents. One set from mom, the other from dad. Therefore, there are slight variations of these proteins in all of us. This is why each of us reacts differently to our environment. It’s why you’re allergic to grass but your sister isn’t. Your body identifies grass as a foreign invader and attacks it. The HLA antigens are thought to be a predisposing factor as to why people develop autoimmune diseases. (9)

In those with celiac disease, the HLA-DQ2 and HLA-DQ8 antigens bind to the gluten protein. This binding activates an immune reaction – gluten is identified as a foreign invader. The immune system ends up destroying cells it was designed to protect.

What’s confusing researchers is that 30% of the population has HLA-DQ2 or HLA-DQ8 antigens. (10) Yet only 1-3% of the population develops celiac disease. It is clear there are other factors involved. We have yet to identify what those may be.

Potential causes of gluten allergies and sensitivities

So far, we’ve explored what we know about gluten allergies. Now, we’ll discuss theories that explain why we might be allergic to gluten.

Infection

Serious infections seem to precede the development of many autoimmune disorders. Celiac disease is no different. Infections may damage the intestinal lining. The damage can result in a condition called intestinal permeability or leaky gut. Leaky gut makes our body more vulnerable to reacting to specific foods. (11) At the time of writing, researchers have yet to determine if infections cause celiac disease or just start the cascade of symptoms.

Smoking

Smokers are less likely to develop celiac disease. (12) It seems that smoking offers some sort of protective effect towards the development of celiac disease. Though, I think we can all agree that the other associated risks of smoking outweigh the potential benefit of protecting against celiac disease.

Breastfeeding

Breastfeeding was originally thought to prevent the development of celiac disease. Unfortunately, that has been disproven. For a deeper dive into breastfeeding’s effect on celiac disease, please see this post.

Socioeconomic conditions