Explainer: what is gluten intolerance?

Luckily, gluten-free diets don’t end here. Lettuce leaf by Shutterstock

Gluten intolerance covers a range of gut problems caused by ingesting proteins found in wheat, barley, rye and in some cases, oats. The three main groups affected are those with a direct sensitivity to gluten, coeliac disease and people who are allergic to wheat. Although symptoms can appear similar and the terms are often used interchangeably, gluten intolerance isn’t the same as coeliac disease.

Coeliac disease is a serious life-long autoimmune condition of the small intestine, in which the body’s immune system attacks itself when someone with the condition eats gluten. This damages the healthy lining of the small intestine and stops nutrients being absorbed from food.

Gluten intolerance is also a permanent condition that damages the small intestine every time gluten is consumed, regardless of whether symptoms are present or not, but it is unclear whether the immune system is involved.

Identifying the active protein

In 1887, British doctor Samuel Gee was the first to make a record of gluten intolerance, which he described as a “malabsorption of ingested food” in children. Removal of wheat flour and wheat products from the diet was later seen to alleviate symptoms associated with the disease – and to this day a gluten free diet is currently the only successful treatment.

It was later found that a particular protein in wheat was active in patients with gluten intolerance and could not be removed from the gut by digestive enzymes. Equivalent proteins in rye, barley and possibly oats were also found to cause problems. So foods and drinks containing malted grains and any processed foods that contain this protein have to be removed from the diet.

The main cause of gluten intolerance is genetics, and the specific genes associated with the condition have been isolated. The genes produce molecules that interact with gluten proteins and activate the abnormal intestinal response. But not all people with the offending genes develop gluten intolerance, which suggests that other environmental factors are implicated. These could include early weaning onto solid food, breast feeding and gastrointestinal infection.

Symptoms in untreated conditions can vary which can lead to delays in diagnosis. Symptoms vary from fatigue, headaches, abdominal complaints, diarrhoea, joint complaints to vitamin and mineral deficiencies, such as iron and calcium. Bones can become weak and brittle.

Gluten intolerance is also associated with other autoimmune diseases: type 1 diabetes, autoimmune thyroid and liver disease and inflammatory bowel disease. An increased risk of intestinal cancer is also associated with undiagnosed gluten intolerance, as are neurological conditions.

How common is gluten intolerance?

Over the past two decades the perception of gluten intolerance has changed from being a rare disease that affects children of northern European ancestry, to a very common condition of people of all ages worldwide with 1.4 million Americans being diagnosed with the condition every year.

The condition recently received high profile coverage in the media after a gluten-free diet was shown to have improved the performances of top sports stars. Recent studies have shown the condition isn’t just confined to western countries or those of northern European descent – gluten intolerance, for example, is as common in the Middle East.

Despite it now being seen as more common, the condition is under-diagnosed for a number of reasons. Often individuals display only mild symptoms, and even though new and more accurate techniques have been introduced diagnosis still depends on determining changes in cells lining the intestine. Because of this it often takes until adulthood to be diagnosed, in fact, more than 60% of newly diagnosed patients are adults, with 15–20% over 60 years of age.

Food for thought

The only known effective treatment for gluten intolerance is a life-long gluten-free diet. But studies have shown that some groups, such as adolescents, find it difficult to keep off gluten products. Poor product information on gluten containing foods is also be a problem for people on gluten free diets, as is cross contamination when food is being made. Useful labelling isn’t always helpful because people differ in their sensitivity to gluten so a particular dose may cause a response in one person, but not in another.

The availability and price of gluten free foods is another factor, often there are limited ranges and are considerably more expensive than conventional products. So in patients on a gluten-free diet, intestinal damage can continue to happen even if in small increments, and may be outside the control of the person with the condition.

The use of starches and gums is the most widespread for mimicking gluten when making gluten-free bakery products, because they have gluten like properties. Some on the milder end of the intolerance scale may not see that having some gluten every now and again is a problem, while for others it’s a battle to maintain a completely gluten-free diet. But the signs are things are getting better – both in terms of diagnosis and available foods on the market.