The Professor: "A gluten-free diet is not good for everyone”

Text: Karin Söderlund Leifler, first published in Swedish in Medicinsk Vetenskap no 3, 2016.

In surveys in the United States, several million people have declared that they eat a gluten-free diet although they have not been diagnosed as coeliac. In Sweden too, there is great interest in gluten and many people say they feel healthier if they eat food that is gluten-free. There is no doubt that, for those with coeliac disease, gluten is the villain of the piece. Treatment for the condition consists of a strictly gluten-free diet. But that does not mean that it is better for everyone to eat non-gluten foods. To ensure the accuracy of the medical tests necessary to diagnose gluten intolerance, you must still have gluten in your diet.

“So if you suspect that you have coeliac disease, you should get tested before you stop consuming gluten,” says Jonas F. Ludvigsson, Professor of Medical Epidemiology and Biostatistics at Karolinska Institutet and paediatrician at Örebro University Hospital. “But if you have already been tested and gluten intolerance has been ruled out, you can reduce your bread intake if you feel better doing so. In that situation, it is not often the case that people cannot eat bread, it is that they feel better if they eat less of it, in the same way that you can feel unwell if you eat large amounts of fatty food, onions or pea soup.”

Gluten-free foods are generally more expensive, and, particularly outside the Nordic countries, also contain more fat and sugar to compensate for the difference in texture in the absence of gluten.

“Gluten-free foods are healthier if you replace a piece of ordinary cake with an apple, but not if you replace a piece of ordinary cake with a piece of gluten-free cake,” says Ludvigsson.

Sweden has one of the highest incidences of coeliac disease, with around 100,000 Swedes diagnosed as gluten intolerant. But research has shown that not everyone can get coeliac disease. There are at least three factors involved in the occurrence of the disease.

Firstly, coeliac disease is an autoimmune condition in which the immune system is triggered to attack the body’s own tissues. Immune systems differ slightly from person to person and coeliac disease only affects people with certain types of HLA genes, specifically HLA types DQ2 and DQ8. But that in itself is not enough. About a third of the country’s population have one of these gene types and most of them do not develop gluten intolerance. The second factor is of course gluten.

“Pretty much all Swedes consume gluten, but only a fraction of us develop coeliac disease, so there must be at least one other factor at play,” he says. “But what that third factor is we don’t yet know.”

Many people are diagnosed as children and coeliac disease is the most common chronic illness amongst children. As a paediatrician with a particular interest in gastro intestinal illnesses, Ludvigsson encounters many young people with coeliac disease. He likes to be able to provide explanations, and much of his work involves motivating children and young people to continue with their gluten-free diet.

“Working with children is great fun and I usually draw pictures to show what the gastric mucosa looks like when a child is unwell and how the intestinal villi will grow back when the child starts on a gluten-free diet. I explain that this makes it easier for the body to absorb nutrients and energy so that the child grows and gets stronger. Children can grasp this even when they are quite young, and I feel that I can often go some way to helping them understand their illness.”

Although coeliac disease mainly manifests itself in intestinal symptoms, the illness also affects many other parts of the body. Ludvigsson’s research group has studied the long-term risks associated with coeliac disease. The research has shown an enhanced risk of conditions such as certain types of cancer, depression, thyroid disorder, diabetes, fractures and complications in pregnancy. The research group has also shown that those with coeliac disease are at greater risk of dying of an illness such as cardiovascular disease.

“Coeliac disease affects many different organ systems. Ongoing inflammation is never good – it can lead to a range of other things. It may be that it is chronic inflammation that lies behind the slightly enhanced risk of cardiovascular disease.”

In addition to the inflammation in a coeliac’s intestine that has been subjected to gluten, there are other explanations for the increased risk of other illnesses and complications. If the intestine is damaged, the rate at which energy and other nutrients are absorbed from food worsens. For example, poor absorption of calcium leads to a weakening of the skeleton, which can increase the risk of fractures. It is also the case that the genetic background required for a person to develop coeliac disease increases the risk of type 1 diabetes and thyroid disorder. So the enhanced risk of diabetes and thyroid disorder in coeliac patients does not necessarily mean that gluten intolerance causes the other illnesses; it can be explained by the underlying genetics. Ludvigsson mentions a further relevant factor in the increased risk of additional diagnoses.

“What is the worst thing you can do if you want to be diagnosed with an illness? Go to see your doctor – because that’s where you’ll get a diagnosis. A coeliac patient is more likely to go to see the doctor and be examined and so more illnesses will be uncovered.”