An experimental carbohydrate diet that restricted processed foods and most sugars has relieved symptoms in eight out of 10 children with inflammatory bowel disease – offering new hope for sufferers of the debilitating condition.

The diet was developed in the 1950s to treat coeliac disease. It was also used for children with Crohn’s disease – and medical records suggest it reduced or even eliminated symptoms for them.

The special diet involves avoiding grains, starches, processed foods, some dairy and most sugars. It includes nutrient- and fibre-rich foods such as vegetables, some fruits, meats and nuts. Bone broth is included to promote gut healing.

Its earlier success sparked the interest of David Suskind, a paediatric gastroenterologist at Seattle Children’s Hospital. He decided to run a pilot study to test the diet.

Twelve 10-17-year-olds with inflammatory bowel disease – which occurs when the immune system attacks the large bowel (ulcerative colitis) or the whole digestive tract (Crohn’s disease) – followed the diet for 12 weeks. They also had counselling and regular visits with a dietitian.

The young patients reported no side effects from the food, although two did find the diet too difficult to follow. After 12 weeks, eight of the remaining 10 patients were in clinical remission. Laboratory tests showed inflammatory markers had decreased.

The diet worked for eight of the 10 children who remained in the study. Photo: Getty

The researchers also measured stool samples. At the start of the study, the patients had “dysbiosis” – an unhealthy imbalance in gut bacteria.

In inflammatory bowel disease, the damaged gut lining struggles to produce enzymes that break down disaccharides (double sugars) and complex carbohydrates into single sugars for absorption. This further injures the lining. Bacteria feed on the undigested sugars, in turn creating dysbiosis and inflammation.

Symptoms include severe diarrhoea, stomach pains and cramping, fever and fatigue, poor appetite and weight loss.

“We saw that the dietary therapy not only improved how most patients felt, their inflammation, but it also dramatically changed the type of bacteria in their gastrointestinal tract,” Dr Suskind said.

“We feel that is a likely mechanism for how diet affects IBD.”

Rates of inflammatory bowel disease have risen steadily in the past 60 to 80 years. In 2013, the condition afflicted about one in 250 people aged 5 to 40 in Australia.

Current Australian guidelines for IBD don’t include diet therapy. Jane Muir, an associate professor at Monash University, said such therapy was a plausible option, but more research was needed.

“There hasn’t been much research into IBD and diet. It’s impossible to get funding, so at least the [special diet] is attracting attention,” she said.

“But we need to understand how it’s working.”

One theory for the diet’s success is its inclusion of healthy, whole foods.

“A lot of patients with Crohn’s, particularly the young ones, have shocking diets,” Dr Muir said. “Maybe they’re just forced to eat well.”

James Lewis, professor of medicine and epidemiology at the University of Pennsylvania, is testing this theory in a trial comparing the special diet with the Mediterranean diet, which is proven for its broad health benefits.

Dr Suskind is on the steering committee for this. The study is in the early phases and it will be some years until results are known.

Dr Muir, who is an expert in developing diet strategies to treat functional gut disorders, said it was too early to prescribe the diet as a treatment for IBD. She was also concerned about its restrictive nature.

“Basically, it cuts out whole food groups,” she said. “And we don’t know the mechanisms of action.”

Dr Suskind acknowledged that researchers didn’t “have all the answers to why the diet works, who the diet will work for, and how to alter the diet to make it easier for families and patients”. His team is running a multicentre trial with Cincinnati Children’s Hospital to investigate further.

Because the special diet is restrictive, it is important to follow it under expert supervision, monitor progress and ensure nutritional requirements are met.