Irritable bowels — the gut reaction

Irritable bowel syndrome can cause many complaints. Photo: Shutterstock


Irritable bowel syndrome (IBS) causes stomach pains in over one in ten Dutch people and can be a considerable disruption to their everyday lives. Nutrition seems to play a key role, but it is not clear as yet precisely how that works. Wageningen University & Research is carrying out innovative research to try and uncover the effects of fibres, probiotics and dietary fat.

A bloated stomach as if you are four months pregnant, intense cramps and diarrhoea, or conversely, constipation. “I hardly dared go outside anymore,” said someone who responded to a report on intestinal research at WUR earlier this year. “I faint from the pain during my night shifts,” said another. “I have real problems with flatulence: it’s painful and so embarrassing,” bemoaned yet another desperate sufferer. Wageningen Food & Biobased Research scientist Nicole de Wit knows all too well what patients with irritable bowel syndrome (IBS) have to deal with and how much impact it has on their daily lives. “It is a disruptive factor at work and in their social lives. Some patients no longer dare go out for a meal or even arrange to meet up anywhere outside the home.”

IBS is a disruptive factor in people’s jobs and social contacts. Some don’t dare leave the house

Being diagnosed with IBS often seems daunting as there is no obvious solution. “It is usually not possible to find physical causes. Patients are referred to the hospital but the tests carried out on the intestines generally don’t show any abnormalities,” says De Wit, who has been working on IBS since 2017, with a particular focus on the effect of diet.

Effective treatment is tricky

If patients meet what are termed the Rome 4 criteria — they have had the complaints for more than six months, with at least one day a week of abdominal pain, plus problems with bowel movements — and physical examination has ruled out other potential conditions, the diagnosis is often IBS, as Ben Witteman explains. He is a gastroenterologist at the Gelderse Vallei hospital and a professor by special appointment at Wageningen. Witteman encourages the research on the relationship between nutrition and IBS. “Especially because I see so many people with these complaints in my daily practice. As a doctor, the first thing I do is reassure people: IBS is an inconvenient condition, but fortunately it’s not dangerous. Then I give them lifestyle advice. Together, we consider their nutrition and exercise, and aspects such as weight, rest, sleep and stress. If changes in these areas don’t offer sufficient support and relief, we consider other treatments, such as extra medication for cramp or constipation. But finding an effective treatment remains tricky.”

The SHIME® is an in vitro model that simulates the digestion and fermentation of food components in the intestines. Photo: Wageningen Food & Biobased Research

Patients themselves often experiment with all kinds of remedies, such as changes to their diet, says researcher De Wit. One of the best-known diets for people with IBS is the Australian FODMAP diet, which eliminates various sugars. However, it’s often difficult to stick to these diets because they are so strict. Doctor Witteman: “Anyway, this diet only works for a small subset of patients: those with diarrhoea or a bloated sensation as the main complaint.”

All in the mind?

It’s known that IBS complaints can be exacerbated by stress. That’s why patients are often advised to avoid stress wherever possible. But there are also people with IBS who don’t feel stressed, not to mention that the complaints usually do not disappear completely when someone starts to relax. De Wit: “Although it’s known that stress can make IBS complaints worse, we have more and more indications that there really is something going on in the large intestine: it seems to be out of equilibrium. The intestinal permeability can sometimes be abnormal in IBS patients — the intestine leaks, so to speak. This produces an immune response that can aggravate the complaints. However, many of the underlying causes of IBS are still largely unknown.”

Four-year study

As regards the intestinal permeability, nutrition seems to be a key factor where making changes could reduce complaints. But it is still unclear how that works. The research that De Wit and her team are carrying out started in 2017 and is funded by the Ministry of Agriculture, Nature and Food Quality in a programme entitled Nutrition to improve quality of life of IBS patients.

It turns out that IBS patients have lower counts of the Bifidobacterium in their intestines

In addition to De Wit’s team and gastroenterologist Dr Witteman, this public-private partnership includes the WUR departments of Human Nutrition and the Laboratory of Microbiology, plus nine companies, mainly nutritional supplement producers. They provide the various nutritional supplements for the three studies with patients that are taking place this year. The supplements include prebiotics (insoluble fibres that can serve as a source of food for the gut bacteria) and probiotics (a group of live bacteria that can influence the gut bacteria in other ways).

The role of nutrition in IBS Sudden bloating, pain, constipation and diarrhoea: life with irritable bowel syndrome can be unpredictable and comes with a lot of uncertainty. Researcher Nicole de Wit of Wageningen University & Research explores how nutrition can aid symptom relief. So far they’ve found two very promising contenders for that out of the 45 screened food components.

Preliminary research

These patient studies were preceded by a lot of preliminary studies, explains De Wit. “We first wanted to know what foods aggravate the condition and what foods lead to fewer complaints. That’s why we asked over 1,600 patients which products lead to complaints. It turned out that people with a range of different complaints were affected by the same kinds of food: greasy, spicy and deep-fried food, onions and cabbage. We also took 90 patients and examined the composition of their gut bacteria. There was no clear pattern that we could relate to their complaints, but we did see that patients generally had low numbers of Bifidobacterium (generally seen as good for health and therefore frequently used in probiotics, ed.) in their intestines.”

Replica intestines

To test various foodstuffs, they then developed a number of in vitro lab models — a kind of mini belly made up of intestinal cells and artificial intestines containing the gut bacteria of a healthy donor (see photo of the SHIME model). De Wit: “We tested 45 food components, from proteins and fatty compounds to fibres and probiotics. We wanted to know what effect they had on the intestinal permeability, inflammatory response and level of serotonin in the intestines, which is not only an indicator for hypersensitivity and pain, but also ensures peristalsis (intestinal movements that play a role in bowel motion patterns, ed.).”

We tested 45 food components in the lab, from proteins to fibres

We tested 45 food components in the lab, from proteins to fibres’ De Wit’s team also wanted to know what nutrition does to the activity of the intestinal bacteria. Therefore the researchers looked at the production of short-chain fatty acids in the intestinal environment — more was often better — and the production of gas — preferably not too much.

Important for a healthy gut bacteria: Bifidobacterium. Photo: Shutterstock

Trying out sachets

The various pre-clinical studies revealed several food components that potentially have a beneficial effect on IBS complaints, for example because they influence the intestinal bacteria or serotonin levels positively. The most promising food components were packaged in sachets and tested in three studies among a total of about 300 IBS patients. For the first study, they selected 180 patients with obstipation problems. The participants were studied for eight weeks, during which they took a supplement (prebiotics or probiotics) or placebo for four weeks. They filled in questionnaires about their complaints and general well-being.

Can supplements help?

The second study consists of 70 IBS patients with a variety of complaints: diarrhoea, obstipation or abdominal pain without any bowel movement problems. De Wit: “We want to find out what the effect is of four nutritional supplements — three insoluble dietary fibres and one protein hydrolysate (fragments of protein molecules, ed.) from cow’s milk on the Bifidobacterium population in their intestines. As said, these bacteria are thought to have a positive effect on intestinal health and our previous research had shown lower counts in IBS patients.”

A cup of whipped cream

The final patient study, with 20 IBS patients, is aimed at demonstrating whether a nutritional supplement based on turmeric can reduce an inflammatory response and stomach complaints caused by high-fat foods. The participants will be given the supplement or a placebo 48 hours before being invited to drink a cup of whipped cream. Measurements will be done through questionnaires and blood tests. The results will all be available by early 2022. So what’s next? De Wit: “Then we’ll hopefully know more about which nutritional supplements could help IBS patients. But we’re not expecting a single quick fix as the complaints vary between patients, so the treatment will too. We’re working towards personal, scientifically-based nutritional advice. While these studies will give us more pointers, the research on the relationship between nutrition and IBS still has a long way to go. We hope that we’ll be able to continue screening food components in the future so that we can offer each IBS patient an appropriate solution.”

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