An expert guide to irritable bowel syndrome (IBS)


Dr Natalia Zarate-Lopez of Cleveland Clinic London on the causes and treatments of a common but under-diagnosed digestive condition

According to estimates from the International Foundation for Gastrointestinal Disorders, 5-10% of the world’s population has irritable bowel syndrome (IBS). Women have the condition more often than men, most patients are under the age of 50, and many are diagnosed only years after their symptoms begin.

The problem is that many people are hesitant about discussing digestive complaints and bowel symptoms with their doctor, so they suffer needlessly in silence for years, says Dr Natalia Zarate-Lopez, consultant gastroenterologist at Cleveland Clinic London.

“Patients frequently undergo multiple investigations and a constant succession of trial-and-error medications. Symptoms are frequently dismissed by doctors when the outcome of investigations is negative. Furthermore, patients are left without an explanation for the cause of their symptoms and left confused by the lack of clear therapeutic strategy,” she explains.

Researchers believe that a combination of factors can lead to IBS. These include:

— Dysmotility, which refers to problems in how the bowel muscles contract and move food through the gastrointestinal (GI) tract.
— Visceral hypersensitivity, meaning that nerves in the GI tract are extra sensitive to physiologic stimulus like food.
— Miscommunication between nerves in the brain and gut, referred to as brain-gut axis dysfunction.
— Changes in the composition of the gut microbiota, which can lead to low-grade inflammation, affecting both gut sensitivity and motility as well as the interaction between the brain and the gut.

“Studies also suggest that people may be at risk if they have a family history of IBS, emotional stress, tension or anxiety, a history of abuse or childhood trauma, food intolerance or have had gastroenteritis,” says Dr Zarate-Lopez. “In fact, IBS is now considered a disorder of the brain-gut axis. The chronic nature of the symptoms can increase the risk of developing anxiety in the long term, and the latter, in turn, influence negatively the emotions generated by the experience of pain and bowel dysfunction, creating a vicious.”

Symptoms are frequently influenced by various types of food, but dietetic interventions need to be carefully considered and individualized according to the patient’s past clinical history, lifestyle and clinical symptoms. “There is no one diet that applies to all,” she continues.

In the case of food, certain elimination diets, undertaken in consultation with a doctor, can help ease discomfort and identify which foods trigger symptoms. Foods typically eliminated include gluten, dairy, sugar, and packaged and processed foods. It is also important to explore habits and routines around food as well as the relation between food and emotional wellbeing.

“Carbohydrates called FODMAPS – an acronym for ‘fermentable oligosaccharides, disaccharides, monosaccharides and polyols’ – appear to have the most impact on wellbeing, and many individuals find relief following a long-term, low-FODMAP diet. This diet needs to be implemented under expert dietician supervision,” advises Dr Zarate-Lopez.

Research-based evidence confirms that a biopsychosocial model is recommended to help patients with IBS symptoms. “This model recognises that biological mechanisms are responsible for symptom generation, but that central mechanisms like emotions, cognitions and mood influence our ability to cope with symptoms and the experience of pain. Finally, external factors like stress or our lifestyle influence the interactions between the brain and the gut,” says Dr Zarate-Lopez. “It is therefore fundamental that doctors provide reassurance, education and a bespoke approach to each individual patient.

This requires a careful clinical assessment, including the patient’s medical history and a physical examination, and, most importantly, an understanding of the impact of symptoms on the patient's quality of life. “Promoting self-management through education empowers the patient to make decisions about their diet and lifestyle, reducing anxiety around their symptoms. Pharmacological options need to be adjusted according to each patient’s unique symptom profile, and it might include medications influencing transit along the gut and pain management, but also neuromodulatory medications that impact positively on the brain-gut axis dysfunction.”

Expertise in managing disorders of the brain-gut axis, like IBS, within a multidisciplinary team is recommended for patients with moderate and severe symptoms. This allows rapid implementation of the most appropriate strategy and access to the diagnostic and therapeutic resources needed. “The ultimate goal is to facilitate patients’ confidence in self-management of their symptoms and improvement of their quality of life,” concludes Dr Zarate-Lopez