CUHK Passions and Pursuits

35 So Much to Stomach Siew Ng: why an inflammatory bowel? why Asia? T he West imports plenty of goods from Asia. But there’s one transfer in the other direction that is very negative indeed. It’s the job of CUHK gastroenterologist Siew Ng to stop that flow. Two decades ago, inflammatory bowel disease was virtually unheard of in Asia. The two main forms, Crohn’s disease and ulcerative colitis, were viewed as a ‘Western disease’ that affected Caucasians, and Caucasians alone. Hong Kong has seen a 30-fold increase in the disease since then. The mainland has experienced an especially pronounced pickup, and is likely to have more than 1.5 million cases of inflammatory bowel disease by the year 2025. That will likely equal or exceed the total in the Western world. Changing diets are a major factor. High levels of fat, meat, sugar, food additives, fast food and carbohydrates trigger the condition. High levels of fibre may prevent it. The condition is rarely life- threatening, but it is debilitating, and mostly affects the young. Patients are in and out of hospital, suffer through multiple operations, have internal bleeding and pain, and often can’t stomach, literally, going to school or managing a family. Professor Ng’s first step was to study the epidemiology of the disease, and find out how common it truly is. She discovered that the incidence in Hong Kong had expanded from 0.1 to 3 cases per 100,000 people over the last two decades. The rapid change demonstrates to Professor Ng that genetic changes alone have not accounted for the spread of the disease. However, there are more than 200 genetic loci—essentially 200 genes—that indicate a propensity to develop inflammatory bowel disease. She has also discovered that people who were breast-fed as babies have at least a 90% lower chance of having the disease. Interestingly, exposure to pets is also a protective factor—exposure to parasites boosts the immune system, Professor Ng has proved in Asia. The use of antibiotics early in life can raise your chances of contracting Crohn’s, depending on the type and dose. Antibiotics are routinely overprescribed in China, especially to children. Professor Ng is working on introducing fecal microbiota from the faeces of a healthy person into an affected patient, aiming to introduce ‘healthy’ bacteria that can fight the disease. Professor Ng’s group established the Asia Pacific Crohn’s and Colitis Epidemiology Study group, or ACCESS, which has expanded to cover 15 countries in the Asia-Pacific region. It has tracked more than 3,000 new cases in the area. Northern China has lower incidence, while Guangzhou in the south has the highest. ‘We don’t know why, but that is really fascinating for me,’ Professor Ng said, ‘and an area for further study.’ Urbanization and the Westernization of diets may both play a part. Ng’s team has been coordinating with laboratories and clinics in Beijing, Shanghai, Guangzhou and Xian to study the disease on the mainland, in the hope of uncovering how environmental factors lead to Crohn’s disease. Ultimately, the aim is to encourage dietary changes and modify gut bacteria to treat the disease, two steps on the path to finding a cure.