Much To StomachSiew Ng asks why inflammatory bowel disease takes root in Asia
The 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.
‘It’s a little bit like seeing history repeat itself,’ Professor Ng says, with what happened 50 years ago in the West now occurring in Asia. The ‘blank sheet’ of her groundbreaking work is what drew her to it.
‘When a disease has stabilized, it’s hard to find out what is causing it,’ Professor Ng notes. ‘But when the disease is still climbing, that’s when you realize there’s something in the environment that is causing it, and that you can do something about it.’
Changing diets are a major factor. High levels of fat, meat, sugar, food additives, fast food and carbohydrates trigger the condition. High levels of fiber 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 cases per 100,000 people to 3 per 100,000 Hongkongers 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.
Still, that evidence gives Professor Ng hope. ‘The antibiotics story is important, because it indicates something you can change,’ she says. To find a cure ‘is the ultimate goal, at least in my lifetime.’
Professor Ng, who holds a position in CUHK’s Department of Medicine and Therapeutics, conducts clinical work at the Prince of Wales Hospital. She is now 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 says, and an area for further study. Urbanization and the Westernization of diets may both play a part.
Inflammatory bowel disease is still relatively rare in other parts of the world such as Latin America and Eastern Europe. It’s likely the ACCESS model can be transplanted to such newly industrialized countries.
‘This work has put Asia onto the map,’ Professor Ng says. ‘And we hope that we can use this to colour the map for the rest of the world.’
Most recently, Ng’s team won a US$1.8 million grant from the Leona M. and Harry B. Helmsley Charitable Trust to fund three years of research to identify microbial organisms and dietary factors that contribute to Crohn’s disease. The grant is part of $5.2 million in funding shared with the Australasian Gastro Intestinal Research Foundation, since Australia has one of the highest incidence in the world. CUHK will coordinate with laboratories and clinics in Beijing, Shanghai, Guangzhou and Xian to study the disease on the mainland.
This is the first such grant in either China or Australia. By comparing the two nations, the teams hope to uncover how environmental factors lead to the disease. Ultimately, the aim is to encourage dietary changes and modify gut bacteria to treat Crohn’s disease, two steps on the path to finding a cure.
By Alex Frew McMillan