Non-alcoholic fatty liver disease has lately become a cause for concern in the medical community here because of the rising incidence and changing demographics.
In the last decade, the incidence has risen to almost 50 per cent of the adult population. Those diagnosed with fatty liver disease do not fit the usual profile of patients who have known risk factors – heavy alcohol drinkers, or those who are obese or diabetic.
New data shows that people without these conditions are now developing the disease. Some are in their 20s and of average weight and appearance, and have one common characteristic – they either drink very little alcohol or none at all. “It’s difficult to know who has this disease without scanning their liver,” said Professor Pierce Chow, Senior Consultant, Division of Surgical Oncology, National Cancer Centre Singapore (NCCS ), who has been leading research on the disease and its relationship to liver cancer.
Fatty liver is defined as a liver with at least 5 per cent fat in its cell content, which can be detected through a biopsy or by MRI , CT or ultrasound scan. However, an ultrasound scan can only pick up a fatty liver when the liver has at least 30 per cent fat.
If caught early, and before the inflamed liver has developed scarring or cirrhosis, the disease can be reversed.
But once it becomes cirrhotic, the disease is irreversible because liver cells have been replaced by scar tissue, making the organ progressively dysfunctional.
Cirrhosis of the liver also puts a person at risk of developing liver cancer.
Another concern is that the simple form of the disease can progress to non-alcoholic steatohepatitis, a more severe and complicated form of fatty liver.
An even more troubling trend has emerged, said Prof Chow. Patients with non-alcoholic fatty liver disease are increasingly observed to bypass this non-alcoholic steatohepatitis stage and cirrhosis, and develop liver cancer.
“This has been noted by a number of international centres, including NCCS , and we are increasingly concerned about it. Global statistics project that in the next 10 to 15 years, non-alcoholic fatty liver disease will be the main cause of liver cancer around the world, surpassing even Hepatitis B and C, which are currently the number one causes,” he said.
The rising incidence of non-alcoholic fatty liver disease in Singapore is consistent with the rest of the developed world.
In the US , non-alcoholic steatohepatitis is the second cause of patients needing a liver transplant. “The epidemiological data is strong but the mechanisms are unclear,” said Prof Chow.
The high incidence rate here was detected by one of Prof Chow’s medical students, Mr Kevin Khaw from Duke-NUS Medical School.
“While attached to the ward and clinic, he noticed from looking at scans that a significant number of patients admitted for gallbladder surgery had non-alcoholic fatty liver disease. He realised that the incidence was higher than expected, so he did a comparison study,” said Prof Chow. The results (which won Mr Khaw a prize at a scientific conference) were staggering. Between 2000 and 2003, only 30 per cent of patients with gallstone disease had concomitant fatty liver disease.
A decade later, between 2010 and 2013, the figure was 50 per cent.
“These are patients who came to consult me for gallstone disease, not liver disease, but our routine scans showed they also had fatty liver,” said Prof Chow.
What is causing it?
Although the jury is still out on what causes non-alcoholic fatty liver disease, the medical community has a few tentative leads, according to Prof Chow.
The causes could be due to many factors.
One hypothesis is that people whose ancestors are genetically well-adapted to cyclical famine have bodies that are particularly efficient at storing consumed calories.
With improved standards of living and increased consumption of food, especially carbohydrates, the body is predisposed to a condition called metabolic syndrome, which increases the risk of diabetes and nonalcoholic liver disease.
Another theory, which is slightly more controversial, is related to changes in the food chain. There is a belief that the epidemic started in the 1970s because of the introduction of industrially manufactured sugar, specifically artificial fructose, into the manufacturing of foods such as biscuits, instant noodles and soft drinks. Fructose has a chemical structure that predisposes people to developing a fatty liver.
Change in intestinal bacteria
A third theory is linked to changes in bacteria in the intestine. Animal studies have shown that when sugar in the diet is modified during digestion, it affects bacteria in the gut. The bacteria interact with receptors in the cells of the intestine known as peroxisome proliferatoractivated receptors (PPAR s), which give off a cascade of messages and signals to the rest of the body to change its metabolism. This might instruct certain organs, the liver for instance, to store fat, leading to fatty liver disease.
Catch it early
Patients in the early stages of fatty liver disease usually display no symptoms. However, as it develops, tiredness, a sensation of bloating, loss of appetite and pain in the right upper abdomen might occur. Should this progress to the non-alcoholic steatohepatitis stage or become cirrhotic, signs will include nausea, jaundice, a swollen abdomen and poor concentration.
If identified early, the disease can be successfully treated so that the liver returns to its non-fatty state.
“It is potentially reversible until it becomes cirrhotic,” said Prof Chow.
He advises patients who have the disease to lose about 10 per cent of their body weight through lifestyle changes, as clinical studies have shown that this consistently reverses fatty liver. One way to do this is to decrease intake of carbohydrates, especially refined sugars.
Exercise is useful too, but to be effective it must be very intensive.
Prof Chow said it is a common misunderstanding among his patients that removing fat from their diet will keep the disease at bay.
“Unfortunately it is not so simple. The good news is you can still manage it through lifestyle adjustments.”
At NCCS, animal studies are being done and there are plans to follow up with a prospective population study. “Not all patients with fatty liver disease will get cancer. We do not know enough, so research is important to allow us to understand who the high risk patients are.
“We want to be able to identify such patients so that we can intervene now to prevent cancer in the future,” said Prof Chow.
All information in this article is accurate as of May 2016, originally published in Singapore Health. Get all the latest updates on healthcare in Singapore at www.singhealth.com.sg.