High-fructose corn syrup, a cheap liquid sweetener, is found in beverages, baked goods and many other processed food products.

The daily consumption of high-fructose corn syrup might aggravate liver damage in people who suffer from non-alcoholic fatty liver disease, a U.S. study suggests.

The common sweetener is found in beverages, processed foods such as gummy bears and some bread and baked goods. The syrup made from corn is a cheaper alternative to sugar or sucrose and easier to blend and transport because of its liquid form.

As a mixture, the chemical composition of high-fructose corn syrup differs from sucrose, and might act differently on the human body. Some suggest there's a link between the increased use of high-fructose corn syrup and the growing incidence of diabetes and obesity in North America.

"We found that increased consumption of high-fructose corn syrup was associated with scarring in the liver, or fibrosis, among patients with non-alcoholic fatty liver disease," Dr. Manal Abdelmalek, an associate professor of medicine at Duke University Medical Center, said in a news release Thursday.

Scarred livers

About 30 per cent of adults in the U.S. have non-alcoholic fatty liver disease (NAFLD), the researchers said. When fat builds up in the liver, it can cause inflammation, then scarring known as cirrhosis of the liver — permanent damage to the liver that leads to a blockage of blood flow through the organ.

A cirrhotic liver no longer removes toxins effectively, leading to accumulation in the blood that, can in turn, impair mental function and lead to personality changes and possibly a coma, according to the Canadian Liver Foundation.

In the study, Abdelmalek and her colleagues looked at 427 adults with non-alcoholic fatty liver disease at eight clinical centres in the U.S.

The team found that 52 per cent of the study subjects consumed between one and six servings a week of fructose-containing beverages and only 19 per cent said they didn't consume any. 

Twenty-nine per cent of the subjects said they drank fructose-containing beverages daily. The people in that group were 2.6 times more likely to show high degrees of fibrosis than those who consumed no fructose-containing beverages.

The researchers factored in other elements that have been shown to influence NAFLD, including age, sex, body mass index, Hispanic ethnicity and total calorie intake. 

Fructose consumption was estimated based on patients' reports of drinking non-diet soda, fruit juices and other sweetened beverages.  

In 2008, Abdelmalek published a study on a small group of patients showing high-fructose corn syrup was associated with non-alcoholic fatty liver disease. The new study, published online in the journal Hepatology, goes a step further, linking consumption of the sweetener to progression or worsening of liver injury.

While only a minority of patients with NAFLD progress to cirrhosis, all are at increased risk of liver failure and liver cancer, which may require a liver transplant. There is no treatment for NAFLD. 

Diet changes for patients

"Our findings suggest that we may need to go back to healthier diets that are more holistic," Abdelmalek said. "High-fructose corn syrup, which is predominately in soft drinks and processed foods, may not be as benign as we previously thought."

The study, as well as previous laboratory research on human and animal tissue, suggest the body metabolizes high-fructose corn syrup in a way that affects insulin sensitivity. Most dietary fructose is processed in the liver.

The results suggest that for patients with NAFLD, reducing the intake of high-fructose corn syrup might be a way to avoid worsening of their disease, the study's authors concluded.

The effect could be similar to the way that low-fat diets reduce the risk of heart disease, Abdelmalek said, even though research on the effect of diet-modification isn't as advanced for liver disease as it is for heart disease.

The next step in the research is to do formal studies that evaluate whether limiting or cutting out high-fructose corn syrup from a patient's diet pays off in health benefits.

Consumers looking to reduce their intake of high-fructose corn syrup can cut back on soft drinks and sweetened beverages, limit candy, cookies, cakes, pies, doughnuts, granola bars, pastries and other baked goods with "glucose-fructose" on the label.

The Corn Refiners Association has launched an aggressive advertising campaign to counter criticism of high-fructose corn syrup, saying it "has the same natural sweeteners as table sugar."

The Center for Science in the Public Interest notes that high-fructose corn syrup and sucrose are identical nutritionally, and the harmful effects of high-fructose corn syrup could just be an urban myth. Nevertheless, the group includes the sweetener in its list of additives to be wary of, advising it "may pose a risk and needs to be better tested. Try to avoid."

One of the study's authors has written a book on the potential role of fructose in obesity and fatty liver disease and has a patent on lowering uric acid to reduce fatty liver disease. No other authors had conflicts of interest.