For liver recovery, sugar intake needs to come down along with fat

Researchers with Oregon State University (OSU) have found that liver damage caused by the typical "Western diet" may be difficult to reverse even if diet is generally improved.

In their study done with laboratory animals, the researchers discovered that a diet with reduced fat and cholesterol could help with weight loss and improved metabolism and health, but did not fully resolve liver damage if the diet was still high in sugar.

The Western diet was defined by the researchers as high in fat, sugar and cholesterol.

Donald Jump, a professor at the OSU College of Public Health and Human Sciences, said, "Many people eating a common American diet are developing extensive hepatic fibrosis, or scarring of their liver, which can reduce its capacity to function, and sometimes lead to cancer."

Liver problems such as nonalcoholic fatty liver disease are surging in the United States, affecting 10 to 35 percent of adults and an increasing number of children. It can happen to more than 60 percent in obese and type-2 diabetic populations.

"Everyone recognizes this is a serious problem," said Kelli Lytle, an OSU doctoral candidate and lead author on the study published on Wednesday in PLOS ONE, an open-access scientific journal. "We're trying to find out if some of the types of dietary manipulation that people use, such as weight loss based on a low-fat diet, will help address it."

"However, a common concern is that many low-fat food products have higher levels of sugar to help make them taste better," Lytle said.

In the research, two groups of laboratory mice were fed a Western diet and then switched to different, healthier diets, low in fat and cholesterol.

Both of the improved diets caused health improvements and weight loss. But one group that was fed a diet still fairly high in sugar, comparable to what is in the Western diet, had significantly higher levels of inflammation, oxidative stress and liver fibrosis.

Complications related to liver inflammation, scarring and damage are projected to be the leading cause of liver transplants by 2020, the researchers noted. Such scarring was once thought to be irreversible, but more recent research has shown it can be at least partially reversed with optimal diet and when the stimulus for liver injury is removed.

"For more significant liver recovery," Jump said, "the intake of sugar has to come down, probably along with other improvements in diet and exercise."

The researchers acknowledged that more research is needed to determine whether a comprehensive program of diet, weight maintenance, exercise and targeted drug therapies can fully resolve liver fibrosis. Endi