Obese youth who have some build-up of fats in their livers and a diet high in fructose may be more likely to develop serious chronic liver damage common in adult alcoholics, a recent study suggests.
Most people have a little bit of fat in their liver. Fatty liver disease can occur when more than 5% of the liver by weight is made up of fat. Excessive drinking can damage the liver and cause fat to accumulate, a condition known as alcoholic fatty liver. When people don’t drink much, they can still develop non-alcoholic fatty liver disease (NAFLD), which is associated with obesity and certain eating habits.
NAFLD is the most common liver disease in Western children, the authors write in Journal of Hepatology. And it is now recognised as the liver’s “manifestation” of metabolic syndrome – a constellation of traits and symptoms that raise a person’s risk for diabetes and heart disease.
For the current study, researchers examined data on 271 obese children and teens in Italy and the UK who underwent liver biopsies to assess fat accumulation. They used food questionnaires to assess fructose consumption and also examined blood levels of uric acid, which can be elevated in people with chronic liver disease.
Foods high in fructose include anything with high fructose corn syrup, like sweetened drinks, candy and many processed foods, but this type of sugar also occurs naturally in fruits, fruit juices and honey.
“Cells don’t use fructose for energy, so 100% of the fructose you eat is metabolised in your liver,” said study co-author Dr Valerio Nobili of Bambino Gesu Children’s Hospital in Rome.
Instead, the body turns fructose into fatty acids, the “bad” kind of cholesterol and triglycerides, which are stored as body fat, Nobili said. “That’s why excess fructose going into the liver is followed by the formation of fatty liver."
All of the study participants had at least some degree of nonalcoholic fatty liver disease, researchers report. About 38% of them, or 102 participants, had more extensive liver damage known as nonalcoholic steatohepatitis (NASH) that happens when fat buildup leads to swelling in the liver and impairs liver function.
Roughly 47 patients with NASH had high uric acid, compared with 30% of participants without NASH, the study also found.
One limitation of the study is that it relied on children and teens to accurately recall and report what they ate, the authors note. The study also didn’t examine whether there was a difference in liver outcomes based on how much fructose participants got from whole fruits, fruit juices or sodas.
Said Dr Jeffrey Schwimmer, a researcher at the University of California, San Diego and director of the Fatty Liver Clinic at Rady Children’s Hospital. “We don’t think that the impact of fructose from fruit is the same as fructose from drinks.”
His advice to parents: “Limit added sugars while further research is done to better understand” how fructose impacts the liver.