A type of liver disease once thought to afflict primarily adult alcoholics appears to be rampant in children.

Some 1 in 10 children in the U.S., or more than 7 million, are thought to have the disease, according to recent studies.

The condition, in which the normally rust-colored organ becomes bloated and discolored by yellowish fat cells, has become so common in non-drinkers that it has been dubbed nonalcoholic fatty liver disease.

The disease's prevalence is alarming doctors who worry about its progression to nonalcoholic steatohepatitis, or NASH, when the fatty liver becomes inflamed and cells are damaged. That leads to the end stage of cirrhosis, when the liver forms scar tissue and ultimately stops working.

The condition's rise is tied to the obesity epidemic—about 40% of obese children have it—but isn't caused solely by being overweight. The disease appears to be growing among normal-weight children too, experts say.