Statin drugs, prescribed to millions of American adults to ward off heart attacks and strokes, can safely reduce cholesterol levels and even reverse narrowing of the arteries in children with inherited High cholesterol, a two-year Dutch study found.

About one in 500 children worldwide is born with the condition, called familial hypercholesterolemia, which can lead to heart attacks in early adulthood.

Cholesterol levels fell 24 percent in children ages 8 to 18 who were given pravastatin, sold as Pravachol, for two years. And artery-narrowing reversed course with no serious side effects.

Lead author Dr. Albert Wiegman said the researchers were surprised to see reversal after just two years, and said it suggests the children may be less likely to have premature heart attacks in adulthood.

“This is probably the first study that has been able to show that kind of reversibility” in children, said Dr. Stephen Daniels, a heart specialist at Cincinnati Children’s Hospital Medical Center who was not involved in the research.

Similar effects have been seen in adults. Up to now, however, research on statins in children involved shorter-term use of the cholesterol-lowering drugs.

Dr. Gregory Wright of Children’s Hospitals and Clinics of Minneapolis and St. Paul, said the study applies only to the inherited condition and there is no way of knowing whether statins would work as well in children who have High cholesterol because of poor diet and lack of exercise. These youngsters account for the vast majority of children with High cholesterol.

A few statins have been approved in the United States specifically to treat familial hypercholesterolemia in children.

The authors said longer studies are needed to confirm that the drugs are safe in children, but Wiegman called the results a strong argument for using statins in children with the inherited disorder.

“If we don’t treat them, I know I can’t look them in their eyes in 15 and 20 years because they won’t be there anymore, so we have to do something,” said Wiegman, a pediatric cardiologist at the University of Amsterdam.

The study appears in Wednesday’s Journal of the American Medical Association.

It was funded primarily by the Prevention Fund of the Dutch government. Bristol-Meyers Squibb, which makes Pravachol, also provided funding but was not involved in the study design or analysis, Wiegman said. He said none of the authors received consulting or speaking fees from statin makers.

Last week, consumer groups said such ties had tainted new cholesterol-lowering guidelines issued by the U.S. government and American Heart Association. The guidelines recommend drugs for millions more at-risk adults. But critics maintain that most of the experts behind the recommendations have industry ties.

The JAMA study involved 204 children with familial hypercholesterolemia. Before getting statins, participants spent three months on a low-fat diet yet still had average LDL cholesterol levels of 239 - more than 100 points higher than recommended. LDL is the bad kind of cholesterol that can clog arteries.

The youngsters took either pravastatin or a dummy pill daily for two years, and were instructed to continue with a low-fat diet and exercise.

LDL levels fell an average of 57 points in children on pravastatin but were virtually unchanged in those who were given dummy pills.

Ultrasound tests showed the thickness of the carotid-artery wall decreased by an average of 10 micrometers in those on pravastatin but increased by an average of 5 micrometers in those on the dummy pill. Thickening in the neck artery can sometimes indicate buildup of fatty plaque.

There were no ill effects on development, hormone levels or liver or muscle tissue. Muscle-wasting and abnormal liver function are among statins’ dangerous but rare side effects.