Children with high levels of cholesterol may not be destined to grow into adults with worrisome levels of the artery-clogging substance, researchers reported Tuesday.

A study of 2,367 Iowa schoolchildren found about three-quarters of the girls and about half of the boys who had high blood cholesterol levels between ages eight and 18 had normal cholesterol counts as young adults."Many children with high cholesterol levels do not become adults with high cholesterol levels," the University of Iowa's Dr. Ronald Lauer and William Clarke wrote in an issue of the Journal of the American Medical Association devoted to cholesterol.

Even among youngsters with the highest cholesterol counts, in the upper 10 percent of children surveyed, nearly two-thirds of the girls and one-third of the boys did not warrant cholesterol-lowering treatment when they reached the ages of 20 to 30.

Researchers do not know why people with high cholesterol as youngsters may turn out to have acceptable levels as adults. But Lauer said the difference may be related to growth or to changes in American eating patterns between 1971, when the study started, and 1985, when the latest tests were done.

Lauer emphasized his findings do not mean that children should feel free to chow down on food rich in cholesterol.