By Maggie Fox, Health and Science Correspondent

WASHINGTON (Reuters) - Children and young adults who have inherited high cholesterol may reduce their risk of clogged arteries by taking vitamins C and E, researchers reported on Monday.

The vitamins improve blood flow through the arteries and may prevent the damage that leads to atherosclerosis, commonly known as hardening of the arteries, the researchers said.

Writing in the journal Circulation, Marguerite Engler of the University of California San Francisco and colleagues said the study is the first to show that vitamins can reverse the damage as well.

"When we gave these children moderate doses of vitamins C and E for six weeks, we saw a significant improvement in blood-vessel function, which is an important indicator of cardiovascular health," Engler said in a statement.

An estimated 50 million U.S. children have high levels of cholesterol, and thus a high risk of heart disease and heart attack. The American Heart Association defines this as cholesterol of 200 or higher and low-density lipoprotein--LDL or "bad" cholesterol--of 130 or higher.

Drugs including statins work very well to lower cholesterol levels in adults but they can have severe side effects and are not usually recommended for children.

"The findings of this study suggest hope for children with abnormally high cholesterol levels that their condition can be improved through vitamin supplements," said Patricia Grady, director of the National Institute of Nursing Research, which helped fund the study.

KIDS NOT GETTING THE RIGHT DIET
Diets rich in fruits and vegetables and low in fat, especially animal fat, have also been shown to lower cholesterol and the risk of heart disease--but most Americans do not eat this kind of diet.

"Our dilemma was that these kids are supposed to be getting...many servings of fruits and vegetables a day but they aren't doing it," Engler said in a telephone interview.
"We thought, 'let's still keep up the diet counseling but also let's try the vitamin supplements'."

Engler's team studied 15 children and young adults age 9 to 20, who had average total cholesterol levels of 242 and LDL levels of 187.

Half the children got daily does of 500 milligrams of vitamin C and 400 international units of vitamin E for six weeks. The other half got placebos. Then the groups were switched.
Better diet alone reduced LDL by about 8 percent, but the vitamins, as expected, did not affect cholesterol levels.

The researchers measured how well the arteries were working by examining flow-mediated dilation of the brachial artery. They were looking for signs of endothelial dysfunction, which can cause blood vessels to stiffen, meaning they do not stretch to accommodate increased blood flow. It is one of the earliest signs of atherosclerosis.
The endothelium is the inner lining of the blood vessels. It releases nitric oxide, which causes the blood vessels to open. The vitamins may restore this process in damaged arteries by reacting with charged particles known as free radicals that damage cells.
Flow-mediated dilation (FMD) of the brachial artery was around 6 at the start and for those patients given placebo or diet alone, but it was 9.5 after the children got the vitamins.

"Normal FMD of the brachial artery in children is reportedly between 8 percent and 12 percent," the researchers wrote.

SOURCE: Circulation. 2003 Aug 11 [Epub ahead of print].