Vitamin supplements could help protect children with abnormally high cholesterol levels from heart attacks in later years, according to a small study.
Children with inherited lipid disorders - some 50 million in the US - are usually advised to avoid the cholesterol-lowering drugs taken by adults. However their condition puts them at high risk for suffering heart attacks as adults.
"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," said lead author of the study Dr Marguerite M. Engler, a professor and vice chair of physiological nursing at the University of California in San Francisco, US.
The findings, to be published in the 2 September issue of the journal Circulation, are the first to be reported from the EARLY (Endothelial Assessment of Risk from Lipids in Youth) trial, a five-year study sponsored by the National Institute of Nursing Research (NINR). The goal of the study is to determine whether or not dietary interventions can improve cardiovascular health in children with inherited hyperlipidemias, the genetic disorders that cause abnormally high cholesterol levels.
"The findings of this study suggest hope for children with abnormally high cholesterol levels that their condition can be improved through vitamin supplements," said NINR director Patricia Grady.
Evidence from large population studies suggests that diets high in antioxidant-rich fruit and vegetables lower the risk of heart attack and strokes in adults. However when given as vitamin supplements, antioxidants have not always been shown to offer significant benefit to heart health.
Engler and colleagues investigated whether vitamin supplements could improve cardiovascular health in children at high risk of heart disease by measuring the function of the endothelium, or inner lining of the blood vessels. Endothelial dysfunction is a precursor to atherosclerosis, or the plaque build-up characteristic of cardiovascular disease.
They measured endothelial function in 15 subjects with inherited lipid disorders: seven females and eight males between the ages of nine and 20. All received nutritional counseling and were put on a diet low in saturated fats and cholesterol for the six-month study.
After the first six-week period, the children were randomly given either 500mg of vitamin C and 400 IU of vitamin E per day or placebos for six weeks. They then went through a six-week washout period in which they got neither vitamin nor placebo supplements. In the final six weeks, the participants received whichever treatment they had not received during the randomized portion of the study.
A single investigator who was blinded to each participant's assigned group measured endothelial function in the brachial artery of the arm using ultrasound every six weeks.
The low-fat diet had no effect on endothelial dysfunction, reported the team, but it was associated with an 8 per cent reduction in LDL cholesterol. The vitamin supplements, however, improved endothelial function, on average, to normal levels found in healthy children.
"The impact was quite significant," Engler said. "These results are encouraging and, if confirmed in further studies, we may be able to improve the cardiovascular health of children with inherited lipid disorders using vitamin supplements," she added.