Twenty children aged between nine and 19 years, all of whom had hereditary high cholesterol, were first fed a stabilizing low-fat diet for six weeks, followed either by a daily dose of 1.2 grams of DHA or a placebo.
The researchers found that in participants taking the DHA supplements the amount of large, buoyant LDL (low-density lipoprotein) and HDL (high-density lipoprotein) particles was significantly increased and small, dense LDL particles were reduced.
"The small size of the 'bad LDL cholesterol' shifted to the large, fluffier type which floats easier in the blood stream without being taken up by the artery wall," said lead researcher Dr Marguerite Engler.
She said that the results, which effectively showed an improvement in the quality of cholesterol, may prevent the build-up of plaque in the artery and reduce the chance of these high-risk children developing heart disease.
The DHA used in the study was supplied by Martek, the biosciences company which extracts DHA fatty acid from microalgae and markets it as an ingredient in infant formulas, nutritional supplements and food products.
A spokesperson for Martek told NutraIngredients-USA.com last month that the company is "growing up from infant formulas with the consumers" - a strategy which will give it a presence in children's diets.
In February the company announced that it had signed a non-exclusive licensing agreement with Kellogg to supply the consumer foods giant with DHA for use in a new line of fortified foods.
Engler added that recent research has already established that DHA increases the ability of blood vessels to dilate or increase blood flow.
Three studies presented at the American Heart Association's scientific sessions in 2003 also indicated that DHA supplementation results in a significant cardioprotective benefit both for patients at risk of developing cardiovascular disease and in healthy subjects.