Lowering levels of low-density lipoprotein (LDL) cholesterol has become an important focus with a variety of experimental, genetic and epidemiological studies linking high levels of LDL-C to an increased risk of heart disease.
Beta-glucan, a non-starch polysaccharide found in oats, has been the subject of increasing attention with reports showing the soluble fibre can decrease LDL-C levels.
The new study, published in the March issue of the American Journal of Clinical Nutrition (Vol. 83, pp. 601-605), reports the results of a placebo-controlled, double-blind parallel trial of a fruit drink fortified with beta-glucan on LDL-C levels of 47 volunteers.
The participants all drank 500 mL of a rice starch-enriched (placebo) fruit drink every day for three weeks, before being randomly assigned to either the placebo or the beta-glucan fortified drink for a further five weeks.
German beverage firm Döhler, who were also involved in the study, supplied the apple or pear-flavoured fruit drinks. The drink was formulated to contain one gram of beta-glucan per 100 grams of beverage, and volunteers were asked to drink 250 mL with two of their daily meals.
The researchers reported that, after five weeks, both control and test groups had similar dietary intakes except for beta-glucan intake.
"In the current study, serum concentrations of total cholesterol decreased significantly by 0.060 millimoles per litre (mmol/L) and those of LDL cholesterol by 0.062 mmol/L," reported lead author Elke Naumann from Maastricht University, Netherlands.
No significant change in HDL cholesterol, triacylglycerols and total lipid-soluble antioxidants was measured. However, serum concentrations of lycopene, and alpha- and beta-carotene were found to be lower in the beta-glucan group.
The mechanism behind the LDL-C lowering activity of beta-glucan is not clear, but the researchers proposed that beta-glucan bound to bile acids, thereby preventing reabsorption in the intestine and increasing excretion. The liver compensates by increasing hepatic cholesterol synthesis to produce more bile.
"We conclude that not only increased bile acid synthesis, but also decreased cholesterol absorption contributes to the cholesterol-lowering effect of beta-glucan," wrote Naumann.
Previous studies using beta-glucan incorporated into beverages, such as oat milk, and other fruit juices reported similar LDL cholesterol-lowering values, but when beta-glucan was incorporated into bread and cookies the results were 'non-significant'.
"These results suggest that the efficacy of beta-glucan preparations increases when they are incorporated into liquid products," said Naumann.
According to a recent report from Leatherhead Food International, the heart health market was valued at $3.6 bn (€3.0 bn) market in 2004, and expects that sales will grow by nearly 60 per cent over the period 2004 to 2009, to reach nearly $5.7 bn (€4.7 bn) by 2009.
Cereals make up the largest slice of the market because they are naturally high in fibre, but foods designed to lower cholesterol reduction continue to dominate in terms of new launches.