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But whether this could offer the possibility of formulating an additional weapon in the armoury against elevated cholesterol levels remains to be seen since the reductions were not as much as expected, possibly due to detrimental interactions between the ingredients.
High cholesterol levels, hypercholesterolaemia, have a long association with many diseases, particularly cardiovascular disease (CVD). This disease kills one person every twelve minutes in South Africa.
Phytosterols and stanols, cholesterol-like molecules derived from plants, are increasingly well known to consumers due to their scientifically proven ability to reduce cholesterol levels. As consumer awareness has increased, the number of products containing plant sterols or plant stanols and their esters has increased..
Few people consuming margarines
However, a recent study from France reported that, despite the widely advertised benefits of using phytosterol-enriched margarines, only 15 percent of the study population of people at high risk of heart disease were consuming the margarines, with only five percent consumed the recommended daily amount (Nutrition, Metabolism and Cardiovascular Diseases, doi:10.1016/j.numecd.2006.07.012).
Researchers from Maastricht University report that combining plant stanol esters with another ingredient receiving increasing attention, beta-glucan - a non-starch polysaccharide found in oats and barley previously reported to decrease LDL-C levels - may reduce cholesterol levels more than beta-glucan alone.
Writing in the Journal of Nutrition, authors Elke Theuwissen and Ronald Mensink report that combination of the two ingredients decreased serum LDL-cholesterol levels by almost ten percent, compared to control muesli.
How the study was done
The controlled, three-period crossover study recruited 40 men and women with mild hypercholesterolaemia and assigned them to randomly receive different types of muesli twice a day for four weeks. The muesli was formulated to provide 5g of wheat fibre (control), 5g of oat beta-glucan, or 5g of oat beta-glucan plus 1,5g of plant stanols.
Numerous clinical trials in controlled settings have reported that daily consumption of 1,5 to 3g of phytosterols/-stanols can reduce total cholesterol levels by eight to 17 percent, representing a significant reduction in the risk of cardiovascular disease.
In this case, the researchers note that the combination of 5g of beta-glucan and 1,5g of stanol esters reduced LDL-cholesterol levels by 9,6 percent, significantly more than the 5,0 percent from the beta-glucan-only muesli, relative to the control.
On the other hand, no changes in serum HDL-cholesterol or triacylglycerol concentrations were observed.
LDL cholesterol significantly lowered
"The combined effects of beta-glucan and plant stanol esters on LDL cholesterol concentrations have not been systematically examined," wrote Theuwissen. "We found that addition of plant stanol esters to the beta-glucan-enriched muesli significantly lowered LDL cholesterol concentrations by 4,4 percent.
"This effect was smaller than the estimated mean change of –8,5 percent for daily intakes of 1,5-1,9g of sterols or stanols. Thus, our findings suggest that the water-soluble fibre beta-glucan reduces the efficacy of plant stanols."
The researchers speculated that the addition of the beta-glucan increased the viscosity of the muesli inside the intestine. This would have a knock-on effect by inhibiting stanol transport into the enterocytes (a type of cell lining the intestinal walls).
"As a result, not only serum concentrations, but also the cholesterol-lowering efficacy of plant stanols, may have been decreased," they said.
"Whether this is indeed true and due to the effect of beta-glucan or the food matrix needs further investigation," they concluded. - (Decision News Media, February 2007)
Read more:
Cholesterol Centre
Fibre, plant sterols and antioxidants
