Almost one-third of cholesterol reductions achieved by consuming a heart-healthy diet are due to plant sterols, suggests a new study from Canada that supports the ingredient's efficacy.
Forty-two subjects with high cholesterol levels were assigned to eat a diet high in soy protein, viscous fibres, and almonds for 80 weeks, and supplemented with plant sterols. At the end of the study, significant reductions were observed in LDL cholesterol levels, report the researchers in the journal Metabolism.
High cholesterol levels, hypercholesterolaemia, have a long association with many diseases, particularly cardiovascular disease (CVD), the cause of almost 50 per cent of deaths in Europe, and are reported to cost the EU economy an estimated €169bn ($202bn) per year.
"In the context of a low-saturated fat diet and in combination with other cholesterol-lowering dietary components, plant sterols appear to exert a very significant effect on LDL-C reduction of the order of 10 per cent for two grams per day of plant sterols," wrote lead author David Jenkins from St Michael's Hospital, Toronto.
"This figure is similar to studies where plant sterols have been given as the only cholesterol-lowering agent."
Numerous clinical trials in controlled settings have reported that daily consumption of 1.5 to 3 grams of phytosterols/-stanols can reduce total cholesterol levels by eight to 17 per cent, representing a significant reduction in the risk of cardiovascular disease.
The new study, which was partly funded by Unilever and many of the scientists admit ties to the company, adhered to the guidelines set out by the National Cholesterol Education Program Adult Treatment Panel III (ATP III). According to these guidelines, LDL cholesterol reductions of 25 to 35 per cent are estimated.
"However, it is not clear what cholesterol reduction each functional food component contributes to the overall cholesterol reduction observed and whether all ingredients have to be present," explained the researchers.
Jenkins and co-workers prescribed the 42 subjects (average age 63) to a diet containing viscous fibres (10 g/1,000 kcal), soy protein (22.5 g/1,000 kcal), and almonds (23 g/1,000 kcal) for 80 weeks. In addition, plant sterols were taken (one gram per 1,000 kcal), except during weeks 52 to 62.
Over the course of the study, LDL-cholesterol levels decreased by an average of 15.4 per cent, while such reductions were only 9.0 per cent in the absence of plant sterols.
Complete data was only available in 18 subjects, but similar reductions were observed, report the researchers, with a 16.7 per cent decrease overall, and 10.3 per cent in the absence of sterols.
The results showed, state Jenkins and co-workers, that plant sterols contribute over one-third of the LDL-cholesterol reductions observed in combination with other cholesterol-lowering foods.
"Increased plant sterol intakes are likely to have been a part of the ancestral human diet at about one gram per day and are part of a more plant-based diet as currently recommended for CHD risk reduction, including green leafy vegetables, raw or dry roasted nuts, and non-hydrogenated vegetable oils," wrote the researchers.
"Their reintroduction into the Western diet to prevent CHD may be seen as similar to the desire to reintroduce fibre into the diet to reduce the risk of a number of chronic diseases.
"Plant sterols therefore appear a good fit with other cholesterol-lowering components in a dietary portfolio to reduce CHD risk," they concluded.
The researchers were affiliated with St Michael's Hospital (Toronto), the University of Toronto, Unilever R&D Vlaardingen, and the Almond Board of California.
Source: Metabolism (Elsevier)
January 2008, Volume 57, Issue 1, Pages 130-139
"Effect of plant sterols in combination with other cholesterol-lowering foods"
Authors: D.J.A. Jenkins, C.W.C. Kendall, T.H. Nguyen, A. Marchie, D.A. Faulkner, C. Ireland, A.R. Josse, E. Vidgen, E.A. Trautwein, K.G. Lapsley, C. Holmes, R.G. Josse, L.A. Leiter, P.W. Connelly, W. Singer