Objective: To measure the relative effects of each of four phytosterol ester-enriched low-fat foods (bread, breakfast cereal, milk and yoghurt) on serum lipids, plasma phytosterols and carotenoids.
Design: : Three research centres undertook a randomised, incomplete crossover, single-blind study consisting of four treatment periods of 3 weeks each, one of which was a control period. Each sterol-enriched test food provided 1.6 g/day of phytosterols as sterol esters.
Setting: General Community.
Subjects: In all 58, free-living men and women with mean age (s.d.) 54 (8) y, moderately elevated plasma total cholesterol 6.2 (0.7) mmol/l and body mass index 26.2 (3.0) kg/m(2).
Main outcome measures: Serum lipids, plasma phytosterols and carotenoids.
Results: Serum total and LDL cholesterol levels were significantly lowered by consumption of phytosterol-enriched foods: milk (8.7 and 15.9%) and yoghurt (5.6 and 8.6%). Serum LDL cholesterol levels fell significantly by 6.5% with bread and 5.4% with cereal. They were both significantly less efficacious than sterol-enriched milk (P<0.001). Plasma sitosterol increased by 17-23% and campesterol by 48-52% with phytosterol-enriched milk and bread. Lipid-adjusted beta-carotene was lowered by 5-10% by sterols in bread and milk, respectively.
Conclusions: This is the first study to demonstrate that cholesterol-lowering effects of plant sterol esters may differ according to the food matrix. Plant sterols in low-fat milk was almost three times more effective than in bread and cereal. Despite phytosterol-enriched cereal products resulting in lower serum cholesterol reductions compared to sterol-enriched milk, the detection of similar changes in plasma phytosterols demonstrated that such products still delivered and released phytosterols to the gut.