1. ¹CSIRO Health Sciences and Nutrition, Adelaide, South Australia, Australia
2. ²Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
3. ³Goodman Fielder Pty Ltd, Sydney, New South Wales, Australia
4. ⁴Baker Medical Research Institute, Melbourne, Victoria, Australia

Correspondence: P Clifton, CSIRO Health Sciences and Nutrition, Adelaide, South Australia, Australia. E-mail: peter.clifton@hsn.csiro.au

Received 23 February 2003; Revised 22 May 2003; Accepted 14 June 2003.

Abstract

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/m².

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 -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.