Safety Evaluation of Phytosterol Esters. Part 4. Faecal Concentrations of Bile Acids and Neutral Sterols in Healthy Normolipidaemic Volunteers Consuming a Controlled Diet either with or without a Phytosterol Ester-enriched Margarine

Abstract

A study was conducted in 12 healthy males and 12 females (mean age 36 years) to assess the impact of a margarine enriched with phytosterol esters on faecal concentrations of bile acids and sterols. During the run-in period, volunteers consumed 40 g of a control margarine for 21 consecutive days if male, and for 28 days if female. Half of the volunteers were then randomly allocated to consume the control margarine for another 21 or 28 days, respectively. The remaining subjects consumed 40 g of a margarine containing 8.6 g vegetable oil phytosterol (46% (w/w) β-sitosterol, 26% campesterol, 20% stigmasterol). Throughout the total study subjects consumed the same diet adjusted for individual energy requirements. The phytosterol ester-enriched spread significantly enhanced faecal neutral sterol concentrations from about 40 mg/g to 190 mg/g dry weight faeces. Faecal neutral sterol metabolites increased from about 30 mg/g to about 50 mg/g. The major parent sterols excreted were cholesterol, sitosterol, campesterol and stigmasterol. Sitosterol, campesterol and stigmasterol comprised 28%, 15% and 12% of the total faecal neutral sterols, reflecting the composition of the sterol enriched margarine. The major sterol metabolites excreted were metabolites formed by, predominantly, oxidation at the 3-position and metabolites saturated at the 5,6 position in a β-configuration. Faecal secondary bile acid concentration was reduced by vegetable oil sterols from 7.6 mg/g dry faeces to 6.0 mg/g. Consumption of vegetable oil phytosterols slightly but significantly increased the faecal concentration of 4-cholesten-3-one. However, 4-cholesten-3-one concentration remained very low (<2 mg/g) and in line with values reported in the literature for subjects fed high or low fat diets. No sterol oxides could be detected in the faeces. We conclude that in healthy adult males and females a high intake of vegetable oil phytosterol esters does increase the amount of neutral sterols in the faeces, as expected, but does not result in the increased formation of bile acids or sterol metabolites.