| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1253362 | Chemistry and Physics of Lipids | 2011 | 7 Pages |
High dose daily intake of plant sterols decreases the uptake of cholesterol in the intestine by competitive mechanisms and thus leads to reduced serum levels of total and LDL-cholesterol. By this, the commercialization of plant sterol enriched ‘functional food’ products is rapidly increasing. Subjects using these kinds of diet present a duplication of their serum plant sterol levels after long-term intake. In analogy to cholesterol, plant sterols such as campesterol and sitosterol can be oxidized to oxyphytosterols and these may counteract the primary anti-atherosclerotic action of cholesterol lowering. In order to investigate the whole spectrum of the consequences following high plant sterol intake a highly sensitive and specific isotope dilution gas chromatography–mass spectrometry method for the analysis of 7-oxygenated campesterol/sitosterol in trace amounts in human serum is presented in this paper. The validation was based on limits for detection and quantification, recovery, precision and minimization of autoxidation during work-up. Our results show an overall coefficient of variation ≤10% for the precision. The lowest limits for detection and quantification for 7α-hydroxy-campesterol were 7 pg/mL and 23 pg/mL, respectively. Data for overall sum recovery ranged from 92% to 115%. We practically used this method for analysis of oxyphytosterols simultaneously with plant sterol concentrations in serum from healthy volunteers. Sixteen subjects were treated with plant sterol enriched margarine (3 g/day) for 28 days. The results showed a significant increase of the oxyphytosterol 7β-hydroxy-sitosterol from 1.19 ± 0.54 (before intake) to 2.24 ± 1.24 ng/mL (mean ± SD; +86.7%; P = 0.007) after intake of the margarine. There was a highly significant correlation between the serum levels of campesterol and the sum of 7-oxygenated campesterol (R2 = 0.915; P < 0.001) and sitosterol and the sum of 7-oxygenated sitosterol (R2 = 0.915; P < 0.001). We can conclude from this study that the analytic method is well suited for detection of OPS, even at trace amounts.
► An isotope dilution GC–MS method for analysis of oxyphytosterols in human serum. ► The detection of 7-oxygenated oxyphytosterols at trace levels is reproducible. ► 7β-OH-Sitosterol increases in serum after intake of plant sterol enriched margarine.
