phytosterols and erucic-acid

Plant stanols lower intestinal cholesterol absorption. This causes a decrease in serum low-density lipoprotein (LDL)-cholesterol, despite a compensatory increase in cholesterol synthesis. We therefore hypothesized that plant stanols also change LDL-cholesterol-standardized concentrations of ubiquinol-10 (a side product of the cholesterol synthesis cascade) and of those fat-soluble antioxidants that are mainly carried by LDL. To examine this, 112 nonhypercholesterolemic subjects consumed low erucic acid rapeseed oil (LEAR)-based margarine and shortening for 4 weeks. For the next 8 weeks, 42 subjects consumed the same products, while the other subjects received products with vegetable oil-based stanols (2.6 g sitostanol plus 1.2 g campestanol daily, n = 36) or wood-based stanols (3.7 g sitostanol plus 0.3 g campestanol daily, n = 34). Consumption of both plant stanol ester mixtures increased cholesterol synthesis and lowered cholesterol absorption, as indicated by increased serum cholesterol-standardized lathosterol and decreased plant sterol concentrations, respectively. Compared with the control group, absolute plasma ubiquinol-10 concentrations were lowered by 12.3% +/- 18.9% (-0.14 microg/mL v. the control group; P =.004; 95% confidence interval [CI] for the difference in changes, -0.05 to -0.22 microg/mL) in the vegetable oil-based group and by 15.4% +/- 13.0% (-0.17 microg/mL v. the control group; P <.001; 95% CI for the difference, -0.08 to -0.27 microg/mL) in the wood-based group. Changes in LDL-cholesterol-standardized ubiquinol-10 concentrations were not significantly changed. The most lipophylic antioxidants, the hydrocarbon carotenoids (beta-carotene, alpha-carotene, and lycopene), decreased most, followed by the less lipophylic oxygenated carotenoids (lutein/zeaxanthin and beta-cryptoxanthin) and the tocopherols. These reductions were related to the reduction in LDL, which carry most of these antioxidants. The decrease in the hydrocarbon carotenoids, however, was also significantly associated with a decrease in cholesterol absorption. LDL-cholesterol-standardized antioxidant concentrations were not changed, except for beta-carotene, which was still, although not significantly, lowered by about 10%. We conclude that the increase in endogenous cholesterol synthesis during plant stanol ester consumption does not result in increased LDL-cholesterol-standardized concentrations of ubiquinol-10, a side product of the cholesterol synthesis cascade. Fur

Topics: Absorption; Adolescent; Adult; Antioxidants; Carotenoids; Cholesterol; Cholesterol, LDL; Diet; Erucic Acids; Fats; Fatty Acids, Monounsaturated; Female; Humans; Male; Margarine; Middle Aged; Phytosterols; Plant Oils; Plants, Edible; Rapeseed Oil; Sitosterols; Solubility; Ubiquinone; Vitamin A; Vitamin E; Wood

Improving oil and protein quality for food and feed purposes is an important goal in rapeseed (Brassica napus L.) breeding programs. Rapeseed contains phytosterols, used to enrich food products, and sinapate esters, which are limiting the utilization of rapeseed proteins in the feed industry. Increasing the phytosterol content of oil and lowering sinapate ester content of meal could increase the value of the oilseed rape crop. The objective of the present study was to identify quantitative trait loci (QTL) for phytosterol and sinapate ester content in a winter rapeseed population of 148 doubled haploid lines, previously found to have a large variation for these two traits. This population also segregated for the two erucic acid genes. A close negative correlation was found between erucic acid and phytosterol content (Spearman's rank correlation, r(s) = -0.80**). For total phytosterol content, three QTL were detected, explaining 60% of the genetic variance. The two QTL with the strongest additive effects were mapped on linkage groups N8 and N13 within the confidence intervals of the two erucic acid genes. For sinapate ester content four QTL were detected, explaining 53% of the genetic variance. Again, a close negative correlation was found between erucic acid and sinapate ester content (r(s) = -0.66**) and the QTL with the strongest additive effects mapped on linkage groups N8 and N13 within the confidence intervals of the two erucic acid genes. The results suggests, that there is a pleiotropic effect of the two erucic acid genes on phytosterol and sinapate ester content; the effect of the alleles for low erucic acid content is to increase phytosterol and sinapate ester content. Possible reasons for this are discussed based on known biosynthetic pathways.

Topics: Brassica napus; Choline; Erucic Acids; Esters; Genetic Markers; Phytosterols; Plant Proteins; Quantitative Trait Loci

Formation of trans fatty acids and cyclic fatty acid monomers was investigated during refining of low erucic acid rapeseed oil. The first steps of the refining process, that is, degumming, neutralization, and bleaching, hardly modified the fatty acid profile. In contrast, deodorization produced substantial quantities of trans fatty acids (>5% of total fatty acids) and small amounts of cyclic fatty acid monomers (650 mg of cyclic fatty acid monomers/kg of oil) when severe conditions (5-6 h at 250 degrees C) were used. Alpha-linolenic acid was the main precursor of cyclic fatty acid monomers. The influence of deodorization on the chemical composition of low erucic acid rapeseed oil was studied additionally. Whereas free fatty acids, peroxides, and tocopherols decreased, neither total polar compounds nor oxyphytosterols changed during deodorization. Oxyphytosterols were identified by GC-MS. Three oxyphytosterols not yet observed in oil were tentatively identified as 6beta-hydroxycampestanol, 6beta-hydroxysitostanol, and 6beta-hydroxybrassicastanol. Brassicasterol oxides were the most abundant oxyphytosterols.

Topics: Erucic Acids; Fatty Acids; Fatty Acids, Monounsaturated; Food Handling; Gas Chromatography-Mass Spectrometry; Hot Temperature; Peroxides; Phytosterols; Plant Oils; Rapeseed Oil; Tocopherols