Comparable reduction in cholesterol absorption after two different ways of phytosterol administration in humans.

PURPOSE: Consumption of phytosterols is a nutritional strategy to reduce cholesterol absorption, but the efficacy of various phytosterol intake modalities remains uncertain. The main objective was to investigate the effects of phytosterol esters (PE) provided either as a spread (dispersed in fat) during a mixed meal or as a minidrink (micro-dispersed in liquid form) after a meal. METHODS: In a randomized, single-blinded crossover design, 12 healthy intubated volunteers tested three different liquid meal sequences with and without PE. The liquid meal (500 mL, Fortisip) contained an oral dose (80 mg) of deuterium-enriched cholesterol (D7C). The intubation was stopped at 240 min, and the fate of sterols was determined in the different phases of duodenal content samples as function of time. A second solid fat-containing meal without sterols was consumed at 270 min. D7C was quantified in chylomicrons and plasma for 8 h. The conditions tested were as follows: (1) no PE added (control), (2) PE in a spread added into a liquid meal (PE-spread meal) and (3) PE given 30 min after a liquid meal as 100-g yoghurt drink (PE-minidrink meal). RESULTS: Addition of PE decreased the incorporation of cholesterol into the duodenum aqueous phase including micelles. PE added as a spread or as a minidrink significantly and comparably lowered meal cholesterol occurrence in chylomicrons (-40 % for PE-spread and -54 % for PE-minidrink, p < 0.0001) compared with the control meal. CONCLUSIONS: PE either dispersed in fat during a meal or micro-dispersed in a liquid form after a meal resulted in a markedly reduced occurrence of meal-derived cholesterol in the circulation at a comparable extent.

Phytosterol ester processing in the small intestine: impact on cholesterol availability for absorption and chylomicron cholesterol incorporation in healthy humans.

Phytosterols (plant sterols and stanols) can lower intestinal cholesterol absorption, but the complex dynamics of the lipid digestion process in the presence of phytosterol esters (PEs) are not fully understood. We performed a clinical experiment in intubated healthy subjects to study the time course of changes in the distribution of all lipid moieties present in duodenal phases during 4 h of digestion of meals with 3.2 g PE (PE meal) or without (control meal) PE. In vitro experiments under simulated gastrointestinal conditions were also performed. The addition of PE did not alter triglyceride (TG) hydrolysis in the duodenum or subsequent chylomicron TG occurrence in the circulation. In contrast, cholesterol accumulation in the duodenum aqueous phase was markedly reduced in the presence of PE (-32%, P < 0.10). In vitro experiments confirmed that PE reduces cholesterol transfer into the aqueous phase. The addition of PE resulted in a markedly reduced presence of meal-derived hepta-deuterated cholesterol in the circulation, i.e., in chylomicrons (-43%, PE meal vs. control; P < 0.0001) and plasma (-54%, PE meal vs. control; P < 0.0001). The present data show that addition of PE to a meal does not alter TG hydrolysis but displaces cholesterol from the intestinal aqueous phase and lowers chylomicron cholesterol occurrence in humans.

Serum Concentration of Plant Sterol Oxidation Products (POP) Compared to Cholesterol Oxidation Products (COP) after Intake of Oxidized Plant Sterols: A Randomised, Placebo-Controlled, Double-Blind Dose‒Response Pilot Study.

Plant sterols (PS) are oxidized to PS oxidation products (POP). This study quantified the change in serum POP compared to cholesterol oxidation products (COP) after the intake of increasing POP doses. This was a double-blind, randomized, placebo-controlled, dose‒response pilot study with healthy individuals in four groups (15 per group). The control group received products with no added PS or POP and treatment groups received daily 20-25 g margarine with added PS (mean 3 g/d) and two cookies (~28 g) for six weeks. Cookies delivered 8.7 (low-dose), 15.2 (medium-dose), or 37.2 (high-dose) mg/d POP. Fasting serum POP and COP were measured at the baseline, days 14, 28, and 42 in all participants and days 7, 21, and 35 in a subset. Sixty individuals completed the study; 52 were included in per protocol analysis. Serum POP increased with increasing POP intake and plateaued at dose >15 mg/d. Stabilized POP concentrations were (mean ± SD) 38.9 ± 6.9, 91.0 ± 27.9, 144.4 ± 37.9 and 203.0 ± 63.7 nmol/L, for control, low-, medium-, and high-dose POP groups, respectively. For all groups, the serum COP ranged from 213 to 262 nmol/L and the average POP/COP ratio was <1. Serum POP concentrations increased non-linearly, reaching stabilized concentrations in <7 days, and remained below COP concentrations after the intake of increasing POP doses.

Oxidation of sitosterol and campesterol in foods upon cooking with liquid margarines without and with added plant sterol esters.

Plant sterol (PS) oxidation products (POP) derived from sitosterol and campesterol were measured in 15 foods cooked with liquid margarine without (control) and with added 7.5% PS. POP were analyzed using a GC-MS method. PS liquid vs. control margarine resulted in a higher median POP content per food portion (1.35mg, range 0.08-13.20mg versus 0.23mg, 0.06-0.90mg), a lower PS oxidation rate (0.63 vs. 1.29%) and lower oxidation susceptibility of sitosterol vs. campesterol. POP formation was highest in shallow-fried potatoes with PS liquid margarine (64.44mg per portion food plus residual fat). Mean relative abundances of epoxy-, 7-keto-, 7-hydroxy- and triol-PS derived from sitosterol and campesterol were 40.0, 34.4, 21.5 and 4.0% with control vs. 44.1, 23.8, 29.6 and 2.4% with PS liquid margarine. In conclusion, PS liquid margarine increased POP content in foods with a POP profile characterized by a higher ratio of epoxy- to 7-keto-derivatives.

Thermal stability of plant sterols and formation of their oxidation products in vegetable oils and margarines upon controlled heating.

Fat-based products like vegetable oils and margarines are commonly used for cooking, which may enhance oxidation of plant sterols (PS) present therein, leading to the formation of PS oxidation products (POP). The present study aims to assess the kinetics of POP formation in six different fat-based products. Vegetable oils and margarines without and with added PS (7.5-7.6% w/w) in esterified form were heated in a Petri-dish at temperatures of 150, 180 and 210°C for 8, 12 and 16min. PS and POP were analysed using GC-FID and GC-MS-SIM, respectively. Increasing PS content, temperature and heating time led to higher POP formation in all tested fat-based products. PS (either naturally occurring or added) in margarines were less susceptible to oxidation as compared to PS in vegetable oils. The susceptibility of sitosterol to oxidation was about 20% lower than that of campesterol under all the applied experimental conditions. During heating, the relative abundance of 7-keto-PS (expressed as% of total POP) decreased in all the fat-based products regardless of their PS contents, which was accompanied by an increase in the relative abundance of 7-OH-PS and 5,6-epoxy-PS, while PS-triols were fairly unchanged. In conclusion, heating time, temperature, initial PS content and the matrix of the fat-based products (vegetable oil vs. margarine) showed distinct effects on POP formation and composition of individual POP formed.

Phytosterol oxidation products (POP) in foods with added phytosterols and estimation of their daily intake: A literature review.

1To evaluate the content of phytosterol oxidation products (POP) of foods with added phytosterols, in total 14 studies measuring POP contents of foods with added phytosterols were systematically reviewed. In non-heated or stored foods, POP contents were low, ranging from (medians) 0.03-3.6 mg/100 g with corresponding oxidation rates of phytosterols (ORP) of 0.03-0.06%. In fat-based foods with 8% of added free plant sterols (FPS), plant sterol esters (PSE) or plant stanol esters (PAE) pan-fried at 160-200°C for 5-10 min, median POP contents were 72.0, 38.1, and 4.9 mg/100 g, respectively, with a median ORP of 0.90, 0.48, and 0.06%. Hence resistance to thermal oxidation was in the order of PAE > PSE > FPS. POP formation was highest in enriched butter followed by margarine and rapeseed oil. In margarines with 7.5-10.5% added PSE oven-heated at 140-200°C for 5-30 min, median POP content was 0.3 mg/100 g. Further heating under same temperature conditions but for 60-120 min markedly increased POP formation to 384.3 mg/100 g. Estimated daily upper POP intake was 47.7 mg/d (equivalent to 0.69 mg/kg BW/d) for foods with added PSE and 78.3 mg/d (equivalent to 1.12 mg/kg BW/d) for foods with added FPS as calculated by multiplying the advised upper daily phytosterol intake of 3 g/d with the 90% quantile values of ORP. In conclusion, heating temperature and time, chemical form of phytosterols added and the food matrix are determinants of POP formation in foods with added phytosterols, leading to an increase in POP contents. Practical applications: Phytosterol oxidation products (POP) are formed in foods containing phytosterols especially when exposed to heat treatment. This review summarising POP contents in foods with added phytosterols in their free and esterified forms reveals that heating temperature and time, the chemical form of phytosterols added and the food matrix itself are determinants of POP formation with heating temperature and time having the biggest impact. The estimated upper daily intakes of POP is 78.3 mg/d for fat-based products with added free plant sterols and 47.7 mg/d for fat-based products with added plant sterol esters. Phytosterols in foods are susceptible to oxidation to form phytosterol oxidation products (POP). This review summarizes literature data regarding POP contents of foods with added phytosterols that were exposed to storage and heat treatments.

Development and validation of methodologies for the quantification of phytosterols and phytosterol oxidation products in cooked and baked food products.

Chromatography-mass spectrometry (GC-MS) methodologies for the analysis of the main phytosterols (PS) and phytosterol oxidation products (POPs) present in 19 different foodstuffs cooked or baked using margarines with or without added plant sterols are presented. Various methods for fat extraction were evaluated to allow the GC-MS analysis of large numbers of prepared vegetable, fish and meat products, egg and bakery items in a practically feasible manner. The optimized methods resulted in a good sensitivity and allowed the analysis of both PS and POPs in the broad selection of foods at a wide range of concentrations. Calibration curves for both PS and POPs showed correlation coefficients (R(2)) better than 0.99. Detection limits were below 0.24mgkg(-1) for PS and 0.02mgkg(-1) for POPs, respectively. Average recovery data were between 81% and 105.1% for PS and between 65.5 and 121.8% for POPs. Good results were obtained for within- and between-day repeatability, with most values being below 10%. Entire sample servings were analyzed, avoiding problems with inhomogeneity and making the method an exact representation of the typical use of the food by the consumer.

Formation of Plant Sterol Oxidation Products in Foods during Baking and Cooking Using Margarine without and with Added Plant Sterol Esters.

Plant sterols (PS) in foods are subject to thermal oxidation to form PS oxidation products (POP). This study measured POP contents of 19 foods prepared by typical household baking and cooking methods using margarines without (control) and with 7.5% added PS (as 12.5% PS-esters, PS-margarine). Median POP contents per portion size of cooked foods were 0.57 mg (range 0.05-1.11 mg) with control margarine versus 1.42 mg (range 0.08-20.5 mg) with PS-margarine. The oxidation rate of PS (ORP) was 0.50% (median) with the PS-margarine and 3.66% with the control margarine. Using the PS-margarine, microwave-cooked codfish had the lowest POP content, with 0.08 mg per portion, while shallow-fried potatoes had the highest POP content, 20.5 mg per portion. Median POP contents in cookies, muffins, banana bread, and sponge cake baked with the control or PS-margarine were 0.12 mg (range 0.11-0.21 mg) and 0.24 mg (range 0.19-0.60 mg) per portion, with a corresponding ORP of 1.38% and 0.06%, respectively. POP contents in all the cooked and baked foods did not exceed 20.5 mg per typical portion size. A wide variation in the distribution of individual POP among different foods existed, with 7-keto-PS and 5,6-epoxy-PS being the major oxidation products.