Plant Sterol Intake Research Articles

The effect of a combination of plant sterol-enriched foods in mildly hypercholesterolemic subjects

The purpose of this study was to evaluate the effect of low-fat products enriched with plant sterols in addition to a National Cholesterol Education Program step 1 diet on serum lipids and lipoproteins. This study was a double-blind, randomised, placebo-controlled cross-over design with a run-in period and 2 intervention periods, each lasting 4 weeks. A total of 46 mildly hypercholesterolemic subjects (age 50.6+/-9.8) completed the trial. The study products consisted of 20 g low-fat margarine (35% fat) and 250 ml low-fat milk (0.7% fat), in total delivering 2.3g plant sterols/d. Serum total and low-density lipoprotein cholesterol were significantly reduced by 5.5% (p<0.001, 95% CI: 2.5; 8.3) and 7.7% (p=0.001, 95% CI: 3.4; 11.9), respectively, by plant sterol-enriched products compared to placebo. Serum apolipoprotein B was significantly reduced by 4.6% (p<0.05, 95% CI: 1.7; 7.5), and apolipoprotein B/apolipoprotein A-I by 3.4% (p<0.05, 95% CI: 0.1; 6.6) after plant sterol intake compared to the placebo supplement. A combination of low-fat margarine and milk enriched with plant sterols significantly reduced low-density lipoprotein cholesterol, apolipoprotein B and the ratio of apolipoprotein B to apolipoprotein A-I in mildly hypercholesterolemic subjects, but had no effect on C-reactive protein and lipoprotein (a) concentrations. Unilever Denmark A/S.

Customary Use of Plant Sterol and Plant Stanol Enriched Margarine Is Associated with Changes in Serum Plant Sterol and Stanol Concentrations in Humans1

The consumption of products enriched with plant sterol or stanol esters lowers serum total and LDL-cholesterol concentrations, thereby most likely reducing the risk of coronary heart disease. However, using plant sterol (not plant stanol) enriched products elevates serum plant sterol concentrations in humans. This may be unwanted because health effects of elevated serum plant sterol concentrations are still controversial. Within postlaunch monitoring of functional foods, we compared serum plant sterol and plant stanol concentrations among users of plant sterol (n = 67) or plant stanol (n = 13) enriched margarines with those of matched nonusers (n = 81) in the ongoing Dutch Doetinchem cohort study. Subjects (aged 29–67 y) were examined in 1994–1998 (before the introduction of enriched margarines) and re-examined in 1999–2003. Serum concentrations of plant sterols and stanols were measured in samples from nonfasting subjects by GLC-MS. Intake of plant sterols was 1.1 ± 0.6 g/d and was associated with a decrease of serum total cholesterol concentration of 0.25 ± 0.91 mmol/L (4%, P < 0.05), a change that differed (P < 0.05) from the nonsignificant increase in nonusers (+2%, 0.12 ± 0.78 mmol/L, P = 0.16). Cholesterol-standardized serum sitosterol and campesterol increased in plant sterol users by 22% (P < 0.0001) and 103% (P < 0.0001), respectively. Cholesterol-standardized serum sitostanol and campestanol increased in plant stanol users by 197% (P = 0.02) and 196% (P = 0.01). To our knowledge, these data are the first to show changes in serum cholesterol, plant sterol, and plant stanol concentrations after (long-term) consumption of plant sterol and stanol enriched margarines in a free-living population in a nonexperimental setting. Whether the increased serum sterol concentrations result in adverse side effects needs to be investigated in future postlaunch monitoring studies.

Food sources of plant sterols in the EPIC Norfolk population

To investigate the intake of plant sterols and identify major dietary sources of plant sterols in the British diet. A total of 24 798 men and women recruited during 1993-1997, participating in the European Prospective Investigation into Cancer (EPIC-Norfolk). A database of the plant sterol (campesterol, beta-sitosterol, stigmasterol, campestanol and beta-sitostanol) content in foods, based on gas-liquid chromatography (GLC) analyses, was linked to nutritional intake data from food frequency questionnaires in the EPIC-Norfolk population. The mean (s.d.) intake of total plant sterols was 300 (108) mg/d for men and 293 (100) mg/d for women. Bread and other cereals, vegetables and added fats were the three major food sources of plant sterols representing 18.6 (8.9), 18.4 (8.5) and 17.3 (10.4)% of the total plant sterol intake respectively. Women had a higher plant sterol density than men (36.4 vs 32.8 mg/1000 kJ, P<0.001) and in relation to energy intake higher intakes of plant sterols from vegetables, bread and other cereals, added fats, fruits and mixed dishes (all P<0.001), whilst men had higher intakes of plant sterols from cakes, scones and chocolate, potatoes (all P<0.001) and other foods (P<0.01). The intake of plant sterols in UK, mainly from bread, cereals, fats and vegetables, is much higher than previously reported but comparable to recent European studies.

Basal plasma concentrations of plant sterols can predict LDL-C response to sitosterol in patients with familial hypercholesterolemia

Familial hypercholesterolemia (FH) is associated with a high risk of coronary heart disease. Pharmacological treatment and diet are both essential for the management of FH. Foods rich in plant sterols (PS) may play an important role in the treatment of patients with these disorders. To test the effect of the intake of PS on low-density lipoprotein (LDL) concentration, endothelial function (EF) and LDL particle size in 30 patients with FH. Randomized and crossover dietary intervention study. Tertiary outpatient care. Thirty-eight were recruited, but only 30 were subjected to four low-fat dietary intervention periods, each of 4 weeks. Each intervention had a different content of cholesterol (<150 or 300 mg/day) and sitosterol (<1 or 2 g/day). Lipid response, EF and LDL particle size were analysed after the intervention. Plasma sitosterol/cholesterol ratio was higher during both plant sterol-rich periods than during the low plant sterols periods. Basal sitosterol concentrations predicted the LDL-cholesterol response during the intake of plant sterol-enriched diets. The change in LDL-cholesterol was significantly greater in subjects in the upper and intermediate tertiles of basal plasma sitosterol concentrations (-21+/-8 mg/dl, P=0.03; -19+/-7 mg/dl, P=0.04, respectively) than in subjects in the lower tertile (8+/-5 mg/dl) when they changed from a low cholesterol diet to a low cholesterol plus plant sterol diet. Our study demonstrates that basal sitosterol values can predict hypolipidemic response in patients with FH.

Phytostérols et risque cardiovasculaire

Phytosterols are natural plant compounds. Phytostanols are derived from phytosterols hydrogenation. Both they inhibit intestinal dietary cholesterol absorption by competition, and they decrease LDL cholesterol by 8-15%, in a dose-dependant manner. They impair carotenoids bioavailability. A very small and variable part of phytosterols and phytostanols is absorbed. No epidemiological data is available for assessing the beneficial of plant sterols intake and cardiovascular risk. In the other hand there are many studies which have shown paradoxically a positive relationship between serum phytosterols concentrations and increase of the coronary heart disease risk. Other studies have established a link between the phytosterols absorption and their plasma and arterial plaque levels. Phytosterols and cholesterol hyperabsorbers subjects would be particularly involved in this unfavourable issue. Phytostanols could have a different effect from that point of view. In animal studies, data are less inconsistent with, in most of the studies, a lesser progression of atheroma lesions, perhaps due to an antiinflammatory effect of phytosterols in atheroma plaque. The place of phytosterols and phytostanols in the therapeutic step for cardiovascular prevention is actually not defined. Many queries are still open. Complementary studies are needed for improving the clinical indications and the efficiency of these compounds.

Combination of plant sterols and diacylglycerol oil lowers serum cholesterol and lipoprotein (a) concentrations in postmenopausal women with mild to moderate hypercholesterolemia

Summary Background & aims Atherogenic blood lipoprotein levels are dramatically increased during menopause. The solubilization of plant sterols (PS) in a diacylglycerol (DAG)-rich oil has recently been proposed as a more effective method of incorporating PS into food products; however, the effect of PS solubilized in DAG oil on serum lipid abnormalities in women after menopause is unknown. The effect of the daily consumption of DAG oil containing PS (4 wt%, PS/DAG) oil on serum lipid parameters was examined in postmenopausal women. Methods Fourteen postmenopausal women with mild to moderate hypercholesterolemia were randomly assigned to treatment with either PS/DAG or DAG (control) oil, and were instructed to replace the ordinary cooking oils used at home for 4 weeks in a crossover manner. Results The average intake of PS from the PS/DAG and control oils were 563 and 50 mg/day, respectively ( P =0.001). During control period, no effect on serum triacylglycerol and cholesterol concentrations was observed. Serum total cholesterol, low-density lipoprotein cholesterol and apolipoprotein B concentrations reduced by 10.2% ( P =0.004), 12.1% ( P =0.003) and 9.7% ( P =0.001) during the PS/DAG oil period compared to the control period, respectively. In addition, a slight but significant ( P =0.023) reduction in serum lipoprotein(a) concentration was observed, especially, in subjects with higher levels of baseline values (>20 mg/dL). Conclusions Dietary PS/DAG oil may be a useful adjunct for the management not only of blood cholesterols, but also of lipoprotein (a) in postmenopausal women.

Dietary Plant Sterols and Cholesterol Metabolism

Plant sterols, naturally occurring in foods of plant origin, reduce cholesterol absorption. Experimental studies show plant sterols to be an important part of the serum-cholesterol lowering effect of certain diets and dietary components. Epidemiological data show that individuals with higher intakes of plant sterols from their habitual diets have lower serum-cholesterol levels. To date, the role of naturally occurring plant sterols for lowering serum cholesterol has probably been underestimated. The consumption of dietary plant sterols should be a part of dietary advice to patients with hypercholesterolemia and the general public for the prevention and management of coronary heart disease.

Sitosterol and cholesterol in chylomicrons of type 2 diabetic and non-diabetic subjects: the relationship with ATP binding cassette proteins G5 and G8 and Niemann–Pick C1-like 1 mRNA

To the Editor: The dyslipidaemia of diabetes is in part related to a disturbance in genes regulating cholesterol absorption and excretion [1]. Sitosterolaemia is associated with increased atherosclerosis [2]. The higher the absorption of cholesterol, the more plant sterol is found in the atherosclerotic plaque [3]. The intestinal cholesterol transporter, Niemann–Pick C1-like 1 (NPC1L1), regulates cholesterol absorption and NPC1L1 mRNA is increased in type 2 diabetic patients [4]. ATP binding cassette proteins (ABC) G5 and G8 regulate cholesterol homeostasis by reexcreting some of the cholesterol and most of the plant sterols from the enterocyte back into the intestinal lumen [2]. Patients with diabetes have decreased ABCG5 and G8 mRNA expression [1]. In diabetes, chylomicron cholesterol is increased. Absorbed plant sterols that enter the circulation are rapidly re-excreted directly into the bile rather than being converted to bile salts. Thus abnormalities in plant sterol absorption may not be detected by examining serum in the fasting state. Foods enriched with plant sterol are being promoted to prevent atherosclerosis. However, the amount needed is more than five times the normal dietary plant sterol intake (0.3–0.4 g/day) and there are no endpoint studies to confirm benefit. Our aim was to examine the effect of a sitosterol-enriched diet on chylomicron composition and to examine the relationship between chylomicron sitosterol and intestinal ABCG5 and G8 and NPC1L1 gene expression. Six type 2 diabetic patients (two male, four female; age 63.8±3.4 years, BMI 29.5±5.6 kg/m, HbA1c 6.6±1.1% [means±SD]) and six control subjects of similar age (three male, three female, age 63.3±4.8, BMI 26.8±2.0 kg/m), none of whom were on statin treatment, were studied. All subjects gave informed consent and the study was approved by the hospital ethics committee. Two of the diabetic patients were treated with diet alone, two with metformin, one with metformin and rosiglitazone, and one with gliclazide. All subjects had previously had duodenal biopsies when undergoing routine gastroscopy for non-specific abdominal symptoms. Subjects with cancer, inflammatory bowel disease and coeliac disease or previous gastric operations were excluded. All subjects were given 1 week of a sitosterol-enriched diet (2.5 g/day), in which sitosterolenriched margarine and milk or yogurt were substituted for their normal dairy products. On the day of the study all subjects had fasting blood taken followed by a 4.60 MJ (1,100 kcal) high-fat test meal containing 2.0 g sitosterol. Blood was sampled at 4 and 6 h following the meal. Chylomicrons were isolated from plasma by ultracentrifugation. Apolipoprotein (Apo) B48 and Apo B100 were determined by gradient gel electrophoresis and quantified by densitometry [2]. Chylomicron cholesterol and sitosterol were determined by gas chromatography and identified using mass spectrometry. NPC1L1, and ABCG5 and ABCG8 mRNA were determined by TaqMan assay and quantified (arbitrary units, AU) by reference to GAPDH [2]. Fasting serum cholesterol for diabetic and control subjects was 5.0±0.9 and 4.7±1.1 mmol/l, respectively, and mean plasma triacylglycerol was 1.6±0.7 vs 2.1±1.3 mmol/l, Diabetologia (2007) 50:217–219 DOI 10.1007/s00125-006-0504-0

Les phytostérols et les phytostanols: quelle place pour la prévention cardiovasculaire?

Phytosterols are natural plant compounds. Phytostanols are derived from phytosterols’ hydrogenation. Both they inhibit intestinal dietary cholesterol absorption by competition, and they decrease LDL cholesterol by 8-15%, in a dose-dependant manner. They impair carotenoids bioavailability. A very small and variable part of phytosterols and phytostanols is absorbed. No epidemiological data is available for assessing the beneficial of plant sterols intake and cardiovascular risk. In the other hand there are many studies which have shown paradoxically a positive relationship between serum phytosterols concentrations and increase of the coronary heart disease risk. Other studies have established a link between the phytosterols’ absorption and their plasma and arterial plaque levels. Phytosterols and cholesterol hyperabsorbers subjects would be particularly involved in this unfavourable issue. Phytostanols could have a different effect from that point of view. In animal studies, data are less inconsistent with, in most of the studies, a lesser progression of atheroma lesions, perhaps due to an anti-inflammatory effect of phytosterols in atheroma plaque. The place of phytosterols and phytostanols in the therapeutic step for cardiovascular prevention is actually not defined. Many queries are still open. Complementary studies are needed for improving the clinical indications and the efficiency of these compounds.

Plasma Concentrations of Plant Sterols: Physiology and Relationship with Coronary Heart Disease

Recently, it has been questioned whether elevated levels of circulating plant sterols increase the risk of coronary heart disease (CHD). To date, no definitive conclusions regarding such a relationship have been reached, nor have there been any studies summarizing the factors that contribute to the observed elevations in plant sterol concentrations in plasma. Thus, the purpose of this review is to systematically compare the plant sterol levels of subjects from the general population and to describe factors that contribute to the variations observed. The question of whether elevated plasma concentrations of plant sterols are associated with an increased risk of CHD was also assessed. Results indicate that the key factors accounting for variations in circulating plant sterol concentrations include: apolipoprotein E phenotypes, ATP-binding cassette transporter polymorphisms, use of statin drugs, presence of metabolic syndrome, dietary intake of plant sterols, gender, and analytical techniques used in the measurement of plant sterols in the plasma. An analysis of the studies examining the relationship between circulating levels of plant sterols and CHD risk in non-sitosterolemic populations revealed no clear associations. Furthermore, it was shown that the above-mentioned factors play an important role in determining the levels of plant sterols in plasma. Since these factors may act as potential confounders, they must be controlled for before more solid conclusions can be reached.

Common Sources and Estimated Intake of Plant Sterols in the Spanish Diet

Plant sterols (PS) are minor lipid components of plants, which may have potential health benefits, mainly based in their cholesterol-lowering effect. The aim of this study was to determine the composition and content of PS in plant-based foods commonly consumed in Spain and to estimate the PS intake in the Spanish diet. For this purpose, the determination of PS content, using a modern methodology to measure free, esterified, and glycosidic sterol forms, was done. Second, an estimation of the intake of PS, using the Spanish National Food Consumption data, was made. The daily intake per person of PS--campesterol, beta-sitosterol, stigmasterol, and stigmastanol--in the Spanish diet was estimated at 276 mg, the largest component being beta-sitosterol (79.7%). Other unknown compounds, tentatively identified as PS, may constitute a considerable potential intake (99 mg). When the daily PS intake among European diets was compared in terms of campesterol, beta-sitosterol, stigmasterol, and stigmastanol, the PS intake in the Spanish diet was in the same range of other countries such as Finland (15.7% higher) or The Netherlands (equal). However, some qualitative differences in the PS sources were detected, that is, the predominant brown bread and vegetable fat consumption in the northern diets versus the white bread and vegetable oil consumption in the Spanish diet. These differences may help to provide a link between the consumption of PS and healthy effects of the diet.

Intake of a Single Morning Dose of Standard and Novel Plant Sterol Preparations for 4 Weeks Does Not Dramatically Affect Plasma Lipid Concentrations in Humans

Recommendations for decreasing the risk of developing cardiovascular disease include increasing the intake of plant sterols and fish oil. The cholesterol-lowering action of plant sterols, when provided in a fish-oil fatty acids vehicle, remains to be investigated in humans. A randomized, crossover-feeding, single-blind trial was conducted in 30 subjects with mild-to-moderate hypercholesterolemia to study the effects on plasma lipids of 2 novel forms of plant sterols: those combined with, or esterified to, fish-oil fatty acids. The treatments were margarine (control), free plant sterols, plant sterols esterified to fatty acids from sunflower oil, plant sterols esterified to very long-chained fatty acids from fish oil, and plant sterols combined with the same amount of very long-chained fatty acids from fish oil. Each sterol-containing food (1.0-1.8 g plant sterols/d) was consumed for 29 d as a single dose with breakfast under staff supervision. Compared with the control treatment, none of the plant sterol preparations reduced plasma total cholesterol or LDL cholesterol, triacylglycerol, apolipoprotein A-I, apolipoprotein B, lipoprotein (a), or C-reactive protein concentration. Relative to the control phase, all plant sterols treatment increased the plasma HDL cholesterol concentration (P < 0.05) by approximately 8%. In conclusion, because standard forms of plant sterols did not reduce plasma cholesterol concentrations, the efficacy of the new formulation of plant sterols cannot be confirmed from the present study design, where plant sterols were given as a single morning dose.

Cholesterol-lowering action of plant sterol-enriched products

Plant sterols are naturally occurring compounds that interfere with cholesterol absorption and thus reduce blood cholesterol levels. The objective of this review is to present recent advances in knowledge of the cholesterol-lowering action of plant sterols, focusing on the efficacy of plant sterol-enriched products, including full-fat, low-fat and non-fat food products. Although the cholesterol-lowering efficacy of plant sterols is well acknowledged, additional studies are needed to determine whether dietary cholesterol levels affect the cholesterol-lowering action of plant sterols, to establish the best time of day to consume plant sterol-enriched products, and to assess the optimal dose frequency of plant sterol intake. Fat spreads enriched with plant sterols/stanols have been shown to be effective in reducing circulating cholesterol levels in healthy adults with both normal and high cholesterol levels, as well as in children with hypercholesterolaemia. Such spreads can be used in combination with other approaches including a healthy diet, statin therapy and exercise for controlling blood cholesterol levels. Originally, plant sterols/stanols have been incorporated into fat spreads and, more recently, into low- or non-fat food products. However, the efficacy of plant sterols as cholesterol-lowering agents depends on their proper solubilization, while the majority of studies to date have incorporated plant sterols into vegetable oil-based spreads. Therefore, until more information is available, data from older studies using full-fat spreads cannot be used as a platform to promote novel and, as of yet, inadequately tested low-fat and non-fat plant sterol-enriched products.

Safety aspects and cholesterol-lowering efficacy of low fat dairy products containing plant sterols

The aim of this study was to investigate whether a plant sterol mixture would reduce serum cholesterol when added to low fat dairy products in subjects with hypercholesterolaemia, and to examine the effects of the mixture on the serum plant sterol and fat-soluble vitamin levels. A parallel, double-blind study. The study was performed in three different locations in Finland. In total, 164 mildly or moderately hypercholesterolaemic subjects participated in the study. The subjects were randomly divided into two groups: a plant sterol group and a control group. The subjects consumed the products for 6 weeks after a 3-week run-in period. The targeted plant sterol intake was 2 g/day in the sterol group. During the treatment period, there was a 6.5% reduction in serum total cholesterol in the sterol group while no change was observed in the control group (P<0.0005). Serum low-density lipoprotein (LDL) cholesterol was reduced by 10.4% in the sterol group and by 0.6% in the control group (P<0.00005). There was no change during the trial in serum high-density lipoprotein (HDL) cholesterol or triacylglycerol concentrations. The HDL/LDL cholesterol ratio increased by 16.1% in the sterol group and by 4.3% in the control group (P=0.0001). Serum plant sterol levels increased significantly (P=0.0001) in the sterol group. None of the fat-soluble vitamin levels decreased significantly when changes in serum total cholesterol were taken into account. The hypocholesterolaemic effect of sterol administration was not influenced by apolipoprotein E phenotype. Yoghurt, low-fat hard cheese and low-fat fresh cheese enriched with a plant sterol mixture reduced serum cholesterol in hypercholesterolaemic subjects and no adverse effects were noted in the dietary control of hypercholesterolaemia.

We-S12:4 Plant sterol intake to reduce risk for coronary heart disease

We-S12:4 Plant sterol intake to reduce risk for coronary heart disease

Simulation of prospective phytosterol intake in Germany by novel functional foods

A blood cholesterol-lowering margarine containing plant sterolesters was the first functional food placed on the European food market pursuant to the regulation (EC) 258/97. In the following years nine further applicants submitted the request to add plant sterol compounds to dairy products, cheeses, bakery products, sausages, plant oils and other products. The European Scientific Committee on Food (SCF) declared a precautionary intake limit of 3 g plant sterols per d by multiple dietary sources. Using the consumption data of the German National Food Consumption Study, carried out from 1985 to 1988 with 23 209 participants, we hypothetically added 0.3-2 g plant sterols to usual daily servings of ten different food products, selected from the novel food applications. We calculated the prospective plant sterol intake regarding each kind of enriched food and by stepwise accumulation of different functional foods in three enrichment scenarios. Within our enrichment context we find a phytosterol intake satiation, if multiple plant sterol-enriched foods are eaten. An enrichment amount of 2 g plant sterols per proposed food serving size results in an intake maximum of 13 g/d.

Estimation of plant sterol and cholesterol intake in Finland: quality of new values and their effect on intake

The Finnish national food composition database Fineli was updated with recent analytical values for plant sterols (PS) (sitosterol, campesterol, stigmasterol, avenasterol, brassicasterols and stanols) and cholesterol. The quality of the new analytical data was assessed. The aims of the present study were: (1) to compare the effect of old and new database values on PS and cholesterol intakes based on average per capita food consumption data; (2) to estimate the current intake and major sources of these compounds in various population groups according to the national FINDIET 1997 survey data. The intake of total PS was 305 mg/d for men and 237 mg/d for women. The respective intakes for cholesterol were 284 mg/d and 201 mg/d. Women had a higher density of PS in their diets than men, whereas the cholesterol density in the diets did not differ between genders. Cereals, margarine, vegetables and vegetable oils were the main food sources of PS. Meat, meat products and eggs were the main sources of cholesterol. A 9 % greater PS intake estimate was obtained with the new PS database compared with the old PS database, probably due to minor methodological differences between the new and old analyses. Notable changes in analytical methods suggest a lower value (-19 %) for cholesterol intake calculated from the new database compared with the old one. We conclude that researchers can have confidence in the new values for PS and cholesterol, because systematic evaluation of the new analytical values showed them to be of high quality.

Intake of dietary plant sterols is inversely related to serum cholesterol concentration in men and women in the EPIC Norfolk population: a cross-sectional study.

We examined the relation between intake of natural dietary plant sterols and serum lipid concentrations in a free-living population. Cross-sectional population-based study of 22,256 men and women aged 39-79 y resident in Norfolk, UK, participating in the European Prospective Investigation into Cancer (EPIC-Norfolk). MAIN EXPOSURE AND OUTCOME MEASURES: Plant sterol intake from foods and concentrations of blood lipids. Mean concentrations of total cholesterol and low-density lipoprotein cholesterol, adjusted for age, body mass index and total energy intake, decreased with increasing plant sterol intake in men and women. Mean total serum cholesterol concentration for men in the highest fifth of plant sterol intake (mean intake 463 mg daily) was 0.25 mmol/l lower and for low-density lipoprotein cholesterol 0.14 mmol/l lower than those in the lowest fifth of plant sterol consumption (mean intake 178 mg daily); the corresponding figures in women were 0.15 and 0.13 mmol/l. After adjusting for saturated fat and fibre intakes, the results for total cholesterol and low-density lipoprotein cholesterol were similar, although the strength of the association was slightly reduced. In a free-living population, a high intake of plant sterols is inversely associated with lower concentrations of total and low-density lipoprotein serum cholesterol. The plant sterol content of foods may partly explain diet-related effects on serum cholesterol concentration.

Proposed mechanisms of cholesterol‐lowering action of plant sterols

AbstractPlant sterols (or phytosterols) are naturally occurring compounds structurally related to cholesterol with different side chain configurations. To date, numerous studies have shown that dietary intake of plant sterols either in their free form or as fatty acid esters is effective at lowering plasma total and low density lipoprotein cholesterol. The main mechanism responsible for the cholesterol‐lowering effect of free and esterified plant sterols is the inhibition of intestinal cholesterol absorption. Several sites within the intestinal tract have been suggested where this inhibition might take place. Different mechanisms, such as competition with cholesterol for solubilisation in dietary mixed micelles, co‐crystallisation with cholesterol to form insoluble mixed crystals, and interference with the hydrolysis process by lipases and cholesterol esterases are believed to contribute to the lowering of serum cholesterol concentrations by plant sterols. There is also emerging evidence that plant sterols interfere with transport‐mediated processes of cholesterol uptake. The consequence of all these actions, although their individual contribution on the overall effect remains to be established, is that intestinal cholesterol absorption is reduced, while more cholesterol is excreted in the faeces.The aim of this review is to summarise the current understanding concerning the mechanism of action by which plant sterols affect cholesterol metabolism and thus exert their cholesterol‐lowering effect. The review will focus on the gut, e.g. on the physico‐chemical effects at the gastric‐duodenal level, on absorptive site effects, and on intra‐cellular trafficking, i.e. effects at the epithelial cell level.

Plant sterols in vegetables, fruits and berries

AbstractThe plant sterol contents of the most important vegetables, fruits and berries available in Finland were determined by capillary gas chromatography. The sample preparation procedure included both acid and alkaline hydrolysis to liberate sterols from their conjugates. The plant sterol contents of fresh vegetables ranged from 51 to 370 mg kg−1 fresh weight (fw) in samples obtained from retail sale. The highest contents (&gt;300 mg kg−1) were measured in broccoli, Brussels sprouts, cauliflower and dill and the lowest (51 mg kg−1) in potato. The range of sterol contents on a dry weight (dw) basis was high, 246–4100 mg kg−1 dw. Considerable variation was also observed when individual samples of some vegetables were compared. Sitosterol was the main sterol (proportion 43–86%) in all vegetables except cucumber and spinach, in which Δ7‐sterols dominated. The total sterol contents were in the range 116–228 mg kg−1 fw in all fresh fruits except avocado, which contained more sterols, 752 mg kg−1 fw. In fresh berries the corresponding range was 60–279 m kg−1 fw. The wild berries lingonberry and blueberry were better plant sterol sources than the cultivated berries blackcurrant, redcurrant and strawberry. In fruits and berries the proportion of sitosterol ranged from 61–93% total sterols. On the basis of the results, the contribution of vegetables, fruits and berries to the total average daily plant sterol intake was estimated to be ca 60 mg.© 2003 Society of Chemical Industry