Cholesterol-lowering effects of plant sterol esters differ in milk, yoghurt, bread and cereal

Study of the effects of a diet supplemented with active components on lipid and glycemic profiles

OBJECTIVES

Currently, there are numerous studies on risk factors for cardiovascular disease and the potential for functional foods to bring benefits or improve people's health. However, most of these studies are conducted with middle-aged individuals. The aim of this study was to evaluate the effects of supplementing a typical diet with some functional components, which are substances that when consumed in small quantities can improve people's welfare.

METHODS

The participants in this study were young; slightly overweight; had normal glucose tolerance; and had lipid values indicating dyslipidemia or close dyslipidemia. Following a 4-wk run-in phase, participants followed either a diet containing foods enriched with ω-3 fatty acids, β-glucans, phytosterols, and vitamin E or an isoenergetic diet without the active components. Sixteen individuals (age range 20 to 37 y) were randomly assigned to one of two groups. At the end of treatment, while fasting, plasma concentrations of triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and total cholesterol were measured. Furthermore, blood glucose was evaluated after fasting and after a meal enriched with β-glucans.

RESULTS

There was a statistically significant reduction (α < 0.05) across the lipid profile. A meal rich in β-glucans produced a glycemic response significantly lower than the nonenriched meal.

CONCLUSION

The dietary supplements used in this work, based on the integration of functional components into the usual diet of the population, have proved effective in reducing peak levels of postprandial glucose and the risk for dyslipidemia. Therefore, these functional components proved a valuable aid in the prevention of cardiovascular diseases and metabolic disorders.

Combined effect of plant sterols and dietary fiber for the treatment of hypercholesterolemia

Hypercholesterolemia is a major contributor for disease burden in both the developed and developing world and an important risk factor for cardiovascular diseases (CVD). Phytosterols (PhS) and dietary fiber (DF) act as low density lipoprotein cholesterol (LDL-C) lowering agents, offering an effective treatment against high blood cholesterol and CVD. The aim of this review was to consider clinical evidence that analyzed the combination of PhS and DF in a cereal carrier for lowering LDL-C. Electronic database searches were carried out to identify peer-reviewed journal articles, from which five intervention studies that combined both components in a cereal carrier were identified and included in the present review. LDL-C lowering effects varied widely among studies, due to large heterogeneity in study design, subject baseline characteristics, length of the interventions, PhS and DF dosage and type of DF used. In relation to a time of intake, three studies suggested a frequency or distribution of the product's consumption during the day, while two studies did not consider this factor. Overall, the selected studies found significant differences on LDL-C concentrations, although not all of them reached the expected outcomes. Future research should be conducted to explore the effect that different types of DF exert on LDL-C when combined with PhS, and to analyze the effect of the product's time of intake in order to suggest an optimal moment of the day for its consumption.

Key points for maximum effectiveness and safety for cholesterol-lowering properties of plant sterols and use in the treatment of metabolic syndrome

According to the American Diabetes Association and the Adult Treatment Panel III, the starting point for treating metabolic syndrome (MS) is a change of lifestyle. In addition, action on the main symptoms of MS by means of dietary supplements, can be helpful in view of the chronic course of the disease. The term 'phytosterols' refers to sterols and stanols composed of lipophilic triterpenes, a family that is widely distributed in the plant kingdom and whose cholesterol-lowering properties have been amply demonstrated. In the light of the recent literature, the key points for maximum effectiveness and safety of sterols are the following. (A) Plant sterols should be taken with meals: clinical trials have shown that when plant sterols are consumed close to mealtimes, low-density lipoprotein cholesterol may decrease by 9.4%, while when they are taken between meals, the reduction is about 6%. (B) The optimal dosage is 2-2.5 g day(-1) in a single dose. More than 3 g day(-1) has not been found to have any additional beneficial effect and increases the risk of side effects. (C) The food matrix used to dissolve the phytosterols should contain a certain amount of fat. A milk-based matrix appears optimal from this point of view.

Consumption of plant sterol-enriched foods and effects on plasma plant sterol concentrations--a meta-analysis of randomized controlled studies

OBJECTIVE

Intake of plant sterol (PS)-enriched foods effectively lowers plasma total- and LDL-cholesterol concentrations while increasing plasma PS concentrations. The magnitude of this increase has not been systematically assessed. This study aimed to investigate the effect of PS-enriched foods on plasma PS concentrations by performing a meta-analysis of randomized controlled studies.

METHODS

Published PS intervention studies reporting plasma PS concentrations were searched through June 2012. Studies were selected that fulfilled pre-defined in- and exclusion criteria. Data were extracted, particularly on campesterol, sitosterol, total- and LDL-cholesterol. Random-effects models were used to calculate net effects while weighing each study by the inverse of its variance. Potential sources of heterogeneity were investigated.

RESULTS

The meta-analysis included data from 41 studies (55 strata) with in total 2084 subjects. The average dose of PS from enriched foods was 1.6 g/d (range: 0.3-3.2 g/d). Plasma sitosterol and campesterol concentrations were increased by on average 2.24 μmol/L (31%) and 5.00 μmol/L (37%), respectively, compared to control. Total- and LDL-cholesterol were reduced by on average 0.36 mmol/L (5.9%) and 0.33 mmol/L (8.5%), respectively. The increase in sitosterol and campesterol was impacted by the dose of PS, the baseline PS concentration and the PS composition of the test products. In the highest PS dose category (2.0-3.2 g/d), increases in sitosterol and campesterol were on average 3.56 and 7.64 μmol/L, respectively.

CONCLUSION

Intake of PS-enriched foods increases plasma sitosterol and campesterol concentrations. However, total PS remain below 1% of total sterols circulating in the blood.

The cholesterol lowering efficacy of plant stanol ester yoghurt in a Turkish population: a double-blind, placebo-controlled trial

Background

We evaluated the cholesterol lowering efficacy of low-fat spoonable yoghurt with 1.9 g/d plant stanols as esters on plasma lipid profiles of Turkish subjects with mild to moderate hypercholesterolemia.

Methods

Using a randomised, double-blind, placebo-controlled study design, intervention (n = 35) and control (n = 35) groups consumed either 115 g low-fat yoghurt with 1.9 g/d plant stanols as esters or placebo yoghurt, respectively, for 4 weeks. Seventy subjects with untreated mild to moderate hypercholesterolemia (aged 23-65 years) were recruited. Changes in the lipid profile, including lipoproteins, apolipoproteins, and triglycerides, and anthropometric measurements were monitored at screening, baseline, and at the end of the second, third, and fourth weeks of intervention. The general linear model repeated measures procedure was used to test differences in the repeated continuous variables between study groups.

Results

Serum total cholesterol (4.6%), LDL cholesterol (6.3%), and non-HDL cholesterol (6.2%) concentrations were reduced significantly from baseline in the plant stanol group compared to the control group (p = 0.007, p = 0.005 and p = 0.005, respectively). A variation in the response of serum total and LDL cholesterol between the subjects in plant stanol group was obtained. No clinically significant change in anthropometrical measurements was observed during the intervention.

Conclusions

The spoonable low-fat yoghurt with 1.9 g/d plant stanols as esters lowered total, LDL, and non-HDL cholesterol levels in Turkish subjects with mild to moderate hypercholesterolemia. Nevertheless variation in baseline cholesterol levels, genetic predisposition of the subjects and compliance may contribute to a large individual variability.

Designer foods and their benefits: A review

Designer foods are normal foods fortified with health promoting ingredients. These foods are similar in appearance to normal foods and are consumed regularly as a part of diet. In this article we have reviewed the global regulatory status and benefits of available designer foods such as designer egg, designer milk, designer grains, probiotics, designer foods enriched with micro and macronutrients and designer proteins. Designer foods are produced by the process of fortification or nutrification. With the advances in the biotechnology, biofortification of foods using technologies such as recombinant DNA technology and fermentation procedures are gaining advantage in the industry. The ultimate acceptability and extensive use of designer foods depend on proper regulation in the market by the regulatory authorities of the country and by creating consumer awareness about their health benefits through various nationwide programs.

Food ingredients as anti-obesity agents: a review

Overweight and obesity have a major impact on global health; their prevalence has rapidly increased in all industrialized countries in the past few decades and diabetes and hypertension are their direct consequences. Pharmacotherapy provides reinforcement for obesity treatment, but should be an adjunctive support to diet, exercise, and lifestyle modification. At present, only orlistat and sibutramine have been approved by the US Food and Drug Administration for long-term use, but sibutramine was withdrawn for sale by the European Medicines Agency. The development of functional foods for the prevention and/or treatment of obesity suppose an opportunity for the food market and involve the knowledge of the mechanisms of appetite and energy expenditure as well as the metabolic sensation of satiety. Strategies for weight control management affect gut hormones as potential targets for the appetite metabolic regulation, stimulation of energy expenditure (thermogenesis), and modifications in the metabolic activity of the gut microbiota. Functional foods for obesity may also include bioactive fatty acids, phenolic compounds, soybean, plant sterols, dietary calcium, and dietary fiber. This review intends to offer an overview of the present situation of the anti-obesity agents currently used in dietary therapy as well as some functional food ingredients with potentially anti-obesity effects.

The effect of high-fiber rye bread enriched with nonesterified plant sterols on major serum lipids and apolipoproteins in normocholesterolemic individuals

BACKGROUND AND AIMS

Plant sterols are naturally occurring cholesterol-lowering compounds which are industrially incorporated in various foods. A novel food carrier is rye bread, the intake of which can be monitored in trials utilizing newly defined plasma biomarkers. Our aim was to determine the effects of plant sterols incorporated into high-fiber rye bread on serum total and LDL cholesterol, apoB/apoA1 and total cholesterol/HDL cholesterol ratios and lipophilic (pro)vitamins in healthy free-living normocholesterolemic individuals.

METHODS AND RESULTS

In this double-blind, dietary intervention trial the subjects (n=68) were randomized to receive a rye bread (9.3g/d fiber) with added plant sterols (2g/d) (active) or without (control). In the second phase of the study the amount of rye bread was doubled providing 18.6g/d fiber and in the active group 4g/d plant sterols. Compliance was monitored utilizing 3-day food diaries and a novel rye fiber-derived biomarker in plasma. Intake of rye bread enriched with 2g/d of plant sterols during two weeks reduced significantly serum total and LDL cholesterol, apoB/apoA1 and total cholesterol/HDL cholesterol ratios by 5.1%, 8.1%, 8.3% and 7.2%, respectively, compared to controls. Correspondingly, the following two-week treatment with 4g/d of plant sterols resulted in 6.5%, 10.4%, 5.5% and 3.7% difference compared to controls, being most pronounced for LDL (0.33 mmol/L). The treatments did not affect lipophilic (pro)vitamin levels.

CONCLUSION

Rye bread enriched with 2-4g/d of nonesterified plant sterols beneficially modifies cardiovascular lipid risk factors in normocholesterolemic subjects compared to controls.

Plant sterols and antioxidant parameters in enriched beverages: storage stability

Plant sterols (PS) stability, antioxidant parameters, and color were studied during 6 months of storage at 4, 24, and 37 °C in three PS-enriched functional beverages. Beverages were skimmed milk with fruit juice and PS (MFJPS), fruit juice and PS (FJPS), and skimmed milk with PS (MPS). No loss in total PS content occurred during storage observing the same values at any given storage time point. Total carotenoids decreased 36% with storage at two months and then remained stable. Total polyphenols showed fluctuations throughout the storage, remaining stable at 6 months and reaching initial values. The antioxidant capacity (TEAC method) increased 18% at 6 months, and there was an increase in color over time and temperature, probably due to Maillard reaction compound formation. The increase in total antioxidant capacity might have helped PS maintenance throughout storage, these beverages being a good PS source even after 6 months of storage.

A comparison of the LDL-cholesterol lowering efficacy of plant stanols and plant sterols over a continuous dose range: results of a meta-analysis of randomized, placebo-controlled trials

PURPOSE

To determine if plant stanols and plant sterols differ with respect to their low-density lipoprotein cholesterol (LDL-CH) lowering efficacies across a continuous dose range.

METHODS

Dose-response relationships were evaluated separately for plant stanols and plant sterols and reductions in LDL-CH, using a first-order elimination function.

RESULTS

Altogether, 113 publications and 1 unpublished study report (representing 182 strata) complied with the pre-defined inclusion and exclusion criteria and were included in the assessment. The maximal LDL-CH reductions for plant stanols (16.4%) and plant stanol ester (17.1%) were significantly greater than the maximal LDL-CH reductions for plant sterols (8.3%) and plant sterol ester (8.4%). These findings persisted in several additional analyses.

DISCUSSION AND CONCLUSIONS

Intakes of plant stanols in excess of the recommended 2g/day dose are associated with additional and dose-dependent reductions in LDL-CH, possibly resulting in further reductions in the risk of coronary heart disease (CHD).

Current and new insights on phytosterol oxides in plant sterol-enriched food

Over the past 15 years, plant sterol-enriched foods have faced a great increase in the market, due to the asserted cholesterol-lowering effect of plant sterols. However, owing to their chemical structures, plant sterols can oxidize and produce a wide variety of oxidation products with controversial biological effects. Although oxyphytosterols can derive from dietary sources and endogenous formation, their single contribution should be better defined. The following review provides an overall and critical picture on the current knowledge and future perspectives of plant sterols-enriched food, particularly focused on occurrence of plant sterol oxidation products and their biological effects. The final objective of this overview is to evince the different aspects of plant sterols-enriched food that require further research, for a better understanding of the influence of plant sterols and their oxides on consumers' health.

Role of phytosterols in lipid-lowering: current perspectives

The cholesterol-lowering effect of plant sterols was first discovered in the early 1950s. However, it is only recently that plant sterols have become clinically important, when advances in food-technology have made it possible to combine sterols with a variety of food products including margarines, yogurts, fruit juices and cereal bars. We review the clinical trial evidence of lipid-lowering efficacy of plant sterols and discuss their implications in routine clinical practice. To generate the evidence we searched the Pubmed database for English language literature, using relevant keywords and medical subject heading (MeSH) terms, and extracted the findings from recently published studies and meta-analyses on this topic. Our findings suggest that the short-term use of food supplements rich in plant sterols is a safe and effective strategy; to maximize the benefits of dietary and lifestyle therapy, either with or without statin therapy, among majority of dyslipidemic patients with need for additional lipid-lowering.

Review article: effects of plant sterols and stanols beyond low-density lipoprotein cholesterol lowering

Consumption of foods and supplements enriched with plant sterols/stanols (PS) may help reduce low-density lipoprotein cholesterol (LDL-C) levels. In this review, we consider the effects of PS beyond LDL-C lowering. Plant sterols/stanols exert beneficial effects on other lipid variables, such as apolipoprotein (apo) B/apoAI ratio and, in some studies, high-density lipoprotein cholesterol (HDL-C) and triglycerides (TG). Plant sterols/stanols may also affect inflammatory markers, coagulation parameters, as well as platelet and endothelial function. Evidence also exists about a beneficial effect on oxidative stress, but this does not seem to be of greater degree than that expected from the LDL-C lowering. Many of these effects have been demonstrated in vitro and animal models. Some in vitro effects cannot be seen in vivo or in humans at usual doses. The epidemiological studies that evaluated the association of plasma PS concentration with cardiovascular disease (CVD) risk do not provide a definitive answer. Long-term randomized placebo-controlled studies are required to clarify the effects of supplementation with PS on CVD risk and progression of atherosclerosis.

Evaluation of cardiovascular risk and oxidative stress parameters in hypercholesterolemic subjects on a standard healthy diet including low-fat milk enriched with plant sterols

A healthy diet and plant sterols (PS) are recommended for reducing low-density lipoprotein (LDL) cholesterol and, subsequently, the risk of premature cardiovascular disease. PS mediate a decrease in fat-soluble vitamin concentration, which can lead to a general impairment of antioxidative defenses and an increase in oxidative stress. Thus, we evaluated the effects of a healthy diet, including PS-enriched low-fat milk, on cardiovascular risk and oxidative stress parameters in hypercholesterolemic subjects. This was a randomized parallel trial employing 40 subjects and consisting of two 3-month intervention phases. After 3 months on a standard healthy diet, subjects were divided into two intervention groups: a diet group and a diet+PS group (2 g/day). Lipid profile, apolipoproteins, high-sensitivity C-reactive protein and oxidative stress parameters were analyzed. Diet significantly reduced total and LDL cholesterol (4.0% and 4.7%, respectively), produced an increase in the level of beta-carotene (23%) and improved the antioxidant capacity of LDL cholesterol particles (4.6%). PS induced a significant decrease in total cholesterol (6.4%), LDL (9.9%) and the apolipoprotein B100/apolipoprotein A1 ratio (4.9%), but led to a decrease in cryptoxanthin level (29%) without any change being observed in the antioxidant capacity of LDL cholesterol particles, total antioxidant status or lipid peroxidation. After 3 months, we observed the positive effect of including a PS supplement in dietary measures, as the lipoprotein-mediated risk of cardiovascular disease was reduced. Despite a decrease in the concentration of cryptoxanthin, no evidence of a global impairment of antioxidative defenses or an enhancement of oxidative stress parameters was found.

Stearate-enriched plant sterol esters lower serum LDL cholesterol concentration in normo- and hypercholesterolemic adults

Studies in our laboratory have previously demonstrated in hamsters a superior cholesterol-lowering ability of plant sterol (PS) esters enriched in stearate compared with linoleate. We therefore conducted a randomized, double-blind, 2-group parallel, placebo-controlled study to test the cholesterol-lowering properties of stearate-enriched PS esters in normo- and hypercholesterolemic adults. Thirty-two adults, 16 per group with equal number of males and females in each group, participated in the 4-wk study. Participants consumed 3 g/d (1 g three times per day with meals) of either PS esters or placebo delivered in capsules. Serum LDL cholesterol concentration significantly decreased 0.42 mmol/L (11%) and the LDL:HDL cholesterol ratio decreased 10% with PS ester supplementation, whereas LDL particle size and lipoprotein subclass particle concentrations (as measured by NMR) were not affected. The percent change in LDL cholesterol was positively correlated with baseline lathosterol concentration (r = 0.729; P = 0.0014), indicating an association between the magnitude of LDL change and the rate of whole-body cholesterol synthesis. Serum campesterol (but not sitosterol) concentration significantly increased in the PS ester group. Serum tocopherol, retinol, and beta-carotene concentrations were not affected by PS ester supplementation. Thus, our findings demonstrate the usefulness of a novel stearate-enriched PS ester compound in decreasing LDL cholesterol in both normo- and hypercholesterolemic adults. The extent to which PS ester fatty acid composition affects intestinal micelle formation and cholesterol absorption in humans requires further study.

Effects of a phytosterol-enriched dairy product on lipids, sterols and 8-isoprostane in hypercholesterolemic patients: a multicenter Italian study

BACKGROUND AND AIMS

Plant sterols, added to several food sources, lower serum cholesterol concentrations. Plant sterol-induced cholesterol lowering is paralleled by a mild decrease in plasma levels of the antioxidant beta-carotene, the amount of this decrease being considered clinically non-significant. Whether the effect on lipid profile of daily consumption of plant sterol-enriched low-fat fermented milk (FM) is paralleled by a concomitant variation in a reliable marker of the oxidative burden like plasma isoprostane levels is unresolved.

METHODS AND RESULTS

The effect of plant sterol consumption on plasma lipid and isoprostane levels of hypercholesterolemic patients was evaluated in a multicenter, randomized double blind study. Hypercholesterolemic patients consumed a FM daily for 6 weeks. Subjects were randomized to receive either 1.6g of plant sterol-enriched FM (n=60) or control FM product (n=56). After 6 weeks of plant sterol-enriched FM consumption, LDL cholesterol was reduced from 166.2+/-2.0 to 147.4+/-2.8 mg/dL (p=0.01). A significant reduction was observed for total cholesterol (from 263.5+/-2.6 to 231.0+/-3.2mg/dL, p=0.01). There was greater LDL cholesterol lowering among hypercholesterolemic patients with higher LDL cholesterol at baseline. We found a reduction of plasma 8-isoprostane in patients taking plant sterol-enriched FM (from 43.07+/-1.78 to 38.04+/-1.14 pg/ml, p=0.018) but not in patients taking the control product (from 42.56+/-2.12 to 43.19+/-2.0 pg/ml, p=NS). Campesterol and beta-sitosterol levels were not influenced by phytosterol consumption.

CONCLUSIONS

Daily consumption of low-fat plant sterol dairy product favourably changes lipid profile by reducing LDL-cholesterol, and may also have an anti-oxidative effect through a reduction of plasma isoprostanes.

Continuous dose-response relationship of the LDL-cholesterol-lowering effect of phytosterol intake

Phytosterols (plant sterols and stanols) are well known for their LDL-cholesterol (LDL-C)-lowering effect. A meta-analysis of randomized controlled trials in adults was performed to establish a continuous dose-response relationship that would allow predicting the LDL-C-lowering efficacy of different phytosterol doses. Eighty-four trials including 141 trial arms were included. A nonlinear equation comprising 2 parameters (the maximal LDL-C lowering and an incremental dose step) was used to describe the dose-response curve. The overall pooled absolute (mmol/L) and relative (%) LDL-C-lowering effects of phytosterols were also assessed with a random effects model. The pooled LDL-C reduction was 0.34 mmol/L (95% CI: -0.36, -0.31) or 8.8% (95% CI: -9.4, -8.3) for a mean daily dose of 2.15 g phytosterols. The impacts of subject baseline characteristics, food formats, type of phytosterols, and study quality on the continuous dose-response curve were determined by regression or subgroup analyses. Higher baseline LDL-C concentrations resulted in greater absolute LDL-C reductions. No significant differences were found between dose-response curves established for plant sterols vs. stanols, fat-based vs. non fat-based food formats and dairy vs. nondairy foods. A larger effect was observed with solid foods than with liquid foods only at high phytosterol doses (>2 g/d). There was a strong tendency (P = 0.054) towards a slightly lower efficacy of single vs. multiple daily intakes of phytosterols. In conclusion, the dose-dependent LDL-C-lowering efficacy of phytosterols incorporated in various food formats was confirmed and equations of the continuous relationship were established to predict the effect of a given phytosterol dose. Further investigations are warranted to investigate the impact of solid vs. liquid food formats and frequency of intake on phytosterol efficacy.

Cholesterol-lowering efficacy of plant sterols in low-fat yogurt consumed as a snack or with a meal

OBJECTIVE

Plant sterols (PS) consumed as a snack may not have the same cholesterol-lowering potential as when consumed with a meal due to poor solubilization. It was hypothesized that the consumption of a single dose, low-fat yogurt rich in PS (1.6 g/d) with a meal over an afternoon snack will lead to favourable changes in plasma lipids, plasma PS concentrations, and cholesterol synthesis without negatively affecting alpha-tocopherol or carotenoids levels.

METHODS

Twenty-six hyperlipidemic males and females completed the randomized trial of three phases (control, single PS dose consumed with a meal, or single PS dose as an afternoon snack) while consuming controlled, low-fat diets. Plasma lipids, cholesterol synthesis rates, plasma PS and serum fat-soluble antioxidants were measured at baseline and after 4 weeks.

RESULTS

Endpoint total cholesterol (TC) levels after the PS snack phase were decreased (p = 0.04) (5.30 +/- 0.2 mmol/L) compared to the control phase (5.53 +/- 0.2 mmol/L). However, endpoints for TC (5.37 +/- 0.2 mmol/L) for PS dose with a meal were comparable to control phase. Low-density lipoprotein-cholesterol tended to be different (p = 0.06) at the end of the intervention phases (3.51 +/- 0.1, 3.43 +/- 0.1, and 3.33 +/- 0.1 mmol/L; control, meal and snack, respectively). Cholesterol fractional synthesis rates were higher (p = 0.007) by 25.8% and 19.5% at the end of the snack and meal phases, respectively, compared with the control phase. Plasma campesterol and beta-sitosterol concentrations, adjusted for TC, were higher (p < 0.01) in the snack phase (2.30 +/- 0.3 and 0.54 +/- 0.1 micromol/mmol, respectively) and in the meal phase (2.00 +/- 0.3 and 0.51 +/- 0.1 micromol/mmol, respectively) when compared to the control phase (1.81 +/- 0.3 and 0.40 +/- 0.1 micromol/mmol, respectively). No changes in alpha-tocopherol or carotenoids levels were detected after adjusting for TC, for all phases.

CONCLUSION

These results indicate that a single dose of PS in low-fat yogurt, provided as a snack, lowers cholesterol levels but does not alter fat-soluble vitamin or carotenoid concentrations in hyperlipidemic participants.

Cholesterol lowering effect of a soy drink enriched with plant sterols in a French population with moderate hypercholesterolemia

Background

Plant sterols are an established non-pharmacological means to reduce total and LDL blood cholesterol concentrations and are therefore recommended for cholesterol management by worldwide-renown health care institutions. Their efficacy has been proven in many types of foods with the majority of trials conducted in spreads or dairy products. As an alternative to dairy products, soy based foods are common throughout the world. Yet, there is little evidence supporting the efficacy of plant sterols in soy-based foods. The objective of this study was to investigate the effect of a soy drink enriched with plant sterols on blood lipid profiles in moderately hypercholesterolemic subjects.

Methods

In a randomized, placebo-controlled double-blind mono-centric study, 50 subjects were assigned to 200 ml of soy drink either enriched with 2.6 g plant sterol esters (1.6 g/d free plant sterol equivalents) or without plant sterols (control) for 8 weeks. Subjects were instructed to maintain stable diet pattern and physical activity. Plasma concentrations of lipids were measured at initial visit, after 4 weeks and after 8 weeks. The primary measurement was the change in LDL cholesterol (LDL-C). Secondary measurements were changes in total cholesterol (TC), non-HDL cholesterol (non-HDL-C), HDL cholesterol (HDL-C) and triglycerides.

Results

Regular consumption of the soy drink enriched with plant sterols for 8 weeks significantly reduced LDL- C by 0.29 mmol/l or 7% compared to baseline (p < 0.05). TC and non-HDL-C concentrations decreased by 0.26 mmol/l and 0.31 mmol/l (each p < 0.05), respectively. Mean reductions in total, LDL and non-HDL cholesterol were significantly greater than in the placebo group (p < 0.05). HDL-C and triglycerides were not affected. Compliance was very high (>96%), and products were well tolerated.

Conclusion

Daily consumption of a plant sterol-enriched soy drink significantly decreased total, non-HDL and LDL cholesterol and is therefore an interesting and convenient aid in managing mild to moderate hypercholesterolemia.

Plant sterols/stanols as cholesterol lowering agents: A meta-analysis of randomized controlled trials

BACKGROUND

Consumption of plant sterols has been reported to reduce low density lipoprotein (LDL) cholesterol concentrations by 5-15%. Factors that affect plant sterol efficacy are still to be determined.

OBJECTIVES

To more precisely quantify the effect of plant sterol enriched products on LDL cholesterol concentrations than what is reported previously, and to identify and quantify the effects of subjects' characteristics, food carrier, frequency and time of intake on efficacy of plant sterols as cholesterol lowering agents.

DESIGN

Fifty-nine eligible randomized clinical trials published from 1992 to 2006 were identified from five databases. Weighted mean effect sizes were calculated for net differences in LDL levels using a random effect model.

RESULTS

Plant sterol containing products decreased LDL levels by 0.31 mmol/L (95% CI, -0.35 to -0.27, P= < 0.0001) compared with placebo. Between trial heterogeneity was evident (Chi-square test, P = <0.0001) indicating that the observed differences between trial results were unlikely to have been caused by chance. Reductions in LDL levels were greater in individuals with high baseline LDL levels compared with those with normal to borderline baseline LDL levels. Reductions in LDL were greater when plant sterols were incorporated into fat spreads, mayonnaise and salad dressing, milk and yoghurt comparing with other food products such as croissants and muffins, orange juice, non-fat beverages, cereal bars, and chocolate. Plant sterols consumed as a single morning dose did not have a significant effect on LDL cholesterol levels.

CONCLUSION

Plant sterol containing products reduced LDL concentrations but the reduction was related to individuals' baseline LDL levels, food carrier, and frequency and time of intake.

Effects of hydrophilic and lipophilic beta-sitosterol derivatives on cholesterol absorption and plasma cholesterol levels in rats

The effects of two phytosterol derivatives of beta-sitosterol, a lipophilic derivative (LPSS) and a hydrophilic derivative (HPSS), on cholesterol uptake and blood lipoprotein levels in rats were compared with those of beta-sitosterol. LPSS and HPSS have solubilities of up to 0.05 g/mL in edible oil and 0.15 g/mL in water at 25 degrees C, respectively. The intragastric administration of either 30 or 50 mg of phytosterols with 10 mg of [4- (14)C]-cholesterol per kg of body weight once a day for 3 consecutive days reduced cholesterol uptake by approximately 30% compared to controls that received cholesterol alone. Feeding a cholesterol-enriched diet containing 1% or 3% beta-sitosterol, LPSS, or HPSS for 2 and 4 weeks resulted in lowered levels of total blood cholesterol and reduced the atherogenic index in all groups. These results indicate that LPSS and HPSS have comparable effects to beta-sitosterol in lowering blood cholesterol levels but they differ from beta-sitosterol in having a solubility advantage.

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

BACKGROUND & AIMS

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

SPONSORSHIP

Unilever Denmark A/S.

Fish-oil esters of plant sterols differ from vegetable-oil sterol esters in triglycerides lowering, carotenoid bioavailability and impact on plasminogen activator inhibitor-1 (PAI-1) concentrations in hypercholesterolemic subjects

BACKGROUND

Consumption of plant sterol (PS) esters lower low-density lipoprotein (LDL)-cholesterol levels by suppressing intestinal absorption of cholesterol. Commercially available PS are mainly esterified to omega-6 fatty acid (FA), such as sunflower oil (SO) FA. Emerging trends include using other sources such as olive oil (OO) or omega-3 FA from fish oil (FO), known to exert potent hypotriglyceridemic effects. Our objective was to compare the actions of different FA esterified to PS on blood lipids, carotenoid bioavailability as well as inflammatory and coagulation markers.

METHODS

Twenty-one moderately overweight, hypercholesterolemic subjects consumed experimental isoenergetic diets enriched with OO (70% of fat), each lasting 28-day and separated by 4-week washout periods, using a randomized crossover design. Diets were supplemented with three PS esters preparations, PS-FO, PS-SO, or PS-OO. All PS treatments contained an equivalent of 1.7 PS g/d, and the PS-FO provided a total of 5.4 g/d FO FA (eicosapentaenoic and docosahexaenoic acids).

RESULTS

There were no differences between PS-containing diet effects on total cholesterol, LDL-cholesterol, or high-density lipoprotein (HDL)-cholesterol levels. However, PS-FO consumption resulted in markedly lower (P < 0.0001) fasting and postprandial triglyceride concentrations compared with PS-SO and PS-OO. These treatments affected plasma beta-carotene (P = 0.0169) and retinol (P = 0.0244), but not tocopherol (P = 0.2108) concentrations. Consumption of PS-FO resulted in higher beta-carotene (P = 0.0139) and retinol (P = 0.0425) levels than PS-SO and PS-OO, respectively. Plasma TNF-alpha, IL-6, C-reactive protein, prostate specific antigen, and fibrinogen concentrations were unaffected by the PS-interventions. In contrast, plasminogen activator inhibitor 1 (PAI-1) concentrations were lower (P = 0.0282) in the PS-FO-fed than the PS-SO, but not the PS-OO (P = 0.7487) groups.

CONCLUSION

Our findings suggest that, in hypercholesterolemic subjects consuming an OO-based diet, PS-FO results in lowered blood triglyceride and PAI-1 concentrations, and higher fat-soluble vitamin levels in comparison to the vegetable oil FA esters of PS (PS-SO and PS-OO). Thus, PS-FO may offer hyperlipidemic subjects a more comprehensive lipid lowering approach while reducing the potential risk of decreased plasma carotenoid concentrations.

A high-saturated fat diet enriched with phytosterol and pectin affects the fatty acid profile in guinea pigs

This paper presents the results of a study whose aim was to test the effects of several doses of pectin and phytosterols on the body weight gain and the FA content in female guinea pigs. The treatments resulted from supplementing with pectin and plant sterol a guinea pig diet (rich in saturated FA), following a 3 x 3 factorial design, with three levels of pectin (0, 3.67 and 6.93%) and three levels of phytosterols (0, 1.37, and 2.45%). Seventy-two female Dunkin Hartley guinea pigs were randomly assigned to the treatment groups (8 animals/group), the duration of the treatment being 4 wk. Pectin dietary intake led to a significant increase in body weight (P < 0.001), food consumption (P = 0.025), and feed efficiency (P < 0.001), but no influence of phytosterols on weight gain or food consumption was detected. We found a significant negative effect of the addition of phytosterols on lauric, myristic, and palmitic acid contents in feces, and a positive effect on their concentration in plasma and liver, but no significant effect on stearic acid content. Apparent FA absorption was assessed by calculating the ratio of FA in feces and diets that the absorption of the different FA could be compared, and the negative effect of phytosterol supplementation on these ratios, especially for lauric and myristic acids, was established.

Effect of low-fat, fermented milk enriched with plant sterols on serum lipid profile and oxidative stress in moderate hypercholesterolemia

BACKGROUND

Plant sterol (PS)-enriched foods have been shown to reduce plasma LDL-cholesterol concentrations. In most studies, however, PSs were incorporated into food products of high fat content.

OBJECTIVE

We examined the effect of daily consumption of PS-supplemented low-fat fermented milk (FM) on the plasma lipid profile and on systemic oxidative stress in hypercholesterolemic subjects.

DESIGN

Hypercholesterolemic subjects (LDL-cholesterol concentrations >or=130 and <or= 190 mg/dL; n = 194) consumed 2 low-fat portions of FM in the same meal daily for 6 wk. Subjects were randomly assigned to 2 groups: low-fat FM enriched with 0.8 g PS ester per portion or control FM. Plasma concentrations of lipids, oxidized LDL, beta-carotene, beta-sitosterol, campesterol, and high-sensitivity C-reactive protein were measured during the trial.

RESULTS

Plasma LDL-cholesterol concentrations were reduced by 9.5% and 7.8% after 3 and 6 wk, respectively, in the 1.6-g/d PS group compared with the control group, whereas plasma triacylglycerol and HDL-cholesterol concentrations were not significantly affected. In addition, there were no significant changes in serum beta-carotene on normalization to LDL cholesterol during the study period in both groups, whereas plasma concentrations of oxidized LDL were reduced significantly in the PS group compared with the control group (-1.73 compared with 1.40 U/L, respectively; P < 0.05). Plasma sitosterol concentrations were increased by 35% (P < 0.001 compared with control); however, campesterol concentrations did not change during the study period.

CONCLUSION

Daily consumption of 1.6 g PS in low-fat FM efficiently lowers LDL cholesterol in subjects with moderate hypercholesterolemia without deleterious effects on biomarkers of oxidative stress.

Examination of encapsulated phytosterol ester supplementation on lipid indices associated with cardiovascular disease

OBJECTIVE

As opposed to traditional food based delivery we examined the efficacy of ingesting encapsulated phytosterol esters on indices of lipid health in hypercholesterolemic adults.

METHODS

We performed a randomized, double-blinded, parallel-group, placebo-controlled, clinical intervention examining 54 men and women (20-70 y of age) with a low-density lipoprotein cholesterol (LDL-C) level > or =3.33 mmol/L. Participants were not taking cholesterol-lowering medications. Treatment consisted of ingesting 2.6 g of encapsulated phytosterol esters (n = 25) or a matching placebo (n = 29) for 12 wk.

RESULTS

Total cholesterol (TC) levels at baseline (mean +/- SD) were 6.29 +/- 0.7 mmol/L in the phytosterol group and 6.00 +/- 0.7 mmol/L in the placebo group. Baseline LDL-C levels were 4.27 +/- 0.7 mmol/L in the treatment group and 4.00 +/- 0.8 mmol/L in the placebo group. Analysis of variance and Tukey's least significant difference post hoc analyses revealed a significant within-group reduction in TC (-0.23 +/- 0.4 mmol/L, P < 0.05) and LDL-C (-0.22 +/- 0.5 mmol/L, P < 0.05) for the phytosterol treatment group. Mean reductions in TC and LDL-C were greater than placebo (P < 0.05). Percentages of change from baseline for TC were -3.52% (95% confidence interval -6.44 to -0.40) for phytosterol treatment and 2.64% (95% confidence interval 0.30-5.60) for placebo. Those for LDL-C were -5.00% (95% confidence interval -9.92 to -0.08) for phytosterol and 4.89 (95% confidence interval 0.24-9.5) for placebo. No other significant effects were observed.

CONCLUSION

Encapsulated phytosterol ester ingestion appears to positively modulate LDL-C. Given that the reduction in LDL-C was not as extensive as in food-based trials, future investigations should examine potential timing and dose issues relative to encapsulated delivery.

Functional foods for the prevention and treatment of cardiovascular diseases: cholesterol and beyond

Cardiovascular disease (CVD) is a major cause of death and disability in many developed countries. The purpose of this literature review is to establish a recommendation for the intake of functional food ingredients in a healthy diet--such as plant sterols (PSs) in low-fat and functional matrices, fatty acid composition and other nutrients of tree nuts and flavonoids in dark chocolate--for the prevention and treatment of CVD. These three specific functional foods are explored in this review, since there is a higher potential for their increased consumption by the population to prevent CVD. First, PS have been added to various nontraditional matrices, such as low-fat products and functional oils, which have shown cholesterol-lowering effects in most clinical trials. Secondly, a growing number of clinical studies indicate that the beneficial effect of tree nuts may not only be due to their fatty acid composition but to other key nutrients, which may provide supplementary health benefits, such as endothelial cell function, as well as decreasing total cholesterol and low-density lipoprotein cholesterol (LDL-C). Lastly, flavonoids in dark chocolate may protect LDL-C particles from undergoing oxidative modification. However, some gaps in our knowledge need to be filled before firm recommendations can be made for habitual dark chocolate consumption. Overall, these functional foods should be considered as an addition to current lipid-lowering recommendations for improving CVD risk.

Milk and the metabolic syndrome

The metabolic syndrome is a cluster of metabolic disorders, namely dyslipidaemia, hypertension, obesity and glucose intolerance. Insulin resistance is the core phenomenon. Co-occurrence is associated with increased cardiovascular disease (CVD) risk. Observational studies found no increased CVD risk with increasing consumption of milk and other dairy products. In several studies dairy consumption was inversely associated with the occurrence of one or several facets of the metabolic syndrome. Many dairy components may contribute to the beneficial effects. Milk and particularly whey appeared insulinotropic when given in a single meal, but not in longer-term intervention. Medium chain fatty acids improve insulin sensitivity. Whey proteins, amino acids, medium chain fatty acids and in particular calcium and other minerals may contribute to the beneficial effect of dairy products on body weight and body fat. Peptides, calcium and other minerals reduce blood pressure. Fermented products and probiotic bacteria decrease absorption of cholesterol, sphingomyelin of cholesterol and fat, calcium of cholesterol, bile acids and fat. Proteins, peptides and bacteria may also reduce plasma cholesterol. Lactose, citrate, proteins and peptides improve weight control, blood pressure and plasma lipids indirectly, by improving calcium bioavailability. Furthermore, dairy consumption improves the bioavailability of folate and other secondary plant components.

Simultaneous intake of beta-glucan and plant stanol esters affects lipid metabolism in slightly hypercholesterolemic subjects

Intake of food products rich in water-soluble fiber beta-glucan and products enriched with plant stanol esters lower serum cholesterol. Combining 2 functional food ingredients into one food product may achieve additional reductions of serum cholesterol. Our objective was to investigate the effects of a simultaneous intake of beta-glucan plus plant stanol esters on lipid metabolism in mildly hypercholesterolemic volunteers. In a randomized, controlled, 3-period crossover study, 40 mildly hypercholesterolemic men and women received muesli in random order twice a day for 4 wk, which provided, in total, 5 g control fiber from wheat (control muesli), 5 g oat beta-glucan (beta-glucan muesli), or 5 g oat beta-glucan plus 1.5 g plant stanols (combination muesli). beta-Glucan muesli decreased serum LDL cholesterol by 5.0% compared with control muesli (P = 0.013). Combination muesli reduced LDL cholesterol by 9.6% compared with control muesli (P < 0.001), and by 4.4% compared with beta-glucan muesli (P = 0.036). Serum HDL cholesterol and triacylglycerol concentrations did not differ after the 3 treatments. Compared with control muesli, beta-glucan muesli increased bile acid synthesis (P = 0.043) and decreased cholesterol absorption (P = 0.011). Addition of plant stanols did not influence bile acid synthesis but decreased cholesterol absorption (P < 0.001) and raised cholesterol synthesis (P = 0.016) compared with control muesli, and the plant stanols decreased cholesterol absorption compared with beta-glucan muesli (P = 0.004). The combination muesli decreased serum concentrations of sitostanol compared with control muesli (P = 0.010). Plasma concentrations of lipid-soluble antioxidants did not differ after the 3 treatments. beta-Glucan muesli effectively lowered serum LDL cholesterol concentrations. The addition of plant stanol esters to beta-glucan-enriched muesli further lowered serum LDL cholesterol, although effects were slightly less than predicted.

Supplementation of test meals with fat-free phytosterol products can reduce cholesterol micellarization during simulated digestion and cholesterol accumulation by Caco-2 cells

Phytosterols have been shown to reduce cholesterol absorption in humans. Supplementing phytosterols in fat-free formulations, however, has yielded controversial results. In the present study, we investigated the effect of supplementing test meals with different fat-free phytosterol products on cholesterol incorporation into mixed micelles during simulated digestion and accumulation of micellar cholesterol by Caco-2 cells: control orange juice (OJ), orange juice supplemented with either multivitamin/multimineral tablets (MVT), multivitamin/multimineral tablets containing phytosterols (MVT+P), and phytosterol powder (PP). These combinations were added to Ensure-based test meals and spiked with cholesterol of natural isotopic composition or 13C2-cholesterol to differentiate external from endogenous cholesterol. After simulated gastric/small intestinal digestion, micelle fractions were analyzed for cholesterol enzymatically (n = 6-20/product) and by high-performance liquid chromatography-tandem mass spectrometry (n = 12/product) and added to Caco-2 cells to determine the accumulation of 13C2-cholesterol (n = 10-24/product). As compared to OJ, PP and MVT+P significantly decreased cholesterol micellarization (determined enzymatically) by 70 +/- 39 (mean +/- SD) and 70 +/- 39%, respectively (P < 0.001, Bonferroni). The stable isotope experiments revealed that both PP and MVT+P reduced cholesterol micellarization [by 25 +/- 12 (P = 0.055) and 21 +/- 8% (P = 0.020), respectively, Fisher's protected LSD test] and Caco-2 cell accumulation (by 28 +/- 8 and 10 +/- 8%, respectively; P < 0.010, Bonferroni). OJ+P did not inhibit micellarization or accumulation of cholesterol by Caco-2 cells. This study shows that fat-free phytosterol-containing products can significantly inhibit cholesterol micellarization and Caco-2 cell bioaccessibility, albeit to different extents depending on individual formulations. This is most likely explained by inhibition of cholesterol micellarization.

Plant stanol esters in low-fat milk products lower serum total and LDL cholesterol

BACKGROUND

Oil-based matrices enriched with plant stanol esters lower serum LDL cholesterol. The effects of low-fat milk products have been less thoroughly examined.

AIM OF THE STUDY

To evaluate the effect of three less explored low-fat milk products enriched with plant stanol esters on serum lipid concentrations in subjects with mild or moderate hypercholesterolemia.

METHODS

A meta-analysis of four unpublished sub-studies (yoghurt, yoghurt single-shot drink: Studies I and II, or milk). All the substudies were randomized, placebo-controlled, double-blind and had a parallel-group design. They were carried out in order to evaluate the effect of low-fat milk products enriched with plant stanol esters on serum lipid concentration. Each stanol-ester-enriched milk product provided 2 g of stanols per day, and in each study the intervention period was 5 weeks. A total of 199 hypercholesterolemic subjects completed the studies.

RESULTS

The pooled treatment difference in total cholesterol was -3.8% (95% CI -6.0 to -1.7, p < 0.001) when stanol was compared to placebo. In LDL cholesterol, the pooled treatment difference was -4.9% (95% CI -7.8 to -1.8, p = 0.002). There were no significant differences between the groups in pooled HDL cholesterol or triacylglycerol concentrations. The results tended to be more pronounced when we were certain that the yoghurt single-shot drink was ingested with lunch, and when the baseline LDL-cholesterol concentration was > or = 3.5 mmol/l.

CONCLUSIONS

These results imply that low-fat milk products enriched with plant stanol esters lower both total cholesterol and LDL cholesterol statistically significantly in subjects with mild or moderate hypercholesterolemia. The changes tended to relate to the baseline LDL-cholesterol concentration.