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

Cocoa flavanol-enriched snack bars containing phytosterols effectively lower total and low-density lipoprotein cholesterol levels

BACKGROUND

Dietary intervention studies incorporating phytosterol-enriched margarine spreads have reported significant decreases in total and low-density lipoprotein (LDL) cholesterol in populations with both normal lipid levels and those with hypercholesterolemia. There is emerging support for more diverse and lower-fat phytosterol-enriched matrixes. Controversy exists, however, over whether phytosterol-enriched foods affect serum fat-soluble vitamins.

OBJECTIVE

We investigated whether a flavanol-rich cocoa snack food containing phytosterols would decrease total and LDL cholesterol levels in subjects with hypercholesterolemia and significantly affect serum fat-soluble vitamins and carotenoids.

DESIGN

A randomized, double-blind parallel arm study design was used. Subjects were randomized to one of two dietary treatments: a cocoa flavanol-enriched snack bar containing 1.5 g phytosterol (n=32), or a control product containing no phytosterols (n=35). Subjects consumed two servings per day.

RESULTS

Consumption of the phytosterol-enriched snack bars but not control bars for 6 weeks was associated with significant reductions in plasma total (4.7%; P<0.01) and LDL cholesterol (6%; P<0.01), and the ratio of total to high-density lipoprotein cholesterol (7.4%; P<0.001). There were no changes in high-density lipoprotein cholesterol, triglycerides, or lipid-adjusted lycopene, beta-cryptoxanthin, lutein/zeaxanthin, alpha-carotene levels, or levels of serum vitamins A or E. A significant reduction in lipid-adjusted serum beta-carotene was observed in the phytosterol but not the no-phytosterol-added group (P<0.05).

CONCLUSIONS

This study supports the use of a novel phytosterol-enriched snack bar to effectively reduce plasma total and LDL cholesterol levels in a population with hypercholesterolemia. The data suggest that the incorporation of this snack food into a balanced diet represents a practical dietary strategy in the management of serum cholesterol levels.

Improvement of cholesterol levels and reduction of cardiovascular risk via the consumption of phytosterols

Hypercholesterolaemia is one of the main factors contributing to the appearance and progression of CVD, which is the main cause of death in the adult population of industrialized societies. By 2020, projections suggest that it will continue to hold first place, by then causing 37 % of all deaths. Therapeutic life-style changes to reduce cardiovascular risk include dietary modifications, such as the inclusion of phytosterols or plant sterols (known since the 1950s to reduce cholesterol levels). These help prevent the absorption of cholesterol and thus condition a reduction in total cholesterol and LDL-cholesterol levels, and ultimately in cardiovascular mortality. The fat-soluble nature of these sterols rendered margarine one of the best vehicles by which to supply them in the diet. Indeed, margarine was the first food to contain cholesterol-reducing phytosterols to be approved by the EU (in agreement with its regulations on new foods and food ingredients, 258/97/CE). Presently, phytosterols can be emulsified with lecithin and thus delivered in non-fat or low-fat foods and beverages. Margarine and dairy products (yoghurt and milk) enriched in phytosterols have proved better at lowering total cholesterol and LDL-cholesterol levels than have enriched cereals and their derivatives, although all can be of help, depending on the characteristics of each subject. The reduction in carotenoid bioavailability caused by sterols is minimized by increasing fruit and vegetable consumption. Individuals who habitually consume phytosterols should also follow traditional advice such as eating less dietary fat and increasing their physical activity. Phytosterols have been shown to be safe and effective in lowering cholesterol levels in many rigorous studies. In few areas of nutrition is there such consensus. Diet professionals should feel comfortable in prescribing phytosterols/stanols for the treatment of hypercholesterolaemia. They are safe whether taken alone or in combination with cholesterol-reducing drugs, such as statins and fibrates. Reinforcement counselling is essential, as therapy is effective only if compliance is good.

Reduced-calorie orange juice beverage with plant sterols lowers C-reactive protein concentrations and improves the lipid profile in human volunteers

BACKGROUND

Dietary plant sterols effectively reduce LDL cholesterol when incorporated into fat matrices. We showed previously that supplementation with orange juice containing plant sterols (2 g/d) significantly reduced LDL cholesterol. Inflammation is pivotal in atherosclerosis. High-sensitivity C-reactive protein (hs-CRP), the prototypic marker of inflammation, is a cardiovascular disease risk marker; however, there is a paucity of data on the effect of plant sterols on CRP concentrations.

OBJECTIVE

The aim of this study was to examine whether plant sterols affect CRP concentrations and the lipoprotein profile when incorporated into a reduced-calorie (50 calories/240 mL) orange juice beverage.

DESIGN

Seventy-two healthy subjects were randomly assigned to receive a reduced-calorie orange juice beverage either without (Placebo Bev) or with (1 g/240 mL; Sterol Bev) plant sterols twice a day with meals for 8 wk. Fasting blood was obtained at baseline and after 8 wk of Placebo Bev or Sterol Bev supplementation.

RESULTS

Sterol Bev supplementation significantly reduced total cholesterol (5%; P < 0.01) and LDL cholesterol (9.4%; P < 0.001) compared with both baseline and Placebo Bev (P < 0.05). HDL cholesterol increased significantly with Sterol Bev (P < 0.02). No significant changes in triacylglycerol, glucose, or liver function tests were observed with Sterol Bev. Sterol Bev supplementation resulted in no significant change in vitamin E and carotenoid concentrations. Sterol Bev supplementation resulted in a significant reduction of CRP concentrations compared with baseline and Placebo Bev (median reduction: 12%; P < 0.005).

CONCLUSION

Supplementation with a reduced-calorie orange juice beverage containing plant sterols is effective in reducing CRP and LDL cholesterol and could be incorporated into the dietary portion of therapeutic lifestyle changes.

The role of dietary supplementation with plant sterols and stanols in the prevention of cardiovascular disease

Several studies have shown that increased levels of low-density lipoprotein (LDL) cholesterol predict cardiovascular events. The Adult Treatment Panel II (ATP II) introduced the principle of therapeutic lifestyle changes, including plant sterols/stanols for the management of LDL cholesterol. Plant sterols and stanols in fat matrices effectively lower LDL cholesterol levels in hypercholesterolemic, diabetic, and healthy human volunteers. Recent studies also show that sterols (2 g/d) lower LDL cholesterol even when incorporated in nonfat matrices. In addition, they may reduce biomarkers of oxidative stress and inflammation. Plant sterols and stanols exert their hypocholesterolemic effects possibly by interfering with the uptake of both dietary and biliary cholesterol from the intestinal tract. Present evidence is accumulating to promote their use for lowering LDL cholesterol levels, as a first line of therapy (as well as adjunctive therapy) in patients on statin therapy.

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.

Effects of plant stanol esters supplied in a fat free milieu by pastilles on cholesterol metabolism in colectomized human subjects

BACKGROUND AND AIM

Nutritional products containing fat-soluble phytosterol esters for serum cholesterol lowering have traditionally been oil-based. Their cholesterol-lowering efficacy when provided by low-fat vehicles with a diet of normal fat content is questionable. The aims of the present study were to find out whether 1-week consumption of plant stanol esters in pastilles alters absorption percentage of labeled esterified and free cholesterol and fecal elimination of sterols, including phytosterols (n = 9), and to define the impact of dietary fat on intestinal sterol ester hydrolysis (n = 8) in colectomized human subjects.

METHODS AND RESULTS

Levels of lipoprotein cholesterol and triacylglycerols, non-cholesterol sterols and squalene in serum, neutral sterols, non-cholesterol sterols, fat and bile acids in feces, cholesterol absorption efficiency and cholesterol synthesis were analyzed at baseline and at the end of the treatment period. Analyses of esterified and free cholesterol and phytosterols were performed during diets with normal and low-fat content. Serum levels of total and low-density lipoprotein cholesterol decreased by 9% and 14%, respectively (P < 0.01 for both), and absorption of 3H-esterified and 14C-free cholesterol decreased in proportion to baseline values (r = -0.58, P < 0.05) by over 40% (P < 0.01) in colectomized patients with stanol ester pastilles. Fecal elimination of cholesterol was increased by about 35% and almost 60% of campestanol and sitostanol esters were hydrolyzed during their transit in gastrointestinal tract when consumed with a normal fat diet (mean daily fat 93 +/- 13g ) for 1 week. The hydrolysis of plant stanol esters was more pronounced with a normal than with a low-fat diet (70% versus 40%, P < 0.001).

CONCLUSIONS

We conclude that plant stanol esters provided in fat free milieu exert favourable effects on serum lipid profile by decreasing absorption of cholesterol in colectomized human subjects, even though the intestinal hydrolysis of plant stanol esters is weaker on low than normal fat diet.

Analysis of oxysterols by electrospray tandem mass spectrometry

Oxysterols are oxygenated derivatives of cholesterol. They are intermediates in cholesterol excretion pathways and may also be regarded as transport forms of cholesterol. The introduction of additional hydroxyl groups to the cholesterol skeleton facilitates the flux of oxysterols across the blood brain barrier, and oxysterols have been implicated in mediating a number of cholesterol-induced metabolic effects. Oxysterols are difficult to analyze by atmospheric pressure ionization mass spectrometry on account of the absence of basic or acidic functional groups in their structures. In this communication, we report a method for the derivatization and analysis of oxysterols by electrospray mass spectrometry. Oxysterols with a 3beta-hydroxy-Delta5 structure were converted by cholesterol oxidase to 3-oxo-Delta4 steroids and then derivatized with the Girard P reagent to give Girard P hydrazones, which were subsequently analyzed by tandem mass spectrometry. The improvement in sensitivity for the analysis of 25-hydroxycholesterol upon oxidation and derivatization was over 1000.

Cholesterol-lowering ability of a phytostanol softgel supplement in adults with mild to moderate hypercholesterolemia

Plant sterols, incorporated into spreads and other food sources, have been shown to lower serum cholesterol concentrations. The effect of phytostanol supplementation in softgel form has not been assessed. Our objective was to examine the effects of sitostanol as sitostanol ester in softgel form on serum lipid concentrations in hypercholesterolemic individuals. Thirty hypercholesterolemic adults were supplemented with 1.6 g of free phytostanol equivalents as phytostanol ester (2.7 g stanol esters) or placebo per day for 28 d in a randomized, double-blind, parallel study design. Phytostanol supplementation resulted in a significant decrease in total cholesterol (TC) (-8%) and LDL-cholesterol (-9%). There were no alterations in concentrations of HDL-cholesterol or TG. Nor were the ratios of LDL/HDL or TC/HDL altered significantly. Thus, use of phytostanol ester softgel supplements improved serum total and LDL-cholesterol concentrations in hypercholesterolemic individuals.

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

OBJECTIVE

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.

DESIGN

A parallel, double-blind study.

SETTING

The study was performed in three different locations in Finland.

SUBJECTS

In total, 164 mildly or moderately hypercholesterolaemic subjects participated in the study.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Plant sterols as dietary adjuvants in the reduction of cardiovascular risk: theory and evidence

Plant sterol-enriched foods are an effective dietary adjuvant in reducing cardiovascular risk by lowering total cholesterol and low density lipoprotein-cholesterol (LDL-C) in serum by up to approximately 15%. The mechanism of action of plant sterols is different from those of 3-hydroxy-3-methylglutaryl coenzyme A inhibitors (statins) and thus their effect is additive. Combining plant sterols with other dietary components known to reduce cholesterol in a portfolio approach has proven to be most effective for reduction of hypercholesterolemia and provide an alternative treatment option for clinicians. Plant sterol-enriched foods provides clinicians with a relatively cheap, safe, and effective way to help patients manage their cardiovascular risk.

Intake occasion affects the serum cholesterol lowering of a plant sterol-enriched single-dose yoghurt drink in mildly hypercholesterolaemic subjects

OBJECTIVE

To determine the impact of intake occasion (with or without a meal), and product fat level on the cholesterol-lowering efficacy of a plant sterol (PS)-enriched (3 g/day) single-dose yoghurt drink.

DESIGN

Double-blind, randomized, placebo-controlled, parallel study with a 4 weeks run-in and 4 weeks intervention period.

SETTING

Subjects recruited from the general community.

SUBJECTS

A total of 184 moderate hypercholesterolaemic subjects (81 men and 103 women) (age 57+/-2 years) completed the study.

INTERVENTIONS

The study product was a 100-g single-dose yoghurt drink with or without added PS in the form of PS esters. The subjects were randomly assigned to one of five 4-week treatments: (i) drink A (0.1% dairy fat, 2.2% total fat) with a meal, (ii) drink A without a meal, (iii) drink B (1.5% dairy fat, 3.3% total fat) with a meal, (iv) drink B without a meal and (v) placebo drink with a meal.

RESULTS

LDL-cholesterol (LDL-C) was significantly lowered when the single-dose drink was taken with a meal independent of its fat content (drink A: -9.5% (P<0.001, 95% CI: -13.8 to -5.2); drink B: -9.3% (P<0.001, 95% CI: -13.7 to -4.9)) as compared to placebo. When consumed without a meal, LDL-C was also significantly decreased (drink A: -5.1% (P<0.05, 95% CI: -9.4 to -0.8); drink B: -6.9% (P<0.01, 95% CI: -11.3 to -2.5) as compared to placebo, however the effect was significantly smaller as compared to the intake with a meal.

CONCLUSION

These results indicate that a PS-ester-enriched single-dose yoghurt drink effectively reduces LDL-C irrespective of the fat content of the product. A substantially larger decrease in serum cholesterol concentration was achieved when the single-dose drink was consumed with a meal emphasizing the importance of the intake occasion for optimal cholesterol-lowering efficacy.

SPONSORSHIP

Unilever Research and Development, Vlaardingen, The Netherlands.

Efficacy and safety of sitosterol in the management of blood cholesterol levels

Elevated levels of plasma LDL cholesterol (LDL-C) represent a major risk factor for cardiovascular disease. Treatments aimed at reducing levels of circulating LDL are regarded, therefore, as cardioprotective. The cholesterol lowering properties of plant sterols have been known for some time and many clinical studies have confirmed the efficacy of sitosterol in lowering plasma LDL-C concentrations. Animal studies have also shown reductions in LDL by sitosterol. The use of animal models has been useful in facilitating the elucidation of specific mechanisms by which this sterol exerts its hypocholesterolemic action. It is well known that plant sterols compete with cholesterol for space within bile salt micelles in the intestinal lumen thereby reducing cholesterol absorption. The understanding of the function of plant sterols in impeding cholesterol absorption has been clarified with the discovery of the adenosine binding cassette transporters, ABCG5/8, involved in the regulation of sterol absorption and secretion into the enterocyte and hepatocyte. Compared to cholesterol and other sterols, sitosterol is preferentially pumped out to the intestinal lumen by the ABCG5/8 transporters. This selective binding of sitosterol to the transporters ultimately results in significant lowering of plasma cholesterol. However, some findings support the hypothesis that plant sterols might be an additional risk factor for coronary heart disease. From the review of these studies, it is apparent that sitosterol is a useful dietary supplement for the lowering of plasma cholesterol. Nevertheless, this plant sterol should be used with caution in certain individuals who have a higher absorption rate of sitosterol.

Different apoptotic mechanisms are involved in the antiproliferative effects of 7beta-hydroxysitosterol and 7beta-hydroxycholesterol in human colon cancer cells

Plant sterols are found in fruits and vegetables. Their cholesterol-lowering effect is well documented. Our study aimed at comparing antiproliferative effects of 7beta-hydroxysitosterol (7beta-OHsito) versus 7beta-hydroxycholesterol (7beta-OHchol) on the human colon cancer cell line Caco-2. When cells were exposed for 32 h to 60 microM 7beta-OHsito or to 30 microM 7beta-OHchol, both compounds caused 50% growth inhibition. Cells treated with 7beta-OHsito showed enhanced caspase-9 and -3 activities followed by DNA fragmentation. In contrast, 7beta-OHchol did not activate caspase-3 and activation of caspase-9 and DNA fragmentation were delayed. The treatment of cells with the caspase inhibitor Z-VAD.fmk retarded the 7beta-OHsito-induced apoptotic process but not that triggered by 7beta-OHchol. Our data suggest that the two compounds in spite of their structural similarities target different cellular pathways, which lead to cell death.

Low-fat formulations of plant stanols and sterols

Clinical trials have shown that an intake of 2 to 3 g/day of esterified plant stanol--when incorporated in margarines or spreads--significantly reduces serum total and low-density lipoprotein (LDL) cholesterol concentrations without affecting serum high-density lipoprotein cholesterol or triglyceride levels. There is also a growing interest in incorporating cholesterol-lowering ingredients into low-fat foods. Esterification of stanols with long-chain fatty acids increases fat solubility by 10-fold and enables the incorporation of plant stanols into different food products, even low-fat foods. It provides a means of introducing an adequate daily amount of stanol for optimal reduction of cholesterol absorption, while maintaining a high-quality food product. Recent clinical trials show that esterified plant stanols effectively reduce serum total and LDL cholesterol levels, even when used in food vehicles with a low-fat content.

The clinical and nutritional implications of lipid-lowering drugs that act in the gastrointestinal tract

PURPOSE OF REVIEW

A new class of cholesterol-lowering therapy that reduces intestinal sterol absorption has recently been introduced. This increases the number of classes of lipid-lowering agents that directly affect gastrointestinal function and raises questions concerning the overall effect of these agents on absorption and nutritional status.

RECENT FINDINGS

A recent assessment notes a paucity of information concerning the factors that affect the bioavailability and intestinal absorption of lipophilic nutrients. By contrast, the specificity of the mechanisms of action of new drugs acting on the gastrointestinal tract may circumvent some of the detrimental effects on nutrient and drug bioavailability that have been noted with older forms of treatment.

SUMMARY

The clinical imperative for aggressive control of lipid and metabolic risk factors makes widespread use, alone or in combination, of lipid-lowering agents that affect the gastrointestinal tract seem increasingly likely. Whilst the opportunity for therapeutic synergy is attractive, care will be required to avoid interference with intestinal absorptive function.

High dietary intake of phytosterol esters decreases carotenoids and increases plasma plant sterol levels with no additional cholesterol lowering

The objective of this study was to measure the effects on serum lipids and plasma phytosterols of 6.6 g/day phytosterols from three foods (bread, breakfast cereal, and spread) consumed for 12 weeks compared with a diet that was not enriched with phytosterols. Thirty-five subjects undertook a nonrandomized, single-blind study consisting of a 2 week baseline period, 6 weeks on high-phytosterol intake, 6 weeks on high-phytosterol intake plus increased fruit and vegetable intake, and a final 2 week washout period. Serum total cholesterol decreased by 8.3% from 6.59 to 6.04 mmol/l, and LDL cholesterol decreased by 12.6% from 4.44 to 3.88 mmol/l. Plasma phytosterol levels increased by 45% (sitosterol) and 105% (campesterol). Cholesterol-adjusted plasma alpha- and beta-carotene levels decreased by 19-23%, lutein by 14%, and lycopene by 11%. Levels of alpha-carotene and lutein increased with extra fruit and vegetables. Only lycopene failed to increase during the washout phase. There were no significant changes in biochemical parameters. Serum LDL cholesterol lowering with 6.6 g/day ingested phytosterols was in the range seen with 1.6-3.2 g/day phytosterols. Lowering of plasma carotenoids was greater than that seen with lower phytosterol intake and was partially reversed by increased fruit and vegetable intake.