High molecular weight oat ß-glucan enhances lipid-lowering effects of phytosterols. A randomised controlled trial.

BACKGROUND & AIMS: Oat ß-glucan (OBG) and phytosterols (PS) are known to lower blood cholesterol levels via different mechanisms. Combination of high molecular weight (MW) OBG and PS in a single functional food could have complementary and/or synergistic effects for optimising heart health. The aim of this study was to investigate the effects of dietary supplementation with high-MW OBG with or without PS on plasma lipids in hypercholesterolaemic individuals. METHODS: In a double-blinded, placebo-controlled, 2 × 2 factorial trial, participants were randomised to receive biscuits fortified with either no PS or OBG (PL, n = 18) or 2 g PS (PS, n = 18), 3 g OBG (OBG, n = 18), or combination of 2 g PS and 3 g OBG (PS-OBG, n = 18) per day for 6 weeks. Primary outcome was fasting plasma total cholesterol (TC) and secondary outcomes were LDL-cholesterol, LDL-C; HDL-cholesterol, HDL-C; triglycerides, TG and TC to HDL-cholesterol (TC:HDL) ratio. RESULTS: TC and LDL-C were significantly lowered following PS (-4.6% and -7.6% respectively; p < 0.05), OBG (-5.7% and -8.6%; p < 0.01) and PS-OBG (-11.5% and -13.9%; p < 0.0001) administration. The reduction in TC in the PS-OBG group was significantly greater compared to PL (p < 0.001) and PS (p < 0.05). PS-OBG group had a significantly greater reduction in LDL-C compared to PL (p < 0.01) but not in comparison to PS or OBG groups. TC:HDL ratio was significantly reduced following PS-OBG (-8.9%; p < 0.01) only, and there was no significant difference found between groups. Plasma TG reduced by 8.4% following PS-OBG, however, this was statistically non-significant. Plasma HDL-C remained unchanged across all groups. CONCLUSIONS: Dietary supplementation with high-MW OBG and PS in a single functional food enhances their lipid-lowering potential. Blood cholesterol lowering by PS and OBG is additive. Delivery of these two bioactive nutrients in a single food allows optimisation of their lipid-lowering effects and may provide added heart health benefits with enhanced compliance. The trial was registered with the Australian New Zealand Clinical Trials Registry at http://www.anzctr.org.au/(ACTRN12618001455257).

Promotion of classic neutral bile acids synthesis pathway is responsible for cholesterol-lowing effect of Si-miao-yong-an decoction: Application of LC-MS/MS method to determine 6 major bile acids in rat liver and plasma.

Si-miao-yong-an decoction (SMYAD), a traditional Chinese medicine formula, significantly reduced plasma TC, LDL-c levels and increased HDL-c level in hyperlipidemia rats. Liver function test and tissue section examination indicated that SMYAD improved liver function and reduced fat accumulation in hyperlipidemia rat liver. A LC-MS/MS method was established and well validated to evaluate major bile acids derived from cholesterol metabolism through the classic neutral pathway and the alternative acidic pathway (cholic acid, chenodeoxycholic acid and their taurine and glycine conjugates) in liver and plasma. Increased total 6 bile acids concentrations in both liver and plasma were observed after oral administration of 12g/kg/d, 24g/kg/d and 36g/kg/d of SMYAD in a dose dependent manner which contributed to eliminate of cholesterol. Cholic acid, taurocholic acid and glycocholic acid act as the main products of bile acid classic neutral synthesis pathway and show sharp increase (p<0.01) after treatment of SMYAD at dosage of 24-36g/kg/d. For liver samples, taurocholic acid level act as the largest growth section, while in plasma samples, cholic acid act as the largest growth section after SMYAD treatment, compared with Model group. By contrast, the main products of alternative acidic pathway (chenodeoxycholic acid and its glycine and taurine conjugates) show no significant increase after treatment of SMYAD. In conclusion, the cholesterol lowing effect of SMYAD may be related with the accelerated transformation of cholesterol into bile acids through the classic neutral pathway.

ESSENS dyslipidemia: A placebo-controlled, randomized study of a nutritional supplement containing red yeast rice in subjects with newly diagnosed dyslipidemia.

OBJECTIVE: Evidence suggests prolonged exposure to lower levels of low-density lipoprotein cholesterol (LDL-C), starting at a younger age, substantially lowers cardiovascular (CV) risk. Accordingly, the CV pandemic affecting younger population in low- to low-middle-income countries, where statin usage is poor even in secondary prevention, may benefit from lipid-lowering nutritional products, as nutritional intervention is generally preferred in these cultures. However, the safety and efficacy of such preparations have not been systematically tested. METHODS: In this multicenter, double-blind study, 191 statin-free subjects with newly-diagnosed hyperlipidemia (LDL-C >120 mg/dL, 3.11 mmol/L) and no evidence of CV disease were randomized to one capsule of a proprietary bioactive phytonutrient formulation containing red yeast rice, grape-seed, niacinamide, and folic acid (RYR-NS) or matched placebo twice daily, along with lifestyle modification, for 12 wk. RESULTS: Mean baseline LDL-C levels were 148.5 ± 24.0 mg/dL (3.85 ± 0.62 mmol/L) and 148.6 ± 21.9 mg/dL (3.85 ± 0.57 mmol/L) in the RYR-NS and placebo groups respectively. Compared with placebo, RYR-NS resulted in a significant reduction in LDL-C (-29.4% versus -3.5%, P < 0.0001) and non-high-density lipoprotein cholesterol (non-HDL-C; -29.8% versus -10.3%, P < 0.0001) at 12 wk. With RYR-NS, 43.4% individuals attained desirable LDL-C levels and 55.4% desirable non-HDL-C levels by week 12, compared to only 0% and 1.1%, respectively, at baseline. No safety issues were observed. CONCLUSION: This study demonstrates the efficacy and safety of RYR-NS in lowering LDL-C and non-HDL-C after 12 wk, with magnitude of LDL-C reduction being comparable to that seen with moderate-intensity statin therapy. Further long-term studies are required to determine the impact of RYR-NS on treatment adherence and clinical outcomes.

Randomised controlled trial of the effect of long-term selenium supplementation on plasma cholesterol in an elderly Danish population.

Although cross-sectional studies have shown a positive association between Se and cholesterol concentrations, a recent randomised controlled trial in 501 elderly UK individuals of relatively low-Se status found that Se supplementation for 6 months lowered total plasma cholesterol. The Danish PRECISE (PREvention of Cancer by Intervention with Selenium) pilot study (ClinicalTrials.gov ID: NCT01819649) was a 5-year randomised, double-blinded, placebo-controlled trial with four groups (allocation ratio 1:1:1:1). Men and women aged 60-74 years (n 491) were randomised to 100 (n 124), 200 (n 122) or 300 (n 119) µg Se-enriched yeast or matching placebo-yeast tablets (n 126) daily for 5 years. A total of 468 participants continued the study for 6 months and 361 participants, equally distributed across treatment groups, continued for 5 years. Plasma samples were analysed for total and HDL-cholesterol and for total Se concentrations at baseline, 6 months and 5 years. The effect of different doses of Se supplementation on plasma lipid and Se concentrations was estimated by using linear mixed models. Plasma Se concentration increased significantly and dose-dependently in the intervention groups after 6 months and 5 years. Total cholesterol decreased significantly both in the intervention groups and in the placebo group after 6 months and 5 years, with small and nonsignificant differences in changes in plasma concentration of total cholesterol, HDL-cholesterol, non-HDL-cholesterol and total:HDL-cholesterol ratio between intervention and placebo groups. The effect of long-term supplementation with Se on plasma cholesterol concentrations or its sub-fractions did not differ significantly from placebo in this elderly population.

Single therapeutic and supratherapeutic doses of anacetrapib, a cholesteryl ester transfer protein inhibitor, do not prolong the QTcF interval in healthy volunteers.

Anacetrapib is a cholesteryl ester transfer protein inhibitor in Phase III development. This double-blind, double-dummy, randomized, placebo- and active-comparator-controlled, 4-period, balanced crossover study evaluated the effects of anacetrapib (100 mg and 800 mg) on QTcF interval in healthy subjects. QTcF measurements were made up to 24 h following administration of single doses of anacetrapib 100 or 800 mg, moxifloxacin 400 mg, or placebo in the fed state. The primary hypothesis was supported if the 90% CI for the least squares (LS) mean differences between anacetrapib 800 mg and placebo in QTcF interval change from baseline were entirely <10 msec at every post-dose time point (1, 2, 2.5, 3, 4, 5, 6, 8, 12, and 24 h). The upper bounds of the 90% CIs for LS mean differences from placebo in changes from baseline in QTcF intervals for anacetrapib 100 and 800 mg were <5 msec at every time point. In conclusion, single doses of anacetrapib 100 and 800 mg do not prolong the QTcF interval to a clinically meaningful degree relative to placebo and are generally well tolerated in healthy subjects.

Effects of ezetimibe on serum polyunsaturated fatty acids in patients with coronary artery disease.

Residual risk of cardiovascular disease might stem, at least partially, from low serum concentrations of n-3 polyunsaturated fatty acid (PUFA). The purpose of this study was to evaluate the effects of ezetimibe on serum lipids and PU-FAs in patients with coronary artery disease who were intolerant of new or high-dose statin therapy. The study population consisted of 13 patients who were intolerant of new statin therapy and 10 patients who were intolerant of high-dose statin therapy for the treatment of low-density lipoprotein (LDL) cholesterol. Patients who were intolerant of high-dose statin therapy continued taking a statin, but at a lower dose during the study period. Blood samples were collected before and 12 weeks after ezetimibe (10 mg). We measured serum lipids and PUFAs including dihomo-γ-linolenic acid, arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid. Ezetimibe significantly decreased LDL cholesterol (138 ± 19 mg/dL to 97 ± 34 mg/dL, P < 0.01), but did not significantly affect high-density lipoprotein cholesterol, triglyceride, or any of the PUFAs measured during the follow-up period. Consequently, it did not affect the ratio of EPA to AA (0.40 ± 0.17 to 0.43 ± 0.18, P = ns) or the ratio of n-3 PUFA to n-6 PUFA (1.10 ± 0.39 to 1.09 ± 0.36, P = ns) during the follow-up period. Ezetimibe in combination with a low-dose statin, or as monotherapy in statin-intolerant patients, decreased LDL cholesterol, but did not significantly affect serum PUFA concentrations in patients with coronary artery disease.

High-dose supplementation with natural α-tocopherol does neither alter the pharmacodynamics of atorvastatin nor its phase I metabolism in guinea pigs.

It has been hypothesized in the literature that intake of high-dosage vitamin E supplements might alter the expression of cytochrome P(450) enzymes (CYP), particularly CYP3A4, which may lead to adverse nutrient-drug interactions. Because previously published studies reported conflicting findings, we investigated the pharmacodynamics of the lipid-lowering drug atorvastatin (ATV), a CYP3A4 substrate, in response to high-dose α-tocopherol (αT) feeding and determined protein expression and activities of relevant CYP. Groups of ten female Dunkin-Hartley guinea pigs were fed a control (5% fat) or a high-fat control diet (HFC; 21% fat, 0.15% cholesterol) or the HFC diet fortified with αT (250 mg/kg diet), ATV (300 mg/kg diet) or both ATV+αT for 6 weeks. Relative to control, HFC animals had increased serum cholesterol concentrations, which were significantly reduced by ATV. High-dose αT feeding in combination with ATV (ATV+αT), albeit not αT feeding alone (αT), significantly lowered serum cholesterol relative to HFC, but did not alter the cholesterol-lowering activity of the drug compared to the ATV treated guinea pigs. Protein expression of CYP3A4, CYP4F2, CYP20A1 and OATP C was similar in all groups. Accordingly, no differences in plasma concentrations of phase I metabolites of ATV were observed between the ATV and ATV+αT groups. In conclusion, feeding guinea pigs high-doses of αT for 6 weeks did neither alter the hepatic expression of CYP, nor the pharmacodynamics and metabolism of ATV. High-dose αT intake is thus unlikely to change the efficacy of drugs metabolized by CYP enzymes, particularly by CYP3A4.

Low intestinal cholesterol absorption is associated with a reduced efficacy of phytosterol esters as hypolipemic agents in patients with metabolic syndrome.

BACKGROUND & AIMS: Phytosterols (PS) lower LDLc, but their effect on metabolic syndrome (MetS) remains unknown. We evaluated whether low-fat milk enriched with PS improves cardiovascular risk factors in these patients. METHODS: A randomised parallel trial employing 24 moderate-hypercholesterolaemic MetS patients and consisting of two 3-month intervention phases. After a 3-month healthy diet, patients were divided into two intervention groups: diet (n = 10) and diet + PS (n = 14) (2 g/day). A control group of 24 moderate-hypercholesterolaemic patients without MetS (matched in age and BMI) underwent the same procedure. RESULTS: Neither dietary intervention nor enrichment of PS induced any improvement in the serum lipoprotein profile of MetS patients. By contrast, in the non-MetS population, a healthy diet effectively reduced TC, LDLc, non-HDLc and Apo B-100, with further decreases in TC (6.9%), LDLc (10.5%), non-HDLc (10.3%), Apo B-100 (6.2%) and Apo B-100/ApoA-I ratio (11.6%) being observed when PS were administered. No differences in LDL diameter, hsCRP or homocysteine were detected in any of the groups after consuming PS. This supplementation produced a significant increase in PS levels only in the non-MetS population. CONCLUSIONS: PS therapy appears to be of little value to MetS patients, likely due to its reduced intestinal cholesterol absorption. The efficacy of PS as hypocholesterolaemic agents is thus limited.

Very high plant stanol intake and serum plant stanols and non-cholesterol sterols.

BACKGROUND: Today, consumers meet abundant supply of functional foods with plant stanol increments for serum cholesterol lowering purposes. However, efficacy and safety of plant stanols intake beyond 4 g/day have remained unexplored. AIM OF THE STUDY: We evaluated the effects of very high daily intake of plant stanols (8.8 g/day) as esters on cholesterol metabolism, and serum levels of plant sterols and stanols. METHODS: In a randomized, double-blind, parallel study of 49 hypercholesterolemic subjects (mean age 62 years, range 41-73) consumed a test diet without (control, n = 24), and with added plant stanol esters (staest, n = 25) over 10 weeks followed by 4 weeks on home diet. Serum lipids, lipoprotein lipids, and non-cholesterol sterols were determined at baseline, during intervention, and 4 weeks afterwards. Cholesterol precursor sterol lathosterol reflected cholesterol synthesis, and serum plant sterols and cholestanol mirrored cholesterol absorption. RESULTS: When compared with controls, 8.8 g/day of plant stanols reduced serum and LDL cholesterol by 12 and 17% (P < 0.01 for both). Synthesis marker lathosterol was increased by 30%, while absorption markers decreased up to 62% when compared with controls (P < 0.001 for both). Serum plant stanols increased slightly, but significantly compared with controls (serum sitostanol during intervention, controls: 16 +/- 1 microg/dL, staest: 37 +/- 2 microg/dL, serum campestanol during intervention, controls: 0.5 +/- 0 microg/dL, staest: 9 +/- 1 microg/dL, P < 0.001 for both). Changes in serum cholesterol, non-cholesterol sterols, and plant stanols were normalized during post-treatment weeks. CONCLUSIONS: Serum plant stanol levels remained at comparable low levels as in studies with daily intake of 2-3 g, and were normalized in 4 weeks suggesting that daily intake of 8.8 g of plant stanols might not increase systemic availability of plant stanols, but reduces effectively serum cholesterol and plant sterol levels.

A preliminary study of atorvastatin plasma concentrations in critically ill patients with sepsis.

OBJECTIVE: A lack of published pharmacokinetic data on statins in sepsis has prompted concerns about their safety and toxicity. This study determined single dose pharmacokinetics of Atorvastatin administered orally to acutely ill patients. DESIGN, SETTING AND PARTICIPANTS: A prospective open label study conducted in a tertiary referral centre on 5 healthy volunteers, 5 acutely ill patients admitted to the medical ward and a heterogeneous cohort of 25 critically ill patients admitted to an intensive care unit. INTERVENTION: All participants received a single oral dose of 20 mg of atorvastatin. MEASUREMENT AND RESULTS: Plasma pharmacokinetics of atorvastatin as measured by maximal plasma concentration (Cmax) and area under the curve (AUC) (0-24 h). Critically ill patients with sepsis had a significantly higher Cmax and AUC as compared to healthy volunteers [110.5(86.5) vs. 5.9(2.50) ng/ml, p < 0.01 and 1,051(810) vs. 67(48) ng h/ml (p < 0.0001)], respectively. Atorvastatin concentrations in the plasma of critically ill patients with sepsis remained supratherapeutic for up to 20 h after a single dose. The AUC was significantly higher for those patients on concomitant CYP 450 inhibitor therapy as compared to those patients not on inhibitors (1,518 +/- 793 vs. 584 +/- 540 ng h/ml, p = 0.0260). CONCLUSIONS: Very high plasma concentrations were achieved in intensive care patients with sepsis. This can only be partly explained by altered metabolism of atorvastatin. Further investigations are essential to better describe the pharmacokinetics of statins in various groups of critically ill patients. Caution should be exercised prior to adopting high dose regimens in patients with severe sepsis.

Preparation, characterization, and in vitro and in vivo evaluation of lovastatin solid lipid nanoparticles.

The purpose of this research was to study whether the bioavailability of lovastatin could be improved by administering lovastatin solid lipid nanoparticles (SLN) duodenally to rats. Lovastatin SLN were developed using triglycerides by hot homogenization followed by ultrasonication. Particle size and zeta potential were measured by photon correlation spectroscopy. The solid state of the drug in the SLN and lipid modification were characterized. Bioavailability studies were conducted in male Wistar rats after intraduodenal administration of lovastatin suspension and SLN. Stable lovastatin SLN having a mean size range of 60 to 119 nm and a zeta potential range of -16 to -21 mV were developed. More than 99% of the lovastatin was entrapped in the SLN. Lovastatin was dispersed in an amorphous state, and triglycerides were in beta(1) form in the SLN. In vitro stability studies showed the slow release and stability of lovastatin SLN. The relative bioavailabilities of lovastatin and lovastatin hydroxy acid of SLN were increased by ~173% and 324%, respectively, compared with the reference lovastatin suspension.

Effect of soy protein containing isoflavones on blood lipids in moderately hypercholesterolemic adults: a randomized controlled trial.

BACKGROUND: Dietary intake of soy protein with isoflavones may be associated with reductions in serum cholesterol. OBJECTIVES: To compare the effects of a water-washed soy protein concentrate with a milk-protein based control on blood lipid levels in hyperlipidemic men and women. METHODS: A randomized, double-blind, controlled clinical trial including 159 subjects. After a 3-week run-in period during which all subjects consumed a milk protein-based supplement, participants were randomized into one of two groups: a control group (continued milk protein) and an intervention group (soy protein) for a five-week period. Fasting venous blood draws for lipid measurement were obtained at baseline, towards the end of the run-in period and at the end of the intervention. Blood isoflavone concentrations were measured at the end of the study. RESULTS: Blood lipid levels were not significantly different between groups at any point in time; and there were no significant associations between blood isoflavones and lipid levels. Significant decreases in total cholesterol (19 mg/dL), and LDL-cholesterol (11 mg/dL), were observed during the run-in period, with no further decreases in lipids during the intervention period in either group. CONCLUSIONS: These results do not support the hypothesis that water-washed soy protein has an effect on blood lipids. Several hypotheses are discussed, highlighting the selective nature of the effect of soy consumption in the population. The cholesterol-lowering effect during the run-in period may be explained by the "regression to the mean effect" and by other factors related to study participation, mainly nutrient displacement induced by the protein supplement.

Plasma clearance of lovastatin versus chinese red yeast rice in healthy volunteers.

OBJECTIVES: It is now accepted that inhibition of cholesterol biosynthesis is effective in the primary and secondary prevention of heart disease. However, the perceived side-effects on muscle and liver reduce the general acceptance of statin drug therapy as well as compliance over the long term, which is necessary for prevention efforts to be successful. Chinese red yeast rice (CRYR) is a supplement containing lovastatin (monacolin K), eight other monacolins, pigments, tannins, and other phytochemicals. The authors previously reported on a double- blind placebo-controlled trial of CRYR supplement in 80 individuals demonstrating a significant decrease in cholesterol levels from 250 mg/dL to 210 mg/dL over 8 weeks independent of diet. The current study compared the pharmacokinetics of CRYR with lovastatin at the same bioeffective dose for lowering cholesterol. METHODS: Eleven (11) healthy volunteers were randomized to a crossover study taking 2400 mg CRYR or 20 mg of lovastatin. RESULTS: The Cmax and area under the curve (AUC) of lovastatin were 22.42 ng/mL, and 80.47 higher than CRYR (p = 0.001 and 0.002, respectively). The Cmax for lovastatin hydroxy-acid was 36.63 ng/mL higher than the Cmax of CRYR hydroxy-acid (p = 0.001). The AUC of lovastatin hydroxy-acid was 258.5 greater than that of CRYR (p = 0.001). CONCLUSIONS: The results suggested that the effect of CRYR on the cholesterol concentration might be caused by the additive and/or synergistic effects of monacolin K with other monacolins and substances in CRYR. It may lead to the ultimate development of a botanical supplement based on CRYR.

Potent hypocholesterolemic activity of the yeast Kluyveromyces marxianus YIT 8292 in rats fed a high cholesterol diet.

The hypocholesterolemic activities of 81 yeast strains were examined in rats fed a high cholesterol diet (HCD). Male Wistar rats were fed an HCD or an HCD supplemented with 10% yeast for 7 d. It was found that the hypocholesterolemic activities of the yeasts varied remarkably between strains. Kluyveromyces marxianus YIT 8292 exhibited the most potent hypocholesterolemic activity among the yeasts that were tested. K. marxianus YIT 8292 significantly decreased not only plasma total cholesterol but also liver total cholesterol when administered as a dietary admixture at a concentration of 3%. In contrast, brewer's yeast and baker's yeast, which have been predominantly used for food, did not exhibit hypocholesterolemic activity even when administered at a concentration of 10%. These results suggest that K. marxianus YIT 8292 may be utilized as a novel food material with the ability to contribute to the prevention of hypercholesterolemia.

Effects of habitual chitosan intake on bone mass, bone-related metabolic markers and duodenum CaBP D9K mRNA in ovariectomized SHRSP rats.

We have demonstrated that the habitual intake of chitosan can decrease bone mass in ovariectomized (OVX) SHRSP rats fed a low-Ca diet (0.1%). In the present study, we examined both the etiology of bone loss induced by dietary chitosan and the preventive effect of vitamin C supplementation. Rats were OVX and maintained on one of the following diets for 6 wk: 10% cellulose (CE). 10% chitosan (CH) or 10% chitosan with sodium ascorbate (CHVC). CH caused a significant reduction in bone mineral density (BMD) and stiffness in femurs and the fourth lumbar vertebrae (L4). There was no significant difference in intestinal Ca absorption between CH and CE, whereas CH intake significantly reduced intestinal P absorption. The bone loss in CH rats was accompanied with an increase in urinary Ca excretion and a decrease in serum Ca as well as a significant increment In serum PTH and 1,25(OH)2D3. The vitamin D receptor and calcium binding protein D9K mRNAs were also significantly increased in the duodenum of CH rats. Vitamin C supplementation to CH caused an increase in the Ca and P contents of femurs as well as BMD of the L4, with a decrease in urinary Ca excretion. These results indicate that dietary chitosan with low Ca intake possibly induces the loss of bone mass by enhancing urinary Ca excretion rather than by inhibiting Ca absorption, and that vitamin C supplementation could prevent bone loss caused by chitosan through the increment of retained Ca followed by suppression of urinary Ca excretion.

Effect of probucol on LDL oxidation and atherosclerosis in LDL receptor-deficient mice.

Probucol is a powerful inhibitor of atherosclerosis in a number of animal models. However, it is unknown whether this is due to the strong antioxidant protection of low density lipoprotein (LDL), to antioxidant effects in the artery wall, or to cellular effects not shared by other antioxidants. To investigate whether murine models are suitable to study the antiatherogenic mechanisms of probucol, three experiments following different protocols were carried out in 135 male and female LDL receptor-deficient (LDLR-/-) mice. Treatment groups received a high (0.5%) or low (0.025%) dose of probucol, or low-dose probucol plus a high dose (0.1%) of vitamin E for periods ranging from 6 to 26 weeks. In all experiments, probucol strongly protected LDL against ex vivo oxidation (lag times exceeding 1400 min in 0.5% probucol-treated mice). Treatment with 0.5% probucol significantly lowered both HDL-cholesterol and plasma apolipoprotein (apo)A-I concentrations. In all three experiments, treatment with 0.5% probucol consistently increased the size of lesions in the aortic origin, from 1.3-fold (n.s.) to 2.9-fold (P < 0.05) in female mice and from 3.6- to 3.7-fold in males (P < 0.001). Even treatment with 0.025% probucol increased atherosclerosis 1.6-fold in male mice (P < 0.01). Addition of the high dose of vitamin E did not attenuate the pro-atherogenic effect of 0.025% probucol. In conclusion, probucol not only failed to decrease but actively increased atherogenesis in LDLR-/- mice in a dose-dependent manner, even though it provided a very strong antioxidant protection of LDL. This suggests that the reduction of atherosclerosis observed in other animal models is due to intracellular effects of probucol not found in mice, to differences in the metabolism of probucol, and/or to an overriding atherogenic effect of the decrease in HDL in murine models.