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Technical Briefs |
-Tocopherol Therapy Does Not Affect HDL Subfractions in Patients with Coronary Artery Disease on Statin Therapy1 University of California Davis Medical Center, Sacramento, California; 2 Liposcience, Raleigh, North Carolina; 3 University of Texas-Houston Medical School, Houston, Texas; 4 University of Texas Southwestern Medical Center, Dallas, Texas;
aaddress correspondence to this author at: Laboratory for Atherosclerosis and Metabolic Research, Department of Medical Pathology & Laboratory Medicine, University of California Davis Medical Center, 4635 Second Avenue, Research Bldg. 1, Rm. 3000, Sacramento, CA 95817; fax: 916-734-6593, e-mail ishwarlal.jialal{at}ucdmc.ucdavis.edu
Abstract
Background: Subfractions of HDL, particularly large HDL (HDL2), are inversely correlated with the severity of coronary artery disease (CAD). 
-Tocopherol (AT) is the main lipid-soluble antioxidant in plasma. Results of a previous small study (n = 44) suggested that either a combination of an antioxidant cocktail [800 IU/day 2R,4'R,8'R-(RRR)-AT plus 1 g vitamin C, 25 mg ß-carotene, and 100 µg selenium] or individual antioxidant vitamins combined with simvastatin–niacin (S-N) therapy attenuated the protective increase in HDL2 seen with S-N alone. Few data are available on the effect of AT therapy alone on HDL subfractions, which we addressed in this study.
Methods: In a prospective placebo-controlled study, we randomized 127 patients with stable CAD to receive high-dose RRR-AT (1200 IU/day for 2 years) or placebo. HDL subfractions (small, medium, and large HDL particles) were analyzed by nuclear magnetic resonance spectroscopy.
Results: AT concentrations significantly increased in the AT arm but not with placebo. No differences were noted between AT and placebo groups in concentrations of total cholesterol, triglyceride, LDL-cholesterol, or HDL-cholesterol. AT therapy did not affect total, small, medium, or large HDL particles compared with baseline or placebo. Furthermore, serum apolipoprotein A1 concentrations did not change after 2 years AT therapy as compared with baseline.
Conclusions: High-dose AT therapy administered for a 2-year period does not negatively affect either HDL subfractions or apolipoprotein A1 in patients with CAD on statin therapy. Thus the negative interaction previously proposed between antioxidant cocktail and statin therapy cannot be attributed to AT.
Numerous clinical and epidemiological studies have demonstrated an inverse relationship between HDL-cholesterol (HDL-C) and the risk of coronary artery disease (CAD) (1)(2). The small HDL subclasses (HDL3) contribute to increased risk, whereas large HDL subclasses (HDL2) are associated with decreased risk for CAD (3)(4). Inflammation and oxidative stress are pivotal in atherosclerosis; dietary micronutrients with antioxidant and antiinflammatory activities may play a critical role in the prevention of CAD (5). Although -tocopherol (AT) has several beneficial effects on lipid peroxidation and inflammation, the results of randomized clinical trials have been equivocal and have been essentially negative (6). HDL Atherosclerosis Treatment Study (HATS) investigators (7)(8)(9) have reported that the combination of an antioxidant (AOX) cocktail [800 IU/day of 2R,4'R,8'R-(RRR)-AT + 1 g vitamin C, 25 mg ß-carotene, and 100 µg selenium] or individual AOX vitamin therapies (vitamins A, E + C, and ß-carotene) attenuated the HDL2-C response that was obtained by simvastatin–niacin (S-N) therapy. Few data are available, however, on the effect of AT therapy alone on HDL subfractions or on LDL and VLDL subfractions. Therefore, we investigated whether RRR-AT supplementation has any effect on lipoprotein subclasses in patients with stable CAD on statin therapy. We recruited and randomized 127 patients in a double-blind manner to placebo or RRR-AT (1200 IU/day) supplementation for 2 years. Selection criteria were nonsmokers, no high-intensity exercisers, not on antioxidant supplementation, no other chronic disease or gastrointestinal problems, no recent infection/trauma/surgery, no pregnancy/lactation, no bleeding diathesis, normal complete blood cell count, normal renal and liver function, alcohol intake <1 ounce/day, and not on thyroid drugs, nonsteroidal antiinflammatory drugs, oral contraceptives, or anticoagulants. The study was performed at University of Texas Southwestern Medical Center, Dallas, Texas, and University of California Davis Medical Center, Sacramento, California, and was approved by both the Institutional Review Boards. All patients gave informed consent. Fasting blood was collected at 5 different time points: baseline and 6, 12, 18, and 24 months. This study was a substudy of the primary trial designed to examine the effect of AT supplementation on carotid atherosclerosis, biomarkers of oxidative stress, and inflammation in patients with CAD on statin therapy. A total of 90 patients (71%) completed the study. Reasons for dropping out included the long study duration, movement of participants to different geographic locations, and 3 deaths (2 in placebo and 1 in AT group). We had 85 samples for analysis of lipoprotein subfractions in the current report.
We analyzed lipids (total cholesterol, triglycerides, LDL, and HDL) (10) and apolipoprotein A1 (apoA1) concentrations. Plasma AT concentrations were measured by reversed-phase HPLC (11) and lipid standardized as described previously (11). Lipoprotein subfractions were measured by nuclear magnetic resonance spectroscopy at Liposcience (12). HDL subfraction measurement included total particles and small (7.3–8.2 nm; HDL3 b and c), medium (8.2–8.8 nm; HDL3 a), and large (8.8–13.0 nm; HDL2 a and b) particles. We also measured VLDL and LDL fractions as total, small, and large particles (12). ApoA1 concentrations were measured by an immunoassay (Beckman Lx 20) at baseline and at 2 years in the sera of patients in the AT group. The intra- and interassay CVs for lipoprotein subclasses and apoA1 were <10%. Data were analyzed using SPSS statistical software. Repeated measures ANOVA were conducted to determine time and dose–response effects followed by appropriate post hoc analyses of parametric and nonparametric data. The level of significance was set at P <0.05. With n = 40 patients per group, the study had a power of 0.9 to detect significant difference in HDL subfractions at the 0.05 significance level.
Demographic variables and baseline laboratory measurements are presented in Table 1 in the Data Supplement that accompanies the online version of this technical brief at http://www.clinchem.org/content/vol53/issue3. Patients were well-matched for age, body mass index, presence of diabetes/hypertension, and statin therapy. No significant difference in lipid concentrations as either a time or a treatment effect was observed in the 2 patient groups (Table 1A
). Compared with baseline concentrations and concentrations in the placebo group, AT concentrations in patients receiving AT therapy significantly increased (P <0.01) as early as 6 months and up to 24 months after therapy (Fig. 1
). Similar results were obtained for lipid-standardized AT concentrations. Concentrations of different HDL subclasses or total HDL particles were not significantly (all P >0.5) different from baseline after 2 years of AT therapy (Table 1B
). Also, no differences were seen between treatment groups at any time point. Furthermore, the measurement of mean (SD) apoA1 concentrations in sera at baseline [134.6 (23.1) mg/L] and after AT therapy for 2 years [132.9 (17.6) mg/L] did not reveal any significant change (P = 0.73). The subclasses of VLDL and LDL also did not significantly differ as either a time or treatment effect (see Table 2 in the online Data Supplement). Thus we observed no change from baseline or difference from placebo in any of the lipoprotein subclasses after 2 years of AT therapy.
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Although the consensus has been that HDL2 renders a protective effect, HDL3 leads to increased risk of CAD. Several lines of evidence in epidemiological studies support a relationship between low AT concentrations and the development of atherosclerosis (5), but the results of prospective and randomized clinical trials have been equivocal (6). HATS investigators(7) tested the effect of an AOX supplement in combination with S-N on coronary stenosis quantitated by angiography. In a 3-year, double-blind trial, 160 patients with CAD, low HDL-C, and LDL-C concentrations within the reference interval were randomly assigned to receive 1 of 4 regimens: S-N, AOX cocktail, S-N plus AOX (S-n + A), or placebos. These authors reported that the mean concentrations of LDL and HDL-C were unaltered in the AOX (n = 39) and the placebo (n = 34) groups; these concentrations changed substantially (by –34% and +25%, respectively) in the S-N group (n = 38). Furthermore, these concentrations changed by –31% and +18%, respectively, in the S-n + A group (n = 40). However, the protective increase in HDL2-C with S-N (42%; measured by nondenaturing polyacrylamide gradient gel electrophoresis) was attenuated by concurrent therapy with antioxidants (S-n + A). The compliance reported for S-N and AOX in this study was 
89%. Subsequently, these authors (8) demonstrated that the increase in HDL-C seen with niacin therapy can result from a reduction in catabolism, an increase in the expression of ABC1 transporter, or an enhancement in the conversion of HDL3 to HDL2C by the phospholipids transfer proteins lecithin: cholesterol acyltransferase and lipoprotein lipase (4)(13). An additional substudy (9) was conducted by the same investigators in a total of 44 patients given S-N for 3 months and randomly assigned to receive 1 of 6 AOX options: 800 IU vitamin E + vitamin C, 25 mg ß-carotene, 50 000 IU vitamin A, 100 µg selenium, the original AOX cocktail, or placebo. The 3 individual vitamin therapies, vitamin A, vitamins E + C, and ß-carotene, were as effective as the cocktail in blunting the HDL2-C response to S-N therapy. The number of patients in each subgroup from the total of 44 was not specified in this study, however. The authors acknowledged the limitation of sample size, with a caution for confirmation of the study. Importantly, none of these patients received supplementation with AT alone, thus prompting us to investigate whether AT therapy alone attenuates HDL2 subfraction compared with placebo in CAD patients on statin therapy. We provide here the evidence that there was no significant difference in lipoprotein subclasses as either a time or a treatment effect. Also, ApoA1 concentrations after AT therapy were not affected. A strength of our study is the greater sample size of patients (n = 85) with CAD followed for 2 years at 5 different time points compared with an earlier study of a small number of patients (n = 44) subdivided into 6 subgroups in which one of the subgroup received vitamins E + C and was studied at only 2 different time points, baseline and 3 months (9). The larger sample size in our study was appropriate not only to measure HDL subfractions but to confirm or refute the notion put forward by HATS Investigators that AOX vitamins, especially AT, have a negative effect on HDL subfractions in CAD patients on statin therapy. Importantly, 
90% of our patients were on statin therapy, similar to the percentage in the HATS study (89% reported compliance for S-N and AOX cocktail). Thus, we conclude that high-dose RRR-AT therapy for 2 years, in patients with CAD on concomitant statin therapy, does not negatively affect HDL subclasses, especially the protective and large HDL subclass HDL2-, although we did not examine the functional characteristics of HDL from the 2 groups. In addition, we report no significant differences in LDL and VLDL subfractions.
In conclusion, the negative interaction previously proposed between AOX cocktail and statin therapy cannot be ascribed to AT. Based on the totality of evidence, we do not recommend high-dose AT supplementation in patients with CAD. In other populations at increased risk, however, vitamin E may still be beneficial, and its use is being tested in randomized clinical trials such as the PiVENS and TONIC trials of patients with nonalcoholic steatohepatitis who also have low HDL and the metabolic syndrome.
Acknowledgments
This work was supported by National Institutes of Health grants R01 AT 00005 and K24 AT 00596 (I.J.). We thank Beverley Huet for statistical analyses.
References
-tocopherol supplementation on LDL oxidation: a dose-response study. Arterioscler Thromb Vasc Biol 1995;15:190-198.The following articles in journals at HighWire Press have cited this article:
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  S. Devaraj, R. Tang, B. Adams-Huet, A. Harris, T. Seenivasan, J. A de Lemos, and I. Jialal Effect of high-dose {alpha}-tocopherol supplementation on biomarkers of oxidative stress and inflammation and carotid atherosclerosis in patients with coronary artery disease Am. J. Clinical Nutrition, November 1, 2007; 86(5): 1392 - 1398. [Abstract] [Full Text] [PDF]
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