Effects of d-α-Tocopherol Supplementation on Experimentally Induced Primate Atherosclerosis

Relationships between Atherosclerosis and Plasma Antioxidant Micronutrients or Red Blood Cell Polyunsaturated Fatty Acids in People Living with HIV

Background: People living with human immunodeficiency virus infection and acquired immune deficiency syndrome (HIV/AIDS) (PLWH) are at an increased risk of cardiovascular disease. Diet-related factors may contribute. The aim of this pilot study was to determine, in PLWH, the relationship between atherosclerosis assessed by carotid intima-media thickness (CIMT) and (A) plasma antioxidant micronutrients and oxidative stress or (B) red blood cell polyunsaturated fatty acids (RBC PUFA), particularly long chain omega-3 polyunsaturated fatty acids (n-3 PUFA). Methods: (A) In a cross-sectional study, subjects had CIMT evaluated by high resolution carotid artery ultrasound. Plasma was collected for vitamin C, measured by spectrophotometry; and alpha- and gamma-tocopherol, retinol, and malondialdehyde—a marker of oxidative stress—using high pressure liquid chromatography and fluorescence spectrophotometry. (B) In a prospective cohort study, other subjects had RBC PUFA measured at baseline, using gas chromatography, and CIMT assessed at baseline and repeated after 2 years. Clinical data was also collected. Results: (A) 91 PLWH participated. Only alpha- and gamma-tocopherol levels were positively correlated with CIMT. In a multivariate analysis, age and systolic blood pressure were significantly associated with CIMT with gamma-tocopherol near significance (p = 0.053). (B) 69 PLWH participated. At baseline, docosahexaenoic acid (n-3 PUFA) and the ratio of docosahexaenoic acid to arachidonic acid (n-6 PUFA) were significantly and negatively correlated with CIMT. However, a multivariate analysis failed to detect a significant relationship either at baseline or 2 years after. Conclusion: In addition to age and systolic blood pressure, atherosclerosis assessed by CIMT might be associated with higher serum gamma-tocopherol levels. There was a non-significant association between CIMT and RBC n-3 PUFA or the ratio of n-3 to n-6 PUFA.

Atherothrombosis and Oxidative Stress: Mechanisms and Management in Elderly

SIGNIFICANCE

The incidence of cardiovascular events (CVEs) increases with age, representing the main cause of death in an elderly population. Aging is associated with overproduction of reactive oxygen species (ROS), which may affect clotting and platelet activation, and impair endothelial function, thus predisposing elderly patients to thrombotic complications. Recent Advances: There is increasing evidence to suggest that aging is associated with an imbalance between oxidative stress and antioxidant status. Thus, upregulation of ROS-producing enzymes such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and myeloperoxidase, along with downregulation of antioxidant enzymes, such as superoxide dismutase and glutathione peroxidase, occurs during aging. This imbalance may predispose to thrombosis by enhancing platelet and clotting activation and eliciting endothelial dysfunction. Recently, gut-derived products, such as trimethylamine N-oxide (TMAO) and lipopolysaccharide, are emerging as novel atherosclerotic risk factors, and gut microbiota composition has been shown to change by aging, and may concur with the increased cardiovascular risk in the elderly.

CRITICAL ISSUES

Antioxidant treatment is ineffective in patients at risk or with cardiovascular disease. Further, anti-thrombotic treatment seems to work less in the elderly population.

FUTURE DIRECTIONS

Interventional trials with antioxidants targeting enzymes implicated in aging-related atherothrombosis are warranted to explore whether modulation of redox status is effective in lowering CVEs in the elderly. Antioxid. Redox Signal. 27, 1083-1124.

α-Tocopherol and Atherosclerosis

Cardiovascular disease is the leading cause of morbidity and mortality in the Western world. There is compelling evidence incriminating oxidative stress in the pathogenesis of the atherosclerotic lesion. Several lines of evidence suggest that antioxidants, especially α-tocopherol, have potential beneficial effects with regard to cardiovascular disease. In vitro, α-tocopherol has been shown to inhibit platelet adhesion and aggregation and smooth muscle cell proliferation, exert anti-inflammatory effects on monocytes, and improve endothelial function. Also, supplementation with α-tocopherol has been shown to decrease lipid peroxidation, platelet aggregation, and pro-inflammatory activity of monocytes. However, clinical trials with α-tocopherol supplementation to date have been equivocal. Thus, although mounting in vitro evidence and animal models provide a sound scientific basis for α-tocopherol supplementation, further clinical trials are required before a definitive recommendation can be made with respect to the primary and secondary prevention of heart disease.

Soluble guanylate cyclase redox state under oxidative stress conditions in isolated monkey coronary arteries

Coronary artery disease is associated with oxidative stress due to the excessive generation of free radicals in the vascular wall. This study investigated the impact of tert‐butyl hydroperoxide (t‐BuOOH), a peroxyl radical generator, on the redox state of soluble guanylate cyclase (sGC) in isolated monkey coronary arteries. Helically cut strips of endothelium‐intact monkey coronary arteries treated with the nitric oxide synthase inhibitor N^G‐nitro‐L‐arginine (10 μmol/L) were exposed for approximately 60 min to either no drug or t‐BuOOH (100 μmol/L) in the presence and absence of α‐tocopherol (300 μmol/L). Relaxation and cGMP levels in response to the sGC stimulator BAY 41‐2272 and the sGC activator BAY 60‐2770 were assessed by organ chamber technique and enzyme immunoassay, respectively. The relaxant response to BAY 41‐2272 was significantly impaired by the exposure to t‐BuOOH, whereas the response to BAY 60‐2770 was significantly augmented. In addition, vascular cGMP accumulation caused by BAY 41‐2272 was decreased by the exposure to t‐BuOOH, whereas for BAY 60‐2770, it was increased. These effects of t‐BuOOH were abolished by coincubation with α‐tocopherol. Furthermore, correlations were observed between BAY compound‐induced relaxant magnitudes and cGMP levels. Therefore, it is concluded that increased oxidative stress leads to disruption of the sGC redox state in monkey coronary arteries. This finding is of great importance for understanding coronary physiology in primates.

An experimental evaluation of the anti-atherogenic potential of the plant, Piper betle, and its active constitutent, eugenol, in rats fed an atherogenic diet

Hypercholesterolemia is a major risk factor for systemic atherosclerosis and subsequent cardiovascular disease. Lipoperoxidation-mediated oxidative damage is believed to contribute strongly to the progression of atherogenesis. In the current investigation, putative anti-atherogenic and antioxidative properties of an ethanolic extract of Piper betle and of its active constituent, eugenol, were sought in an experimental animal model of chronic hypercholesterolemia. Atherogenic diet-fed rats that received either Piper betle extract orally (500mg/kg b.wt) or eugenol orally (5mg/kg b.wt) for 15days (commencing 30days after the atherogenic diet had been started) exhibited the following variations in different parameters, when compared to atherogenic diet-fed rats that received only saline: (1) significantly lower mean levels of total cholesterol, triglycerides, low-density lipoprotein cholesterol and very low density lipoprotein cholesterol in both serum and hepatic tissue samples; (2) lower mean serum levels of aspartate amino-transferase, alanine amino-transferase, alkaline phosphatase, lactate dehydrogenase and lipid-metabolizing enzymes (lipoprotein lipase, 3-hydroxy-3-methyl-glutaryl-CoA reductase; (3) significantly lower mean levels of enzymatic antioxidants (catalase, superoxide dismutase, glutathione peroxidase, glutathione-S-transferase) and non-enzymatic antioxidants (reduced glutathione, vitamin C and vitamin E) and significantly higher mean levels of malondialdehyde in haemolysate and hepatic tissue samples. Histopathological findings suggested a protective effect of the Piper betle extract and a more pronounced protective effect of eugenol on the hepatic and aortic tissues of atherogenic diet-fed (presumed atherosclerotic) rats. These results strongly suggest that the Piper betle extract and its active constituent, eugenol, exhibit anti-atherogenic effects which may be due to their anti-oxidative properties.

Meta-analysis: low-dose intake of vitamin E combined with other vitamins or minerals may decrease all-cause mortality

It has been suggested that vitamin E alone or combined with other vitamins or minerals can prevent oxidative stress and slow oxidative injury-related diseases, such as cardiovascular disease and cancer. A comprehensive search of PubMed/MEDLINE, EMBASE and the Cochrane Library was performed. Relative risk was used as an effect measure to compare the intervention and control groups. A total of 33 trials were included in the meta-analysis. Neither vitamin E intake alone (RR=1.01; 95% CI, 0.97 to 1.04; p=0.77) nor vitamin E intake combined with other agents (RR=0.97; 95% CI, 0.89 to 1.06; p=0.55) was correlated with all-cause mortality. Subgroup analyses revealed that low-dose vitamin E supplementation combined with other agents is associated with a statistically significant reduction in all-cause mortality (RR=0.92; 95% CI, 0.86 to 0.98; p=0.01), and vitamin E intake combined with other agents is associated with a statistically significant reduction in mortality rates among individuals without probable or confirmed diseases (RR=0.92; 95% CI, 0.86 to 0.99; p=0.02). Neither vitamin E intake alone nor combined with other agents is associated with a reduction in all-cause mortality. But a low dose (<400 IU/d) of vitamin E combined with other agents is correlated with a reduction in all-cause mortality, and vitamin E intake combined with other agents is correlated with a reduction in the mortality rate among individuals without probable or confirmed diseases.

Pre-treatment with α-tocopherol and Terminalia arjuna ameliorates, pro-inflammatory cytokines, cardiac and apoptotic markers in myocardial infracted rats

OBJECTIVE

This study was aimed to evaluate the cardioprotective potential of combination of T. arjuna and α-tocopherol in isoproterenol induced myocardial injury.

METHODS

Wistar albino rats were pre-treated with hydroalcoholic extract of T. arjuna (HETA) and α-tocopherol (100 mg/kg b. w) daily for 30 days. Isoproterenol (ISP, 85 mg/kg b.w) was administered on 28th and 29th days at an interval of 24 hr.

RESULTS

ISP treated rats showed significant increase in lipid peroxidation (MDA), cardiac markers (CK-MB, SGOT, Trop I and LDH), pro-inflammatory cytokine (IL-6, CRP, TNF-α) levels and apoptotic markers (Bcl-2/Bax) as compared to healthy group. Pre-treatment with HETA 100 mg/kg b. w, reduced the elevated levels of these markers and significant effect (p<0.05) were observed with the combination of HETA and α-tocopherol at a dose of 100 mg/kg b. w, which was further confirmed by histopathological studies.

CONCLUSION

The present study concluded that the combination of α-tocopherol (100 mg/kg b. w) and hydroalcoholic extract of T. arjuna (100 mg/kg b. w) augments endogenous antioxidant compounds of rat heart and also prevents the myocardium from ISP-induced myocardial injury and it may have therapeutic and prophylactic value in the treatment of ischemic heart disease.

Protective effects of vitamin E and selenium against dimethoate-induced cardiotoxicity in vivo: biochemical and histological studies

There is considerable interest in the study of free radical-mediated damage to biological systems due to pesticide exposure. However, there is a lack of consensus as to which determinations are best used to quantify future risks arising from xenobiotic exposure and natural antioxidant interventions. Our study investigated the potential ability of selenium and/or vitamin E, used as nutritional supplements, to alleviate cardiotoxicity induced by dimethoate. Female Wistar rats were exposed for 30 days either to dimethoate (0.2 g L⁻¹ of drinking water), dimethoate+selenium (0.5 mg kg⁻¹ of diet), dimethoate+vitamin E (100 mg kg⁻¹ of diet), or dimethoate+selenium+vitamin E. The exposure of rats to dimethoate promoted oxidative stress with a rise in malondialdehyde, advanced protein oxidation, and protein carbonyl levels. An increase of glutathione peroxidase, superoxide dismutase, and catalase activities was also noted. A fall in acetylcholinesterase and Na⁺ K⁺-ATPase activities, glutathione, nonprotein thiols, vitamins C and E levels was observed. Plasma levels of cholesterol, triglycerides, and low density lipoprotein-cholesterol increased and those of high density lipoprotein-cholesterol decreased. Coadministration of selenium or vitamin E to the diet of dimethoate-treated rats ameliorated the biochemical parameters cited above. The histopathological findings confirmed the biochemical results and the potential protective effects of selenium and vitamin E against cardiotoxicity induced by dimethoate.

A possible role for 15-lipoxygenase in atherogenesis

It is well accepted that high levels of low-density lipoprotein (LDL) cholesterol in the plasma are associated with increased risk of atherosclerosis. The cellular and molecular mechanisms linking the two however, have not been fully resolved. One of the processes involved in atherogensis that has been intensively studied in this regard is the oxidation of LDL. Oxidation may convert LDL into an atherogenic form, which incites an inflammatory and proliferative response characteristic of the atherosclerotic lesion. One of the potential mediators in this process is the lipid peroxidating enzyme 15-lipoxygenase, which has been shown to be induced in the atherosclerotic lesion and is capable of oxidizing LDL. In this article, we review the motivation for looking at mechanisms of LDL oxidation and the proposed involvement of 15-lipoxygenase in the pathogenesis of the disease.

Vitamins A and E reverse gasoline vapors-induced hematotoxicity and weight loss in female rats

In this study, gasoline vapors-induced hematotoxicity, growth-depression and weight-loss reversal effect of vitamins A (retinol) and E (α-tocopherol) was assessed in female Wistar albino rats. The rats were exposed to gasoline vapors (17.8 2.6 cm 3/h/m3/day), 6 hours/day, 6 days/week, for 20 weeks. Vitamins A and E at prophylactic dosage (400 and 200 IU/kg/day, respectively) were orally administered to the rats, separately, in the last 2 weeks of exposure. The levels of hemoglobin (Hb), hematocrit or packed cell volume (PCV), red blood cells (RBC), growth rate and weight gain in the rats exposed to the vapors were significantly lower (p < 0.05) compared, respectively, to the levels obtained for control rats. On the other hand, the levels of white blood cells (WBCs) in the test rats were significantly higher (p < 0.05) compared, respectively, with the level obtained for female control rats. These observations indicated that exposure to gasoline vapors may cause hematotoxicity, growth depression and weight loss in female rats. However, administration of vitamins A and E was observed to produce a significant recovery (p < 0.05) in hematotoxicity, growth depression and weight loss observed to be associated with exposure to gasoline vapors, although the rats administered with vitamin E were noted to respond more favorably than those administered with vitamin A. This suggests that although retinol and α-tocopherol may be used to reverse or prevent hematotoxicity, growth depression and weight loss in subjects exposed to gasoline vapors, the reversal potency of α-tocopherol is higher than that of retinol.

Alpha-tocopherol is ineffective in preventing the decomposition of preformed lipid peroxides and may promote the accumulation of toxic aldehydes: a potential explanation for the failure of antioxidants to affect human atherosclerosis

The decomposition of peroxidized lipids of low-density lipoprotein (LDL) has been suggested to be involved in atherosclerosis. In this study, an in vitro system with 13-hydroperoxylinoleic acid (13-HPODE) was used to determine the effects of antioxidants on its decomposition. Decomposition of 13-HPODE was not affected by alpha-tocopherol, several other antioxidants, or antioxidant enzymes. Moreover, the inclusion of alpha-tocopherol during the decomposition of 13-HPODE resulted in an accumulation of aldehydes. Further oxidation of aldehydes to carboxylic acids by a number of oxidases was prevented by alpha-tocopherol. Conversely, the formation of carboxylic acids may be conducive to plaque stabilization via immunomodulation, rapid degradation, and by calcium sequestration. Thus, the inhibition of formation of carboxylic acids could be a serious deleterious effect of antioxidant treatment. In contrast, alpha-keto acids, like pyruvic acid, promoted the conversion of 13-HPODE to 13-hydroxylinoleic acid (13-HODE) by readily undergoing decarboxylation into acetate. These observations suggest that agents that promote the reduction of lipid peroxides into lipid hydroxides could be far more effective in treating cardiovascular diseases as opposed alpha-tocopherol-like antioxidants that could affect additional steps in the oxidation cascade.

Very-high-dose alpha-tocopherol supplementation increases blood pressure and causes possible adverse central nervous system effects in stroke-prone spontaneously hypertensive rats

Tocopherols and tocotrienols constitute the vitamin E family. Although alpha-tocotrienol is the most neuroprotective form of vitamin E proved to be effective against stroke, alpha-tocopherol is the most abundant in nature and is used most often for disease prevention/treatment. A recent metaanalysis of human studies suggested that alpha-tocopherol supplementation increases all-cause mortality. Therefore, we investigated the effects of alpha-tocopherol ( approximately 44 mg/kg body weight; equivalent to 2,600 mg/human/day) on the central nervous system (CNS) of stroke-prone spontaneously hypertensive rats (SHRSP). SHRSP treated with high dose alpha-tocopherol had significantly higher blood pressure than untreated controls fed a basal diet that contained approximately 4 mg tocopherols/kg body weight, but neither group experienced a change in degree of lipid peroxidation in serum or CNS tissue. Biochemical/immunohistochemical analyses demonstrated that expressions of phosphorylated neurofilament H protein, glial fibrillary acidic protein and cathepsin D in the CNS tissue were significantly enhanced in alpha-tocopherol-supplemented rats, whereas expressions of SOD2 and Bcl-xL were diminished in response to alpha-tocopherol supplementation. Similarly, the frequency of cathepsin D-positive cells, corresponding mostly to microglial cells, was significantly increased in alpha-tocopherol-supplemented rats. Alpha-tocopherol supplementation also increased the number of lysosomes and lipofuscin granules in perikarya of both hippocampal pyramidal and Purkinje cells. Furthermore, alpha-tocopherol supplementation increased the frequency of glial filaments and lipofuscin granules in astrocytes and lysosomes in microglial cells that were frequently occupied with phagocytosed inclusion structures. The present results are the first to suggest that a very high dose of alpha-tocopherol supplementation increases blood pressure in SHRSP rats and influences the CNS tissue in a manner that seems adverse.

Neither antioxidants nor genistein inhibit the progression of established atherosclerotic lesions in older apoE deficient mice

Supplements and diets enriched in antioxidants and soy isoflavones are purported to reduce cardiovascular disease risk. Many experimental studies have demonstrated inhibitory effects of antioxidants and soy isoflavones on the development of fatty streaks in animal models. However, it is still unknown whether antioxidants and isoflavones have comparable inhibitory effects on the progression of advanced stages of atherosclerosis. This is an important question because clinical trials in humans have not supported a cardio-protective role for antioxidants or isoflavones. Thus, we examined the effects of antioxidants and genistein on the progression and composition of established, advanced atherosclerotic lesions in the innominate arteries (IA) of older apolipoprotein E-deficient (apoE(-/-)) mice. Thirty-week-old male apoE(-/-) mice were fed chow with or without genistein (0.27%, w/w) for 6, 12 and 24 weeks. Twenty-week-old male apoE(-/-) mice were fed chow with or without a cocktail of antioxidants (vitamin E 0.2%, w/w; vitamin C 0.05%, w/w; and beta carotene 0.5%, w/w) for 10, 16, and 22 weeks. There were no significant differences in total plasma cholesterol, body weight, average lesion or medial area, or changes in lesion composition with either treatment in comparison to control mice.

Nutrient supplements and cardiovascular disease: a heartbreaking story

Observational data have identified associations between carotenoids, folic acid, and vitamin E, or metabolites altered by these nutrients, and cardiovascular disease (CVD) risk. Despite biological plausibility, for the most part, data derived from nutrient supplement trials using moderate to high doses of single nutrients or nutrient combinations (exceeding amounts to avoid nutrient deficiency) have been disappointing. The data for vitamin D is not yet adequate to evaluate; observational data suggest were a relationship to exist it would be related to nutrient insufficiency. There is some evidence that use of nutrient supplements intended to decrease CVD risk has resulted in unanticipated adverse consequences. Potential discrepancies between observational and interventional data include concerns of residual confounding by diet and lifestyle patterns, publication bias against studies with null or negative outcomes, reliance on secondary rather than primary prevention trials, and unaccounted for contribution of genotypic variations. At this time there are insufficient data to recommend the routine use of nutrient supplements to prevent or treat CVD. In the recent past we have learned a great deal about anticipated and unanticipated consequences of nutrient supplementation and cardiovascular outcomes. As a result, we are in a better position to adjudicate new potential relationships as data emerge.

Vitamins and cardiovascular disease

CVD is a major cause of mortality and morbidity in the Western world. In recent years its importance has expanded internationally and it is believed that by 2020 it will be the biggest cause of mortality in the world, emphasising the importance to prevent or minimise this increase. A beneficial role for vitamins in CVD has long been explored but the data are still inconsistent. While being supported by observational studies, randomised controlled trials have not yet supported a role for vitamins in primary or secondary prevention of CVD and have in some cases even indicated increased mortality in those with pre-existing late-stage atherosclerosis. The superiority of combination therapy over single supplementation has been suggested but this has not been confirmed in trials. Studies have indicated that beta-carotene mediates pro-oxidant effects and it has been suggested that its negative effects may diminish the beneficial effects mediated by the other vitamins in the supplementation cocktail. The trials that used a combination of vitamins that include beta-carotene have been disappointing. However, vitamin E and vitamin C have in combination shown long-term anti-atherogenic effects but their combined effect on clinical endpoints has been inconsistent. Studies also suggest that vitamins would be beneficial to individuals who are antioxidant-deficient or exposed to increased levels of oxidative stress, for example, smokers, diabetics and elderly patients, emphasising the importance of subgroup targeting. Through defining the right population group and the optimal vitamin combination we could potentially find a future role for vitamins in CVD.

Cellular, molecular and clinical aspects of vitamin E on atherosclerosis prevention

Randomised clinical trials and epidemiologic studies addressing the preventive effects of vitamin E supplementation against cardiovascular disease reported both positive and negative effects, and recent meta-analyses of the clinical studies were rather disappointing. In contrast to that, many animal studies clearly show a preventive action of vitamin E in several experimental settings, which can be explained by the molecular and cellular effects of vitamin E observed in cell cultures. This review is focusing on the molecular effects of vitamin E on the cells playing a role during atherosclerosis, in particular on the endothelial cells, vascular smooth muscle cells, monocytes/macrophages, T cells, and mast cells. Vitamin E may act by normalizing aberrant signal transduction and gene expression in antioxidant and non-antioxidant manners; in particular, over-expression of scavenger receptors and consequent foam cell formation can be prevented by vitamin E. In addition to that, the cellular effects of alpha-tocopheryl phosphate and of EPC-K1, a composite molecule between alpha-tocopheryl phosphate and l-ascorbic acid, are summarized.

Nuclear factor-kappa B, p38, and stress-activated protein kinase mitogen-activated protein kinase signaling pathways regulate proinflammatory cytokines and apoptosis in human placental explants in response to oxidative stress: effects of antioxidant vitamins

Preeclampsia is a potentially fatal complication of human pregnancy characterized by hypertension, proteinuria, and edema. Placental oxidative stress is a key element in the pathogenesis of the syndrome and results in the release of a cocktail of factors, including proinflammatory cytokines and apoptotic debris, that in turn cause activation of the maternal endothelium. The intermediary molecular mechanisms underlying this release are unknown, but they represent a potential target for therapeutic interventions. We examined activation of signaling pathways during hypoxia-reoxygenation of villous explants in vitro. Hypoxia-reoxygenation activated the p38 and stress-activated protein kinase mitogen-activated protein kinase (MAPK) and the nuclear factor-kappaB pathways. Downstream consequences included increased tissue concentrations and secretion of tumor necrosis factor-alpha and interleukin-1 beta, increased expression of cyclooxygenase-2, and increased apoptosis. Administration of vitamins C and E to explants blocked activation of the p38 and stress-activated protein kinase MAPK and nuclear factor-kappaB pathways. Vitamin administration or p38 pathway inhibition also reduced cyclooxygenase-2 expression, tumor necrosis factor-alpha and interleukin-1 beta secretion, and the levels of apoptosis. We conclude that oxidative stress is a potent inducer of placental synthesis and release of proinflammatory factors. Most of these effects are mediated through the p38 MAPK and nuclear factor-kappaB pathways and can be effectively blocked by vitamins C and E in vitro.

Alpha-Tocopherol Distribution in Lipoproteins and Anti-Inflammatory Effects Differ between CHD-Patients and Healthy Subjects

OBJECTIVE

The purpose of this study was to investigate the dose-dependent effects of RRR-alpha-tocopherol supplementation in coronary heart disease (CHD) patients and healthy subjects on plasma alpha-tocopherol levels, plasma lipoprotein distribution, LDL oxidation, and inflammatory plasma markers.

METHODS

12 patients with coronary heart disease and 12 healthy subjects were supplemented with increasing dosages of RRR-alpha-tocopherol at 100, 200 and 400 mg/day for a period of 3 weeks per dose. Lipoproteins were separated by FPLC and ultracentrifugation. Alpha-tocopherol was measured by HPLC. Resistance of LDL to oxidation was determined by reading the absorption at 234 nm after CuCl2-induced oxidation. Clinical chemistry and inflammatory markers were measured on automated analysis systems.

RESULTS

Plasma alpha-tocopherol concentrations at baseline were comparable between CHD-patients and healthy subjects (21.7 +/- 4.7 micromol/L and 25.8 +/- 7.6 micromol/L, respectively). CHD-patients showed a significant increase (59%) of plasma alpha-tocopherol concentrations to 34.6 +/- 9.8 micromol/L at a dosage of 100 mg/day RRR-alpha-tocopherol, whereas healthy subjects showed a significant (54%) increase to 39.7 +/- 6.1 micromol/L only with 400 mg/day RRR-alpha-tocopherol. In addition, CHD-patients showed a significantly increased enrichment of alpha-tocopherol in VLDL. Supplementation (200 mg/day) caused a significant decrease of the acute phase plasma proteins C-reactive protein (CRP) (-65%) and fibrinogen (-24%).

CONCLUSION

Our data demonstrate that CHD-patients require lower dosages of alpha-tocopherol supplementation than healthy subjects to exert biological effects on plasma lipoproteins and acute phase response.

Effects of vitamin E on oxidative stress and atherosclerosis in an obese hyperlipidemic mouse model

Vitamin E is a natural antioxidant that has been used in animal and human studies to determine its potential in reducing cardiovascular risk; however, a detailed study in an established obese model of atherosclerosis has yet to be performed. In our current study, we show that obesity and hyperlipidemia cause a synergistic, age-related increase in urinary isoprostane levels in mice deficient in both leptin and low-density lipoprotein receptor (ob/ob;LDLR-/-). Based upon this observation, we hypothesized that vitamin E supplementation would induce potent antiatherogenic effects in this model. Lean and obese LDLR-/- mice were provided vitamin E (2000 IU/kg) in a Western-type high-fat diet for 12 weeks. Plasma lipid parameters, such as total cholesterol (TC), triglyceride (TG) and free fatty acid, were significantly higher in obese mice compared to lean mice at baseline (P<.001). Western-type diet (WD) feeding caused an increase in TC levels in all groups (P<.001); however, TG (P<.001) and free fatty acid (P<.01) were elevated only in lean mice following WD feeding. Vitamin E supplementation neither influenced any of these parameters nor reduced urinary isoprostanes in lean or obese mice. Vitamin E supplementation in ob/ob;LDLR-/- mice resulted in a trend toward a reduction in atherosclerotic lesion area (P=.10), although no differences in lesion area were noted in lean LDLR-/- animals. These data provide evidence that vitamin E supplementation is not sufficient to reduce extreme elevations in systemic oxidative stress due to hyperlipidemia and obesity and, thus, may not be cardioprotective in this setting.

The effect of tocopheryl phosphates on atherosclerosis progression in rabbits fed with a high cholesterol diet

The effect of tocopheryl phosphate on atherosclerosis progression has been studied in rabbits, fed with a 2% cholesterol diet and compared with an equivalent amount of alpha-tocopheryl acetate. The results show that the atherosclerotic-preventing effect of the phosphate derivative was more pronounced than that of the acetate derivative. alpha-Tocopheryl phosphate was also more potent in diminishing the expression of CD36 than the acetate derivative.

Novel antioxidant compounds from the aqueous extract of the roots of Decalepis hamiltonii (Wight and Arn.) and their inhibitory effect on low-density lipoprotein oxidation

Roots of Decalepis hamiltonii are consumed as pickles and as a health drink in southern India for their health benefits. The antioxidant properties of the root extracts have been shown previously; this paper reports the isolation of antioxidant compounds from the aqueous extract of the roots of D. hamiltonii. Five novel antioxidant compounds were isolated and characterized by NMR and MS. The compounds exhibited free radical scavenging activity in vitro and inhibited low-density lipoprotein oxidation. This study demonstrates that the root extract of D. hamiltonii is a cocktail of several antioxidant compounds with health implications.

Should doctors discourage nutritional supplementation? A cardiovascular perspective

Cardiovascular disease is the major cause of death in most western countries, and current preventive treatment is relatively ineffective. There are theoretical reasons why nutritional therapy-antioxidant vitamins, minerals and omega 3 oils-should be beneficial. Because of some negative trials, there is the risk of tossing the baby out with the bath water. This paper reviews how nutritional therapy could assist in a comprehensive preventive approach to reduce heart disease-especially primary prevention. It stresses the need to separate primary prevention-initiated by oxidation of LDL in the vessel wall, and secondary prevention-the consequences of plaque rupture. Because a therapy is ineffective in the secondary preventive role, does not mean that it could not have a primary preventive action. There are many positive studies utilizing nutritional therapies, these are detailed in this paper, and a comprehensive preventive programme including these is suggested.

Different palm oil preparations reduce plasma cholesterol concentrations and aortic cholesterol accumulation compared to coconut oil in hypercholesterolemic hamsters

Several studies have reported on the effect of refined, bleached and deodorized palm oil (RBD-PO) incorporation into the diet on blood cholesterol concentrations and on the development of atherosclerosis. However, very little work has been reported on the influence of red palm oil (RPO), which is higher in carotenoid and tocopherol content than RBD-PO. Thus, we studied the influence of RPO, RBD-PO and a RBD-PO plus red palm oil extract (reconstituted RBD-PO) on plasma cholesterol concentrations and aortic accumulation vs. hamsters fed coconut oil. Forty-eight F1B Golden Syrian hamsters (Mesocricetus auratus) (BioBreeders, Watertown, MA) were group housed (three/cage) in hanging polystyrene cages with bedding in an air-conditioned facility maintained on a 12-h light/dark cycle. The hamsters were fed a chow-based hypercholesterolemic diet (HCD) containing 10% coconut oil and 0.1% cholesterol for 2 weeks at which time they were bled after an overnight fast and segregated into four groups of 12 with similar plasma cholesterol concentrations. Group 1 continued on the HCD, Group 2 was fed the HCD containing 10% RPO in place of coconut oil, Group 3 was fed the HCD containing 10% RBD-PO in place of coconut oil and Group 4 was fed the HCD with 10% reconstituted RBD-PO for an additional 10 weeks. Plasma total cholesterol (TC) and non-high-density lipoprotein-cholesterol (HDL-C) (very low- and low-density lipoprotein) concentrations were significantly lower in the hamsters fed the RPO (-42% and -48%), RBD-PO (-32% and -36%) and the reconstituted RBD-PO (-37% and -41%) compared to the coconut oil-fed hamsters. Plasma HDL-C concentrations were significantly higher by 14% and 31% in hamsters fed the RBD-PO and RPO compared to the coconut oil-fed hamsters. Plasma triglyceride (TG) concentrations were significantly lower in hamsters fed RBD-PO (-32%) and the reconstituted RBD-PO (-31%) compared to the coconut oil-fed hamsters. The plasma gamma-tocopherol concentrations were higher in the coconut oil-fed hamsters compared to the hamsters fed the RPO (60%), RBD-PO (42%) and the reconstituted RBD-PO (49%), while for plasma alpha-tocopherol concentrations, the coconut oil-fed hamsters were significantly higher than only the RPO-fed hamsters (21%). The coconut oil-fed hamsters also had significantly higher plasma lipid hydroperoxide concentrations compared to RBD-PO (112%) and the reconstituted RBD-PO (485%). The hamsters fed the coconut oil diet excreted significantly more fecal total neutral sterols and cholesterol compared to the hamsters fed the RBD-PO (158% and 167%, respectively). The coconut oil-fed hamsters had significantly higher levels of aortic total, free and esterified cholesterol compared to the hamsters fed the RPO (74%, 50% and 225%, respectively), RBD-PO (57%, 48% and 92%, respectively) and the reconstituted RBD-PO (111%, 94% and 94%, respectively). Also, aortic free/ester cholesterol ratio in the aortas of hamsters fed RPO was significantly higher than in those fed the coconut oil (124%). In conclusion, hamsters fed the three palm oil preparations had lower plasma TC and non-HDL-C and higher HDL-C concentrations while accumulating less aortic cholesterol concentrations compared to hamsters fed coconut oil.

Vitamin E, oxidative stress, and inflammation

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the Western world. Its incidence has also been increasing lately in developing countries. Several lines of evidence support a role for oxidative stress and inflammation in atherogenesis. Oxidation of lipoproteins is a hallmark in atherosclerosis. Oxidized low-density lipoprotein induces inflammation as it induces adhesion and influx of monocytes and influences cytokine release by monocytes. A number of proinflammatory cytokines such as interleukin-1beta (IL-1beta), IL-6, and tumor necrosis factor-alpha (TNF-alpha) modulate monocyte adhesion to endothelium. C-reactive protein (CRP), a prototypic marker of inflammation, is a risk marker for CVD and it could contribute to atherosclerosis. Hence, dietary micronutrients having anti-inflammatory and antioxidant properties may have a potential beneficial effect with regard to cardiovascular disease. Vitamin E is a potent antioxidant with anti-inflammatory properties. Several lines of evidence suggest that among different forms of vitamin E, alpha-tocopherol (AT) has potential beneficial effects with regard to cardiovascular disease. AT supplementation in human subjects and animal models has been shown to decrease lipid peroxidation, superoxide (O2-) production by impairing the assembly of nicotinamide adenine dinucleotide phosphate (reduced form) oxidase as well as by decreasing the expression of scavenger receptors (SR-A and CD36), particularly important in the formation of foam cells. AT therapy, especially at high doses, has been shown to decrease the release of proinflammatory cytokines, the chemokine IL-8 and plasminogen activator inhibitor-1 (PAI-1) levels as well as decrease adhesion of monocytes to endothelium. In addition, AT has been shown to decrease CRP levels, in patients with CVD and in those with risk factors for CVD. The mechanisms that account for nonantioxidant effects of AT include the inhibition of protein kinase C, 5-lipoxygenase, tyrosine-kinase as well as cyclooxygenase-2. Based on its antioxidant and anti-inflammatory activities, AT (at the appropriate dose and form) could have beneficial effects on cardiovascular disease in a high-risk population.

Place of drug therapy in the treatment of carotid stenosis

Carotid stenosis is an important cause of transient ischaemic attacks and stroke. The cause of carotid stenosis is most often atherosclerosis; contributing to the pathogenesis of the lesion are endothelial injury, inflammation, lipid deposition, plaque formation, fibrin, platelets and thrombin. Carotid stenosis accounts for 10-20% of cases of brain infarction, depending on the population studied. Despite successful treatment of selected patients who have had an acute ischaemic stroke with tissue plasminogen activator and the promise of other experimental therapies, prevention remains the best approach to reducing the impact of ischaemic stroke. High-risk or stroke-prone patients can be identified and targeted for specific interventions. At this juncture, treatment of carotid stenosis is a well established therapeutic target and a pillar of stroke prevention. There are two main strategies for the treatment of carotid stenosis. The first approach is to stabilise or halt the progression of the carotid plaque through risk factor modification and medication. Hypertension, diabetes mellitus, smoking, obesity and high cholesterol levels are closely associated with carotid stenosis and stroke; control of these factors may decrease the risk of plaque formation and progression. The second approach is to eliminate or reduce carotid stenosis through carotid endarterectomy or carotid angioplasty and stenting. Carotid endarterectomy, which is the mainstay of therapy for severe carotid stenosis, is beyond the scope of this review. Anticoagulants seem to play little role (if any) in the medical (i.e. non-surgical) treatment of carotid stenosis. Adoption of a healthy lifestyle combined with the reduction of risk factors has been shown to lead to a reduction in the extent of carotid stenosis. The medical treatment of carotid stenosis should be based on the triad of the reduction of risk factors, patient education, and use of antiplatelet agents.

Role of bilirubin, vitamin C and ceruloplasmin as antioxidants in coronary artery disease [CAD]

A study has been carried out on 250 CAD patients to see how the serum levels of three antioxidants i.e., Vitamin C, Bilirubin and Ceruloplasmin are related to the CAD risk factors and characteristics in these patients. The number of severe category CAD patients declined by 7-18% with increasing serum levels of the three antioxidants and, triple vessel disease declined by 14-20%. A decline of 39% in Myocardial Infarction (MI) occurred with increasing serum Ceruloplasmin. Serum Ceruloplasmin was significantly lower in the MI group compared to the non MI group CAD patients. There was a steady and a significant decline in the mean values of serum levels of cholesterol, Triglyceride, VLDL cholesterol along with BMI with increasing serum level. The study indicates that with increasing serum levels of the three antioxidants studied, the % MI along with % Triple vessel disease and severity of CAD goes down suggesting that the modifiable risk factors have to be suitably modified in order to maintain a reasonably high level of these antioxidants, as the risk factors are inversely related to the serum antioxidant levels.

Dietary antioxidants and paraoxonases against LDL oxidation and atherosclerosis development

Oxidative modification of low-density lipoprotein (LDL) in the arterial wall plays a key role in the pathogenesis of atherosclerosis. Under oxidative stress LDL is exposed to oxidative modifications by arterial wall cells including macrophages. Oxidative stress also induces cellular-lipid peroxidation, resulting in the formation of 'oxidized macrophages', which demonstrate increased capacity to oxidize LDL and increased uptake of oxidized LDL. Macrophage-mediated oxidation of LDL depends on the balance between pro-oxidants and antioxidants in the lipoprotein and in the cells. LDL is protected from oxidation by antioxidants, as well as by a second line of defense--paraoxonase 1 (PON1), which is a high-density lipoprotein-associated esterase that can hydrolyze and reduce lipid peroxides in lipoproteins and in arterial cells. Cellular paraoxonases (PON2 and PON3) may also play an important protective role against oxidative stress at the cellular level. Many epidemiological studies have indicated a protective role for a diet rich in fruits and vegetables against the development and progression of cardiovascular disease. A large number of studies provide data suggesting that consumption of dietary antioxidants is associated with reduced risk for cardiovascular diseases. Basic research provides plausible mechanisms by which dietary antioxidants might reduce the development of atherosclerosis. These mechanisms include inhibition of LDL oxidation, inhibition of cellular lipid peroxidation and consequently attenuation of cell-mediated oxidation of LDL. An additional possible mechanism is preservation/increment of paraoxonases activity by dietary antioxidants. This review chapter presents recent data on the anti-atherosclerotic effects and mechanism of action of three major groups of dietary antioxidants-vitamin E, carotenoids and polyphenolic flavonoids.

Vitamin E and Cardiovascular Disease: Observational Studies

Basic research suggests that oxidative stress may play an important role in many chronic diseases and provides plausible mechanisms by which natural antioxidants such as vitamin E may delay or prevent steps in atherogenesis. Dietary research has shown that those who consume higher amounts of fruits and vegetables have lower rates of heart disease and stroke, raising the possibility that antioxidants are protective. Results from large-scale human observational studies suggest that antioxidant consumption reduces the risk of developing cardiovascular disease (CVD). Both case-control and prospective cohort studies have carefully explored the relationship between vitamin E intake and plasma and tissue vitamin E levels and the risk of CVD. In many, but not all, of these studies vitamin E intake over an extended period was associated with decreased risk of cardiovascular events. Results from studies of blood levels are more limited and less consistent. This presentation summarizes data from the major observational studies. Overall, they support the possibility that vitamin E intake either from food or supplements may reduce risk of CVD; however, these studies have important limitations. For example, uncontrolled confounding can be similar in magnitude to the observed health effects, and antioxidant consumption may be merely a marker for a different cardioprotective factor (such as exercise or diet) that is responsible for these effects. In the search for small to moderate effects, randomized trials may be helpful, although to date, data from large-scale trials have been inconsistent. Several large-scale trials currently under way will help identify the potential benefits of vitamin E in the primary prevention of CVD and other chronic illness. Some are designed to test vitamin E alone as well as in combination with other antioxidant supplements because it is possible that antioxidants may be most effective if taken in particular combinations. Currently, the American Heart Association maintains that there are insufficient efficacy data from completed randomized trials to justify population-wide recommendations for use of vitamin E supplements in disease prevention.

Retardation of atherosclerosis by overexpression of catalase or both Cu/Zn-superoxide dismutase and catalase in mice lacking apolipoprotein E

Oxidative stress has been suggested to potentiate atherogenesis. However, studies that have investigated the effect of antioxidants on atherosclerosis showed inconsistent results, ie, atherosclerosis was either retarded or not changed by dietary antioxidants. This report directly examined the effect of overexpressing Cu/Zn-superoxide dismutase (Cu/Zn-SOD) and/or catalase on atherosclerosis and lipid peroxidation in mice lacking apolipoprotein E (ApoE-/-). Based on lipid staining of the en face of the aorta tree and the serial sections of the proximal aorta, ApoE-/- mice overexpressing catalase or both Cu/Zn-SOD and catalase had smaller and relatively early stages of atherosclerotic lesions (eg, foam cells and free lipids) when compared with ApoE-/- mice, who developed more advanced lesions (eg, fibrous caps and acellular areas). In addition, the retarded development of atherosclerosis was correlated with a reduced F2-isoprostanes in the plasma and aortas in ApoE-/- mice overexpressing catalase or both Cu/Zn-SOD and catalase. In contrast, the levels of F2-isoprostanes and atherosclerosis in the ApoE-/- mice overexpressing Cu/Zn-SOD alone were comparable to ApoE-/- control mice. These observations implied that endogenously produced hydrogen peroxide, but not superoxide anions, contributed to the formation of oxidized lipids and the development of atherosclerosis in ApoE-/- mice.

Cosupplementation with vitamin E and coenzyme Q10 reduces circulating markers of inflammation in baboons

BACKGROUND

Inflammation and oxidative stress are processes that mark early metabolic abnormalities in vascular diseases.

OBJECTIVES

We explored the effects of a high-fat, high-cholesterol (HFHC) diet on vascular responses in baboons and the potential response-attenuating effects of vitamin E and coenzyme Q(10) (CoQ(10)) supplementation.

DESIGN

We used a longitudinal design by subjecting 21 baboons (Papio hamadryas) to sequential dietary challenges.

RESULTS

After being maintained for 3 mo on a baseline diet (low in fat and cholesterol), 21 baboons were challenged with an HFHC diet for 7 wk. The serum C-reactive protein (CRP) concentrations did not change. Subsequent supplementation of the HFHC diet with the antioxidant vitamin E (250, 500, or 1000 IU/kg diet) for 2 wk reduced serum CRP concentrations from 0.91 +/- 0.02 to 0.43 +/- 0.06 mg/dL. Additional supplementation with CoQ(10) (2 g/kg diet) further reduced serum CRP to approximately 30% of baseline (0.28 +/- 0.03 mg/dL; P = 0.036 compared with the HFHC diet). Introduction of the HFHC diet itself significantly decreased serum P-selectin (from 48.8 +/- 7.2 to 32.9 +/- 3.7 ng/dL, P = 0.02) and von Willebrand factor (from 187.0 +/- 10.1 to 161.9 +/- 9.0%, P = 0.02) concentrations. However, neither vitamin E alone nor vitamin E plus CoQ(10) significantly altered the serum concentrations of P-selectin or von Willebrand factor.

CONCLUSIONS

Dietary supplementation with vitamin E alone reduces the baseline inflammatory status that is indicated by the CRP concentration in healthy adult baboons. Cosupplementation with CoQ(10), however, significantly enhances this antiinflammatory effect of vitamin E.

Anti-peroxidation effects of vitamin E on low density lipoprotein and milk fat globule membrane of lactating goats: in vivo versus metal ion challenge in vitro

Ruminants are animals with mild oxidation risk considering characteristics of their plasma. The purpose of the present study was to determine if surplus vitamin E supplementation further improved their peroxidation status. Four lactating goats (Capra ibex ibex) receiving a single intramuscular injection of 3000 IU d-alpha-tocopheryl acetate were monitored daily for a week. Plasma and milk levels of thiobarbituric acid reactive substances (TBARS) were measured to estimate the peroxidation status of overall body and mammary gland, respectively. Lipid hydroperoxide content of low density lipoprotein (LDL) and milk fat globule membrane (MFGM) were determined both immediately after isolation and after metal ion challenge to evaluate their spontaneous peroxidation in vivo and peroxidation susceptibility in vitro, respectively. The results showed that while plasma and milk levels of alpha-tocopherol peaked at day 2, the corresponding TBARS dropped to their lowest weekly levels. Content of preformed lipid hydroperoxides in LDL and MFGM remained unchanged (P>0.05) during the study period, while peroxidation in LDL and MFGM on extended exposure to Cu(2+) was prevented by vitamin E enrichment. Therefore, surplus vitamin E was beneficial to the peroxidation-resistant mechanisms of the overall body and those specifically within mammary gland of lactating goats. Furthermore, peroxidation resistance of LDL and MFGM to copper challenge in vitro also benefited from vitamin E enrichment despite the fact their endogenous peroxidation seemed unresponsive. The hypothesis that peroxidation of LDL and MFGM of lactating goats in situ, which proceeds with metal ion-independent mechanisms, is minor was discussed.

Anti-atherosclerotic effects of vitamin E--myth or reality?

Atherosclerosis and its complications such as coronary heart disease, myocardial infarction and stroke are the leading causes of death in the developed world. High blood pressure, diabetes, smoking and a diet high in cholesterol and lipids clearly increase the likelihood of premature atherosclerosis, albeit other factors, such as the individual genetic makeup, may play an additional role. Several epidemiological studies and intervention trials have been performed with vitamin E, and some of them showed that it prevents atherosclerosis. For a long time, vitamin E was assumed to act by decreasing the oxidation of LDL, a key step in atherosclerosis initiation. However, at the cellular level, vitamin E acts by inhibition of smooth muscle cell proliferation, platelet aggregation, monocyte adhesion, oxLDL uptake and cytokine production, all reactions implied in the progression of atherosclerosis. Recent research revealed that these effects are not the result of the antioxidant activity of vitamin E, but rather of precise molecular actions of this compound. It is assumed that specific interactions of vitamin E with enzymes and proteins are at the basis of its non-antioxidant effects. Vitamin E influences the activity of several enzymes (e.g. PKC, PP2A, COX-2, 5-lipooxygenase, nitric oxide synthase, NADPH-oxidase, superoxide dismutase, phopholipase A2) and modulates the expression of genes that are involved in atherosclerosis (e.g. scavenger receptors, integrins, selectins, cytokines, cyclins). These interactions promise to reveal the biological properties of vitamin E and allow designing better strategies for the protection against atherosclerosis progression.

Does vitamin E supplementation prevent cardiovascular events?

In recent years, vitamin E has been investigated as a cardioprotective agent. Experimental studies have identified potential mechanisms by which vitamin E may inhibit the development of atherosclerosis, and observational studies of individuals without coronary disease suggest that vitamin E intake may prevent future cardiovascular events. Secondary prevention trials to date have demonstrated little benefit from vitamin E supplementation. It remains possible, however, that supplementation may be useful among certain high-risk groups, including those with nutritional deficiencies. Limited data from completed primary prevention trials also indicate minimal cardioprotection from vitamin E, but large-scale trials now in progress may yet show benefit. Results from ongoing trials will contribute powerfully to the totality of evidence on which to formulate both appropriate clinical recommendations for individual patients and a rational public health policy for the population as a whole. At this time, there is insufficient evidence for issuing a public health recommendation to use vitamin E supplements to prevent cardiovascular disease (CVD). Rather, increased intake of fruits, vegetables, and other antioxidant-rich foods should be promoted as part of a healthy diet because they provide nutritional benefits beyond any potential antioxidant effect. Moreover, even if found to reduce CVD risk, vitamin supplement use should be considered an adjunct, not an alternative, to established cardioprotective measures, such as smoking abstention, avoidance of obesity, adequate physical activity, and control of high blood pressure and hyperlipidemia.

Dietary and circulating antioxidant vitamins in relation to carotid plaques in middle-aged women

BACKGROUND

The results of the few studies conducted on the relation between antioxidant vitamins and carotid atherosclerosis have been inconclusive.

OBJECTIVE

We evaluated the association between preclinical carotid atherosclerosis, as determined by high-resolution B-mode ultrasound, and both the intake amounts and plasma concentrations of antioxidant vitamins.

DESIGN

Among 5062 participants in Progetto Atena, a population-based study on the etiology of cardiovascular disease and cancer in women, 310 women were examined by B-mode ultrasound to detect early signs of carotid atherosclerosis. The participants answered a food-frequency questionnaire, and their plasma concentrations of vitamin E, vitamin A, and carotenoids were measured. None of the women took vitamin supplements.

RESULTS

The occurrence of atherosclerotic plaques at the carotid bifurcation was inversely associated with tertiles of vitamin E intake; the test for a linear trend across tertiles was significant (P < 0.05). Similarly, the ratio of plasma vitamin E to plasma cholesterol was inversely related to the presence of plaques at the carotid bifurcation; the test for a linear trend across tertiles was significant (P < 0.02). No association was found between the intake of other antioxidant vitamins (vitamins A and C and carotenoids) or their plasma concentrations and the presence of carotid plaques.

CONCLUSIONS

An inverse association was found between both the intake amount and plasma concentration of vitamin E and preclinical carotid atherosclerosis in middle-aged women. This association was independent of other cardiovascular risk factors, was not related to vitamin supplements, and supports the hypothesis that low vitamin E intake is a risk factor for early atherosclerosis.

Antioxidant vitamins and prevention of cardiovascular disease: epidemiological and clinical trial data

Naturally occurring antioxidants such as vitamin E, beta-carotene, and vitamin C can inhibit the oxidative modification of low density lipoproteins. This action could positively influence the atherosclerotic process and, as a consequence, the progression of coronary heart disease. A wealth of experimental studies provide a sound biological rationale for the mechanisms of action of antioxidants, whereas epidemiologic studies strongly sustain the "antioxidant hypothesis." To date, however, clinical trials with beta-carotene supplements have been disappointing, and their use as a preventive intervention for cancer and coronary heart disease should be discouraged. Only scanty data from clinical trials are available for vitamin C. As to vitamin E, discrepant results have been obtained by the Alpha-Tocopherol, Beta Carotene Cancer Prevention Study with a low-dose vitamin E supplementation (50 mg/d) and the Cambridge Heart Antioxidant Study (400-800 mg/d). The results of the GISSI-Prevenzione (300 mg/d) and HOPE (400 mg/d) trials suggest the absence of relevant clinical effects of vitamin E on the risk of cardiovascular events. Currently ongoing are several large-scale clinical trials that will help in clarifying the role of vitamin E in association with other antioxidants in the prevention of atherosclerotic coronary disease.

Dynamics of LDL oxidation in ischemic stroke patients

OBJECTIVE

Oxidative modification of human low density lipoprotein (LDL) plays an important role in the development of atherosclerosis. The aim of this study was to evaluate the oxidative modification of LDL in the group of patients with ischemic stroke.

MATERIAL AND METHODS

In the group of 43 patients 3 months after ischemic stroke and in the age and sex-matched control group, the kinetics of LDL oxidation and level of vitamin E were estimated. The susceptibility of LDL to oxidation was evaluated in isolated LDL exposed to in vitro oxidation. In 26 patients, after diet change, clinical and laboratory investigations were repeated 9 months later.

RESULTS

In the patient group, susceptibility of LDL to oxidation was enhanced, lag phase was significantly shorter in comparison with the control group. After a change in diet, significant elongation of the lag phase was observed.

CONCLUSION

Diet change improves LDL resistance to oxidation and may influence prognosis in stroke patients.

Antioxidant vitamins and the risk of carotid atherosclerosis. The Perth Carotid Ultrasound Disease Assessment study (CUDAS)

OBJECTIVES

This study examined whether dietary intake or plasma levels of antioxidant vitamins were independently associated with common carotid artery intima-media (wall) thickness (IMT) or focal plaque, or both, in a large, randomly selected community population.

BACKGROUND

Oxidation of low-density lipoprotein (LDL) cholesterol is thought to be important in early atherogenesis. Antioxidant micronutrients may therefore protect against lipid peroxidation and atherosclerotic vascular disease.

METHODS

We studied 1,111 subjects (558 men and 553 women; age 52 +/- 13 years [mean +/- SD], range 27 to 77). We measured dietary vitamin intake and fasting plasma levels of vitamins A, C and E, lycopene and alpha- and beta-carotene and performed bilateral carotid artery B-mode ultrasound imaging. RESULTS; After adjustment for age and conventional risk factors, there was a progressive decrease in mean IMT, with increasing quartiles of dietary vitamin E intake in men (p = 0.02) and a nonsignificant trend in women (p = 0.10). Dietary vitamin E levels accounted for 1% of the variance in measured IMT in men. For plasma antioxidant vitamins, there was an inverse association between carotid artery mean IMT and plasma lycopene in women (p = 0.047), but not in men. None of the other dietary or plasma antioxidant vitamins, nor antioxidant vitamin supplements, were associated with carotid artery IMT or focal carotid artery plaque.

CONCLUSIONS

This study provides limited support for the hypothesis that increased dietary intake of vitamin E and increased plasma lycopene may decrease the risk of atherosclerosis. No benefit was demonstrated for supplemental antioxidant vitamin use.

Vitamin E: protective role of a Janus molecule

Since the discovery of vitamin E in 1922, its deficiency has been associated with various disorders, particularly atherosclerosis, ischemic heart disease, and the development of different types of cancer. A neurological syndrome associated with vitamin E deficiency resembling Friedreich ataxia has also been described. Whereas epidemiological studies have indicated the role of vitamin E in preventing the progression of atherosclerosis and cancer, intervention trials have produced contradictory results, indicating strong protection in some cases and no significant effect in others. Although it is commonly believed that phenolic compounds like vitamin E exert only a protective role against free radical damage, antioxidant molecules can exert other biological functions. For instance, the antioxidant activity of 17-beta-estradiol is not related to its role in determining secondary sexual characters, and the antioxidant capacity of all-trans-retinal is distinguished from its role in rhodopsin and vision. Thus, it is not unusual that alpha-tocopherol (the most active form of vitamin E) has properties independent of its antioxidant/radical scavenging ability. The Roman god Janus, shown in ancient coins as having two faces in one body, inspired the designation of 'Janus molecules' for these substances. The new biochemical face of vitamin E was first described in 1991, with an inhibitory effect on cell proliferation and protein kinase C activity. After a decade, this nonantioxidant role of vitamin E is well established, as confirmed by authoritative studies of signal transduction and gene regulation. More recently, a tocopherol binding protein with possible receptor function has been discovered. Despite such important developments in understanding the molecular mechanism and the targets of vitamin E, its new Janus face is not fully elucidated. Greater knowledge of the molecular events related to vitamin E will help in selecting the parameters for clinical intervention studies such as population type, dose response effects, and possible synergism with other compounds.