Dietary supplementation with n-3 polyunsaturated fatty acids and vitamin E after myocardial infarction: results of the GISSI-Prevenzione trial. Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto miocardico

Antioxidants and endothelial dysfunction in hyperlipidemia

Endothelial function is abnormal in a variety of diseased states such as hypercholesterolemia and atherosclerosis. This may be secondary to decreased synthesis of nitric oxide (NO) and/or increased degradation of NO due to interaction with superoxide anions. More recent experimental observations demonstrate increased production of superoxide in hyperlipidemia, suggesting that endothelial dysfunction in these states is in part secondary to increased NO metabolism. Enzymes proposed to be involved in increased superoxide production may include xanthine oxidase, the NO synthase, and the NAD(P)H oxidase. Superoxide rapidly reacts with NO to form peroxynitrite (ONOO-), a highly reactive intermediate with cytotoxic properties. Despite experimental evidence for the oxidative stress concept in causing endothelial dysfunction, the results of recent randomized trials to test the influence of antioxidants on coronary event rates and prognosis in patients with coronary artery disease were very disappointing. In all of these studies the use of vitamins such as vitamin E failed to improve the prognosis. In contrast, treatment with angiotensin converting enzyme inhibitors or cholesterol- lowering drugs improved endothelial dysfunction, prevented the activation of superoxide-producing enzymes in cholesterol-fed animals, reduced coronary event rates, and improved prognosis in patients with coronary artery disease. Therefore, inhibition of superoxide production at the enzymatic level rather than symptomatic superoxide scavenging may be the better choice of treatment.

Does vitamin E decrease heart attack risk? summary and implications with respect to dietary recommendations

The hypothesis that oxidative stress has a role in atherosclerosis rests on a large body of experimental work carried out in animal models of heart disease. The situation is more complex in humans, in that the results from vitamin E supplementation trials have been conflicting. Nonetheless, there is emerging information that alpha-tocopherol may play a critical role in maintaining the function of key cellular components in the atherosclerotic process through its ability to inhibit the activity of protein kinase C, a key player in many signal transduction pathways. alpha-Tocopherol modulates pathways of platelet aggregation, endothelial cell nitric oxide production, monocyte/macrophage superoxide production and smooth muscle cell proliferation. Regulation of adhesion molecule expression and inflammatory cell cytokine production by alpha-tocopherol has also been reported. More studies are required to relate alpha-tocopherol intakes to optimal tissue responses in humans.

Is there a vitamin E paradox?

In addition to epidemiologic studies that suggest a benefit for high intakes of alpha-tocopherol, studies of supplementation in humans have clearly shown that alpha-tocopherol decreases lipid peroxidation, platelet aggregation, and functions as a potent anti-inflammatory agent. In the five large prospective clinical trials with alpha-tocopherol therapy, four have shown a beneficial effect on cardiovascular end-points (two studies on a primary end-point and two studies on other cardiovascular end-points). Thus, the totality of evidence based on the epidemiologic data, in-vitro studies and animal models, and the clinical trials appears to support a benefit for alpha-tocopherol supplementation in patients with pre-existing cardiovascular disease. However, definitive recommendations must await ongoing clinical trials.

Prevention of chemically induced diabetes mellitus in experimental animals by polyunsaturated fatty acids

Previous studies showed that essential fatty-acid deficiency, conjugated linoleic acid, and a peroxisome proliferator-activated receptor-gamma binding agent such as troglitazone can prevent the development of diabetes mellitus in experimental animals. In the present study, we observed that oral supplementation with oils rich in omega-3 eicosapentaenoic acid and docosahexaenoic acid and omega-6 gamma-linolenic acid and arachidonic acid could protect the animals against alloxan-induced diabetes mellitus. These oils rich in omega-3 and omega-6 fatty acids not only significantly attenuated chemical-induced diabetes mellitus but also restored the antioxidant status to normal range. Changes in the concentrations of different fatty acids shown by the phospholipid fractions of plasma, liver, and muscle tissues that occurred as a result of alloxan-induced diabetes mellitus also reverted to normal in these animals. Based on these results and the known mechanisms of alloxan, we suggest that omega-3 and omega-6 long-chain fatty acids can prevent chemically induced diabetes mellitus by enhancing the antioxidant status and suppressing production of cytokines.

Vitamin E and atherosclerosis: beyond prevention of LDL oxidation

Atherosclerosis is a chronic inflammatory disease of the arterial wall. Observational and experimental studies indicate that dietary vitamin E supplementation is associated with reduced risk of atherosclerosis. Evidence indicates that vitamin E, in addition to inhibition of oxidative modification of LDL, may inhibit atherogenesis through several other mechanisms at the molecular and cellular levels, which also include its nonantioxidant functions.

Long-chain omega 3 fatty acids, blood lipids and cardiovascular risk reduction

Increasing evidence suggests that omega 3 fatty acids derived from fish and fish oils may play a protective role in coronary heart disease and its many complications, through a variety of actions, including effects on lipids, blood pressure, cardiac and vascular function, prostanoids, coagulation and immunological responses. Interesting differences between the effects of highly purified eicosapentaenoic acid and docosahexaenoic acid are emerging, which may be relevant in the choice of omega 3 fatty acid for incorporation into food products. On the basis of our current knowledge, we believe it is justified to recommend, particularly to high-risk populations, an increased dietary intake of omega 3 fatty acids through the consumption of fish.

Low-dose aspirin and vitamin E in people at cardiovascular risk: a randomised trial in general practice. Collaborative Group of the Primary Prevention Project

BACKGROUND

In addition to the treatment of specific cardiovascular risk factors, intervention which interferes with the general mechanisms of atherosclerosis could further reduce the incidence of cardiovascular events. We aimed to investigate in general practice the efficacy of antiplatelets and antioxidants in primary prevention of cardiovascular events in people with one or more major cardiovascular risk factors.

METHODS

We did a randomised controlled open 2x2 factorial trial to investigate low-dose aspirin (100 mg/day) and vitamin E (300 mg/day) in the prevention of cardiovascular events, in people with one or more of the following: hypertension, hypercholesterolaemia, diabetes, obesity, family history of premature myocardial infarction, or individuals who were elderly.

FINDINGS

4495 people (2583 female, mean age 64.4 years) were included in the trial. After a mean follow-up of 3.6 years the trial was prematurely stopped on ethical grounds when newly available evidence from other trials on the benefit of aspirin in primary prevention was strictly consistent with the results of the second planned interim analysis. Aspirin lowered the frequency of all the endpoints, being significant for cardiovascular death (from 1.4 to 0.8%; relative risk 0.56 [95% CI 0.31-0.99]) and total cardiovascular events (from 8.2 to 6.3%; 0.77 [0.62-0.95]). Severe bleedings were more frequent in the aspirin group than the no-aspirin group (1.1% vs 0.3%; p<0.0008). Vitamin E showed no effect on any prespecified endpoint. Analyses were by intention-to-treat.

INTERPRETATION

In women and men at risk of having a cardiovascular event because of the presence of at least one major risk factor, low-dose aspirin given in addition to treatment of specific risk factors contributes an additional preventive effect, with an acceptable safety profile. The results on vitamin E's cardiovascular primary preventive efficacy are not conclusive per se, although our results are consistent with the negative results of other large published trials on secondary prevention.

Effects of fish oils and fish on cardiovascular disease

The effects of fish oils, fish, and omega-3 (n-3) fatty acids on cardiovascular functions and outcomes in recently published studies are reviewed. The original hypothesis that eating fish is protective has been largely sustained but refined to indicate benefit mainly in those who are at increased risk. Biologic plausibility has been extended from the established benefit of lipid-lowering to improvements in vascular and arterial functions. A major intervention trial in patients with cardiovascular disease has confirmed the benefits of moderate amounts of long-chain n-3 fatty acids. Thus, the triad of evidence comprising epidemiology, biologic plausibility, and interventional success through a randomized, controlled trial has been established.

Susceptibility of LDL to oxidative modification in healthy volunteers supplemented with low doses of n-3 polyunsaturated fatty acids

The objective of the present study was to evaluate the oxidative susceptibility of LDL in human volunteers following supplementation with various low doses (<1 g/d) of n-3 polyunsaturated fatty acids (PUFA). Sixty-two healthy volunteers (thirty-seven males and twenty-five females, aged 19-63 years) were recruited to take part in a randomised placebo-controlled trial. Volunteers were required to take 0.9, 0.6 or 0.3 g n-3 PUFA as fish oil or placebo capsules daily for 16 weeks. Susceptibility of LDL to oxidative modification was assessed by measuring the production of conjugated dienes and thiobarbituric acid-reactive substances in LDL oxidised by Cu2+ (15 microM) or 2,2'-azobis(2-amidinopropane) dihydrochloride (1 mM) for 5 h. Plasma fatty acid and LDL-fatty acid composition, cholesterol levels and antioxidant concentrations were also measured. While post-treatment n-3 PUFA compositions of plasma and LDL reflected the capsule contents, no meaningful differences in antioxidant concentrations or cholesterol levels were observed between the groups. Supplementation with low doses of n-3 PUFA as fish oil did not influence the oxidative susceptibility of LDL. The results of the present study suggest that moderate dietary intakes of n-3 PUFA do not significantly influence the susceptibility of LDL to oxidative modification in vitro.

n-3 polyunsaturated fatty acid supplementation, monocyte adhesion molecule expression and pro-inflammatory mediators in Type 2 diabetes mellitus

AIMS

To examine the effect of n-3 polyunsaturated fatty acid supplements on the monocyte surface expression of adhesion molecules involved in proatherogenic monocyte-endothelial interactions, and on pro-inflammatory mediators in Type 2 diabetes mellitus.

METHODS

Twenty-nine subjects with Type 2 diabetes and 21 controls without diabetes were studied. Monocyte expression of leucocyte function-associated antigens 1 and 3, intercellular adhesion molecule-1, and the major histocompatibility complex class II molecule HLA-DR were measured using a laser flow cytometric method. Supplementation with 2.08 g n-3 fatty acids for 21 days was undertaken and measurements repeated. Plasma soluble adhesion molecule concentrations, plasminogen activator inhibitor-1 activity and antigen and pro-inflammatory mediators (cysteinyl leukotriene and monocyte leukotriene B4) were also measured.

RESULTS

Groups did not differ in monocyte expression of adhesion molecules or HLA-DR, or in leukotriene production although plasma soluble adhesion molecule concentrations were higher in the diabetes groups (P<0.05). n-3 fatty acid supplementation influenced neither the expression of these molecules nor plasma soluble adhesion molecule concentrations or leukotriene production.

CONCLUSIONS

This study does not support increased monocyte adhesion molecule expression or abnormal monocyte production of pro-inflammatory mediators as mechanisms for increased atherogenic risk in Type 2 diabetes. Cardioprotective actions of n-3 fatty acids may not be mediated through these mechanisms.

Later management of documented ischaemic heart disease: secondary prevention and rehabilitation

Patients may present with a variety of syndromes related to ischaemic heart disease. These include unstable or stable angina pectoris, acute myocardial infarction, and occasionally cardiac failure without prior anginal pain or infarction. For the purposes of this review, it will generally be assumed that the condition has been stabilised, though one important aspect of the rehabilitation process is the recognition of continuing or recurrent problems such as angina pectoris and cardiac decompensation. This should then be followed by appropriate intervention. The key components of post-hospital management of such patients are: (i) support; (ii) education; (iii) assessment; (iv) intervention (if necessary); (v) therapy; and (vi) lifestyle modification.

Position of the American Dietetic Association: food fortification and dietary supplements

Wise food choices provide the necessary foundation for optimal nutrition. Science has not fully identified the specific chemical components that account for the benefits of healthy eating patterns. Selection of a variety of foods, using tools such as the USDA/HHS Dietary Guidelines for Americans and the USDA Food Guide Pyramid, is the best way to provide a desirable balance, without excessive intakes of macronutrients, micronutrients and other beneficial components of foods. Nevertheless, for certain nutrients and some individuals, fortification, supplementation, or both may also be desirable. Nutrient intakes from all these sources should be considered in dietary assessments, planning and recommendations. The recommendations of the National Academy of Sciences' Food and Nutrition Board provide a sound scientific basis for vitamin and mineral intakes. Intakes exceeding those recommendations have no demonstrated benefit for the normal, healthy population. Dietetics professionals should base recommendations for use of fortified foods or supplements on individualized assessment and sound scientific evidence of efficacy and safety. It is the position of the American Dietetic Association that the best nutritional strategy for promoting optimal health and reducing the risk of chronic disease is to wisely choose a wide variety of foods. Additional vitamins and minerals from fortified foods and/or supplements can help some people meet their nutritional needs as specified by science-based nutrition standards such as the Dietary Reference Intakes (DRI).

Antioxidant supplements to prevent heart disease. Real hope or empty hype?

Antioxidants in foods and supplements are being widely promoted for their health benefits. Protection from heart disease is one claim that seems compelling in light of scientific evidence and large-scale observational studies. But will antioxidant supplements help your patients? To examine this question, Dr Tran reviews numerous clinical studies and evaluates the discrepancies between observational and clinical results.

Cost-effectiveness analysis of n-3 polyunsaturated fatty acids (PUFA) after myocardial infarction: results from Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto (GISSI)-Prevenzione Trial

OBJECTIVE

To estimate the cost effectiveness of treatment with n-3 polyunsaturated fatty acids (PUFA) for secondary prevention after myocardial infarction (MI).

DESIGN AND SETTING

The cost-effectiveness analysis of n-3 PUFA treatment after MI was based on morbidity and mortality data and the use of resources obtained prospectively during the 3.5 year follow-up period of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto (GISSI)-Prevenzione study. The cost-effectiveness analysis took into account the incremental number of life-years gained and the incremental costs for hospital admissions, diagnostic tests and drugs, applying a 5% discount rate. The value for money of n-3 PUFA treatment was assessed using the cost-effectiveness ratio and the number needed to treat (NNT) approach.

PERSPECTIVE

Third-party payer.

MAIN OUTCOME MEASURES AND RESULTS

The incremental cost-effectiveness ratio for n-3 PUFA in the basecase scenario was 24,603 euro (EUR, 1999 values) per life-year gained (95% confidence interval: 22,646 to 26,930). Sensitivity analysis included the analysis of extremes, producing estimates varying from EUR15,721 to EUR52,524 per life-year gained. 172 patients would need to be treated per year with n-3 PUFA, at an annual cost of EUR68,000, in order to save 1 patient. This is comparable with the NNT value, and associated annual cost for simvastatin, but less costly than that for pravastatin.

CONCLUSIONS

The cost effectiveness of long term treatment with n-3 PUFA is comparable with other drugs recently introduced in the routine care of secondary prevention after MI. Since the clinical benefit provided by n-3 PUFA is additive, this therapy should be added to the established routine practice, with additive costs.

Oxidant stress, anti-oxidants and essential fatty acids in South Indian vegetarians and non-vegetarians

Vegetarians are known to have a low incidence of cardiovascular diseases and lower blood pressure compared to non-vegetarians. The exact cause for this is not known. In the present study, it was found that, in general, vegetarians (female > males) have a higher concentrations of anti-oxidant enzymes: catalase and superoxide dismutase in their RBC membranes and lower levels of plasma lipid peroxides compared to non-vegetarians. Both male and female non-vegetarians were found to have a higher n-3/n-6 ratio compared to vegetarians. These results suggest that vegetarians have a higher anti-oxidant status and low levels of n-3 fatty acids. It remains to be seen whether this alterations in the oxidant and anti-oxidant status and n-3 concentrations explains the lower incidence of cardiovascular diseases and lower blood pressure in vegetarians.

Fish oil in people with type 2 diabetes mellitus

BACKGROUND

People with type 2 diabetes mellitus are at increased risk from cardiovascular disease. Dietary fish oils are known to reduce triglyceride levels, but their impact on cholesterol levels, glycemic control and vascular outcomes are not well known.

OBJECTIVES

To determine the effects of fish oil supplementation on cardiovascular outcomes, cholesterol levels and glycemic control in people with type 2 diabetes mellitus.

SEARCH STRATEGY

We carried out a comprehensive search of the Cochrane Controlled Trials Register, Medline, Embase, Lilacs, bibliographies of relevant papers and contacted experts for identifying additional trials. Date of last search: September 2000.

SELECTION CRITERIA

All randomized placebo-controlled trials in which fish oil supplementation was the only intervention in people with type 2 diabetes were included. Authors were contacted for missing information.

DATA COLLECTION AND ANALYSIS

Three investigators performed data extraction and quality scoring independently with discrepancies resolved by consensus.

MAIN RESULTS

Eighteen trials including 823 participants followed for a mean of 12 weeks were included. Doses of fish oil used ranged from 3 to 18 g/day. No trials with vascular event or mortality endpoints were identified. The outcomes studied were glycemic control and lipid levels. Meta-analysis of pooled data demonstrated a statistically significant effect of fish oil in lowering triglycerides by 0.56 mmol/l (95% CI -0.71 to -0.40 mmol/l) and raising LDL cholesterol by 0.21 mmol/l (95% CI 0.02 to 0.41 mmol/l). No statistically significant effect was observed for fasting glucose, HbA1c, total or HDL cholesterol. The triglyceride lowering effect and the elevation in LDL cholesterol were most marked in those trials that recruited people with hypertriglyceridemia and used higher doses of fish oil. No adverse effects of the intervention were reported.

REVIEWER'S CONCLUSIONS

Fish oil supplementation in type 2 diabetes lowers triglycerides, may raise LDL cholesterol (especially in hypertriglyceridemic patients on higher doses of fish oil) and has no statistically significant effect on glycemic control. Trials with vascular event or mortality defined endpoints are needed.

Removal of fat from cow's milk decreases the vitamin E contents of the resulting dairy products

The present study was undertaken to determine whether decreases in fat contents result in lower vitamin E contents. Milk samples of varying fat contents (half and half, whole milk, reduced-fat milk, low-fat milk, and nonfat milk) were obtained from a local dairy on six different occasions. alpha-Tocopherol was the major form of vitamin E (>85%); gamma-tocopherol and alpha-tocotrienol were present to a lesser extent. As the fat contents of milk products decreased from 11 to 0.3%, the vitamin E contents decreased. For example, raw milk as compared to nonfat milk had both higher (-tocopherol contents (45.5 +/- 4.6 vs. 4.5 +/- 0.5 microg/100 g; P < or = 0.0001) and higher total lipids (3.46 +/- 0.49 vs. 0.30 +/- 0.07 g/100 g; P < or = 0.0001). Vitamin E, cholesterol, and total lipids increased as cream was added back to nonfat milk during production. For every 1 mg cholesterol increase, there was an increase of approximately 4 microg of alpha-tocopherol; for every 1 g total lipids increase, the alpha-tocopherol content increased by 17 microg. These data demonstrate that removal of milk fat markedly decreases the vitamin E content of various milk products.

Lipid modulation and systemic inflammation

N-6 and n-3 PUFAs from the diet are absorbed and reach the cell where they interact with fatty acid binding proteins within cell membranes and cytoplasm. They are processed in the endoplasmic reticulum (desaturation-elongation reactions, lipid synthesis, eicosanoid and epoxide production) and in peroxisomes (beta-oxidation, synthesis, oxidation products). They interact with receptors, ion channels, and nuclear elements; the result is modulation of gene expression. PUFA-induced alterations result in modulation of local and systemic inflammation and inflammatory disease activity.

Assessment of dietary therapies in a canine model of Batten disease

The neuronal ceroid lipofuscinoses (NCLs) are inherited neurodegenerative diseases that occur in a number of animal species, including dogs. A study was conducted to determine whether the resupply of nutrients lost in NCL English Setter dogs would modify the course of the disease. Carnitine and polyunsaturated fatty acids have been reported to be reduced in NCL English Setters. Therefore, the normal laboratory diets of NCL dogs were supplemented with carnitine, fish oil and corn oil and the disease progression was compared with that of an untreated litter mate. The following specific prognostic indicators of NCL were monitored: cognitive function, brain atrophy, brain glucose metabolism and lifespan. Carnitine, with or without lipid supplements, dramatically delayed the progression of cognitive decline in NCL dogs. When fish oil and corn oil only were supplied, brain atrophy was reduced. A combination of all three supplements preserved cognitive function and increased lifespan by 10%. However, brain glucose hypometabolism and cerebral atrophy were not reduced. The results in this study indicated that the effectiveness of therapeutic interventions can be assessed by non-invasive methods at a relatively early stage of the disease process. Our study suggests that dietary supplementation with carnitine is a promising new approach for delaying or preventing the cognitive decline in dogs, and perhaps, with human NCL patients.

Beneficial effect(s) of n-3 fatty acids in cardiovascular diseases: but, why and how?

Low rates of coronary heart disease was found in Greenland Eskimos and Japanese who are exposed to a diet rich in fish oil. Suggested mechanisms for this cardio-protective effect focused on the effects of n-3 fatty acids on eicosanoid metabolism, inflammation, beta oxidation, endothelial dysfunction, cytokine growth factors, and gene expression of adhesion molecules; But, none of these mechanisms could adequately explain the beneficial actions of n-3 fatty acids. One attractive suggestion is a direct cardiac effect of n-3 fatty acids on arrhythmogenesis. N-3 fatty acids can modify Na+ channels by directly binding to the channel proteins and thus, prevent ischemia-induced ventricular fibrillation and sudden cardiac death. Though this is an attractive explanation, there could be other actions as well. N-3 fatty acids can inhibit the synthesis and release of pro-inflammatory cytokines such as tumor necrosis factoralpha (TNFalpha) and interleukin-1 (IL-1) and IL-2 that are released during the early course of ischemic heart disease. These cytokines decrease myocardial contractility and induce myocardial damage, enhance the production of free radicals, which can also suppress myocardial function. Further, n-3 fatty acids can increase parasympathetic tone leading to an increase in heart rate variability and thus, protect the myocardium against ventricular arrhythmias. Increased parasympathetic tone and acetylcholine, the principle vagal neurotransmitter, significantly attenuate the release of TNF, IL-1beta, IL-6 and IL-18. Exercise enhances parasympathetic tone, and the production of anti-inflammatory cytokine IL-10 which may explain the beneficial action of exercise in the prevention of cardiovascular diseases and diabetes mellitus. TNFalpha has neurotoxic actions, where as n-3 fatty acids are potent neuroprotectors and brain is rich in these fatty acids. Based on this, it is suggested that the principle mechanism of cardioprotective and neuroprotective action(s) of n-3 fatty acids can be due to the suppression of TNFalpha and IL synthesis and release, modulation of hypothalamic-pituitary-adrenal anti-inflammatory responses, and an increase in acetylcholine release, the vagal neurotransmitter. Thus, there appears to be a close interaction between the central nervous system, endocrine organs, cytokines, exercise, and dietary n-3 fatty acids. This may explain why these fatty acids could be of benefit in the management of conditions such as septicemia and septic shock, Alzheimer's disease, Parkinson's disease, inflammatory bowel diseases, diabetes mellitus, essential hypertension and atherosclerosis.

Is there a potential therapeutic role for vitamin E or other antioxidants in atherosclerosis?

In-vitro studies and animal model studies provide an ever-growing body of evidence, direct and indirect, that oxidation of low-density lipoprotein and/or related oxidative mechanisms play a role in atherogenesis. However, two recent, very large, carefully conducted clinical intervention trials using adequate doses of vitamin E demonstrated no effect on a composite end-point of non-fatal infarction, stroke or death from cardiovascular causes. Why the unexpected negative results? Possibly because the animal intervention evidence on which these trials were based deals primarily with very early lesions (fatty streaks). That evidence does not necessarily provide a basis for predicting what antioxidant intervention will do in patients with advanced lesions, particularly when the end-points used relate to unstable plaques and fatal thrombosis, events for which we have no adequate animal models. Nor does it necessarily follow that the same antioxidants used successfully in animals will be effective in humans. The strength of the evidence for the oxidative modification hypothesis is such that negative clinical trials with one particular antioxidant, in patients with very advanced coronary heart disease and lasting only 3-5 years, should not be taken as refutation of the hypothesis. Perhaps different kinds of human trials are needed, trials in which the development of new lesions is measured, in order to test whether antioxidants can decrease the rate of initiation and early progression of atherosclerosis as they do in animals. The answer to the title query is 'Probably, but it is too soon to say'.

Risks of coronary heart disease in women: current understanding and evolving concepts

The population of older individuals in the United States is growing rapidly. Because women generally live longer than men and make up the majority of this aging population, the elucidation of health issues related to older women is important. Cardiovascular disease is the leading cause of death and disability for women and claims the lives of more women than the next 14 causes combined. The majority of these deaths are due to atherosclerotic coronary heart disease, with nearly 250,000 women dying of myocardial infarction each year. There is evidence that women with suspected or established cardiovascular disease have not benefited fully from recent advances in the detection and management of coronary heart disease. Regardless of the mechanism and extent of the effect that sex differences have on approaches to cardiovascular disease, women appear to benefit from proven efficacious therapies, and the longer-term outcomes associated with these treatments are positive. The data regarding women and coronary heart disease are rapidly evolving and sometimes conflicting. The intent of this article is to summarize the most current understanding of coronary heart disease risks in women, highlighting the impact of prevention, and to discuss the latest novel findings that may become important in our armamentarium for prevention of coronary heart disease.

Fish oil-derived fatty acids, docosahexaenoic acid and docosapentaenoic acid, and the risk of acute coronary events: the Kuopio ischaemic heart disease risk factor study

BACKGROUND

Previous findings concerning the serum levels of fish-derived (n-3) fatty acids and coronary heart disease are inconsistent. The purpose of this study was to investigate the association between the serum n-3 end-product fatty acids docosahexaenoic acid (DHA), docosapentaenoic acid (DPA), and eicosapentaenoic acid and the risk of acute coronary events in middle-aged men.

METHODS AND RESULTS

We studied this association in the Kuopio Ischaemic Heart Disease Risk Factor Study, a prospective population study in Eastern Finland. Subjects were randomly selected and included 1871 men aged 42 to 60 years who had no clinical coronary heart disease at baseline examination. A total of 194 men had a fatal or nonfatal acute coronary event during follow-up. In a Cox proportional hazards' model adjusting for other risk factors, men in the highest fifth of the proportion of serum DHA+DPA in all fatty acids had a 44% reduced risk (P=0.014) of acute coronary events compared with men in the lowest fifth. Men in the highest fifth of DHA+DPA who had a low hair content of mercury (</=2.0 microgram/g) had a 67% reduced risk (P=0.016) of acute coronary events compared with men in the lowest fifth who had a high hair content of mercury (>2.0 microgram/g). There was no association between proportion of eicosapentaenoic acid and the risk of acute coronary events.

CONCLUSIONS

Our data provide further confirmation for the concept that fish oil-derived fatty acids reduce the risk of acute coronary events. However, a high mercury content in fish could attenuate this protective effect.

Therapeutic potential of vitamin E in heart disease

Low density lipoprotein (LDL) oxidation is considered an important step in the atherogenic process. Oxidatively modified particles induce the expression of adhesion molecules, stimulate the production of inflammatory cytokines and impair endothelial function. The measurement of oxidised LDLs in vivo is very difficult, therefore most investigators rely on the measurement of in vitro oxidability of these particles to evaluate their deleterious effects. Supplementation with water and lipid soluble anti-oxidant vitamins, especially vitamin C and E, significantly increase the resistance to LDL oxidation. Vitamin E supplementation also improves endothelium-dependent vasodilation in hypercholesterolaemic and subjects who smoke cigarettes. Epidemiological studies have not consistently demonstrated a protective effect of vitamin E consumption as food or supplements on coronary events or stroke. Likewise, only one of five large prospective trials has shown a beneficial effect of vitamin E supplementation on cardiovascular events or mortality. One report showed that supplemented haemodialysed patients had a lower incidence of cardiovascular events. Thus, presently, there is not enough evidence to widely recommend the use of vitamin E supplements for vascular protection.

The postprandial effect of components of the Mediterranean diet on endothelial function

OBJECTIVES

This study investigated the postprandial effect of components of the Mediterranean diet on endothelial function, which may be an atherogenic factor.

BACKGROUND

The Mediterranean diet, containing olive oil, pasta, fruits, vegetables, fish, and wine, is associated with an unexpectedly low rate of cardiovascular events. The Lyon Diet Heart Study found that a Mediterranean diet, which substituted omega-3-fatty-acid-enriched canola oil for the traditionally consumed omega-9 fatty-acid-rich olive oil, reduced cardiovascular events.

METHODS

We fed 10 healthy, normolipidemic subjects five meals containing 900 kcal and 50 g fat. Three meals contained different fat sources: olive oil, canola oil, and salmon. Two olive oil meals also contained antioxidant vitamins (C and E) or foods (balsamic vinegar and salad). We measured serum lipoproteins and glucose and brachial artery flow-mediated vasodilation (FMD), an index of endothelial function, before and 3 h after each meal.

RESULTS

All five meals significantly raised serum triglycerides, but did not change other lipoproteins or glucose 3 h postprandially. The olive oil meal reduced FMD 31% (14.3 +/- 4.2% to 9.9 +/- 4.5%, p = 0.008). An inverse correlation was observed between postprandial changes in serum triglycerides and FMD (r = -0.47, p < 0.05). The remaining four meals did not significantly reduce FMD.

CONCLUSIONS

In terms of their postprandial effect on endothelial function, the beneficial components of the Mediterranean and Lyon Diet Heart Study diets appear to be antioxidant-rich foods, including vegetables, fruits, and their derivatives such as vinegar, and omega-3-rich fish and canola oils.

Studies of LDL oxidation following alpha-, gamma-, or delta-tocotrienyl acetate supplementation of hypercholesterolemic humans

In vitro tocotrienols (T3s) have potent vitamin E antioxidant activity, but unlike tocopherols can inhibit cholesterol synthesis by suppressing 3-hydroxy-3-methyl-glutarylCoA (HMG-CoA) reductase. Because hypercholesterolemia is a major risk factor for coronary artery disease and oxidative modification of low-density lipoprotein (LDL) may be involved in atherogenesis, we investigated whether daily supplements of placebo, or alpha-, gamma-, or delta- (alpha-, gamma-, or delta-) tocotrienyl acetates would alter serum cholesterol or LDL oxidative resistance in hypercholesterolemics in a double-blind placebo controlled study. Subjects were randomly assigned to receive placebo (n = 13), alpha- (n = 13), gamma- (n = 12), or delta- (n = 13) tocotrienyl acetate supplements (250 mg/d). All subjects followed a low-fat diet for 4 weeks, then took supplements with dinner for the following 8 weeks while still continuing diet restrictions. Plasma alpha- and gamma-tocopherols were unchanged by supplementation. Plasma T3s were undetectable initially and always in the placebo group. Following supplementation in the respective groups plasma concentrations were: alpha-T3 0.98 +/- 0.80 micromol/l, gamma-T3 0.54 +/- 0.45 micromol/l, and delta-T3 0.09 +/- 0.07 micromol/l. Alpha-T3 increased in vitro LDL oxidative resistance (+22%, p <.001) and decreased its rate of oxidation (p <. 01). Neither serum or LDL cholesterol nor apolipoprotein B were significantly decreased by tocotrienyl acetate supplements. This study demonstrates that: (i) tocotrienyl acetate supplements are hydrolyzed, absorbed, and detectable in human plasma; (ii) tocotrienyl acetate supplements do not lower cholesterol in hypercholesterolemic subjects on low-fat diets; and (iii) alpha-T3 may be potent in decreasing LDL oxidizability.

Endothelial dysfunctions: common denominators in vascular disease

The past 20 years have witnessed enormous progress in our understanding of the biology of vascular endothelium and its role in cardiovascular disease. Stemming from the seminal observations of Furchgott, the concept of a continuous regulation of vascular tone by normal endothelium and alterations of such control in disease states has become one of the most enlightening concepts of cardiovascular research. This review covers a few updates on the topic, illustrating selective areas of recent progress in our understanding of endothelial function in the control of leucocyte adhesion, atherogenesis and vascular tone, as well as the alterations that cause and accompany vascular disease.

Diet and coronary heart disease: clinical trials

Dietary intervention trials using coronary heart disease (CHD) mortality and morbidity as endpoints have demonstrated that restriction of dietary total and saturated fat or replacement of the latter with polyunsaturated fatty acids (PUFAs), in particular n-3 PUFAs, is of great benefit with respect to CHD risk. This is likewise the case for intervention trials using angiographic endpoints, with many studies showing that such diets not only retard progression of coronary atherosclerosis but can cause regression as well. The role that antioxidants, such as vitamin E, may play in the development and progression of CHD is less clear. The results of large-scale clinical trials evaluating the effect of vitamin E supplementation on CHD risk do not support the concept that this agent is cardioprotective. The purpose of this report is to review dietary intervention trials that support a direct relationship between diet, lipoproteins, and CHD risk.

Dietary supplements and cardiovascular disease

Consumer use of dietary supplements has increased considerably in recent years, and interest in using supplements to treat or prevent chronic diseases such as cardiovascular disease is particularly high. This review examines several popular dietary supplements used for cardiovascular disease, their likely points of intervention, and what is known to date about their efficacy and safety.

n-3 polyunsaturated fatty acids and the cardiovascular system

n-3 Polyunsaturated fatty acids, mainly those contained in fish oils, are candidates for inclusion in secondary prevention programmes for coronary heart disease, based on the results of recent randomized trials in humans. Marine n-3 polyunsaturated fatty acids retard coronary atherosclerosis and appear to prevent fatal arrhythmias; and they decrease mortality subsequent to myocardial infarction.

Evidence for oxidative activation of c-Myc-dependent nuclear signaling in human coronary smooth muscle cells and in early lesions of Watanabe heritable hyperlipidemic rabbits: protective effects of vitamin E

BACKGROUND

Oxidized LDL (oxLDL) promotes atherogenesis, and antioxidants reduce lesions in experimental models. OxLDL-mediated effects on c-Myc are poorly characterized, and those on c-Myc nuclear pathways are completely unknown. c-Myc stimulates smooth muscle cell (SMC) proliferation and could be involved in atherosclerosis. We investigated the early effects of oxLDL and alpha-tocopherol on c-Myc, its binding partner Max, and the carboxy-terminal domain-binding factors activator protein-2 and elongation 2 factor in human coronary SMCs. We also investigated whether 9-week treatment of Watanabe heritable hyperlipidemic (WHHL) rabbits with diet-enriched alpha-tocopherol reduces c-Myc expression and oxLDL in the left coronary artery.

METHODS AND RESULTS

OxLDL enhanced c-Myc/Max expression and transcription by cotransfection assay and the nuclear activities of E2F and activator protein-2 by binding shift and supershift in coronary SMCs. alpha-Tocopherol significantly reduced these molecular events. Furthermore, alpha-tocopherol reduced early lesions, SMC density, and the immunohistochemical presence of c-Myc, which colocalized with oxLDL/foam cells in the coronaries of WHHL rabbits.

CONCLUSIONS

We provide the first evidence that oxLDL and alpha-tocopherol may influence c-Myc activation and several c-Myc-dependent signaling pathways in human coronary SMCs. The observation that in vivo, an antioxidant reduces both c-Myc and oxLDL in early coronary lesions of rabbits is consistent with, but does not prove, the hypothesis that c-Myc-dependent factors activated by oxidative processes contribute to atherogenesis and coronary heart disease.