The Effect of Vitamin E on Cardiovascular Diseases

The Effect of Vitamin E on Cardiovascular Diseases

Zaheer Abbas
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The Effect of Vitamin E on Cardiovascular Diseases

Introduction

Cardiovascular diseases (CVDs) are the number one killer in the world today which causes close to 18 million deaths every year. Hypertension, hyperlipidemia, diabetes, and oxidative stress are some of the risk factors that play a significant role in the development of the atherosclerosis, myocardial infarction, and stroke. Antioxidants such as vitamin E have received some attention in the past years as being useful in the prevention and treatment of CVDs.

Vitamin E is a fat-soluble antioxidant that is instrumental in neutralization of free radicals, lessening of oxidative stress, and amelioration of the endothelial function. Nevertheless, its cardiovascular protection is controversial, and some studies indicate that it is effective, and others indicate that it has little or no effect. This paper examines the processes through which vitamin E affects cardiovascular health, the clinical evidence and the possible impacts and drawbacks.

 

Understanding Vitamin E

Vitamin E is a combination of eight compounds that occur naturally, which are categorized into two groups:

1.     Tocopherols

o   Alpha (alpha) -tocopherol (most biologically active form)

o   Beta (β)-tocopherol

o   Gamma (γ)-tocopherol

o   Delta (δ)-tocopherol

2.     Tocotrienols

o   Alpha, beta, gamma and delta tocotrienols

Of these, α-tocopherol is the most investigated and supplemented form, because it is very bioavailable in human beings.

 


Sources of Vitamin E

Vitamin E is acquired by food and supplements. It is found commonly in food:

·        Oils: sunflower oil, olive oil, soybean oil

·        Nuts and seeds: almonds, hazelnut, sunflower seeds

·        Spinach, broccoli (Green Vegetables)

·        Foods Adding Fortification: Cereals, margarine

 


Mechanisms of Vitamin E in Cardiovascular Protection

Vitamin E can produce its cardioprotective actions in a number of ways:

1. Antioxidant Properties

·        Inhibits Free Radicals: Reactive oxygen species (ROS) are known to cause LDL oxidation that is a major process in atherosclerosis. Vitamin E transfers electrons to free radicals and stops oxidative damage.

·        Decreases Lipid Peroxidation: Vitamin E slows down the formation of lipid-peroxidation in arteries by preventing the oxidation of LDL cholesterol.

2. Anti-Inflammatory Effects

·        Regulates Cytokines: Vitamin E reduces pro inflammatory cytokines, such as TNF-a and IL-6, associated with endothelial dysfunction.

·        Inhibits NF-kB Pathway: This dampens down vascular inflammation which is a major consideration in the development of atherosclerosis.




3. Improves Endothelial Function

·        Increases Nitric Oxide (NO) Bioavailability: Nitric Oxide (NO) is necessary in vasodilation. Vitamin E is beneficial in preserving the activity of endothelial NO synthase (eNOS) enhancing blood circulation.

·        Lowers the Apoptosis of Endothelial Cells: Prevents oxidative damage of blood vessels and preserves the integrity of blood vessels.

4. Antiplatelet and Antithrombotic Effects

·        Lowers Platelet Aggregation: Vitamin E acts to prevent platelet adhesion that reduces the chances of thrombus formation.

·        Regulates Prostaglandins: Influences the thromboxane A2 (a vasoconstrictor), which allows a healthier circulation of blood.

5. Cholesterol Regulation

·        Block HMG-CoA Reductase: Research indicates that vitamin E has a small effect of reducing LDL cholesterol.

·        Increases HDL Function: Increases the function of HDL to clear the cholesterol off the arterial walls.

 

Vitamin D: Functions and Effects


Clinical Evidence on Vitamin E and Cardiovascular Diseases

A number of large trials have also explored the effect of vitamin E supplementation on the outcome of CVD with variable results.

Supportive Studies

·        Cambridge Heart Antioxidant Study (CHAOS, 1996):

o   Discovered that vitamin E (400 800 IU/day) decreased non-fatal myocardial infarction by a factor of 77 percent.

o   Nonetheless, there was no notable outcome on total mortality.

·        Women’s Health Study (WHS, 2005):

o   Documented a 24 percent decrease in cardiovascular mortalities in women above 45 years who were taking vitamin E supplements.

·        Secondary Prevention Studies:

o   According to some meta-analyses, vitamin E is potentially useful with high-risk groups (diabetics, smokers, elderly) by lowering the oxidative stress.

 

Contradictory or Neutral Studies

·        Heart Outcomes Prevention Evaluation (HOPE, 2000):

o   Vitamin E (400 IU/day) did not reduce the major cardiovascular events in high-risk patients significantly.

·        GISSI-Prevenzione Trial (1999):

o   Did not find any cardiovascular advantage of vitamin E in patients with post-MI.

·        SELECT Trial (2011):

o   The supplement (400 IU/day) of vitamin E had no effect on preventing prostate cancer or CVD and had the additional effect of increasing hemorrhagic stroke by a small amount.

 

Possible Reasons for Discrepancies

·        Variation in dosage: When used in high doses it can be pro-oxidant.

·        Population Differences: The benefits may be more in individuals who have an increased oxidative stress (e.g. diabetics).

·        Vitamin E form: 75 percent of trials were with 3-tocopherol; 3-tocopherol and tocotrienol supplements have some extra perks.

 

Potential Risks and Limitations of Vitamin E Supplementation

Vitamin E is otherwise safe but too much of it (more than 1,000 IU/day) can be dangerous:

·        Risk of increased Bleeding: high doses have the ability to inhibit platelet aggregation, which increases risk of hemorrhage.

·        Pro-Oxidant Effects: At extremely high doses, the substance can actually reify the oxidative harm.

·        Drug Interactions: Can interact with anticoagulants (warfarin) and statins.

·        Mixed Results on Meta-Analyses: Other studies depict no substantial CVD benefits, and it is questionable whether to be widely supplemented.

 

Recommendations for Vitamin E Intake in Cardiovascular Health

Considering the contradictory evidence, it is possible to make the following recommendations:

·        Preferred Dietary Intake: Vitamin E should be derived naturally, in food, and not supplements.

·        Risk Population Supplementation: Diabetics and smokers as well as individuals with proven deficiencies may be supplemented under medical supervision.

·        Do not take Mega-Doses: Take only the recommended daily allowance (RDA: 15 mg/day in adults).

·        Combination Therapy: Vitamin E might be more effective in combination with other antioxidants (vitamin C, selenium).

 

Conclusion

Vitamin E has a potential of cardiovascular protection because of its anti-oxidant, anti-inflammatory and endothelial-enhancing activities. But the clinical trials have had mixed results and it is possible that its advantages are dose-dependent, population-specific, and health-condition dependent. Although dietary vitamin E is good, supplementation without regard is not advised everywhere. It should be determined how various forms of vitamin E work synergistically and how those can be used in an individual approach to cardiovascular prevention in the future.

In the meantime, the most sensible strategy in limiting the risk of cardiovascular complications is a diet high in natural forms of vitamin E, along with heart-friendly lifestyle.

 

 

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