High-Dose Vitamin C A New Therapeutic ApproachOctober 2006
By Laurie Barclay, MD
Vitamin C Lowers Coronary Heart Disease Risk
Several recent studies confirm vitamin C’s strong protective effects against cardiovascular disease. In one trial, men in the highest third of vitamin C intake had a remarkable 66% lower risk of coronary heart disease than men in the lowest third—even after controlling for various cardiovascular risk factors.29 This result is all the more striking because many of the men studied were smokers.
Moreover, in a meta-analysis of studies that followed subjects for more than 10 years, the use of vitamin C supplements containing at least 700 mg of ascorbic acid reduced risk of coronary artery disease by 25%.30 And in the largest, longest study to examine the association between vitamin C intake and heart disease risk, women who used vitamin C supplements had a 28% reduction in coronary heart disease compared to women who did not supplement with the vitamin.31 In this massive Harvard Medical School study, which followed more than 85,000 female nurses for 16 years, higher vitamin C intake predicted lower heart disease risk—even after adjusting for age, smoking, and other risk factors. A particularly striking finding from this study is that women who did not use vitamin C supplements but instead obtained vitamin C exclusively from dietary sources did not experience significant protection against heart disease. This led the Harvard scientists to conclude that vitamin C supplements alone appeared to decrease the risk of coronary heart disease.
Vitamin C Status Tied to Heart Attack Risk
Several recent studies suggest that ensuring optimal vitamin C status not only protects against cardiovascular disease, but also greatly lessens the risk of suffering a life-threatening heart attack.
For example, in a Finnish study of middle-aged men without evidence of pre-existing heart disease, men who were deficient in vitamin C were 3.5 times more likely to suffer heart attacks compared to those who were not deficient in the vitamin, even after adjusting for smoking and other pertinent risk factors.32 This led the researchers to propose that vitamin C deficiency, as assessed by low plasma concentration, is a risk factor for heart attack.
In another study, subjects in the highest quartile of vitamin C intake had a stunning 80% lower risk of heart attack compared to those in the lowest quartile.33 Moreover, a British study found that plasma vitamin C concentrations were dramatically lower in men who had just suffered their first acute heart attack than in apparently healthy volunteers.34
Maintaining optimal vitamin C levels may thus provide powerful protection against potentially fatal heart attacks.
Vitamin C Also Reduces Damage Caused by Heart Attacks
In addition to helping prevent heart attacks, vitamin C may also reduce damage to crucial heart muscle following a heart attack, and decrease the incidence of further cardiovascular events.
For example, in a large study of patients who had suffered an acute heart attack, supplementing with high doses of vitamins C (1200 mg daily) and E (600 mg daily) for one month significantly reduced the combined rate of death, new heart attack, and other severe complications by about 20%.35 The researchers speculated that these potent antioxidants may have helped to mitigate oxidative damage to the heart muscle caused by the heart attack.
After an acute heart attack, the heart muscle’s failure to pump blood effectively may cause dangerously low blood pressure, a condition known as cardiogenic shock. Blood concentrations of vitamin C and other critical antioxidants are diminished in patients with cardiogenic shock, suggesting that the heart muscle uses these antioxidants to counteract oxidative damage.36 Depletion of antioxidants (including vitamin C) is also associated with failure to restore coronary blood flow following an acute heart attack.37
Several studies suggest that treatment with vitamin C, given alone or in combination with vitamin E, may reduce complications and improve outcome after an acute heart attack. Vitamin C may provide several benefits in this setting, such as improving electrical conduction throughout the heart muscle,38 lowering levels of clotting factors that increase risk for stroke,39 reducing oxidative stress and inflammation, and preventing detrimental changes in heart shape and function.40
Research shows that vitamin C also helps increase exercise tolerance after an acute heart attack.41 In one study, taking 2000 mg of supplemental vitamin C before exercise helped improve exercise capability. Scientists believe that vitamin C helps relieve oxidative stress-related damage to the sympathetic nervous system following heart attack.
One type of damage that occurs after an acute heart attack is ischemia-reperfusion injury, in which areas of heart muscle whose blood supply has been cut off are damaged when blood flow is restored. This type of injury is also associated with angina, or chest pain caused by coronary heart disease, and may contribute to aging and vascular disease.42 Because this type of cellular injury is thought to be caused by free radical damage, antioxidants such as vitamin C may be protective, as demonstrated in a score of animal studies.43-46
Clinical and experimental research suggests that vitamin C may protect against other diseases of the heart and blood vessels, including atrial fibrillation (irregular heart beat that increases the risk of stroke), dilated cardiomyopathy (an enlarged, weakened heart), congestive heart failure, and impaired blood flow regulation.54-57 Vitamin C may confer other additional benefits to heart disease patients by preserving the ability to respond to drugs used to treat coronary heart disease, as well as through its effects in supporting healthy body weight.58-61
Vitamin C Reduces Dangers of Blood Lipids
Scientists long ago discovered that high levels of low-density lipoprotein (LDL) are important predictors of coronary heart disease risk. The chemical state of these lipids, however, also affects risk. For example, a recent report showed that LDL oxidation increased risk for coronary heart disease by an astonishing 14-fold, especially in patients 60 years of age or younger.62 Chemical testing indicates that high doses of vitamin C can block dangerous blood lipid oxidation by about 75%.63
Research demonstrates that daily supplementation with a mixture of vitamin C and other antioxidant nutrients can reduce lipid peroxidation following a heart attack, suggesting that antioxidant supplements may be valuable for patients with a history of cardiovascular disease.64 One analysis suggests that vitamin C may in fact be even more beneficial than other commonly used antioxidants in protecting against lipid oxidation.65
In animal studies, vitamin C deficiency has been linked to high cholesterol, and high doses of vitamin C have been shown to promote the breakdown of cholesterol. Thus, in animals, vitamin C helps to lower blood cholesterol. While further studies are needed to assess whether these intriguing effects may hold true in humans,66-68 a study from 2005 showed that like cholesterol-lowering statin drugs, vitamin C reduced the activation of receptors that are involved in arterial wall inflammation, a crucial step in triggering the formation of atherosclerotic plaque. This finding led the scientists to note that vitamin C may share some common mechanisms of action with statin drugs, and deserves further investigation of its role in treating coronary heart disease.69
Additional research suggests that administering an extract of citrus fruit along with vitamin C may boost vitamin C’s ability to combat lipid oxidation and promote healthy blood lipid levels. While rich in vitamin C, citrus extract also contains health-promoting compounds known as flavonoids, and the combination of vitamin C and citrus flavonoids may be more beneficial than either agent alone in supporting cardiovascular health.70
Abundant evidence now supports the benefits of high-dose vitamin C for cardiovascular health, in addition to its well-documented roles in boosting immune health and fighting infections.
Provocative new studies strongly attest to vitamin C’s ability to help prevent coronary heart disease, improve survival following cardiac events, and reduce the complications of heart attack. Furthermore, vitamin C is a potent antioxidant capable of protecting blood vessels from atherosclerotic damage, and levels of vitamin C appear to predict both survival and cardiovascular health.
Easily overlooked and long taken for granted, high-dose vitamin C increasingly appears to be an essential element of any program to boost cardiovascular protection and extend the healthy life span.
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