Vitamin C’s health-boosting benefits go far beyond fighting the common cold and flu. In fact, nutritional scientists have discovered that this potent antioxidant is crucial in supporting the health of the cardiovascular system, kidneys, bones, respiratory system, and more.
Unfortunately, many people fail to consume enough vitamin C to realize its vast array of health benefits. Most adults wrongly assume that the 75-90 mg of vitamin C recommended by the federal government is an optimal daily dose. In fact, this “recommended dietary allowance” is only enough to prevent vitamin-deficiency disease states such as scurvy—but not nearly enough to support optimal health.
The Nobel prize-winning scientist Dr. Linus Pauling was among the first to recognize the importance of high-dose vitamin C supplementation more than 30 years ago. Since then, scientists have amassed impressive evidence supporting the numerous benefits of high-dose vitamin C.
In this article, we examine recent studies supporting the efficacy of high-dose vitamin C in preventing and fighting infections, improving endothelial function, reducing heart attack risk, promoting longevity, and enhancing cancer survival.
Vitamin C Suppresses Cell Damage, Promotes Immune Health
Dr. Linus Pauling noted that vitamin C is a critically important water-soluble antioxidant, as it protects proteins and lipids from free radical damage associated with infection, intensive exercise, and other stres-sors that can injure cells.1-3 These very properties make vitamin C a valuable agent for improving immune function. By suppressing oxidative stress, vitamin C increases the life span of immune cells and reduces infection-related cellular damage.4-7 This bolsters the immune system’s ability to fend off a broad range of infectious agents.
Interestingly, research has clearly demonstrated that during times of infection, concentrations of vitamin C are rapidly depleted in the blood and in white blood cells. Scientists have found that supplementation with vitamin C improves several important parameters of immune function. Therefore, supplementing with vitamin C during infection may protect immune cells and strengthen their ability to fight infectious pathogens.8
Dr. Linus Pauling
Vitamin C Helps Prevent and Fight Infections
Vitamin C not only speeds recovery from infections, but more important, may also help to prevent the onset of infections. Study after study has shown that vitamin C can dramatically reduce infection time as well as boost one’s resistance to infections. For example, studies of vitamin C supplementation in military personnel and other subjects living in close quarters have shown that pneumonia occurred a remarkable 80-100% less often in subjects taking vitamin C than in those who did not supplement with the vitamin.9
Similar protection against the onset of infection has been observed in children in developing countries, who are highly vulnerable to developing life-threatening infections. In this at-risk population, daily supplementation with up to 1000 mg of vitamin C, along with the mineral zinc, greatly reduced the likelihood of developing potentially deadly pneumonia, malaria, and infection-related diarrhea.8 In addition, supplementation with vitamin C improved outcomes even when infections had already occurred. The study authors suggested that vitamin C helps strengthen children’s resistance to infectious organisms. Based on these findings, it is vital that young children receive appropriate supplementation with vitamin C.
Vitamin C intake has been found to speed resolution of upper respiratory tract infections in young people. Students who supplemented with hourly doses of 1000 mg of vitamin C for six hours and then three times daily thereafter exhibited an extraordinary 85% decrease in cold and flu symptoms compared to those who took pain relievers and decongestants for their infectious symptoms.10
These benefits of improved healing are not limited to children and young adults. Elderly patients that were hospitalized with pneumonia or bronchitis showed substantial improvement following supplementation with vitamin C.11 In a study of women with non-specific vaginal infection, locally administered vitamin C significantly improved symptoms and led to a reduction in bacterial count.12
Vitamin C’s strength in countering bacterial infection was further demonstrated in a study of the dangerous breed of bacteria known as Helicobacter pylori, or H. pylori. Chronic infection of the stomach with H. pylori contributes to gastritis, stomach ulcers, and even deadly gastric cancer.13 In an epidemiological study, however, high intake of the powerful antioxidant vitamins C and E was associated with an astounding 90% reduction in the risk of developing stomach cancer.14 Lending additional support to these findings is another study showing that infection with H. pylori was a major risk factor for gastric cancer in patients with low vitamin C intake, but not in those with high vitamin C intake.18 By protecting against infection with H. pylori, vitamin C may thus help to prevent potentially fatal stomach cancer as well as other painful gastrointestinal complications.
Vitamin C may even have an important role to play in the ongoing global battle to contain the ubiquitous HIV virus.19-21 For example, laboratory experiments indicate that high concentrations of vitamin C are preferentially toxic to HIV-infected cells, thereby promoting their destruction while sparing uninfected immune cells.21 In other laboratory studies of human immune cells, vitamin C helped suppress the HIV virus.19 Moreover, in a clinical study of HIV-infected patients, subjects with advanced immune deficiency who supplemented with high doses of vitamin C and the potent antioxidant N-acetylcysteine exhibited significant improvements in several measures of immune system function.20
Vitamin C Supports Endothelial Function and Protects the Heart
As the aforementioned studies attest, vitamin C’s ability to help prevent and fight infection by strengthening the body’s natural defenses against disease-causing pathogens is uncontested. Less recognized—but perhaps equally important—are the many other ways in which vitamin C supports optimal health.
Mounting evidence, for example, associates higher vitamin C levels with protection against cardiovascular disease, America’s leading cause of premature death. Vitamin C may help support the heart and vascular system by protecting against endothelial dysfunction, preventing heart attacks, and countering the dangerous oxidation of blood lipids.
Scientists now know that one of the instigating factors in cardiovascular disease is the insidious process known as endothelial dysfunction, in which blood vessel walls become stiffer and less able to dilate in response to the body’s need for increased blood flow.
While elevated levels of the amino acid homocysteine hasten endothelial dysfunction, scientists have discovered that pretreatment with vitamin C (1000 mg daily for one week) reduces oxidative stress and thus protects the delicate vascular endothelium from the damaging effects of elevated homocysteine.22
Similarly, researchers have found that while eating a meal high in fat temporarily impairs endothelial function for up to four hours in healthy individuals, pretreatment with the antioxidant vitamins C and E prevents this impairment.23 Scientists have also shown that vitamin C may reduce oxidative stress and subsequent endothelial dysfunction.24
In a study of patients with coronary heart disease, vitamin C enhanced the ability of coronary arteries to expand in response to a naturally occurring vasodilator.25
Smokers often have a drastically impaired endothelium. Vitamin C has likewise demonstrated powerful effects against endothelial dysfunction caused by smoking. In one trial, subjects who received pretreatment with 2000 mg of vitamin C had an impressive 59% reduction in a clinical measure associated with endothelial dysfunction.26 In a similar study, German researchers found that either short-term vitamin C infusion or long-term vitamin C treatment markedly increased blood flow to the heart muscle in smokers.27 In this same trial, long-term supplementation with vitamin C also increased blood flow to the heart muscle in patients with high blood pressure.27
How does vitamin C protect endothelial cells? Although its precise mechanisms of action are not yet fully understood, researchers have discovered that vitamin C, at high doses, activates an enzyme that may be involved in reducing the oxidative stress that can contribute to endothelial dysfunction.28