The Benefits of Vitamin C
What can vitamin C do for your health?
By Kathleen Zelman, MPH, RD/LD
Reviewed by Louise Chang, MD
Vitamin C is one of the safest and most effective nutrients, experts say. It may not be the cure for the common cold (though it's thought to help prevent more serious complications). But the benefits of vitamin C may include protection against immune system deficiencies, cardiovascular disease, prenatal health problems, eye disease, and even skin wrinkling.
A recent study published in Seminars in Preventive and Alternative Medicine that looked at over 100 studies over 10 years revealed a growing list of benefits of vitamin C.
"Vitamin C has received a great deal of attention, and with good reason. Higher blood levels of vitamin C may be the ideal nutrition marker for overall health," says study researcher Mark Moyad, MD, MPH, of the University of Michigan. "The more we study vitamin C, the better our understanding of how diverse it is in protecting our health, from cardiovascular, cancer, stroke, eye health [and] immunity to living longer."
"But," Moyad notes, "the ideal dosage may be higher than the recommended dietary allowance."
How Much Vitamin C Is Enough?
Most of the studies Moyad and his colleagues examined used 500 daily milligrams of vitamin C to achieve health results. That's much higher than the RDA of 75-90 milligrams a day for adults. So unless you can eat plenty of fruits and vegetables, you may need to take a dietary supplement of vitamin C to gain all the benefits, Moyad says. He suggests taking 500 milligrams a day, in addition to eating five servings of fruits and vegetables.
"It is just not practical for most people to consume the required servings of fruits and vegetables needed on a consistent basis, whereas taking a once-daily supplement is safe, effective, and easy to do," Moyad says. He also notes that only 10% to 20% of adults get the recommended nine servings of fruits and vegetables daily.
Moyad says there is no real downside to taking a 500-milligram supplement, except that some types may irritate the stomach. That's why he recommends taking a non-acidic, buffered form of the vitamin. "The safe upper limit for vitamin C is 2,000 milligrams a day, and there is a great track record with strong evidence that taking 500 milligrams daily is safe," he says.
Still, American Dietetic Association spokeswoman Dee Sandquist, RD, suggests doing your best to work more fruits and vegetables into your diet before taking supplements.
"Strive to eat nine servings of fruits and vegetables daily, because you will get a healthy dose of vitamin C along with an abundance of other vitamins, minerals, and phytochemicals that are good for disease prevention and overall health," she says.
While a cup of orange juice or a half-cup of red pepper would be enough to meet your RDA for Vitamin C, here are all the foods and beverages you'd need to consume to reach 500 milligrams (mg):
The Health Benefits of Vitamin C
According to recent research, vitamin C may offer health benefits in these areas:
1. Stress. "A recent meta-analysis showed vitamin C was beneficial to individuals whose immune system was weakened due to stress -- a condition which is very common in our society," says Moyad. And, he adds, "because vitamin C is one of the nutrients sensitive to stress, and [is] the first nutrient to be depleted in alcoholics, smokers, and obese individuals, it makes it an ideal marker for overall health."
2. Colds. When it comes to the common cold, vitamin C may not be a cure. But studies show that it can help prevent more serious complications. "There is good evidence taking vitamin C for colds and flu can reduce the risk of developing further complications, such as pneumonia and lung infections," says Moyad.
3. Stroke. A recent study in the American Journal of Clinical Nutrition found that those with the highest concentrations of vitamin C in their blood were associated with 42% lower stroke risk than those with the lowest concentrations. The reasons for this are not completely clear. But what is clear is that people who eat plenty of fruits and vegetables have higher blood levels of vitamin C.