When you feel a cold coming on, have you ever reached for a vitamin C supplement to keep the sniffling and coughing at bay? You’re not alone. Taking vitamin C supplements is common in the United States, with about 35 percent of adults taking multivitamins that contain vitamin C and 12 percent taking a separate vitamin C supplement, according to the National Institutes of Health (NIH).
“Vitamin C is an essential nutrient, which means that we need to get it from food or supplements in order for us to meet our needs,” says Tamar Samuels, RDN, cofounder of Culina Health based in New York City.
Most vitamin C supplements contain vitamin C in the form of ascorbic acid, which is comparable in bioavailability to the vitamin C that naturally occurs in foods, according to the NIH. “Vitamin C and ascorbic acid are the same thing, and the terms can be used synonymously,” Samuels says.
The NIH recommends that adults get 75 milligrams (mg) of vitamin C per day for women and 90 mg daily for men; smokers should get an additional 35 mg per day, and pregnant and breastfeeding women should get 85 and 120 mg, respectively.
According to the Mayo Clinic, most people source enough vitamin C through diet alone — it’s readily available in citrus fruits, peppers, tomatoes, and berries, among other fruits and vegetables. One medium orange, for example, has 70 mg of vitamin C.
“Generally, healthy individuals with no medical conditions can meet their needs for vitamin C by consuming a varied diet in vitamin C–rich foods,” Samuels says.
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And that’s the best way to get your fix, according to Michelle Zive, PhD, RD, a nutrition coach based in San Diego. “Supplements can help with filling dietary gaps, however, food is always a better way to get the nutrient,” she says, adding that by eating the whole food, you benefit from the food’s other nutrients as well.
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But for a higher dose of vitamin C, you may consider supplements. “Most vitamin C supplements start with 100 to 500 mg per capsule, which is definitely higher than the vitamin C content found in vitamin C–rich foods,” Samuels says. (Note that according to the NIH, you may be at risk of consuming too much vitamin C if your combined intake from food and supplements exceeds 2,000 mg per day.)
So what are the potential benefits of higher levels of vitamin C? Here, explore five benefits of vitamin C supplements supported by research.
And remember, it’s always a good idea to let your doctor know about all of the supplements you are taking or plan to take, as they can pose unintended health risks for certain groups or interact with other medications you’re taking. In particular, vitamin C supplements may be harmful for people taking statins and certain types of cancer drugs.
1. Vitamin C Supplements Can Help Reduce the Length and Severity of Illness
It’s unlikely that vitamin C can protect you from coming down with a cold, but supplementing with it may help reduce the length and severity of your sickness, according to a review published in The Cochrane Database of Systematic Reviews. Of the studies the researchers looked at, all of which involved supplementing with more than 0.2 grams (g) of vitamin C per day, some found that vitamin C reduces the duration of colds. Even though the results were somewhat varied, with some showing no benefit, the researchers concluded that supplementing with vitamin C may still be worthwhile since it’s safe and inexpensive.
Vitamin C supplements may help you recover from more serious illnesses, as well. According to a meta-analysis published in April 2019 in Nutrients, vitamin C supplements reduced the length of intensive care unit stays by about 8 percent and shortened the duration of mechanical ventilation for patients by 18.2 percent. For the studies, vitamin C doses of 1 to 3 g were used.
2. Supplementing With Vitamin C Treats Scurvy
It may come as no surprise that scurvy — a disease that results from vitamin C deficiency — is commonly treated with vitamin C supplementation. According to research, the recommendation is to take 1 to 2 g of vitamin C for the first two or three days of treatment, 500 mg a day for the next week, then 100 mg a day for up to three months afterward.
“The majority of people treated for scurvy experience symptom improvement within 48 hours and are fully recovered within 14 days,” says Kelly Springer, RD, owner of Kelly’s Choice based in Skaneateles, New York.
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3. Vitamin C Supplements Protect Various Aspects of the Heart
Vitamin C helps the heart in a few ways. For one, it may help with blood pressure management. According to a meta-analysis published in The American Journal of Clinical Nutrition, vitamin C supplements (the median dose was 500 mg) helped people with high blood pressure reduce their systolic blood pressure by 4.85 millimeters of mercury (mm Hg) and their diastolic blood pressure by 1.67 mm Hg.
Other research published in the Journal of the American Heart Association found that high vitamin C intake was associated with a lower risk of stroke, most significantly among those who took between 200 and 550 mg of vitamin C a day.
Finally, though there’s not enough research to say that vitamin C supplements can prevent cardiovascular disease or that being deficient in the vitamin may put you at increased risk of dying from it. According to a review published in August 2016 in the International Journal of Molecular Sciences, vitamin C deficiency increases the risk of mortality from cardiovascular disease, likely because vitamin C may improve blood vessel function and lipid profiles. However, the current literature provides little support for the widespread use of vitamin C supplementation to reduce cardiovascular risk or mortality at this time.
4. It Can Lower the Risk of Gout
Gout, a painful form of inflammatory arthritis, is caused by having too much uric acid in the body, according to the Centers for Disease and Control Prevention. Eating a healthy diet with limited alcohol intake can lower the risk of gout — and vitamin C supplements can help as well.
“Some studies have found that vitamin C may moderately reduce uric acid levels in people who have gout,” Samuels says. According to a meta-analysis published Arthritis Care & Research, vitamin C supplements (the median dose was 500 mg) lowered serum uric acid by 0.35 milligrams per deciliter (mg/dL). Normal uric acid levels are 1.5 to 6 mg/dL in women and 2.5 to 7 mg/dL in men, according to a review published in Frontiers in Bioscience.
5. Vitamin C May Make Cancer Treatments More Effective
At this point, it’d be wrong to say vitamin C can prevent or cure cancer, but it may be a beneficial addition to cancer treatment. A meta-analysis published in the European Journal of Cancer, for instance, found that people with breast cancer who supplemented with vitamin C had a reduced risk of mortality.
And it appears that vitamin C may boost standard treatments as well, Dr. Zive says.
According to a small study published in March 2017 in Cancer Cell, taking high doses of vitamin C for two months during cancer treatment weakened the cancer cells and made radiation and chemotherapy more effective.
It’s worth noting, however, that most of this research involves taking vitamin C intravenously rather than orally, Samuels says. Anyone undergoing cancer treatment should consult with their healthcare providers before taking vitamin C or any other supplements because of the risks of potential interactions with their cancer treatments.