Vitamin C: What You Need to Know

If you picture an orange when you think of vitamin C, you’re right on. The fruit, as well as other citrus fruits, is a vitamin C powerhouse.

Vitamin C provides an array of health benefits, though it doesn’t get nearly as much attention as vitamin D. That’s probably because far fewer Americans are deficient in it, says Dr. Gail Feinberg, chair of the primary care department at Touro University California College of Osteopathic Medicine. “Most people are getting a daily dose of vitamin C from their routine diets,” she says.

Still, it’s important to appreciate the benefits of vitamin C, because without it, we’d all have scurvy — a now-rare disease in developed countries that can cause swollen, bleeding gums and other wounds. Here’s what else you need know about this under-appreciated vitamin:

What Is Vitamin C?

Also known as L-ascorbic acid, vitamin C is a water-soluble vitamin, which means that if you take in more than your body needs, you pee it out. (Fat-soluble vitamins like A and D, on the other hand, are mostly stored in your fat tissues and liver, and are eliminated more slowly.) Because your body doesn’t make vitamin C itself, you have to consume it, either in foods that naturally contain it or that are fortified with it, or with supplements, according to the National Institutes of Health Office of Dietary Supplements.

[See: The Best Plant-Based Diets.]

Health Benefits of Vitamin C

Here’s where the research stands on vitamin C’s various benefits:

Protection against free radicals. Vitamin C is a natural antioxidant, which means it helps protect against damage from free radicals, or molecules that can damage your cells. Your body is always generating free radicals, but certain experiences like smoking, sunbathing and even exercising can bring on more. Because vitamin C is a free-radical scavenger, balancing the inflammatory cascade with vitamins and other anti-inflammatory nutrients (like selenium, zinc and vitamins A and E) and not letting inflammation spin out of control can help you feel better, says Robin Foroutan, an integrative registered dietitian nutritionist in New York City and a spokesperson for the Academy of Nutrition and Dietetics.

Tissue health. Vitamin C is also key for skin and hair, bone and joint, and cardiovascular health because it’s “an important cofactor in our own synthesis of collagen,” Foroutan says. In other words, it helps your body process collagen, which is well-known to keep those tissues young. In the case of blood vessels, that means keeping them flexible and able to easily constrict and expand.

Eye health. Your eyes contain high concentrations of vitamin C, which may help explain why some research has shown that people with vitamin C-rich diets may be less likely to get cataracts. Also, vitamin C may be helpful for individuals with a certain kind of age-related macular degeneration, according to the American Academy of Ophthalmology. Taking 500 milligrams of vitamin C daily could help slow the disease. It’s important to keep in mind that vitamin C and other supplements aren’t a cure for AMD, but they could help slow it in some people with the early to middle stages of the disease, according to the academy.

Weight control. Some research has linked vitamin C consumption with a lower body mass index and body fat percentage, although exactly why is unclear, Foroutan says.

Nutrient absorption. Vitamin C also partners with iron for optimal absorption, especially when the iron is not from meat, says Isabel Maples, a registered dietitian based in Haymarket, Virginia, and a national spokesperson for the Academy of Nutrition and Dietetics. To improve iron intake, pair a vitamin C-rich food with one that’s rich in iron.

Such combinations of iron and vitamin C include:

— Orange juice with breakfast cereal.

— Tomatoes and beans in chili.

— Bell pepper strips dipped in hummus.

Spinach with steak.

Many people believe that vitamin C is something of a “magic bullet” in fighting colds and that it can shield you from an array of other serious, chronic conditions. But studies suggest that reputation is overstated.

Here is where the latest research stands regarding vitamin C’s efficacy in fighting colds and several chronic conditions:

Cold prevention. There’s a popular myth that vitamin C can prevent or shorten colds. But this idea — which took hold in the 1970s — isn’t backed up by research. Clinical studies “failed to demonstrate (vitamin C’s) efficacy” in fighting colds, according to research published in Frontiers in Immunology in 2020.

Disease prevention. While some people believe vitamin C may help prevent conditions ranging from heart disease and cancer to depression and Alzheimer’s disease, there’s not enough research yet to support these claims, Feinberg says.

[READ: Myths About COVID-19 Vaccines.]

Vitamin C and COVID-19

Can vitamin C help COVID-19 patients with mild or severe symptoms? To date, there is “insufficient evidence” for the federal government’s COVID-19 Treatment Guidelines Panel to recommend for or against using vitamin C to treat the disease in either patients who aren’t critically ill or those who are severely sick, according to the National Institutes of Health.

To date there’s also no evidence that vitamin C can help mitigate or prevent COVID-19. For example, research published this February in JAMA Network Open found that treating ambulatory patients with COVID-19 with high-dose zinc gluconate, vitamin C “or a combination of the two supplements did not significantly decrease the duration of symptoms compared with standard of care.”

How Much Vitamin C Should You Have Daily?

The recommended daily allowance of vitamin C is 90 milligrams for adult men and 75 milligrams for adult women. “Smokers need 35 milligrams more than that each day because of all the free radical damage they expose themselves to from cigarette smoke,” Foroutan says. Folks who are exposed to a lot of secondhand smoke or ultraviolet rays may consider upping their dosage, too.

You can check your levels of vitamin C with a simple blood test from your doctor. If you’re seriously deficient, you’ll feel it — and feel the improvements quickly upon correcting the issue, Feinberg says. “Early symptoms include weakness, irritability, weight loss and vague muscle or joint pain.”

Most people can get enough vitamin C by eating a balanced diet with sufficient fruits and vegetables. “In the U.S., deficiency occurs mostly in severely malnourished people, drug and alcohol abusers or those living in poverty or on diets that are devoid of fruits and vegetables,” Maples says.

It’s important to keep in mind that just because you’re not deficient in vitamin C you’re getting enough. Foroutan compares vitamin C levels to a bank account: You can have just enough money in your account to scrape by and pay your bills, but it’s better to have a robust account. “You can have just enough vitamin C to not have scurvy, and that’s what the RDA (recommended dietary allowance) is all about. This would be called chronic nutrient insufficiency — you’re getting enough to not get the deficiency disease, but that’s about it. Your body has to prioritize which vitamin C-dependent functions are most necessary. A better way would be to aim for optimum nutrient levels so that your cell membranes have the vitamin C they need to squelch free radicals, your adrenals have enough to function optimally and your skin has enough to make more collagen for skin and blood vessel repair and your immune system can balance inflammation.”

Consult with a registered dietitian or your health care provider to determine what is the optimal vitamin C intake for you.

Can You Overdose on Vitamin C?

Because vitamin C is water soluble, it’s pretty hard to consume too much, experts say. Still, more isn’t always better. For example, overdoing the vitamin C on a regular basis can lead to diarrhea and abdominal bloating, Feinstein says. Nausea, vomiting, cramps and other gastrointestinal issues can also occur. And some research has linked vitamin C intake with a certain type of kidney stone in men, so supplementation isn’t usually recommended for men and others at risk for oxalate stones.

How to Get Enough Vitamin C

It’s pretty easy to consume the recommended amount of vitamin C through food, says Brittney Bearden, a sports dietitian with Texas Health Sports Medicine in Dallas.

These are good sources of vitamin C:

— Citrus fruits.

— Rose hip tea.

— A cup of strawberries.

— Two medium kiwis.

— A fruit smoothie with 1 cup of orange juice, ½ cup of frozen fruit and ½ cup of Greek yogurt.

When to Take a Vitamin C Supplement

While most Americans are just fine without taking a vitamin C supplement, if you are at risk for or have been tested for a vitamin C deficiency, supplementation is a good idea. Even if you don’t have or aren’t at risk for a vitamin C deficiency, taking an over-the-counter supplement or multivitamin that contains 500 to 1000 milligrams daily won’t hurt you, Feinberg says, “as long as you are not taking a combination pill with massive amounts of fat-soluble vitamins … which can cause toxicity.”

Ask a registered dietitian or your health care provider if a vitamin C supplement makes sense for you.

More from U.S. News

Top Iron-Rich Foods to Fight Iron Deficiency

Best Vitamins and Minerals for Older Adults

Foods That Can Support Your Immunity

Vitamin C: What You Need to Know originally appeared on usnews.com

Update 08/26/21: This story was previously published at an earlier date and has been updated with new information.

Correction 09/02/21: A previous version of this story incorrectly included two snack choices in a list of good sources of vitamin C.

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