|June 27, 2024

What Is Vitamin C, and What Does It Do?

By Molly Apel
Reviewed by Theresa Greenwell for Scientific Accuracy on 03/26/2024

What Is Vitamin C, and What Does It Do?

  • Vitamin C is a water-soluble vitamin that’s easy to find in some of the tastiest fruits and vegetables.
  • The antioxidant powers of vitamin C help protect cells in your skin, body and brain from the damaging effects of free radicals.
  • Your neurotransmitter function, healing process and immune system all rely on vitamin C.
  • Vitamin C supplements can help you reduce the symptoms and duration of a cold, help you absorb iron and improve your health. Keep reading for more vitamin C benefits and how to take it.

We all know it’s important, but what does vitamin C actually do? Can orange juice really help your body beat a cold? Vitamin C benefits range from boosting your T-cells, to helping your neurons function and your body repair injuries. Here’s the low-down on what vitamin C does, recommended doses and how to get more of it in your diet. (Spoiler: You’re getting a lot of it already from foods besides orange juice).

What is vitamin C?

Orange slices in water

Vitamin C, otherwise known as ascorbic acid, is a key player in several critical processes and functions in your body. Vitamin C is essential in the creation of collagen, L-carnitine, connective tissues and certain neurotransmitters. It also helps our immune systems, healing and protecting from damaging free radicals.[1]

You might be surprised how many foods have high amounts of vitamin C, from citrus fruits to leafy green veggies.Below is a list of foods that are some of the best sources of vitamin C. In 1 cup of each of these foods you’ll get:[2]

  • Guavas: 337 mg
  • Sweet red pepper: 190 mg
  • Strawberries: 97.6 mg
  • Pink grapefruits: 93.9 mg
  • Broccoli (steamed): 81.2 mg
  • Pineapple: 78.9 mg
  • Brussels sprouts: 74.8 mg
  • Lemon: 44.5 mg

How does vitamin C help a cold?

Woman with hand on head

In 1970, Dr. Linus Pauling concluded from research that vitamin C could protect us from getting colds. He went on to suggest it might have a role in protecting us from cancer as well. He became famous for these claims, but unfortunately, scientists later found he was a bit too optimistic about his study results.[3]

Here’s the bad news first: No studies support the idea that vitamin C can help you avoid getting a cold. However, the good news is research has confirmed that vitamin C reduced the duration of colds in adults by 8% and in children by 14%. This is one of the best reasons to have a vitamin C supplement on hand, especially when you’re feeling run-down.[4]

Studies show that ascorbic acid (vitamin C) helps support the immune system by boosting the strength of T-cells, a valuable type of white blood cell. Vitamin C helps the T-cells resist attacks from infections.[5]

Related: How to Support Your Immune System Naturally

Other impressive vitamin C benefits

Claims about the benefits of vitamin C range from its ability to shorten your cold to its potential to support heart health. Here are some science-backed ways your body puts vitamin C to work:

Antioxidant powers

Sliced grapefruits

Antioxidants are compounds that protect you from damaging free radicals. Free radicals are molecules that contain a form of oxygen that pulls electrons from molecules in your body. Most often, those electrons come out of your body’s cell walls, causing those walls to break down and the cell to then fall apart. That matters because damaged cells don’t function properly. Vitamin C is a good electron donor, giving free radicals the electrons they need without causing damage to your cell walls.[6]

Neurotransmitter function

orange and a cup of vitamin c tablets

Vitamin C plays a critical role in brain function. There are high concentrations of ascorbate (a version of ascorbic acid or vitamin C) within your brain’s neurons. According to animal studies, vitamin C supplements also might protect neurons from the damaging effects of Alzheimer’s, Parkinson’s and Huntington’s diseases.[7]

Healing and collagen production

Woman holding hands out to sun

Vitamin C teams up with collagen in your body’s process of making repairs. One study on guinea pigs showed that vitamin C supplementation helped in the process of tissue repair by yielding super-tough scars.[8] To get the biggest benefits of collagen protein, make sure you’re getting enough vitamin C in your diet.

Iron absorption

Sliced steak on white plate

In food tests, people who ate meals that included ascorbic acid (vitamin C) were found to have increased iron absorption. If you’re anemic, your doctor might prescribe a vitamin C supplement to be taken with your iron supplement.[9]

Heart health

man preparing to eat a salad

While there is no direct correlating science, compiled results of several studies that followed participants for 10 years found that the people who took a daily vitamin C supplement had a 24% lower risk of coronary heart disease. That’s a strong enough reason to take a daily vitamin C supplement.[10]

What’s more, in a study of 29 trials, people who were given vitamin C supplements had a noticeable reduction in blood pressure. While it’s not a substitute for a high-blood pressure medicine, if your blood pressure tends to be high, talk to your doctor about whether vitamin C supplements might help.[11]

Lower instance of gallstones

Dropper of vitamin C

Gallstones are the accumulation of cholesterol into “stones” that try to pass through the gallbladder. These gallstones seem to be common in people who eat a diet of primarily high-fat meats and dairy. A study of people who took vitamin C supplements reported a much lower instance of having gallstones. If you have a tendency to get gallstones, your doctor might suggest you eat a diet high in vitamin C and take vitamin C supplements.[12]

The bottom line: From helping protect cells from damage to supporting immunity, vitamin C is essential in many processes in our bodies.

How much vitamin C do I need?

Sliced and whole lemons on white counter

The National Institutes of Health Office of Dietary Supplements recommends that adult men need 90 mg and women need 75 mg per day. The recommended maximum is 2,000 mg a day.

If you’re getting too much vitamin C in your diet, usually the first sign will be canker sores appearing in your mouth. Don’t worry, those go away quickly — but be sure to cut back on whatever you’re eating that’s high in vitamin C (check the list of foods above). If you’re getting too much from your supplement, your body will let you know with nausea, cramps or a disaster-pants situation. But it’s a water-soluble vitamin, which means your body will generally take what it needs and pass the rest out of your body as waste.

There are some special situations that may make your body require more vitamin C. For example, if you are exposed to secondhand smoke, your body requires about 35 mg more vitamin C per day to repair the cellular damage caused by the free radicals in cigarette smoke.[13]

If you don’t get enough vitamin C (as in, less than 10 mg a day over a few weeks), you increase your risk of getting a nasty disease called scurvy. The good news is, because vitamin C is so readily available in a healthful diet, the odds are high that you’re getting enough. If you’re not a fan of fruits and vegetables, take a 500 or 1000 mg supplement.

If you’re taking certain medications such as blood thinners, hormones or statins, vitamin C can complicate the medicine’s effects. Be sure to check with your doctor before adding a new supplement to your routine.

Focus on whole foods to get enough vitamin C

Eggs and greens in skillet

The best way to get vitamins is by way of the food you eat. Because high levels of vitamin C are found in lots of tasty, healthful foods, it’s easy to get enough of it from your diet. If you’re not sure you’re getting enough, use this guide to start eating more vegetables. You can also easily and safely add a vitamin C supplement to your diet.

The bottom line: Adult men should get 90 mg and women need 75 mg per day, but no more than 2,000 mg a day. If you think you’re not getting enough, take a supplement. It’s a water-soluble vitamin, so your body will get rid of what it doesn’t need.

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