Medically reviewed by Alan Carter, Pharm.D. — Written by Joseph Nordqvist
Vitamin C is a vital nutrient for health. It helps form and maintains bones, skin, and blood vessels. It is also an antioxidant.
Vitamin C occurs naturally in some foods, especially fruits and vegetables. Vitamin C supplements are also available.
Other names for vitamin C include L-ascorbic acid, ascorbic acid, and L-ascorbate.
In this article, learn more about why we need vitamin C, how much we need it, and where to find it.
Vitamin C is water soluble, and the body does not store it. To maintain adequate levels of vitamin C, people need to consume food that contains it every day.
The body needs vitamin C for various functions. Here are some of them:
- It helps the body produce collagen, L-carnitine, and some neurotransmitters.
- As an antioxidant, it helps remove unwanted substances known as reactive oxidative species (ROS) from the body.
- It helps the body absorb iron.
- It boosts the immune system.
- It enhances wound healing.
Vitamin C’s antioxidant activity may help reduce inflammation and lower the risk of developing various conditions, including some cancers.
The body needs vitamin C to produce collagen. This is the main component of connective tissue and makes up 1–2% of muscle tissue.
Collagen is a vital component in fibrous tissues such as:
- the cornea
- the gut
- blood vessels
The benefits of vitamin C may include the following.
Vitamin C helps the body produce collagen and is present in skin, muscle, and other tissues.
People with a low intake of vitamin C may experience slower wound healing, as their bodies will be less able to produce collagen.
During times of recovery, healthcare professionals may recommendTrusted Source supplements for people with low vitamin C levels.
Vitamin C may benefitTrusted Source cardiovascular health for several reasons. Studies have suggested that it may:
- have antioxidant properties
- help widen the blood vessels
- improve nitric oxide production
- help reduce plaque instability in atherosclerosis
However, there is not enough evidenceTrusted Source to suggest that taking supplements will help protect heart health.
Cataracts and age-related macular degeneration
Experts believe that oxidative stress may be a factor in both conditions, so any benefit may be due to vitamin C’s antioxidant activity.
A 2019 studyTrusted Source looked at 31 people aged around 60 years to see whether or not taking vitamin C supplements made a difference to their glucose levels after eating.
After taking supplements for 4 months, the participants’ glucose levels and blood pressure improved, compared with taking a placebo. This suggests that vitamin C could, one day, be a treatment for diabetes.
One 2020 studyTrusted Source looked at 432 people who took iron supplements for iron deficiency anemia. Some took vitamin C with their iron supplement, and others did not.
However, both groups saw similar increases in iron, suggesting that vitamin C supplementation is unnecessary for this purpose.
Air pollution consists of various substances and chemicals that can have a negative impact on people’s health.
Some researchTrusted Source has suggested that a combination of vitamin C and vitamin E may have an antioxidant effect that can help reduce symptoms of asthma and chronic obstructive pulmonary disease.
During an allergic reaction, the immune system triggers an inflammatory response that can lead to symptoms such as swelling and hives. During this process, the body produces ROS, which can lead to oxidative stress.
In a 2018 study-Trusted Source, 71 people with skin or respiratory allergies received various doses of intravenous vitamin C, and the researchers observed the severity of the participant’s symptoms. Their paper concludes that taking a high dose of vitamin C may help reduce allergy symptoms.
They also found evidence to suggest that low vitamin C levels were common in people with allergies.
In a 2014 study trusted Source, 70 people took 2 grams of either vitamin C or a placebo and then spent 20 minutes on a life raft in a wave pool. Those who took the supplement had lower levels of seasickness.
Many people believe that vitamin C can cure a common cold, but research has not confirmedTrusted Source this.
However, taking dosages of 200 milligrams (mg) or more per day may benefit people who:
- participate in extreme physical activity
- have exposure to cold temperatures
- have low vitamin C levels due to smoking
Vitamin C may help treat cancer, though experts have not confirmed this.
As an antioxidant, vitamin C protects the body from oxidative stress, which can occur when ROS levels are high. Oxidative stress can lead to cell damage and may play a role in some cancers.
A 2015 mouse studyTrusted Source found that taking high doses of vitamin C may slow the growth of some types of cancerous tissue. The paper suggests that vitamin C could, one day, become a new treatment for colorectal cancer.
Also, the authors of a 2013 reviewTrusted Source suggest that vitamin C might work well alongside other treatments to benefit people with cancer.
The National Cancer InstituteTrusted Source note that some alternative therapists already use intravenous vitamin C when treating cancer, fatigue, and infections. However, they note that more research is necessary.
Intravenous vitamin C does not currently have approvalTrusted Source from the Food and Drug Administration (FDA) to treat cancer.
The Office for Dietary SupplementsTrusted Source advises people to consume the following recommended daily allowances (RDA) of vitamin C per day:
Additional vitamin C is necessary during pregnancy and while breastfeeding.
The best sources of vitamin C are fresh fruits and vegetables. However, heat and cooking in water can destroy some of the vitamin C content in these foods, so eating raw foods is best.
Some good sources of vitamin C include:
- red and green peppers
- oranges and orange juice
- spinach and other green, leafy vegetables
- green peas
Those at risk of vitamin C deficiency includeTrusted Source:
- people who smoke or have exposure to secondhand smoke
- infants who consume only evaporated or boiled milk
- people who do not consume a varied diet
- people with certain health conditions, especially those that involve intestinal malabsorption
Smoking and having exposure to other pollutants can lead to oxidative stress. Antioxidants, such as vitamin C, can help reduce oxidative stress.
People who smoke tend to have lower levels of vitamin C than people who do not smoke. This may be due to having higher levels of oxidative stress.
Smoking also causes inflammation and damage to the mucous membranes of the mouth, throat, and lungs.
Vitamin C is necessary for healthy mucosa and helps reduce inflammation, so the National Institutes of Health (NIH) recommend that people who smoke consume an extra 35 mgTrusted Source of vitamin C each day.
The recommended maximum intake of vitamin C for adults is 2,000 mg per dayTrusted Source.
Taking too much vitamin C is unlikely to cause any significant problems, but if a person consumes more than 1,000 mg of vitamin C per day, they will not absorb it all. This may lead to diarrhea and gastrointestinal discomfort.
People are unlikely to consume too much through their diet, and their bodies cannot store it. However, having a high intake through supplements may result in kidney stones.
This may also increase the risk of cardiovascular problems in females after menopause, but there is not enough evidence to confirm this.
People with hereditary hemochromatosis, which is an iron absorption disorder, should talk to their healthcare professional before taking vitamin C supplements. Having high vitamin C levels could lead to tissue damage.
Vitamin C is an antioxidant and essential nutrient that has many functions. For example, it helps produce collagen, reduce oxidative stress, and enhance wound healing.
Fresh fruits and vegetables are good sources of vitamin C. Some people take supplements, but it is always best to check with a healthcare professional first to make sure they are safe to use.