Vitamin C: Why is it important?

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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.

ROS are substances such as free radicals that result from natural bodily processes, exposure to pollution, and other factors. They can lead to oxidative stress, which can, in turn, cause cell damage.

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:

• tendons
• ligaments
• skin
• the cornea
• cartilage
• bones
• the gut
• blood vessels

Low levels of vitamin C in the body can lead to scurvy. Symptoms of scurvy include swollen joints, bleeding gums and loose teeth, anemia, and tiredness.

The benefits of vitamin C may include the following.

Wound healing

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 recommend supplements for people with low vitamin C levels.

Cardiovascular health

Vitamin C may benefit 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

This could help protect against heart disease and hypertension, or high blood pressure.

However, there is not enough evidence to suggest that taking supplements will help protect heart health.

Cataracts and age-related macular degeneration

Vitamin C may help lower the risk of cataracts and slow the progression of age-related macular degeneration. However, more research is needed.

Experts believe that oxidative stress may be a factor in both conditions, so any benefit may be due to vitamin C’s antioxidant activity.

Diabetes

A 2019 study 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.

Anemia

Vitamin C enhances the absorption of iron, and some healthcare professionals recommend taking vitamin C supplements with iron tablets to improve absorption in people with iron deficiency anemia.

One 2020 study 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.

Pollution

Air pollution consists of various substances and chemicals that can have a negative impact on people’s health.

Some research 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.

Allergies

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, 71 people with skin or respiratory allergies received various doses of intravenous vitamin C, and the researchers observed the severity of the participants’ 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.

Motion sickness

In a 2014 study, 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 confirmed 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 study 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 review suggest that vitamin C might work well alongside other treatments to benefit people with cancer.

The National Cancer Institute 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 approval from the Food and Drug Administration (FDA) to treat cancer.

The Office for Dietary Supplements advise 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
• grapefruit
• kiwifruit
• strawberries
• spinach and other green, leafy vegetables
• tomatoes
• potatoes
• green peas

Learn more about sources of vitamin C here.

Those at risk of vitamin C deficiency include:

• 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 mg of vitamin C each day.

The recommended maximum intake of vitamin C for adults is 2,000 mg per day.

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.

Learn more about what happens if a person takes too much vitamin C here.

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.