Below is a table comparing all of the vitamin C supplements in this article.

Vitamin C has many benefits. According to the National Institutes of Health (NIH)Trusted Source, the body uses vitamin C to make collagen, which is an essential part of connective tissues and plays a role in wound healing. Vitamin C also aids the formation of L-carnitine, a chemical in the brain that turns fat into energy.

Furthermore, vitamin C is involved in protein metabolism and helpsTrusted Source the body absorb iron in plant foods. The NIH also mentions vitamin C’s antioxidant activity and its important role in the immune system. A 2018 studyTrusted Source suggests that this antioxidant activity may offer protection against pollution damage, which may cause lung cancer, asthma, or chronic obstructive pulmonary disease (COPD).

There is a wide range of scientific research into the benefits of vitamin C for certain health conditions. For instance, the authors behind a 2021 study suggest that people with type 2 diabetes may benefit from vitamin C supplementation as it may help improve their blood pressure and glycemic control.

The NIH suggestsTrusted Source that vitamin C may help reduce a person’s chance of developing heart conditions, as it helps widen blood vessels and increase nitric oxide production, but more research is needed.

Another 2021 studyTrusted Source suggests that high dose intravenous (IV) vitamin C may reduce some of the side effects of cancer therapy. Other work found that high dose vitamin C may also have anticancer propertiesTrusted Source through its ability to inhibit the migration and metastasis of breast cancer cells.

However, people should speak with a doctor before taking high doses of vitamin C.

According to the National Institutes of Health (NIH)Trusted Source, vitamin C deficiency is rare in the United States.

However, although most people can get enough vitamin C from fruits and vegetables, others may have difficulty getting enough vitamin C from their diet.

Those who may be at risk of vitamin C deficiency include:

• older adults
• people with alcohol use disorder
• people with an eating disorder
• people who smoke, as cigarette smoke increases the damageTrusted Source that free radicals cause, resulting in a higher need for vitamin C
• people who eat restricted diets for medical reasons
• people with certain medical conditions, such as kidney disease that requires hemodialysis, conditions that cause malabsorption, and some types of cancer
• infants who drink boiled cow’s milk — the heat destroys the small amount of vitamin C it contains

Anyone concerned that they have a deficiency can ask a doctor for blood tests to determine which nutrients they need. A long-term vitamin C deficiency can lead to scurvy.

According to the NIHTrusted Source, a person should consume the following amounts of vitamin C per day:

Additionally, people who are pregnant or lactating will require more vitamin C:

Typically, the small intestine absorbs up to 100 mgTrusted Source of vitamin C from food per day. Once the cells have become saturated with vitamin C, they cannot absorb more.

However, some believe that taking very large doses of vitamin C, or “megadosing,” is beneficial. This may stem from a 1976 paperTrusted Source indicating that high dose vitamin C could prolong the lives of people with terminal cancer.

However, more recent studies have yet to repeat this result.

Vitamin C doses of over 2,000 mgTrusted Source per day may cause side effects, such as:

• diarrhea
• nausea
• abdominal cramps

People with particular health conditions and those who take certain medications may also need to avoid vitamin C supplements. These conditions include hemochromatosis, which causes the body to store too much iron, and kidney stones.

Vitamin C may also interact with chemotherapy treatment.

The Food and Drug Administration (FDA) cannot approve or regulateTrusted Source vitamin C products before they go on sale. For this reason, people need to discuss taking any new supplement with a doctor and choose products carefully.

There are several forms of vitamin C. In supplements, vitamin C usually comes in the form of ascorbic acid. However, some supplements contain other forms, such as sodium ascorbate, calcium ascorbate, or ascorbic acid with bioflavonoids.

There are various ways people can take vitamin C, including:

• capsules
• chewable gummies
• effervescent tablets
• powders
• liquids
• sprays

Some people may prefer the convenience of swallowing tablets, while others may prefer a powder to mix into drinks.

People with problems absorbing nutrients may prefer a sublingual supplement, which a person places under the tongue, as the body absorbs these in the mouth rather than the intestines.

Eating more fruits and vegetables is the best way for someone to naturally increase their vitamin C intake.

The NIHTrusted Source suggests:

• half a cup of raw sweet red pepper, which contains 95 mg of vitamin C
• three-quarters of a cup of orange juice, which contains 93 mg of vitamin C
• half a cup of broccoli and half a cup of strawberries, which totals 97 mg of vitamin C
• one medium orange and half a cup of cooked cabbage, which totals 98 mg of vitamin C

Some companies also fortify their breakfast cereals with added vitamin C.

High heat, water-based cooking methods, and prolonged storage can destroy some foods’ vitamin C content.

For this reason, the NIH suggests lightly steaming or microwaving vegetables to retain more of their nutrients.

People taking more than 1,000 mg of vitamin C daily may have a high chance of developing stomach pain, diarrhea, and flatulence.

The National Library of MedicineTrusted Source associates vitamin C supplementation via IV with adverse effects, such as headaches, dizziness, and flushing. Migraine may also occur with daily doses of 6 g.

It also writes that high amounts of vitamin C can increase a person’s risk of developing kidney stones.

It also states that doctors may not recommend vitamin C supplementation if a person has a blood condition, which may include sickle cell disease, thalassemia, and hemochromatosis.

Vitamin C may interactTrusted Source with some medications, such as chemotherapy and radiation medication. The NIH also mentions that vitamin C has interacted with medications for controlling blood cholesterol levels.

People should speak with a doctor before taking a vitamin C supplement to ensure it will not interact with current medications or health conditions.

Vitamin C deficiency can be fatal without treatment. A person should consult with a doctor if they have symptoms that may indicate a vitamin C deficiency.

These symptoms include:

• small red or purple spots on the skin
• inflamed, swollen, or bleeding gums
• wobbly teeth or tooth loss
• corkscrew-shaped hairs
• depression
• fatigue
• joint pain

A person should also contact a doctor before taking vitamin C, particularly if they have a medical condition, are pregnant, or take any medications.

Below are answers to some common questions about vitamin C.

How much vitamin C should a person take?

According to the NIH, the recommended daily vitamin C intake for most non-lactating adults is 75–90 milligrams (mg)Trusted Source.

Can vitamin C damage the kidneys?

According to the NIHTrusted Source, there is some evidence that high doses of vitamin C can increase the risk of kidney stones. Ingesting high amounts of vitamin C can increase oxalate in the urine, which could lead to kidney stones, especially in people who have renal disorders.

However, the NIH also states there is conflicting evidence of whether kidney stones and vitamin C intake are related. The organization says that people most at risk of kidney stones due to ingesting too much vitamin C are those with existing high amounts of oxalate in their urine.

Should people take vitamin C daily?

People should aim to ingest the NIH’s recommended daily intake of vitamin C per day, which is 75–90 mgTrusted Source for non-lactating adults.

One source of vitamin C is fruit and vegetables. For example, three-quarters of a cup of orange juice contains 106%Trusted Source of a person’s RDA of vitamin C.

However, the NIH says that there is an upper tolerable limit of how much vitamin C a person can consume before experiencing side effects such as diarrhea and nausea. This depends on age, as detailed below:

• 1–3 years: 400 mg
• 4–8 years: 650 mg
• 9–13 years: 1,200 mg
• 14–18 years: 1,800 mg
• 19+ years: 2,000 mg

Which form of vitamin C is best?

Some people find that ascorbic vitamin C causes digestive discomfort. Buffered vitamin C can help reduce the risk of stomach irritation.

Additionally, vitamin C supplements come in various forms, from tablets and capsules to powders and sprays. People who do not want to swallow tablets can opt for a supplement they can dissolve in water or spray directly into their mouth. Other people may prefer a chewable supplement.

What is a good source of vitamin C to take daily?

People can get their vitamin C from different foods, such as:

• citrus fruits
• red and green pepper
• baked potatoes
• strawberries
• broccoli
• fortified cereal

What is a trusted brand of vitamin C?

Nordic Naturals and subscription services such as Care/of and Ritual are some popular brands selling vitamin C supplements. They use third-party testing to assess the safety and purity of their products, meaning people can feel more secure about what the supplement contains.

People should check lab results and ingredient lists carefully before buying a supplement.

Most people get enough vitamin C by eating a varied diet including fruits and vegetables. However, some people may need to take a supplement.

All forms of vitamin C work in much the same way, but people should always choose a reputable seller and consider the dose, quality, and price point before buying a product.

Consuming too much vitamin C may cause side effects, and vitamin C supplements are not suitable for everyone. It is always best to consult a doctor or registered dietitian before taking a vitamin C supplement.