Key facts
Vitamin C, also known as ascorbic acid or ascorbate, is a natural antioxidant that can be found in a variety of fresh foods and is essential to keeping you healthy and your body functioning well. . Show Why is vitamin C important for my health?Vitamin C has many important functions in the body, including keeping your skin, bones and connective tissue healthy as well as help your body absorb iron. Some people incorrectly believe vitamin C will help prevent you from catching the common cold. While there have been many attempts to support this idea with research-based evidence, there is still no convincing proof of a significant benefit. A high dose of vitamin C taken as soon as you get symptoms may, however, lessen the duration of a cold. A major vitamin C deficiency (consuming less than 7mg per day, or around one segment of orange, for more than 4 weeks) can lead to scurvy. This condition can involve bone and blood vessel disease, bleeding, pain in the hands and feet, and in extreme cases, death. What are some good natural sources of vitamin C?Vitamin C is found in many fruits and vegetables. Fruits include citrus fruits such as oranges, grapefruit and lemon, kiwi fruit, blackcurrants, strawberries and guava. Vegetables, including broccoli, cauliflower, cabbage, cooked kale, Brussels sprouts and Chinese cabbage. The amount of vitamin C in fruits and vegetables varies, and can be influenced by season, transportation, shelf life and storage time. Eating fresh fruit and vegetables is ideal because cutting, bruising, cooking, heating or exposing food to certain materials can destroy the vitamin C. To boost your intake, try adding in a fruit or vegetable that’s high in vitamin C to some of your meals, or having an orange as a snack. Should I take vitamin C supplements?The best way to give your body the vitamins it needs is to eat a varied diet that includes healthy proteins (such as lean meats and poultry, fish, eggs, dairy, nuts, seeds, legumes and beans) and a variety of fresh fruit and vegetables. Taking a vitamin C supplement will increase the amount of that specific vitamin in your body but won’t necessarily mean you’re getting the nutrients, minerals, vitamins and dietary fibre that come with a balanced diet. Eating whole foods is a healthier approach. For example, that orange you eat contains so much more than just vitamin C — it also contains a range of other vitamins and minerals that help your body absorb and make good use of these nutrients. If you are on a restrictive diet, such as a vegan diet, or you have a health condition that impacts how you eat foods or how you absorb nutrients, you may need to take vitamin supplements to avoid deficiency and stay healthy. Before taking any vitamin supplement — and particularly if you are on a restrictive diet — speak with your doctor or an accredited dietitian. What is the recommended dose of vitamin C?The Australian Government publishes a Recommended Dietary Intake (RDI) for each vitamin, allowing you to check that you are getting the right amount. Adults need around 45mg of vitamin C daily — this equates to around half an orange or a cup of strawberries. Breastfeeding women need more — around 85mg daily — while children need a little less, at around 35mg to 40mg daily. There is some evidence to suggest that people who smoke cigarettes may need larger amounts of vitamin C than non-smokers to prevent deficiency — one of many reasons to consider quitting smoking. If you are concerned about your vitamin C intake, keep a food diary to record what you eat and talk to your doctor or dietitian.FIND A HEALTH SERVICE — Our Service Finder can help you find doctors, pharmacies, hospitals and other health services. When taken as directed, Vitamin C supplementation is not usually associated with significant side effects. However, talk to your doctor before you start taking supplements and follow the instructions on the packaging. If you choose to take supplements to help you reach your RDI, then unless you have a diagnosed deficiency it is best to take a multivitamin. This reduces the likelihood that you will overdose on any one vitamin. Can I take too much vitamin C?High doses of a vitamin supplement are not necessarily healthy. Taking too much vitamin C in the form of a vitamin supplement can result in nausea, abdominal cramps, headaches, fatigue, kidney stones and diarrhoea. High doses of vitamin C can also interfere with the way your body absorbs other essential nutrients, such as iron. Consuming healthy foods that contain vitamin C is not only the preferred way to ensure you reach your recommended intake, it’s also the best way to avoid taking too much. Do not take more than 1,000 mg per day in the form of a vitamin C supplement. If you are concerned that you have taken too much of a vitamin C supplement, call the Poisons Information Centre (13 11 26) immediately.
Vitamin C, or L-ascorbic acid, is an essential nutrient. That means your body doesn't make it, so you have to get it through diet or supplements. Vitamin C is in many foods, such as oranges, red, and green peppers, and kiwi.
Research has confirmed some general health benefits of vitamin C. When it comes to using it as a treatment or preventive measure for specific conditions, though, many of the studies have been inconclusive or found no benefit. This article goes over the uses of vitamin C, symptoms of a deficiency, possible side effects and precautions, proper dosages, and how to get more vitamin C through your diet.
Dietary supplements are not regulated in the United States, meaning the Food and Drug Administration (FDA) does not approve them for safety and effectiveness before products are marketed. When possible, choose a supplement that has been tested by a third party, such as USP (United States Pharmacopeia), Consumer Labs, or NSF International. However, even if supplements are third-party tested, they are not necessarily safe for all or effective in general. It is important to talk to your healthcare provider about any supplements you plan to take and check in about any potential interactions with other supplements or medications.
Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietician, pharmacist, or doctor. No supplement is intended to treat, cure, or prevent a disease. Vitamin C has been marketed for use to treat and/or prevent many conditions, from the common cold and COVID-19 to arthritis and Alzheimer's disease. Even so, there's scant evidence to support most claims about vitamin C.
What researchers have learned is that vitamin C appears to play a lot of important roles in your body. The most beneficial aspect may be its antioxidant activity.
Supplement use should be tailored to your specific health issues and needs. Before starting a supplement, talk to a qualified healthcare provider, such as a doctor, registered dietitian, or pharmacist, Vitamin C is an antioxidant, meaning it's one of many natural substances that may help treat, slow, or prevent some health problems. They do this by neutralizing free radicals, which are unstable molecules that can damage cells and cause disease. When you have a lot of free radicals in your system, it can cause a condition called oxidative stress (OS). Research has linked many chronic diseases to OS. Preventing or reducing OS may help stave off these and other health problems by: However, research into using antioxidants to treat or prevent specific conditions has been a mixed bag. Free radicals come in many types and some are harder for antioxidants to scavenge. Their location in your body can also make a difference, as certain environments (e.g., inside a cell versus in fluids outside the cell) can make the antioxidant activity more or less successful. Moreover, researchers say it's important to be "realistic about where, when and to what extent oxidative stress is part of a disease." So, as they learn more about the disease processes and the role of OS, researchers may yet find roles for antioxidants like vitamin C.
In the meantime, while they're generally considered good for your health, don't expect vitamin C or any other antioxidants to take the place of other treatments. Oxidative stress is believed to play a role in the development of some cardiovascular disease (cardio means heart, vascular refers to blood vessels). A major reason for this is that oxidative stress can trigger atherosclerosis, which is the thickening or hardening of arteries due to the buildup of plaque made from cholesterol, fat, and other substances. This can lead to coronary artery disease. Studies have also suggested that oxidative stress may play some role in: Even so, research into vitamin C for treating and preventing heart disease has mostly found no effect.
One promising bit of information came out in a 2020 study. It showed that vitamin C supplements helped lower blood pressure in people with hypertension. Hypertension, especially when combined with atherosclerosis, is a risk factor for heart disease.
Molecules in your body become free radicals when they're exposed to things like environmental pollutants, smoking cigarettes, and chronic inflammation. A lot of research has investigated the role of antioxidants, including vitamin C, in cancer care and prevention. However, the results have yielded inconsistent results. Most studies have found that vitamin C supplementation either on its own or in combination with other supplements cannot prevent or treat cancer.
Some studies have shown that high-dose intravenous (IV) vitamin C, when used in supportive care, can improve quality of life and reduce the side effects of standard cancer treatments. When it comes to cancer, it's become clear that antioxidants aren't all good or all bad. Studies have also shown that antioxidants may:
Some healthcare providers recommend eating more antioxidant-containing fruits and vegetables, as people with diets rich in vitamin C may have a lower risk of getting certain types of cancer. However, it's important to remember that no one food will prevent cancer. Moreover, vitamin C supplements themselves do not appear to prevent cancer. Eating a well-balanced diet in general, including antioxidants, is beneficial for your overall health.
Future studies are needed to establish the role of antioxidants like vitamin C in cancer. Talk to your oncologist before starting any supplements during cancer treatment. Gout is a common and extremely painful type of arthritis that mainly affects the big toes. It's caused by excess uric acid (a waste product) in the blood, which causes crystals to form in the joints. The crystals then cause inflammation, which causes painful attacks. Several studies have shown that vitamin C can prevent gout by lowering levels of uric acid in the blood. This may, at least in part, be due to its antioxidant activity. Uric acid levels appear to be higher in people with significant oxidative stress. However, a 2021 review of studies concluded that, while results have been promising, more high-quality studies in humans need to be done to say for sure that it's a safe and effective treatment or preventive measure. In anemia, your blood doesn't contain enough red blood cells, which carry oxygen from your lungs to all of your body's tissues. The most common type of anemia involves a deficiency of iron, which your body needs to make red blood cells. Vitamin C is known to help your body absorb some nutrients. Among healthcare providers, that led to a long-standing practice of recommending vitamin C supplements along with iron supplements for treating anemia. A 2019 article found that vitamin C increased iron absorption by 67%. A 2020 study casts doubt on that, though. It found that iron supplements alone improved anemia just as much as iron plus vitamin C. The different results may be related to what kind of iron people took. Nonheme iron from plant sources is better absorbed with vitamin C. Heme iron, like those found in meat, is better absorbed in general because it has higher bioavailability than nonheme iron. More research is needed to sort this out. Vitamin C's best-known use is for boosting the immune system. It does this by:
Studies show vitamin C's effect on the immune system may help with certain infections, such as:
Vitamin C is also sometimes used orally (by mouth) or topically (applied to the skin) for skin healing. According to research, vitamin C use may:
These abilities are believed to be largely due to vitamin C's antioxidant activity along with its ability to promote collagen production in the skin. This is likely better achieved with nutritional intake (including supplements) rather than topically because collagen is present in deeper layers of skin and can't penetrate the outer layers to get there.
Collagen is a protein in your body that makes tissues strong, resilient, and able to tolerate stretching. It's in skin, bone, muscles, tendons, and cartilage. Traditional wisdom about vitamin C for the common cold may not be as wise as you think. Research has provided mixed evidence about vitamin C for treating or preventing these respiratory infections. Once again, it's a mixed bag. Several studies, including a large systematic review of the evidence, suggest vitamin C supplements:
Even these points aren't firmly concluded, though. For example, one systematic review including eight studies found vitamin C may only have a minimal or no effect on how long your cold lasts. However, a separate meta-analysis found it may shorten the duration. More research needs to be done before researchers can draw any firm conclusions. Age-related macular degeneration (AMD) is an eye disorder that can, over time, cause blindness. Research has been inconclusive on whether vitamin C and other antioxidants can prevent AMD. But some research suggests it may slow it down. The Age-Related Eye Disease Study (AREDS), a large clinical trial, included almost 3,600 older adults with AMD. The participants were divided into four groups and given different treatments:
After six years, the participants who got supplements had less AMD progression. However, researchers can't be sure that vitamin C itself made a difference. This is an older study, though, and since then, a number of other studies have failed to show that vitamin C alone is helpful against AMD. Research from 2017 concludes that vitamin C "probably" doesn't prevent or delay AMD and that vitamin E and beta carotene do not. Vitamin C's antioxidant activity may play a role in brain heath. Research suggests regular dietary intake plus supplements may protect you from neurodegeneration related to aging and diseases such as: Vitamin C may even help treat or lower your risk of mental health disorders including:
Studies suggest vitamin C deficiency may contribute to the development of these mental and neurodegenerative conditions, and that supplementation may help alleviate symptoms. However, this work is preliminary and more research is needed. Vitamin C deficiency is rare in developed countries. In the United States only about 8.4% of the population is believed to be vitamin C deficient. You'd have to get less than 10 milligrams (mg) per day from food for about a month to feel the effects of a vitamin C deficiency. In severe cases, this can lead to scurvy (which is rare in the U.S.) Symptoms of scurvy include:
Vitamin C deficiency is treated with vitamin C supplements. Some symptoms improve within the first 24 hours of treatment. Others may take a few weeks to go away. A deficiency occurs either from insufficient nutrient intake in the diet or increased losses due to poor absorption. People who don't consume various foods, mainly fruits and vegetables, are at a greater risk of vitamin C deficiency. Smokers have a higher requirement for vitamin C, so smoking may also be a risk factor. Additionally, people with malabsorption disorders may become deficient because they can't absorb enough vitamin C. Symptoms of a vitamin C deficiency include: If you have these symptoms and know your vitamin C intake is low, or if you rarely eat fruits and vegetables, talk with your healthcare provider about whether supplements are right for you. Vitamin C is generally considered safe, but high doses can cause side effects. These may include:
Higher doses are more likely to lead to side effects. Doses over 2,000 milligrams a day may increase the risk of diarrhea and kidney stones. If you have a history of kidney stones, taking more than 1,000 milligrams a day may increase your chances of having more. Vitamin C supplements are not right for everyone. Talk to your healthcare provider first if any of the following apply to you:
Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs. For most healthy people, it is easy to get adequate amounts of vitamin C through food. You can meet your recommended dietary allowance (RDA) for vitamin C each day by eating just one of the following:
The RDA for vitamin C is as follows:
Two important caveats to these recommendations are:
Taking high doses may be appropriate for some people, but most of the time, it provides no extra benefit. Your body controls how much vitamin C it absorbs.
That means it'll take what it needs from food and supplements, and anything beyond that comes out in your urine. Taking 1,000 milligrams a day or more actually drops your absorption rate by about 50%. The tolerable upper intake level (TUL) is the highest amount you can safely take. Doses beyond that are more likely to cause side effects. For vitamin C, the daily TUL is different for different groups: Adults: 2,000 milligrams Children by age:
The TUL during pregnancy is the same as those for your age group. Excessive amounts of vitamin C (above TUL) can result in:
If you're healthy, taking recommended levels of vitamin C supplements generally doesn't pose risks. If you take estrogen or estrogen-based contraceptives, vitamin C may increase the risk of hormonal side effects. This is because vitamin C may slow the rate at which estrogen leaves your body. Vitamin C can also increase the absorption of certain drugs, such as: Vitamin C supplementation can make some medications less effective including:
This is not a complete list of interactions that may occur with vitamin C. Let your healthcare provider and pharmacist know about everything you're taking, including prescription and over-the-counter drugs, vitamins, and herbal supplements. Talk to your healthcare provider before starting vitamin C supplementation or adjusting your intake.
Store vitamin C supplements in a closed container, away from exposure to light. Frequently Asked Questions
Vitamin C is readily available in your diet and most people can get the required amounts from food.
Multiple vitamin C supplement formulations are readily available. You can buy them from most stores and websites that sell nutritional supplements. It is always best to get your nutrients from food rather than supplements. Fruits and vegetables, especially citrus fruits, are good sources. Foods naturally rich in vitamin C include:
If you don't get enough vitamin C from what you eat, a supplement can help get you to the right levels. Vitamin C supplements are available as a single nutrient supplement or combination supplement. You can find them in many forms, such as:
You may also see different types of vitamin C, including:
No one form is more effective than another. Remember to look at the dosages and avoid exceeding the TUL. Also, pay attention to units of measure. The RDA for vitamin C is in milligrams (mg), but vitamin C labels may list grams (g) or micrograms (mcg).
Dietary supplements aren't regulated by the U.S. Food and Drug Administration (FDA). When possible, choose a supplement that's been tested by a trusted third party, such as: This ensures their purity and that the contents match the label. It doesn't guarantee effectiveness. Vitamin C supplements have been marketed for many conditions. It's the best treatment for vitamin C deficiency. As an antioxidant and anti-inflammatory, vitamin C has been studied for its uses in heart disease prevention, gout, immunity, and more. It is best to get vitamin C from your food. If you don't, a supplement can help you meet your goals. Talk to your healthcare provider before taking supplements.
The right dosage for you depends on several factors, including age and medical conditions. Vitamin C can interact with certain medications and cause side effects at high levels, so it is important to discuss with your healthcare provider about whether supplementation is appropriate for you. |
What is vitamin C good for?
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