Vitamin C For Runners: Benefits, Sources And How Much Do You Need?

Vitamin C is probably best known for its association with the immune system, but that is only part of the reason it matters to runners. It is also needed to make collagen, helps the body absorb iron from plant foods and acts as an antioxidant, giving it several roles that are relevant to training and recovery.

Most runners who eat a varied diet should be able to get enough vitamin C from food. Taking large doses in supplement form is a different matter, however, and there is little evidence that doing so will make you run faster or recover significantly better.

What Is Vitamin C?

Vitamin C, also known as ascorbic acid, is a water soluble vitamin that the human body cannot make itself. We therefore need to obtain it regularly through our diet.

It performs several important functions within the body. Vitamin C is required for the production of collagen, contributes to normal immune function and acts as an antioxidant. It also improves the absorption of non haem iron, the form of iron found in plant foods.

Because vitamin C is water soluble, the body does not store large amounts of it in the same way it can store some fat soluble vitamins. Regularly eating foods containing vitamin C is therefore more important than occasionally consuming a very large amount.

Why Is Vitamin C Important For Runners?

One of the most interesting roles for runners is collagen production. Collagen is a major structural protein found in tissues including skin, tendons, ligaments, cartilage and bone, and vitamin C is required for normal collagen formation.

That doesn't mean taking a vitamin C tablet will strengthen your tendons or prevent running injuries. It does mean that getting enough vitamin C is part of providing the body with the nutrients it requires to maintain healthy connective tissue.

Its relationship with iron is also particularly relevant to runners. Iron is essential for transporting oxygen around the body, and vitamin C can improve the absorption of iron from plant foods.

Vitamin C And Iron Absorption

There are two main forms of dietary iron. Haem iron is found in animal foods, while non haem iron is found in plant foods and is generally less readily absorbed by the body.

Vitamin C can increase the absorption of non haem iron, which makes food combinations worth thinking about. Adding peppers to a lentil dish, eating vitamin C rich fruit with an iron fortified breakfast cereal or combining beans with tomatoes are simple examples of bringing vitamin C and plant based iron together.

This doesn't mean vitamin C supplements should be used to treat iron deficiency. If you suspect you have low iron levels, particularly if you are experiencing persistent tiredness or an unexplained decline in running performance, seek appropriate medical advice rather than trying to correct the problem yourself with supplements.

Read more about the importance of iron to runners here.

Does Vitamin C Help Your Immune System?

Vitamin C contributes to normal immune function, but that doesn't mean taking large amounts will prevent runners from becoming ill. Immune health is influenced by many factors, including overall nutrition, sleep, recovery, training load and exposure to infections.

This can become particularly relevant during periods of demanding training when runners may be putting greater physical stress on their bodies. Getting enough vitamin C is important, but supplements aren't a substitute for adequate energy intake, a varied diet, sufficient sleep and sensible recovery between demanding sessions.

Is Vitamin C An Antioxidant?

Vitamin C acts as an antioxidant, helping to protect cells against oxidative damage. Exercise increases the production of reactive oxygen species, so it might seem logical that runners should consume as many antioxidants as possible.

The reality is more complicated because some of the oxidative stress created by exercise appears to be involved in signalling processes that help the body adapt to training. This has raised questions about whether regularly taking very high doses of antioxidant supplements could interfere with some training adaptations.

The research isn't strong enough to conclude that taking vitamin C supplements will prevent you from improving as a runner. It does, however, provide another reason not to assume that very large supplemental doses must be better than getting an appropriate amount through a balanced diet.

Can Vitamin C Improve Running Performance?

There is no convincing evidence that taking extra vitamin C will make a well nourished runner faster. Studies examining vitamin C and exercise have produced mixed results for measures including endurance performance, muscle soreness, muscle damage and training adaptations.

There has also been research into whether high doses of vitamins C and E could reduce some of the cellular responses associated with endurance training. Although some differences in these responses have been observed, that hasn't consistently translated into poorer improvements in measures such as aerobic fitness or running performance.

For recreational runners, vitamin C is therefore much better viewed as an essential nutrient than as a performance supplement. Correcting an inadequate intake is very different from taking increasingly large amounts in the hope of gaining an additional training advantage.

Does Vitamin C Help You Recover After Running?

Vitamin C supplements are sometimes promoted on the basis that their antioxidant properties could reduce inflammation, muscle damage or soreness after hard exercise. Research into exercise recovery has produced inconsistent results, and there isn't good evidence that routinely taking large doses leads to meaningfully better recovery for most runners.

Recovery also depends on much more than a single vitamin. Eating enough overall, replacing carbohydrate after demanding sessions, consuming sufficient protein, staying hydrated and getting enough sleep are likely to be considerably more important than relying on a vitamin C supplement.

Read more about recovery nutrition here.

What Are The Best Sources Of Vitamin C?

Fruit and vegetables are the main dietary sources of vitamin C. Citrus fruits such as oranges and grapefruit are well known examples, but peppers, kiwifruit, strawberries, broccoli, Brussels sprouts, tomatoes and potatoes can also make useful contributions.

The foods available will naturally vary around the world, and many other fruits and vegetables can provide vitamin C. A varied diet containing different types and colours of fruit and vegetables is a more practical approach than relying on one particular food.

Vitamin C content can be reduced by prolonged storage and some methods of cooking because the vitamin is water soluble and sensitive to heat. Eating a mixture of raw and cooked fruit and vegetables can help provide a regular supply.

Vitamin C isn't just found in fruit. Vegetables can be great sources too, with Brussels sprouts providing plenty of this important vitamin.

How Much Vitamin C Do Runners Need?

There isn't a universally agreed separate vitamin C requirement specifically for runners. Recommendations for the general adult population also vary between countries and health authorities, which explains why different figures may appear depending on where you look.

In the United States, for example, the recommended daily amount for adults is 90 mg for men and 75 mg for women, while smokers are advised to consume an additional 35 mg. Recommendations elsewhere can be different, so runners should follow the nutritional guidance relevant to the country where they live.

For most people, however, the practical message is similar wherever they are. A varied diet containing plenty of fruit and vegetables will normally provide significant amounts of vitamin C alongside many other useful nutrients.

Do Runners Need More Vitamin C?

Heavy exercise increases metabolic demands and oxidative stress, which has led to suggestions that athletes might need more vitamin C than people who are less active. That doesn't automatically mean runners need vitamin C supplements or a special athlete specific dose.

Someone eating enough food to support regular training and consuming plenty of fruit and vegetables may already have a relatively high vitamin C intake. The more important question is therefore whether your overall diet is meeting your nutritional needs rather than assuming running automatically creates a need for supplementation.

Runners who restrict their food intake, follow a particularly limited diet or consistently eat very little fruit and vegetables may need to look more carefully at what they are consuming. Individual circumstances differ, so professional dietary advice can be useful when there are concerns about nutritional adequacy.

Should Runners Take Vitamin C Supplements?

For most runners with an adequate diet, there is little reason to routinely take high dose vitamin C supplements. Supplements may have a role where dietary intake is inadequate or a deficiency has been identified, but that is different from using large amounts in the belief that they will improve running performance.

A food first approach also provides much more than vitamin C. Fruit and vegetables contain fibre, minerals and a wide range of other nutrients and plant compounds that aren't replicated simply by taking an isolated vitamin tablet.

If you do use a supplement, check the amount it contains rather than assuming a higher dose offers greater benefits. Supplements can contain many times the normal daily requirement, even though there is no evidence that runners need extremely high vitamin C intakes simply because they exercise.

Read more about supplements for runners here.

Can You Take Too Much Vitamin C?

Yes, although getting excessive amounts from ordinary foods is unlikely to be a problem for most healthy people. The greater concern is very high supplemental intakes, which can cause gastrointestinal problems including diarrhoea, nausea and abdominal cramps.

Different health authorities use different upper intake recommendations. In the United States, for example, the tolerable upper intake level for adults is 2,000 mg per day, but this shouldn't be interpreted as a target or as an amount runners should aim to consume.

There are also circumstances where high supplemental doses require particular caution. People with some conditions affecting iron metabolism, for example, may need to avoid large amounts of supplemental vitamin C because of its ability to increase iron absorption.

Can Runners Become Vitamin C Deficient?

Severe vitamin C deficiency causes scurvy, although this is uncommon among people who have access to and regularly eat a varied diet. Deficiency can still occur, particularly with extremely restricted diets, very low fruit and vegetable intake, certain health conditions or circumstances that affect nutritional intake or absorption.

Symptoms of significant deficiency can include tiredness, weakness, bleeding gums, bruising and poor wound healing. These symptoms can have many other causes, however, so runners shouldn't assume they have a vitamin C deficiency based on symptoms alone.

For most runners, prevention is straightforward. Eating enough overall and regularly including a variety of fruit and vegetables should provide vitamin C alongside many of the other micronutrients needed to support general health.

What Should Runners Remember About Vitamin C?

Vitamin C matters to runners, but probably not for the reasons suggested by many supplement products. Its real value comes from being an essential part of normal nutrition, with important roles in collagen formation, iron absorption, antioxidant protection and immune function.

Getting enough is important, but getting enormous amounts isn't necessarily better. Current evidence doesn't show that routinely taking high dose vitamin C improves running performance or recovery, while there are legitimate reasons to be cautious about repeatedly using large antioxidant doses around training.

A varied diet containing plenty of fruit and vegetables remains the best starting point. For most runners, that provides vitamin C alongside a much wider range of nutrients that support health, training and recovery.