Vitamin C is a very important nutrient that’s abundant in many fruits and vegetables. Getting enough of this vitamin is especially important for maintaining a healthy immune system. It also plays an important role in wound healing, keeping your bones strong, and enhancing brain function .
Interestingly, some claim that vitamin C supplements provide benefits beyond those that can be obtained from the vitamin C found in food. One of the most common reasons people take vitamin C supplements is the idea that they help prevent the common cold .
Vitamin c Iron Toxicity
However, many supplements contain extremely high amounts of the vitamin, which can cause undesirable side effects in some cases.
This article explores the overall safety of vitamin C, whether it’s possible to consume too much, and the potential adverse effects of taking large doses.
Vitamin C is a water-soluble vitamin, which means it dissolves in water.
In contrast to fat-soluble vitamins, water-soluble vitamins do not get stored within the body.
Instead, the vitamin C that you consume gets transported to your tissues via body fluids, and any extra gets excreted in urine (1Trusted Source).
Since your body does not store vitamin C or produce it on its own, it’s important to consume foods that are rich in vitamin C daily (1Trusted Source).
However, supplementing with high amounts of vitamin C can lead to adverse effects, such as digestive distress and kidney stones.
That’s because if you overload your body with larger-than-normal doses of this vitamin, it will start to accumulate, potentially leading to overdose symptoms (3Trusted Source).
It’s important to note that it’s unnecessary for most people to take vitamin C supplements, as you can easily get enough by eating fresh foods, especially fruits and vegetables (1Trusted Source).
SUMMARYVitamin C is water-soluble, so it’s not stored within your body. If you consume more than your body needs, it’s excreted in your urine.
The most common side effect of high vitamin C intake is digestive distress.
In general, these side effects do not occur from eating foods that contain vitamin C, but rather from taking the vitamin in supplement form.
You’re most likely to experience digestive symptoms if you consume more than 2,000 mg at once. Thus, a tolerable upper limit (TUL) of 2,000 mg per day has been established (1Trusted Source, 3Trusted Source, 4Trusted Source, 5Trusted Source).
The most common digestive symptoms of excessive vitamin C intake are diarrhea and nausea.
Excessive intake has also been reported to lead to acid reflux, although this is not supported by evidence (1Trusted Source, 3Trusted Source, 4Trusted Source, 5Trusted Source).
If you’re experiencing digestive problems as a result of taking too much vitamin C, simply cut back your supplement dose or avoid vitamin C supplements altogether (3Trusted Source, 4Trusted Source, 5Trusted Source).
SUMMARYIngesting more than 2,000 mg of vitamin C per day may lead to gastrointestinal upset, including symptoms like diarrhea and nausea.
Vitamin C is known to enhance iron absorption.
It can bind to non-heme iron, which is found in plant foods. Non-heme iron is not absorbed by your body as efficiently as heme iron, the type of iron found in animal products (6Trusted Source).
Vitamin C binds with non-heme iron, making it much easier for your body to absorb. This is an important function, especially for individuals who get most of their iron from plant-based foods (7Trusted Source).
One study in adults found that iron absorption increased by 67% when they took 100 mg of vitamin C with a meal (8Trusted Source).
However, individuals with conditions that increase the risk of iron accumulation in the body, such as hemochromatosis, should be cautious with vitamin C supplements.
Under these circumstances, taking vitamin C in excess may lead to iron overload, which can cause serious damage to your heart, liver, pancreas, thyroid, and central nervous system (9Trusted Source, 10Trusted Source, 11Trusted Source).
That said, iron overload is highly unlikely if you don’t have a condition that increases iron absorption. Additionally, iron overload is more likely to occur when excess iron is consumed in supplement form.
SUMMARYSince vitamin C increases iron absorption, consuming too much of it is a concern for individuals with conditions that lead to iron accumulation in the body.
Excess vitamin C is excreted from the body as oxalate, a bodily waste product.
Oxalate typically exits the body via urine. However, under some circumstances, oxalate may bind to minerals and form crystals that can lead to the formation of kidney stones (12Trusted Source).
Consuming too much vitamin C has the potential to increase the amount of oxalate in your urine, thus increasing the risk of developing kidney stones (13Trusted Source).
In one study that had adults take a 1,000-mg vitamin C supplement twice daily for 6 days, the amount of oxalate they excreted increased by 20% (13Trusted Source).
High vitamin C intake is not only associated with greater amounts of urinary oxalate but also linked to the development of kidney stones, especially if you consume amounts greater than 2,000 mg (6Trusted Source, 14).
Reports of kidney failure have also been reported in people who have taken more than 2,000 mg in a day. However, this is extremely rare, especially in healthy people (15Trusted Source).
SUMMARYConsuming too much vitamin C may increase the amount of oxalate in your kidneys, which has the potential to lead to kidney stones.
Since vitamin C is water-soluble and your body excretes excess amounts of it within a few hours after you consume it, it’s quite difficult to consume too much.
In fact, it is nearly impossible for you to get too much vitamin C from your diet alone. In healthy people, any extra vitamin C consumed above the recommended daily amount simply gets flushed out of the body (16Trusted Source).
To put it in perspective, you would need to consume 29 oranges or 13 bell peppers before your intake reached the tolerable upper limit (17Trusted Source, 18Trusted Source).
However, the risks of vitamin C overdose are higher when people take supplements, and it is possible to consume too much of the vitamin in some circumstances.
For example, those with conditions that increase the risk of iron overload or are prone to kidney stones should be cautious with their vitamin C intake (6Trusted Source, 10Trusted Source, 19Trusted Source).
All the adverse effects of vitamin C, including digestive distress and kidney stones, appear to occur when people take it in mega doses greater than 2,000 mg (20Trusted Source).
If you choose to take a vitamin C supplement, it is best to choose one that contains no more than 100% of your daily needs. That’s 90 mg per day for men and 75 mg per day for women (21Trusted Source).
SUMMARY:It’s nearly impossible to consume too much vitamin C from food. However, if you’re supplementing with this vitamin, you can minimize your risk of getting too much by taking no more than 90 mg per day if you’re a man, or 75 mg per day if you’re a woman.
Vitamin C is generally safe for most people.
This is especially true if you get it from foods, rather than supplements.
Individuals who take vitamin C in supplement form are at greater risk of consuming too much of it and experiencing side effects, the most common of which are digestive symptoms.
However, more serious consequences, such as iron overload and kidney stones, may also result from taking extreme amounts of vitamin C (3Trusted Source).
Fortunately, it’s easy to prevent these potential side effects — simply avoid vitamin C supplements.
Unless you have a vitamin C deficiency, which rarely occurs in healthy people, it is probably unnecessary for you to take large doses of this vitamin.
Is It Possible to Have a Vitamin C Overdose?
Supplement marketers go into overdrive during cold and flu season, advertising products that promise to decrease your odds of getting sick. Vitamin C is among the best-known, most accessible antioxidants that have been touted to help prevent you from getting sick.
Also called ascorbic acid, vitamin C is one of the many water-soluble nutrients found naturally in fruits and vegetables. Many people also take supplements to ensure they’re getting enough of it. This has raised concerns over the likelihood of an accidental overdose.
Too much vitamin C can cause undesirable effects. However, a severe overdose is rare and unlikely. The key is to learn how much vitamin C you really need.
Vitamin C is a type of antioxidant. It helps protect the body from free radicals that damage and destroy otherwise healthy cells. In this respect, getting enough of the nutrient is just one way you can support your body’s natural defenses against illness. This is how it gained its reputation as a virus-fighting vitamin.
It also helps increase iron absorption, which is essential for growth and overall body functions. Not having enough vitamin C can lead to a potentially deadly condition known as scurvy.
Oranges and orange juices are perhaps the best-known sources of vitamin C, but other items in the produce aisle are chock-full, including:
- bell peppers
You probably don’t need a vitamin C supplement if you eat a lot of fruits and vegetables. In fact, just one serving of any of the above foods likely will get you to your daily quota.
According to the National Institutes of HealthTrusted Source, the average adult woman requires 70mg of vitamin C a day. The average man requires 90mg. Recommended amounts are higher for pregnant and nursing women.
It’s important to discuss your individual nutritional needs with your doctor. The maximum recommended amount, or upper limit, is 2,000mg per day for all adults.
Taking more than the upper limit for vitamin C isn’t life-threatening, but you may experience side effects like:
- abdominal pain
- nausea (and possible vomiting)
- sleeping problems
People with hemochromatosis are in danger of a vitamin C overdose. This condition causes your body to store excessive amounts of iron, which is exacerbated by taking too much vitamin C. This condition can lead to body tissue damage.
Vitamin C supplements may also interact with certain medications. This is especially true of medications for heart disease and cancer. Be sure to check with your doctor before taking a supplement.
Despite what supplement makers have led you to believe, there is no scientific evidence that vitamin C directly prevents colds and flu viruses. In fact, the National Center for Complementary and Alternative Medicine says that taking these costly supplements only slightly minimizes the duration of a cold. Furthermore, taking vitamin C after getting sick doesn’t help at all.
You’re better off saving your money and making sure you get enough vitamin C in your daily diet instead. As with other preventive health measures, the best way to ward off cold and flu viruses is to take care of yourself. You can accomplish this by:
- getting adequate sleep every night
- exercising regularly
- eating nutritious foods
- refraining from excess caffeine and alcohol