How Much Vitamin C is Too Much? Side Effects of Consuming Excess Vitamin C

2010-08-12

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The Role of Vitamin C

Vitamin C, also known as ascorbic acid, is important for many functions in the body. It helps form collagen, which helps skin cells renew themselves. Iron is better absorbed when paired with vitamin C, one reason that iron-fortified orange juice is now found on store shelves. Vitamin C is vital for connective tissues and bones to grow and develop properly. A deficiency can result in weakened capillaries which are more prone to hemorrhage. In children, poor bone growth and bone lesions are possible. It’s important to know how much vitamin C is too much, because it can potentially be harmful.

Oranges are just one of many foods rich in vitamin C.

Vitamin C Deficiency

Scurvy, a severe deficiency of vitamin C is uncommon in developed countries. It was the main killer of sailors during the 1500’s, when large sailing ships commonly went on journeys, which lasted for months. After fresh food and produce ran out at the beginning of a voyage, sailors often suffered loose teeth, blackened gums, and joint pain. It was not uncommon for over half a ship’s crew to die from scurvy or other diseases caused by poor nutrition.

Recommended Daily Allowance (RDA)

Vitamin C is water soluble, meaning that it is not stored in the body and must be replenished daily. Women need 75 mg daily and men need 90 mg daily to prevent deficiency. Since smoking destroys vitamin C, smokers should take in an additional 35 mg daily. Eating a healthy diet is preferable to taking supplement pills since other nutrients are obtained from a variety of foods. However, multiple studies evaluating vitamin C benefits use 500 mg daily as a suggested dosage. For most adults, a supplement is not harmful and can help boost vitamin C intake if the diet is low in fresh fruits and vegetables.

Food Sources of Vitamin C

Vitamin C is found in all fruits and vegetables in varying amounts. The best sources include citrus fruits, red and green peppers, tomatoes, broccoli, turnip greens, white and sweet potatoes, and cantaloupe. Five servings daily of a mix of fruits and vegetables provides more than 200 mg of vitamin C. Even picky eaters should be able to get adequate vitamin C from their daily diet. Below are some vitamin C-rich foods:

Red pepper, 1/2 cup, 95 mg
Broccoli, 1 cup cooked, 74 mg
Orange juice, 1 cup 97 mg
Cantaloupe, 1 cup 59 mg

Toxicity

Toxicity results when too much vitamin C is consumed, but how much is too much? The maximum upper limit dose of vitamin C is 2000 mg daily, or 2 g. Some unproven health claims for preventing or shortening the duration of viral illnesses, such as colds, and preventing or treating cancer or atherosclerosis, may call for as much as 10 g daily, or 10,000 mg. Taking high doses over a period of time can cause the urine to become too acidic, leading to kidney stones. Individuals with certain types of anemia such as thalassemia can suffer from iron overload. The most noticeable side effects include nausea and vomiting.

Treatment

Fortunately, toxicity is very rare, partially due to vitamin C’s water solubility. Eliminating excess supplements and avoiding foods high in vitamin C can help quickly reverse toxicity. The best treatment for toxicity is prevention. Don’t go overboard if you choose to take a daily supplement. Inform your healthcare provider, especially if you have diabetes or kidney problems, to be sure it is safe to take a supplement. Knowing how much vitamin C is too much and the signs to look for can help keep your vitamin C intake at a healthy level.