Diseases & Conditions
Vitamin C (Ascorbic Acid)
Vitamin C (ascorbic acid) is essential for the formation, growth, and repair of bone, skin, and connective tissue (which binds other tissues and organs together and includes tendons, ligaments, and blood vessels). Vitamin C helps maintain healthy teeth and gums. It helps the body absorb iron, which is needed to make red blood cells. Vitamin C also helps burns and wounds heal. Like vitamin E, vitamin C is an antioxidant: It protects cells against damage by free radicals, which are by-products of normal cell activity that participate in chemical reactions. Some of these reactions can be harmful.
Vitamin C Deficiency
Not eating enough fresh fruits and vegetables can cause the deficiency. People feel tired, weak, and irritable. Severe deficiency, called scurvy, causes bruising, gum and dental problems, dry hair and skin, and anemia. The diagnosis is based on symptoms and sometimes blood tests. Increasing consumption of fresh fruits and vegetables or taking supplements by mouth usually corrects the deficiency.
In adults, vitamin C deficiency usually results from a diet low in vitamin C. For example, vitamin C deficiency may result from a diet deficient in fresh fruits and vegetables. Also, cooking can destroy some of the vitamin C in food. Pregnancy, breastfeeding, disorders that cause a high fever or inflammation, surgery, and burns can significantly increase the body's requirements for vitamin C and the risk of vitamin C deficiency. Smoking increases the vitamin C requirement by 30%.
Scurvy: Severe vitamin C deficiency causes scurvy. Scurvy in infants is rare because breast milk usually supplies enough vitamin C and infant formulas are fortified with the vitamin. Scurvy is rare in the United States but may occur in alcoholics and older people who are malnourished.
Did You Know...
Cooking can destroy some of the vitamin C in foods. Pregnancy, breastfeeding, fever, surgery, and smoking greatly increase the body's requirements for vitamin C.
Adults feel tired, weak, and irritable if their diet is low in vitamin C. They may lose weight and have vague muscle and joint aches.
The symptoms of scurvy develop after a few months of deficiency. Bleeding may occur under the skin (particularly around hair follicles or as bruises), around the gums, and into the joints. The gums become swollen, purple, and spongy. The teeth eventually loosen. The hair becomes dry and brittle, and the skin becomes dry, rough, and scaly. Anemia may develop. Infections may develop, and wounds do not heal.
Infants may be irritable, have pain when they move, and lose their appetite. Infants do not gain weight as they normally do. In infants and children, bone growth is impaired, and bleeding and anemia may occur.
Diagnosis and Treatment
The diagnosis of scurvy is based on symptoms. Measuring the vitamin C level in blood can help establish the diagnosis, but this test is not always available. In children, x-rays are done to check for impaired bone growth.
The deficiency can be prevented by consuming the recommended amounts of fresh fruits and vegetables or by taking the recommended amount of vitamin C in daily supplements. Smokers require more.
Scurvy is treated with high doses of daily vitamin C supplements. Most symptoms disappear after 1 to 2 weeks. Vitamin C plus iron supplements can cure the anemia.
Vitamin C Excess
Some people take high doses of vitamin C because it is an antioxidant, which protects cells against damage by free radicals. Free radicals are thought to contribute to many disorders, such as atherosclerosis, cancer, lung disorders, the common cold, eye cataracts, and memory loss. Whether taking high doses of vitamin C protects against or has any beneficial effect on these disorders is unclear. Evidence of a protective effect against cataracts is strongest.
High doses (up to the safe upper limit—2000 milligrams a day) of vitamin C are usually not toxic to healthy adults. Occasionally, higher doses cause nausea or diarrhea and interfere with the interpretation of some blood test results.
Last full review/revision August 2007 by Larry E. Johnson, MD, PhD
Source: The Merck Manual Home Edition