Vitamin C (ascorbic acid) is essential for collagen formation and helps to maintain the integrity of connective tissue, bone and dentin. It is essential for wound healing and facilitates recovery from burns. Vitamin C also facilitates the absorption of iron. Severe deficiency results in scurvy, which is characterised by haemorrhages and abnormal bone and dentin formation. The adverse effects of more mild degrees of vitamin C deficiency are not known. Vitamin C is an anti-oxidant but the benefit of vitamin C supplements is a subject of many claims but very little evidence.
Vitamin C is found in a wide variety of fruit and vegetables. Good sources include:
Incidence The incidence of vitamin C deficiency peaks in children aged 6-12 months who are fed a diet deficient in citrus fruits or vegetables. Incidence also peaks in the elderly.
Risk Factors Risk factors include the following:
Symptoms Early symptoms of scurvy are malaise, lethargy, myalgia and arthralgia. Other symptoms include skin changes with easy bruising, gum disease, loosening of teeth and poor wound healing.
Signs The gums become swollen, purple, spongy, and friable. The skin shows papules and haemorrhages around hair follicles, petechiae and multiple bruises. Nail splinter haemorrhages may occur. In the later stages, jaundice, generalised oedema, oliguria, neuropathy, fever, and convulsions may occur.
Investigations Plasma ascorbic acid levels are reduced. Ascorbic acid levels in the white blood cell-platelet layer of centrifuged blood are more significant. A positive capillary fragility test is an almost constant finding, and anaemia is common. Bleeding, coagulation, and prothrombin times are all normal.
Management Ascorbic acid replacement therapy.
Prognosis Scurvy is fatal if untreated. Patients respond quickly to oral therapy.
Prevention Recommendations for dietary intake range from 40 to 200 mg per day. During pregnancy and lactation, intake should be between 100 and 200 mg daily.
The recommended upper limit is 2 g/day. Despite claims of benefit, very high doses of vitamin C have not been shown to decrease the incidence or severity of the common cold or protect against malignant disease or atherosclerosis. Very high doses do acidify the urine, may cause diarrhoea, predispose to urinary calculi and promote iron overload.
Internet and Further Reading
Acknowledgements EMIS is grateful to Dr Colin Tidy for authoring this article. The final copy has passed peer review of the independent Mentor GP authoring team. ?EMIS 2004.