Vitamin C (ascorbic acid) is a water-soluble vitamin essential in the human diet because the body is unable to synthesise it. It is found in a wide variety of fruit (especially grapefruit, lemons, limes, blackcurrants, oranges and kiwi fruit) and vegetables (eg, broccoli, green and red peppers, tomatoes, cabbage, sprouts, and sweet potatoes). It is also found in fresh milk, fish and offal such as liver and kidney.
Vitamin C is essential for collagen formation and helps to maintain the integrity of skin and connective tissue, bone, blood vessel walls and dentine. It is essential for wound healing and facilitates recovery from burns. It also facilitates the absorption of iron.
Vitamin C is an antioxidant. Despite claims of benefit, very high doses of vitamin C have not been shown to decrease the incidence of the common cold in the general population. It may slightly reduce the duration of the cold. In people exposed to brief periods of severe physical exercise or cold environments, there may be some benefit to supplementation to ward off colds.
Very high doses of vitamin C can acidify the urine, may cause diarrhoea, can predispose to urinary calculi and can cause iron overload.
Chronic, severe deficiency of vitamin C results in scurvy, which is characterised by haemorrhages and abnormal bone and dentine formation. The adverse effects of more mild degrees of vitamin C deficiency are not known. The body's pool of vitamin C can be depleted within 1-3 months. People suffering with vitamin C deficiency may also have other vitamin deficiencies and malnutrition.
- Scurvy is generally rare.
- The incidence of scurvy peaks in children aged 6-12 months who are fed a diet deficient in citrus fruits or vegetables.
- Incidence also peaks in the elderly.
- The UK Low Income Diet and Nutrition Survey carried out between 2003 and 2005 found evidence of vitamin C deficiency in an estimated 25% of men and 16% of women. Another 20% of the population had vitamin C levels in the depleted range.
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- Infants who are fed only cows' milk during the first year of life.
- Alcoholism and conforming to food fads.
- Low-income families, who tend not to buy foods high in vitamin C.
- Victims of famine, and refugee populations.
- Cigarette smoking, which affects the absorption of vitamin C. Vitamin C is also used up more quickly in those who smoke.
- Increased need due to increased utilisation in pregnant and lactating women, thyrotoxicosis, surgery, and burns.
- People with type 1 diabetes and those on haemodialysis or peritoneal dialysis, because of increased vitamin C requirements.
- Anorexia nervosa or anorexia from other diseases such as AIDS or cancer.
- Chronic diarrhoea, which increases faecal loss. Risk is increased in those with Crohn's disease and ulcerative colitis, because of reduced vitamin C absorption.
Presentation of scurvy
- Early symptoms are malaise and lethargy.
- Shortness of breath, arthralgia and myalgia develop after several months.
- Skin changes include easy bruising, petechiae and poor wound healing.
- Gum disease and loosening of teeth are common.
- Emotional changes, including irritability, can be apparent.
- Dry mouth and dry eyes may occur.
- In the later stages, jaundice, generalised oedema and heart failure, haemopericardium, neuropathy, convulsions and sudden death may occur.
- Skin changes can include perifollicular hyperkeratotic papules, perifollicular haemorrhages, purpura, and ecchymoses. These are seen most commonly on the legs and buttocks. There may be poor wound healing and breakdown of old scars. Alopecia may occur.
- In the nails, splinter haemorrhages may occur.
- Gums can bleed and become swollen, friable and infected; petechiae can occur on the mucosae.
- Conjunctival haemorrhage, flame-shaped haemorrhages, and cotton-wool spots may be seen. Bleeding into the periorbital area, eyelids, and retrobulbar space may occur.
- A scorbutic rosary (where the sternum sinks inwards at the costochondral junctions) may occur in children.
- High-output heart failure due to anaemia can be seen and hypotension may occur late in the disease.
- Fractures, dislocations, tenderness of bones and bleeding into muscles and joints are possible.
- Oedema may occur late in the disease.
- Loss of weight secondary to anorexia is common.
- Clinical suspicion because of a typical history and picture often points towards diagnosis.
- Vitamin C levels may help but often the best way to confirm diagnosis is to watch for resolution of symptoms with vitamin C treatment.
- A positive capillary fragility test may be found.
- Anaemia is common.
- Bleeding, coagulation, and prothrombin times are all normal.
- X-rays can assess for fractures and dislocations. They may also show subperiosteal elevation, alveolar bone reabsorption and ground-glass appearance of the bone cortex.
- Treatment is ascorbic acid replacement therapy.
- Supplements should be combined with intake of foods high in vitamin C.
- Any other dietary deficiencies should also be treated.
Gastrointestinal effects are the most common adverse clinical events associated with acute, high doses of vitamin C given over a short period of time.
- Scurvy is fatal if untreated.
- Patients respond quickly to oral therapy and complete recovery is usually expected.
- An adequate dietary intake of vitamin C is essential.
- Around 90% of vitamin C in the diet comes from fuit and vegetables. Cooking reduces vitamin C content by 30-40%.
- The recommended daily intake of vitamin C in the diet depends on age and sex.
- UK Dietary Reference Values for Food Energy and Nutrients for the United Kingdom suggest that the recommended nutrient intake for children aged 1-10 is 30 mg/day, children aged 11-14 is 35 mg/day and children aged over 15 and adults is 40 mg/day.
- Recommended nutrient intakes increase in pregnancy to 50 mg/day in the last trimester of pregnancy and, during lactation, to 70 mg/day.
- As a rough guide, one large orange will provide the recommended daily intake of vitamin C for an average adult.
Further reading & references
- Goebel L et al; Scurvy, Medscape, Aug 2011
- Douglas RM, Hemila H, Chalker E, et al; Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. 2007 Jul 18;(3):CD000980.
- Mosdol A, Erens B, Brunner EJ; Estimated prevalence and predictors of vitamin C deficiency within UK's J Public Health (Oxf). 2008 Dec;30(4):456-60. Epub 2008 Sep 23.
- Schleicher RL, Carroll MD, Ford ES, et al; Serum vitamin C and the prevalence of vitamin C deficiency in the United States: 2003-2004 National Health and Nutrition Examination Survey (NHANES). Am J Clin Nutr. 2009 Nov;90(5):1252-63. Epub 2009 Aug 12.
- Vitamin C deficiency, BMJ Evidence Centre, updated 2012
- Report on Health and Social Subjects 41, Dietary Reference Values for Food Energy and Nutrients for the United Kingdom, Report of the Panel on Dietary Reference Values of the Committee on Medical Aspects of Food Policy
|Original Author: Dr Colin Tidy||Current Version: Dr Michelle Wright||Peer Reviewer: Dr Helen Huins|
|Last Checked: 16/10/2012||Document ID: 1546 Version: 23||© EMIS|
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