MEDICAL MATTERS:A lack of vitamin C can cause serious problems
WATCHING PIRATES of the Caribbeanrecently got me thinking about a medical aspect of the Golden Age of Piracy. From 1680 to 1730, Blackbeard and his fellow pirates had to deal with the consequences of scurvy, a disease caused by a deficiency of vitamin C in the diet.
Scurvy, first described by Hippocrates, troubled sailors and soldiers without access to fresh fruit and vegetables. The Scottish naval surgeon Sir James Lind first described the effective treatment of scurvy with citrus fruits in A Treatise of the Scurvyin 1753. With increased awareness of the necessity of fresh fruits and vegetables in our diet, the rate of scurvy declined through the 18th century.
For many years, doctors presumed that scurvy was a rare finding in the developed world. But a 2008 study discovered that some 25 per cent of men and 16 per cent of women from low-income populations in the UK are vitamin C deficient. And in the US, research from 2004 found that 7 per cent of apparently healthy middle-class participants had low levels of vitamin C in their bodies.
Scurvy is caused by a deficiency of vitamin C (ascorbic acid), a nutrient found in citrus fruits, green vegetables, tomatoes and peppers.
Unlike many other animals, humans cannot synthesise the vitamin, so a deficiency, most often because of poor diet, can lead to abnormal collagen formation.
Without normal collagen, blood vessels become fragile and red blood cells can escape into the skin.
This leads to skin discoloration, a classic finding in scurvy. Other, early symptoms include fatigue, nausea and weight loss. Common clinical signs are gum swelling and bleeding, poor wound healing, and floccular hyperkeratosis, a condition caused by excess keratin around hair follicles that results in skin eruptions.
Scurvy can also present as bruising on the abdominal wall, gastro-intestinal haemorrhage, bleeding into the soft tissue and joints and haemorrhagic ulceration of the lower limbs.
It can take as little as one month after changing your diet to one that excludes sources of ascorbic acid for symptoms to begin. Blood concentrations below 20 µmol/L are associated with non-specific symptoms, such as fatigue, loss of appetite and irritability.
As concentrations drop further, bruising appears first in the buttocks and legs, probably due to the increased orthostatic pressure on the damaged blood vessels in the lower part of the body.
Smokers have greater vitamin C requirements than non-smokers, which predisposes them to scurvy.
Older people and those with an alcohol dependency are also more likely to develop the condition.
But as the recent research suggests, it is those in the lowest socioeconomic groups who are most at risk. Because fresh fruit and vegetables are more expensive than some processed foods, people on low incomes may avoid consuming fresh produce.
This is a feature that is likely to worsen as the recession bites and unemployment rises and could lead to a greater prevalence of vitamin C deficiency here.
A key to diagnosis is a well constructed dietary history. This is because some people with a vitamin C deficiency may have normal blood levels of ascorbic acid. But other lab results such as anaemia support the diagnosis; a careful physical examination looking for skin and other signs is also crucial.
Vitamin C is important in the absorption and metabolism of many nutrients that affect the production of red blood cells. For example, it helps the conversion of iron from the ferric to ferrous form, which is required for iron absorption from the gastrointestinal tract.
Because the response to treatment with vitamin C is so rapid, it is reasonable to try a course of treatment in those cases where the diagnosis may not be clear cut. Some patients report symptom improvement in as little as 24 hours, although it is usual to continue treatment with 300mg of vitamin C daily for a number of weeks. Adults require 40mg per day of vitamin C, an amount readily consumed as part of a balanced diet.
