Monday, 23 January 2012

IMFW: Avast, Ye Scurvy Dogs!

Today's Interesting Medical Fact of the Week is about scurvy! Everyone's favourite pirate-borne illness, caused by a lack of vitamin C. Humans and other higher primates share with guinea pigs and bats the dubious distinction of being some of the few animals to suffer from the disease; most other animals can synthesize their own vitamin C, but we don't produce the necessary enzyme. Consequently, although we always think of fruit and vegetables as the only cure for scurvy, in fact simply eating the meat of any animal which produces its own vitamin C can prevent scurvy occurring and will have enough vitamin C to partly treat the illness. Some organs will contain more vitamin C than others; liver and parts of the central nervous system are particularly high in vitamin C. So if you're stuck on a boat in the middle of the ocean, don't fret about finding lemons - just eat a passing seal. If it's vitamin C you need, though, raw is better than cooked. Yum.

Although the benefits of citrus fruits for scurvy had been suggested time and again by various people, it was James Lind who publicly established that scurvy could be treated through eating citrus fruit in 1747, in what has been described as the "world's first clinical trial"... although that might be taking it a bit far. On a voyage, he divided up twelve scurvy sufferers into 6 groups, and treated each group with a different dietary supplement daily. They all received the same diet but in addition, group one were given cider, group two sulfuric acid, group three vinegar, group four half a pint of seawater (poor group four), group five a daily lemon and two oranges, and group six were given barley water and some kind of spicy paste. He ran out of citrus fruit after just six days, but by that time one of the sailors in group five was restored to health and the other had significantly improved; the only other group to show any improvement was group one. He published his results with a general review of the theories behind the disease in 1753 in A Treatise of the Scurvy.

Lind was a bit of a legend; one of his recommendations when still trying to work out what caused scurvy was for the Navy to grow watercress on big wet blankets on-board ship (watercress is very high in vitamin C); a recommedation which was actually taken up in 1775 and Navy ships were provided with seeds.

Scurvy was only really eradicated from the Royal Navy in the 1790s when the suggestions of Lind and others that lemon juice be used on ships was finally taken up by Gilbert Blane, a Scottish doctor who instituted several health reforms in the Navy. The health of sailors improved significantly as a result, making lemons (and later, limes) an important factor in British successes in the Napoleonic wars.

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