Feature: Forgotten Knowledge

SUNDAY, 7 NOVEMBER 2010

Scurvy is rarely seen in the Western world, but this has not always been the case. It was once a prevalent disease with no treatment, and its cause was a mystery. We now know that it is caused by a deficiency of vitamin C and can be prevented by a good diet. But in the course of history, this knowledge had to be discovered twice.

Scurvy can be easily treated by simply reintroducing vitamin C into the diet. Left untreated however, scurvy is inevitably fatal. Before the discovery of a cure, scurvy played a massive role in naval history. It was particularly prevalent in the age of sailing ships, when there were limitations on carrying fresh supplies of fruit and vegetables and long periods were spent on board ship. Ships rarely travelled far from port out of fear of the deadly disease. It was not unheard of for ships to return to port with 90 per cent of the crew having succumbed to scurvy.

In 1747, James Lind conducted what is probably one of the first examples of a formal clinical trial into the prevention of scurvy aboard ships. His work was based on that of Johann Bachstrom, who had noted in 1734 that scurvy was solely due to “a total abstinence from fresh vegetable food and greens”. Lind conducted his work whilst on board the British naval ship HMS Salisbury, where many of the crew were suffering from the effects of scurvy. He carried out his studies on 12 of the crew who had succumbed, subdividing them into pairs for the experiment. Isolating these six groups from the rest of the crew, he provided them with various treatments alongside their regular rations: these included cider, acid, seawater and lemons. At the end of the six-day trial, Lind had used the entire supply of fruit on board the ship, but his findings changed naval history. The pair of sailors who received the lemon supplement made a staggering recovery, while the health of all the other sailors in the trial deteriorated.

This study clearly showed that scurvy could be prevented by the addition of citrus fruit to the sailors’ diets. These findings were eventually adopted by the Royal Navy in 1790, 40 years after Lind’s discovery. The ability to cure scurvy gave the Royal Navy a massive tactical advantage during the Napoleonic wars. Ships were able to travel further from port for longer periods and hold blockades for years at a time. Unsurprisingly, other navies soon adopted a similar solution.

It seems shocking then that during Robert Scott’s 1911 expedition to the South Pole, one of the Royal Navy surgeons is recorded as saying: “There was little scurvy in Nelson’s days; but the reason is not clear, since, according to modern research, lime juice only helps to prevent it”. How was it that the crew, who were on an expedition at the beginning of the 20th century, did not know how to treat an ailment that had been successfully cured over 100 years earlier?

The loss of knowledge has been attributed to several factors. Firstly, Lind showed in his work that there was no connection between the acidity of the citrus fruit and its effectiveness at curing scurvy. In particular, he noted that acids alone (sulphuric acid or vinegar), would not suffice. Despite this, it remained a popular theory that any acid could be used in place of citrus fruit. This misconception had significant consequences.

When the Royal Navy changed from using Sicilian lemons to West Indian limes, cases of scurvy reappeared. The limes were thought to be more acidic and it was therefore assumed that they would be more effective at treating scurvy. However, limes actually contain much less vitamin C and were consequently much less effective. Furthermore, fresh fruit was substituted with lime juice that had often been exposed to either air or copper piping. This resulted in at least a partial removal of vitamin C from the juice, thus reducing its effectiveness.

The discovery that fresh meat was able to cure scurvy was another reason why people no longer treated the condition with fresh fruit. This discovery led to the belief that perhaps scurvy was not caused by a dietary problem at all. Instead, it was thought to be the result of a bacterial infection from tainted meat. In fact, the healing properties of fresh meat come from the high levels of vitamin C it contains.

Finally, the arrival of steam shipping substantially reduced the amount of time people spent at sea, therefore the difficulties in carrying enough fresh produce were reduced. This decreased the risk of scurvy so that less effective treatments, such as lime juice, proved effective enough to deal with the condition most of the time. Unfortunately, this meant that knowledge of the most effective treatment for scurvy was gradually lost.

It was not until 1907 that Axel Holst, a professor of hygiene and bacteriology at the University of Oslo, and a paediatrician named Theodor Frølich, rediscovered the lost cure for scurvy. They became interested in a disease called beriberi, which is now known to be caused by a thiamine (vitamin B1) deficiency. They used guinea pigs to test their hypothesis that beriberi was the result of a nutritional deficiency. Their decision to use guinea pigs was crucial; apart from humans and other primates, most animals are able to synthesise vitamin C themselves. Guinea pigs – by chance – cannot, and although they did not develop beriberi, they did develop the symptoms of scurvy. Had Holst and Frølich chosen almost any other animal, they would not have discovered that guinea pigs develop scurvy when fed on a diet of just grain.

Holst and Frølich went on to show that they could prevent scurvy by simply feeding the guinea pigs lemon juice, something that Lind had shown a century and a half earlier. While their original publication on these results was not well received (since the idea of nutritional deficiencies was seen as something of a novelty at the time), the model they had developed with guinea pigs was vital to subsequent work on scurvy and vitamin C.

The work of James Lind on board the HMS Salisbury will no doubt forever be remembered in the history books as a great turning point in science, while the loss of that knowledge continues to be overlooked. The cost of those mistakes to human lives may be firmly in the past, but the tale still holds relevance within the modern world. Time and again during the history of scurvy, individuals put their own agendas and beliefs ahead of scientific results, the consequences of which should not be forgotten.

Andrew N Holding is a postdoc at the MRC Laboratory of Molecular Biology