Friday, April 4, 2008
SCIENCE- Vitamins and Diet (Part II)
In part one of our series on vitamins we saw how the voyages of discovery uncovered a hitherto unknown scientific fact about diet- that not getting enough of certain types of foods led to disease. No longer was diet simply a matter of getting enough to keep from starving. Suddenly what you ate could be as important as how much there was to eat. One such dietary disease, scurvy, almost incapacitated the British navy by the end of the 18th century and forced the addition of limes to the diet of the British sailor. Brits are referred to as limeys to this day as a result. They had solved the problem but they still didn’t know why it had happened in the first place.
It wasn’t only the British navy that had problems with disease related to being ship bound. By the second half of the nineteenth century Japan was modernizing and attempting to develop as a maritime power. Japanese sailors didn’t get scurvy. Their diet of fish, rice, and fresh vegetables prevented this from becoming a problem. What they did get was beri-beri. A disease characterized by nerve damage that caused severe weakness and eventually death. (The name comes from a Sri Lankese term for “very weak”) By the 1880s almost a third of the Japanese navy was suffering from beri-beri and, as you can well imagine, this was a cause for some concern among the commanders. The Director General of the Japanese navy was a bright fellow named Kanehiro Takaki who noticed that other navies, such as the British, didn’t have this problem. He also noticed that his officers didn’t suffer from the disease in the numbers that the average sailor did. (See a trend shaping up here?) He was quick to catch on to the fact that it might have something to do with the difference in diet between the officers and regular sailors, since the officers diet was far more varied. Taking a page from the Brits, he introduced meat, evaporated milk and barley to the sailors diet and the beri-beri disappeared. Now science had been marching forward since the voyages of discovery and it was now common knowledge that food was not “just food”. It had been discovered that food was composted of proteins, fats, and carbohydrates. Takaki incorrectly surmised that a lack of sufficient protein had been the problem. And since he was in charge, that was that.
But just like scurvy, beri-beri continued to be a problem among populations on land. (Even today it kills thousands of people and we know what causes it.) An epidemic of beri-beri was occurring in the Dutch East Indies (what we now call Indonesia) and prompted the Dutch government to send a group of physicians to deal with the problem in 1886. By this time the germ theory of disease was all the rage (having been first stated by Agostino Bassi to explain muscardine disease in silkworms in 1835) and one of these doctors, a fellow named Christiaan Eijkman decided some germ must be the cause. To test his hypothesis he brought with him a group of chickens to use as experimental animals. His idea was to breed the chickens, infect them with the disease, isolate the germ involved, and hopefully formulate an antitoxin that could be used on the human populace. This, however, was a total failure. Try as he might he was completely unable to infect the chickens with beri-beri. So he gave up.
And then, a little while later, the chickens came down with beri-beri.
Well, perhaps not actual beri-beri. What they had contracted was a very similar disease called Avian Polyneuritis but this didn’t deter Eijkman since he knew that beri-beri was also a form of polyneuritis. He immediately set about trying to infect other chickens, isolate the germ involved and create an antitoxin. This, however, was again a total failure.
And then to add insult to injury, the chickens got better on their own.
But being a good scientist, Eijkman was not married to his original hypothesis, He realized that if the chickens had gotten sick and then well without the normal signs of infectious disease he must be dealing with something else entirely. He set about to find out what variable in the chicken’s environment had changed that might coincide with their changes in health. Finally he tracked it down.
The hospital he worked in had a new cook.
It seemed that the previous cook had taken to feeding the chickens the leftovers of the human residents of the hospital. And the chickens started getting sick. When the new cook had taken over he had put them back on their old diet they had gotten better. What was the difference? The residents diet was heavy on polished white rice. The same thing that the Japanese sailors had gotten sick eating. Natural rice comes with an oily husk. The oils in that husk become rancid over time so to preserve the rice the hulls are “polished” away, leaving smooth white grains that can be preserved for long periods of time if kept dry. Making it an ideal foodstuff to take on a long sea voyage in which there is no refrigeration. When the new cook had arrived he decided that human food was too good for the chickens and started feeding them rice with the husk on again. As a result, they had gotten better. Just as the Japanese sailors had when barley was substituted for the white rice in their shipboard diet.
And here’s where Eijkman made one of those great intuitive insights that science depends on from time to time. He reckoned that if germs weren’t the culprit, and that something in the diet was responsible but not something commonly known as a staple of life- fats, carbohydrates, or protein, then it must be some trace of another substance that was necessary for life. It was widely known that traces of some substances were deadly if ingested in even small amounts. Arsenic was one such deadly trace substance. They were called poisons. There must be some poison in the white rice which something in the hulls neutralized.
Unfortunately this insight was completely wrong. But the idea that there were traces of poison in common foodstuffs and traces of antidotes to those poisons in parts of the very same foodstuffs set off a flurry of scientific experimentation.
Suffering from ill health himself Eijkman left Indonesia soon after this but an associate of his named Gerrit Grijns was finally able to put the pieces together. In 1901 he published a paper that stated the rice hulls were not an antidote for a toxin in the rice but rather contained something that was itself essential for life.
This was a revolutionary idea. There were traces of something in the diet that humans could not live without. It was the beginning of the idea of a “balanced diet”. It didn’t take long for the idea to catch on like wild fire. If Beri-beri was a deficiency disease, then it was logical that Scurvy was as well, In 1906 English biochemist Fredrick Hopkins suggested that Rickets was also a deficiency disease. Six years later, in 1912, Polish biochemists Casimir Funk would add the disease Pellegra to the list of diseases caused by dietary insufficiency. All this would pay off with the grand prize of science when in 1929 Hopkins and Eijkman would share the Nobel Prize for their discovery of the nature of trace elements in diet and health.
But what were these needed but unknown dietary supplements?