The vital amines.
The word "vitamin," derived from the Latin "vita" and "amine," is in fact something of a misnomer since not all vitamins are amines. However, the very first vitamin, isolated by Casimir Funk in 1912, was indeed an amine and was given the name "thiamine." In the late nineteenth century, the mechanized rice mill was introduced in Asia. It produced attractive white rice, but it also produced a new disease that came to be called "beriberi." In the native language of Sri Lanka, beriberi means "weakness" and describes a condition of progressive muscular degeneration, heart irregularities and emaciation. Kanehiro Takaki, a Japanese medical officer, studied the high incidence of the disease among sailors in the Japanese navy from 1878-1883 and discovered that on a ship where the diet was mostly polished rice, among 276 men, 169 cases of beriberi developed and 25 men died during a nine-month period. On another ship, there were no deaths and only 14 cases of the disease. The difference was that the men on the second ship were given more meat, milk and vegetables. Takaki thought this had something to do with the protein content of the diet, but he was wrong.
About 15 years later a Dutch physician in the East Indies, Christiaan Eijkman, noted that chickens fed mostly polished rice also contracted beriberi but recovered when fed rice polishings. He thought that the starch in the polished rice was toxic to the nerves, but he was wrong. And that's when Funk entered the picture. The Polish-born biochemist determined that it wasn't something that was present in white rice that was the problem, it was something that was absent, namely the outer coating, the rice "hulls." Funk managed to show that an extract of rice hulls prevented beriberi and introduced the term "vitamine" for substances in food that could prevent specific diseases.
A short time later, E.V. McCollum and Marguerite Davis at the University of Wisconsin discovered that rats given lard as their only source of fat failed to grow and developed eye problems. When butterfat or an ether extract of egg yolk was added to the diet, growth resumed and the eye condition was corrected. McCollum suggested that whatever was present in the ether extract be called fat soluble "A," and that the water extract Funk had used to prevent beriberi be called water-soluble factor "B." When the water-soluble extract was found to be a mixture of compounds, its components were given designations with numerical subscripts. The specific anti-beriberi factor was eventually called vitamin B1, or thiamine. As other water soluble substances which were required by the body were discovered, they were added to the B vitamin list.
Other vitamins were subsequently identified and given the designations C, D and E in order of their discovery. Vitamin K was so called because its discoverer, the Danish biochemist Henrik Dam, proposed the term "Koagulations Vitamin" because it promoted blood coagulation.
Are there still unrecognized vitamins? Not likely. Patients have now been successfully kept alive for many years using only an intravenous formula that incorporates the known vitamins.
Joe Schwarcz is the director of McGill University's Office for Science and Society. Read his blog at chemicallyspeaking.com.
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|Publication:||Canadian Chemical News|
|Date:||Jan 1, 2013|
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