Casimir Funk (1884-1967), Polish-born American biochemist, one of the first scientists to document the importance of vitamins. The word vitamin comes from vitamine, the term coined by Funk early in his research for the then-unknown substance in food that prevents vitamin-deficiency diseases such as beriberi, rickets, and scurvy.

Born in Warsaw, Poland, Funk received a doctorate in organic chemistry from the University of Bern, Switzerland, in 1904. He took a research position at the Pasteur Institute in Paris, France, then served as head of the biochemistry department at the Cancer Hospital Research Institute in London, England. In 1915 Funk immigrated to the United States where he held several industrial and university positions.

While at the Pasteur Institute in 1911, Funk demonstrated that a pigeon disease similar to beriberi, a human disorder, could be cured by feeding the birds shavings from polished rice. He also found that the antiberiberi property in this bird feed was amine, an organic compound derived from ammonia. The following year Funk suggested that beriberi, rickets, and scurvy were vitamin-deficiency diseases that could be prevented with vital amines, or vitamines. He reported his findings in a report, The Vitamines (translated 1922). Subsequent research showed that not all dietary substances essential to good health are amines, and the term was shortened to vitamins.

In 1936 Funk discovered the molecular structure of vitamin B₁, also known as thiamine, and developed a method for synthesizing it. He also conducted research on animal hormones and the biochemistry of cancer, diabetes, and ulcers, and devised improved methods for the commercial production of many drugs. He served as president of the Funk Foundation for Medical Research in Albany, New York, from 1940 until his death.