118 Vitamins
Eijkman believed that something in brown rice cured beriberi and wrote a report
claiming victory over the disease. He never considered looked at it the other way: that beriberi was caused by the absence of something that was present in brown rice.
Frederick Hopkins was an American medical researcher who was born as the Civil
War broke out in 1861. In 1900 he isolated an amino acid. (Other researchers had discovered two others before him but had not investigated their importance.) Hopkins called his
amino acid tryptophan. From a review of other research, he found that farm animals could
not be kept alive if their only sources of protein were things that included no tryptophan. No
matter how much protein they got, animals seemed to require trace amounts of tryptophan
to survive.
By 1906 chemists had isolated at least 13 amino acids. Each was an essential building
block of protein molecules. It occurred to Hopkins that these particular amino acids (which
were commonly found in foods) were essential to life. Not for the protein and calories they
provided; those could come from anywhere. There was something else these amino acids
provided that was essential to life—even if only supplied in trace amounts.
Hopkins reviewed Eijkman’s work and discovered that it was an amino acid in brown
rice feed that prevented beriberi. He found that it was not just fruit that prevented scurvy (as
first discovered by Lind in 1747). It was a particular amino acid in fruit.
Hopkins decided that diseases such as beriberi, scurvy, pellagra, and rickets were not
caused by a thing (a germ) but by the absence (o