Thomas Burr Osborne (August 5, 1859 – January 29, 1929) was an American biochemist who, with Lafayette Mendel, independently discovered Vitamin A,[1] though Elmer McCollum and Marguerite Davis were ultimately given credit, as they had submitted their paper first by three weeks.

Osborne, who developed methods for their isolation and purification, by means of which he discovered the chemical differences in proteins of various plants.

"[9] The American chemist Thomas B. Osborne was (viewed retropectively) head and shoulders above most of his contemporaries: compulsive attention to meticulous purification, reproducibility, error analysis, etc.

In their early work, they studied the deadly poison ricin which is classified as a type 2 ribosome inactivating protein (RIP) from castor beans.

At the Connecticut experimental station they developed a lab with about 200 rats whose dietary intake was carefully controlled.

Baker:[12] The science of nutrition thus evolved beyond the caloric energy of food, turning to the structural issue of essential amino acids.