Harry Steenbock (August 16, 1886, Charlestown, Wisconsin – December 25, 1967, Madison, Wisconsin) was a Professor of Biochemistry at the University of Wisconsin–Madison. Steenbock graduated from Wisconsin in 1916, where he was a member of Phi Sigma Kappa fraternity.
Steenbock was born in Charlestown, Wisconsin and grew up on a model farm outside New Holstein, Wisconsin. His graduate advisor at the University of Wisconsin–Madison, was Edwin B. Hart. His first publication reported the results of the single-grain experiment on which he assisted with Hart and Stephen Moulton Babcock. During his graduate career, Steenbock also served as an asistant in the lab of Elmer McCollum. When McCollum and another assistant Marguerite Davis published their discovery of what came to be called vitamin A, Steenbock thought he deserved more credit than he received. Steenbock carried on the vitamin A work in Madison, after McCollum accepted an offer from Johns Hopkins University.
In 1923, Steenbock demonstrated that irradiation by ultraviolet light increased the vitamin D content of foods and other organic materials. After irradiating rodent food, Steenbock discovered that the rodents were cured of rickets. It is now known that vitamin D deficiency is a cause of rickets.
Using $300 of his own money, Steenbock patented his invention. Steenbock's irradiation technique was used for food stuffs, but most memorably for milk. By the expiration of the patent in 1945, rickets had all but been eliminated.