He worked as a
pediatrician at the
Rockefeller University before going into private practice. He also worked at the
Beth Israel Hospital, New York, and at the
Hebrew Infant Asylum in New York, modernising the institution. He was able to study nutrition in patients who were admitted for long periods in those hospitals. Hess suggested that
rubella was caused by a
virus in 1914. He showed that the missing factor in scurvy was present in citrus fruits and tomatoes, also demonstrating that some dried milk preparations were anti-scorbutic and that
pasteurization reduced this effect in fresh milk. Along with Mildred Fish, he conducted studies between 1914 and 1920 to elucidate the etiology of scurvey by withholding orange juice from institutionalized infants until they developed hemorrhages as a result of the disease; he conducted similar studies to elucidate the etiology of rickets. His work led him to state that the process of food manufacture and preservation should aim to preserve the nutritional value of fresh food in his 1921 Harvey lecture, a concept widely recognised today. He determined that rickets could be prevented with cod liver oil or exposure to
ultraviolet light, and that certain foods could be used to treat rickets after exposure to
ultraviolet light. He ascertained that
cholesterol or a closely related compound also behaved in the same way, and he worked with
Adolf Otto Reinhold Windaus and published a paper with Windaus in 1927 entitled
Development of marked activity in ergosterol following ultraviolet irradiations, showing that rickets could be prevented in rats with irradiated
ergosterol. Windaus was awarded the
Nobel Prize in chemistry for this work in 1928. Windaus gave Hess credit for his part in the work, and shared the Nobel Prize money with him. Hess was a member of the American Pediatric Society and the
Association of American Physicians, and was awarded an honorary
Doctor of Science degree by the
University of Michigan. He was given the
John Scott Award by the
Franklin Institute in 1927, and the John Mather Smith Award in 1931. That same year, he was elected to the
American Philosophical Society. ==Personal life==