Bernhard Naunyn began his medical education at the age of 21 in Berlin. He received his medical degree 2 years later and, in 1863, took a position as assistant to Friedrich Frerichs, a renowned clinician in Berlin. In Frerichs' lab Naunyn was given considerable freedom and he developed a keen interest in metabolic pathology. Although primarily interested in clinical medicine Naunyn developed a reliance on the experimental laboratory in his attempts to understand disease and disease treatment. In his studies on "stomach fermentations" Naunyn recognized the contrafermentation property of benzene. He became curious about the effects of benzene on the patient and soon came to realize that humans excrete phenol after having received benzene. Curious about the fate of other hydrocarbons he collaborated with O. Schultzen, another of Frerichs' assistants and published a treatise entitled "the behavior of benzene-derived hydrocarbons in the animal organism". Following this excursion into metabolism research Naunyn concentrated on more traditional studies. Throughout his career he emphasized the application of science to medicine. He was head of a number of renowned clinics including Dorpat (1869-1871), Bern (1871-1872), Konigsberg (1872-1888), and Strasborg (1888-1904).
In 1898 Naunyn published his classic treatise Der Diabetes Melitus where he "counteracted the prevailing opinion of the supposed benefit of a high-protein diet in the treatment of diabetes melitus".1 Naunyn attributed his interest in metabolic pathology especially related to the liver, pancreas, and diabetes to the stimulation he received from Frerichs and his coworkers in Frerichs' clinic. Naunyn's memoir was published in 1925, the year he died.
Ref: Memoirs, Thoughts, and Convictions by Bernhard Naunyn Edited by David l. Cowen. Science History Publications, USA 1994. 1 Quoted from JAMA editorial, 208 p. 1183 (1969)