K. D. Schwenke, Teltow

According to Liebig’s understanding of the metabolism, ’plastic food‘ is first converted into organic components of blood and then of tissue and subsequently degraded to urea by several oxidations. To him, the nitrogen content of urine hence reflected the metabolic intensity.

Liebig hoped to learn about actual changes in matter in vivo from reaction-induced changes in compounds produced by the organism, such as uric acid and urea. He was convinced that chemical formulae could be a means of getting insight into metabolic processes. Despite its speculative nature this idea was of some heuristic help to research as it illustrated certain physiological processes. The understanding of physiological processes included the existence of a vital force which is ’bound to explorable laws‘ and which emerges from the specific organization of atoms (actually molecules) of complex (macromolecular) compounds.

In the disputes of Liebigs’s animal chemistry many of his speculative ideas, including those of force (muscle force) being generated by protein degradation, or of a transferability of chemical models to complex metabolic processes, were rejected. Some fundamental ideas of Liebig’s animal chemistry, however, have become a lasting part of physical and clinical chemistry. They were essential for the development of dietetics into an independent scientific discipline. EU03/03

Keywords: Justus von Liebig / Animal Chemistry’/ nutrition science / science history

Sie finden den Artikel in deutscher Sprache in Ernährungs-Umschau 03/03 ab Seite 102.