David Rittenberg (November 11, 1906 – January 24, 1970) was an American biochemist who pioneered the isotopic tagging of molecules.

[3] His introduction of the use of 2H[4] as a tracer to follow the fate of various different compounds in human metabolism changed the prevailing scientific theory, from a static, "wear and tear" view of metabolic processes, to a dynamic theory in which there is constant and rapid buildup and degradation of body constituents.

In their Biographical Memoir[1] David Shemin and Ronald Bentley described the approach in these terms: The metabolites containing 2H had properties essentially indistinguishable from their natural analogs by the methods commonly used.

Subsequent developments have shown that they were true prophets.From 1935 onwards Schoenheimer and Rittenberg published a long series of papers in the Journal of Biological Chemistry on the general topic of 2H as an indicator in the study of intermediary metabolism, starting with a general introduction to the topic,[5] and continuing to 1938 with a study of hydrogen in amino acids.

[6] From 1939 onwards Schoenheimer and Rittenberg continued on the same road with a further long series of papers in the Journal of Biological Chemistry on protein metabolism, starting by describing some general considerations.