Cr. Transition metal. Historically used to make medical instruments shiny and easier to clean. Still in there as a component of the stainless steels they tend to be made of now. Important as a source of dermatitis and used as a radioactive tracer in dilutional measurement of blood volume
Required as a trace element in metabolism and involved in a not very well-defined way with Insulin effect and carbohydrate metabolism.
Cr3+ is good, Cr6+ bad.
35mcg per day for men, 25mcg for women is suggested as a daily requirement by the US NIH and about this quantity is found in the usual intake. Chromium is added to iv feeds.