Assertion: vitamin d's form | /r/HasProperty | controlled
Facets:
value: tightly
type: MANNER
Source sentences:
text: Both D3 and D2 precursors are transformed in the liver and kidneys into 25-hydroxyvitamin D, the non-active “storage” form, and 1,25-dihydroxyvitamin D, the biologically active form that is tightly controlled.