Sulforaphane-nitrile is the dominant metabolite in human plasma following broccoli sprout consumption, is excreted more slowly than sulforaphane-derived dithiocarbamates, has a half-life of approximately 9.9 hours compared to 2.7 hours for dithiocarbamates, and results in prolonged systemic exposure without corresponding bioactivity in prostate cells.

When broccoli sprouts are eaten, gut bacteria break down a compound called glucoraphanin into either an active form that triggers cellular defenses or an inactive form that stays in the blood for days. The inactive form, sulforaphane-nitrile, does not interact with key cellular targets that turn on protective genes or block cancer-related enzymes, so even though it lingers in the body, it does nothing to protect cells. The active form is quickly cleared, but the inactive form builds up and remains for much longer.