A composition is described for the delivery of known and measurable quantity of agents derived from glucoraphanin and/or glucoraphanen used to induce in-vivo production of chemoprotective compounds. The composition comprises an extract from a first brassicaceae plant source comprising at least one glucosinolate compound (such as glucoraphanin and/or glucoraphanen) along with a myrosinase enzyme derived from a second brassicaceae plant source. The composition can be used in capsules or in foods such as biscuits, muesli bars or cereals to induce