Vegetables contain unknown compounds with important health promoting effect. The described project defined and tested a two-step screening procedure for identification of such compounds. Step 1 is initial screening according to three criteria: 1.1, chemically reactive functional groups; 1.2, toxicity at high concentrations or other bioactivity; and 1.3, presence in healthy foods. Step 2 is testing for minimum criteria defining health-promoting compounds: 2.1, positive or biphasic ("hormesis") responses in bioassay; 2.2, human tissue concentrations corresponding to beneficial effects in bioassay; and 2.3, possibility to control content in food. Falcarinol from carrots fulfilled all 6 criteria and subsequently showed anticancer effect in rats.