A carotenoids, vitamin C and vitamin K. Isothiocyanates are a class of compounds recently identified at Johns Hopkins University as being one key to the anticancer properties of cruciferous vegetables. The most active isothiocyanate is sulfor-aphane. Fresh, commercial broccoli has widely varying amounts of isothiocyanates and sulforaphane, depending on the plant strain, growing methods and time of harvesting. Also, the absorption and utilization of these compounds can be hampered by poor preparation or digestion. Indoles are another key to anticancer activity.
Broccoli helps prevent stomach and colon cancer, as do other members of the cruciferous family.