Sulforaphane is an isothiocyanate produced when the enzyme myrosinase in cruciferous vegetables acts on glucoraphanin. This enzyme reaction requires mechanical disruption of the plant cell, which is why chopping or chewing cruciferous vegetables is necessary before cooking for maximum sulforaphane production. Brief blanching after chopping preserves myrosinase activity; boiling before chopping destroys it.
The Mechanisms of Cancer Cell Suppression
- Nrf2 pathway activation: sulforaphane is the most potent known dietary activator of Nrf2, the master regulator of antioxidant and detoxification gene expression; Nrf2 activation induces over 200 genes involved in cellular protection
- Phase II enzyme induction: sulforaphane induces glutathione S-transferase and other phase II enzymes that conjugate carcinogens for excretion before they can damage DNA
- Cancer cell apoptosis: in cell and animal studies, sulforaphane induces programmed cell death in cancer cells while leaving normal cells unharmed; the selectivity is due to higher oxidative stress in cancer cells
- Epigenetic modification: sulforaphane inhibits histone deacetylase enzymes, reactivating silenced tumour suppressor genes in cancer cells
- Anti-angiogenesis: inhibits the formation of blood vessels that feed tumour growth
Broccoli Sprouts: The Concentrated Source
Broccoli sprouts contain 20 to 50 times more glucoraphanin than mature broccoli. Two tablespoons of fresh broccoli sprouts provide as much sulforaphane as 250 grams of broccoli. NutritionFacts.org reviews research suggesting that broccoli sprouts represent one of the most cost-effective anti-cancer dietary interventions available. They can be grown at home in a jar in 4 to 5 days.