Broccoli is high in vitamin C, as well as dietary fiber; it also contains multiple nutrients with potent anti-cancerproperties, such as diindolylmethane and small amounts of selenium.^[9] A single serving provides more than 30 mg of vitamin C and a half-cup provides 52 mg of vitamin C.^[10] The 3,3'-Diindolylmethane found in broccoli is a potent modulator of the innate immune response system with anti-viral, anti-bacterial and anti-cancer activity.^[11][12] Broccoli also contains the compound glucoraphanin, which can be processed into an anti-cancer compound sulforaphane, though the benefits of broccoli are greatly reduced if the vegetable is boiled.^[13] Broccoli is also an excellent source of indole-3-carbinol, a chemical which boosts DNA repair in cells and appears to block the growth of cancer cells.^[14][15]

Boiling broccoli reduces the levels of suspected anti-carcinogenic compounds, such as sulforaphane, with losses of 20–30% after five minutes, 40–50% after ten minutes, and 77% after thirty minutes.^[13] However, other preparation methods such as steaming,^[16] microwaving, and stir frying had no significant effect on the compounds.^[13]

Broccoli has the highest levels of carotenoids in the brassica family.^[17] It is particularly rich in lutein and also provides a modest amount of beta-carotene.^[17]

A high intake of broccoli has been found to reduce the risk of aggressive prostate cancer.^[18] Broccoli consumption may also help prevent heart disease.^[19]