Some studies have shown issues with mice who took the supplement form, but the negative effect hasn’t been shown in a human study, yet.
I ain’t afraid of cancer...I had broccoli for lunch. Broccoli kills cancer. A lot of people don’t know that, it’s not out yet. It’s true. You find out you got some cancer...(click) get yourself a bowl of broccoli. That’ll wipe it right out in a day or two.
Cauliflower too. Cauliflower kills the really big cancers. The ones you can see through clothing from across the street. Broccoli kills the little ones. The ones that are slowly eating your way from inside...while your goofy, half- educated doctor keeps telling you, “your doing fine Jim.” In fact bring your doctor a bowl of broccoli. He’s probably got cancer too.
-George Carlin

https://en.wikipedia.org/wiki/Cruciferous_vegetables
Cruciferous vegetables are vegetables of the family Brassicaceae (also called Cruciferae) with many genera, species, and cultivars being raised for food production such as cauliflower, cabbage, kale, garden cress, bok choy, broccoli, Brussels sprouts, mustard plant and similar green leaf vegetables. The family takes its alternative name (Cruciferae, Neo-Latin for “cross-bearing”) from the shape of their flowers, whose four petals resemble a cross.
FULL LIST AT LINK..................