Broccoli Can Damage And Kill Cells
Sulforaphane is actually a double-edged sword, because it has been scientifically proven to kill cancer cells. However, a major problem with the substance is that it also kills healthy cells, similar to the same result as receiving chemotherapy.
Consuming broccoli can do these things to your cells:
Poisons mitochondria (cell energy generators)
Disrupts epithelial barriers (can poke holes in sheets of cells)
Depletes glutathione levels (the most important antioxidant inside our cells)
Inhibits microsomal enzymes in the endoplasmic reticulum (cellular manufacturing and detoxifying centers)
Sources:
https://en.wikipedia.org/wiki/Broccoli
http://www.diagnosisdiet.com/is-broccoli-good-for-you
http://healthyeating.sfgate.com/broccoli-bad-thyroid-9761.html