I add it primarily to the boil. Essentially, this stuff is a silicone based product that prevents bubbles from persisting (an antisurfactant). It was developed in the 1950's and has been long-since proven as food safe. The best part is that normally this stuff drops out of the wort quickly, but the boil keeps it in suspension. So while you are boiling, it does its magic. When the boil is done and you cool it, it drops out into the break material and you can siphon off it.
Same thing in the fermenter. You can prevent blow-offs by adding a bit to the fermenter. The active fermentation churning around in your vessel keeps the stuff in suspension, and it prevents the formation of persistent krausen formation. Once fermentation ceases, the stuff drops out into the trub.
Regardless, you can ingest the stuff with no harm to your body. They actually use this stuff to make anti-gas pills for people with bloating or gas problems. Very safe.
It also will not hurt your head retention on your finished beers (in fact, there are some theoretical reasons why it might actually improve it).
Magic stuff, right up there with Star-San and 5.2 stabilizer. But I guess those might be considered cheating too!