I'm gonna call scam on this one. Just like how pills won't grow you a bigger dick, they're not going to shrink parts either lol
The only natural way I've seen anyone seemingly reduce the size of their boobs has been to get ripped at the gym. Female body builders (who aren't taking any steroids) seem to have a redistribution going on and the fact their pecs get more muscly always seems to lessen everything else.
Also, strength building workouts are a natural way to elevate hormones like like T. Also a quick Google search brought this up
http://ifitandhealthy.com/how-to-increase-testosterone-levels/ Plenty of foods also have estrogen in them. Soy especially (and soy is in damn near everything these days). Researchers are finally starting to link up increased instances of some cancers to a proliferation of soy in the body. Even some men are coming down with breast cancer because of too much estrogens in their bodies.