It's important to note that the calmness is thought only to occur with people who did not receive sufficient androgen in the womb to develop a properly "male" brain.  If you do not come into this category, then estrogens or phytoestrogens are likely to cause anxiety.
I don't say that this is the case, just something to watch out for.
Incidentally, as Flamesabers has indicated, we are all different, but in my case, it takes about 3g/day to keep me calm and relaxed, on average.  Best to work your way up to that dose, unless you feel lucky!
B.