There is a whole lotta info going around on these lignan things.
I've read that soy phytoestrogens are 'free' and so wreak havoc on your health, and I've also read that they are 'directed' and so couldn't possibly do anything to you.
I've read that flax seed phytoestrogens are 'bonded' and so, because they aren't 'free' they are much safer. I've also read that flax phytoestrogens have been associated with cancer.
I've read that many popular brands of fish oil have dangerous levels of mercury and PCTs. I've also read that the levels of PCTs and mercury in most fish oil products adhere to legal standards and won't cause any harm.
As for most things, there's information both ways. So, read some stuff, make up your won mind, listen to your body.
Vary/limit/cycle your intake so you aren't exposing yourself to too much of anything potentially dangerous. Too much water can cause you harm - just something to think about.