I believe the medical profession finally decided a while back that not every one is sensitive to sodium when it comes to blood pressure. You have to determine whether or not you're sodium sensitive.
On the other hand, sodium does tend to make you retain water, does it not?
Also, some diet gurus advise against eating certain fermented foods, including soy sauce (and beer, dammit.)
Somebody correct me if I'm wrong, but I've heard that soy sauce is a western concoction. I believe tamari is actually used in the Far East. Same taste, but less salty and not as strong.
That's my contribution to soy sauce trivia.