I took Primal Defense for a while. I'm not sure how much it helped, but it didn't cause me any problems. Something to keep in mind- it's got iron in it. I'm on Cipro at the moment, and they suggest that you take Primal Defense on an empty stomach. I gave up, because I just couldn't find a time to take the pill that was more than 6 hours before or 2 hours after the Cipro, have an empty stomach, and conveniently remember to take it.
I do like the fact that it's shelf stable, and if it weren't for the warnings about mixing iron suppliments with Cipro, I'd still be taking it.