Apparently it can also among other things help out with Mercury poisoning protecting you from it! I just found this out today.

http://altmedicine.about.com/od/herbsupplementguide/a/tulsi.htm

There is alot more on it, I just found this part interesting.

In Sanskrit, tulsi means literally "the incomparable one" and has been revered since ancient times. Tulsi, the holy basil, is said to have grown at the site of Christ’s crucifixion and is associated with St. Basil’s feast.