Should I believe it?
Well, that is a good question. I would say it is up to your decision. I just passed by the good articles online and share it to everyone but cannot guarantee anything.
The result of oil pulling is claimed in many articles are fascinating but I am, as the author, cannot guarantee that this method is going to work as expected. At least you should not use this method, if you are in risk or find yourself allergic to the oil or any substances in the oil.
Before you decide whether you should do this oil pulling, you can find more information on the link below.
http://en.wikipedia.org/wiki/Oil_pulling
http://www.oilpulling.com
www.youtube.com/watch?v=SaCJW5wpRSU
www.guideforselfhealing.com/2007/06/05/how-to-do-oil-pulling