I bought 4 bottles of betel nut from HerbsForever last year, to see if it would help. (60 capsules/450mg each capsule). I just followed the instructions as per dosage on the bottle. Was a bit frightened to take more.
With 'conversations' with Newport through posts, I believe that high dosages are required to be taken to kill large roundworms. I think you need to be careful when taking betel nut. Newport might be able to give you more info on betel nut if you want. You could try searching 'betel nut' through the forums, you should find some helpful posts.