다잖아

'They say so, you know'

-다잖아 quotes what people say and leans on it as a reason: 엄청 스트레스가 제일 안 좋다잖아 'they say stress is the worst thing for you.' The speaker treats the report as common knowledge the listener ought to accept. Its near neighbour -대잖아 does the same job in a shorter contraction; the difference is in the shape of the quoted verb, not the meaning.

Register: casual