Possible bradycardia reasons??

What do you think is the greatest possible reason that causes bradycardia or very slow pulse rate, less than 60 a minute. Some doctors say that deficiency of some minerals and vitamins is the reason while some suggest it is because of drug side effect other than the reasons of stress, lack of exercise or structural defects. Please reply.
Source: Doc2Doc BMJ Cardiology - Category: Cardiology Authors: Source Type: forums