My magnesium and B-12 were recently checked and are okay. I have had an asymptomatic heart arrhythmia for years and I want to keep it that way. That is my concern about PPIs. ( My gastro Dr did not want me to stop the Nexium). Do you suggest that PPIs would be safe for me to use? And do you recommend that the max dosage for Zantac should not exceed 150 mg twice a day? Thank you.