Is Pomegranate & Acai juice ok with blood pressure medications?

I am taking a betablocker called Coreg & ACE Inhibitor called Benicar . I was wondering if drinking those juices will interact with my medications. Don't ask me to ask that to my doctor because they know nothing about those juices. They knkow nothing about supplements or herbs so I wonder why they always say : "please check with your doctor before taking this supplement " LOL