Using prunes or prune juice as a Boron source?

Hello everybody,

My mom has been suffering from severe bone density loss and osteoporosis for few years now and recovering from each fracture is becoming harder and harder. The latest treatment she was on, with biologics Reclast, made her get serious infection so this treatment  had to be stopped. Until her next DEXA scan we’re thinking of trying more natural approach, by trying to strengthen her bones with supplements and one bit of information I need help with is finding out which one is better source of boron - dried prunes or prune juice. Oh, and if anyone has used prunes as a boron source, did you experience diarrhea as a side effect?

Thanks