Beet juice has always been one of the stars of any sort of vegetable juice therapy, along with carrot and celery. You never want to drink it without mixing with another juice, usually carrot, to soften the blow.
I had an uncle get tremendous relief from an unbelievably bad and crippling case of rheumatiod arthritis by drinking mix of carrot, beet, and celery juice every day. It didn't cure him by any stretch but it sure gave him far greater mobility.