A little personal note here:
I've been taking herbs to support my liver and kidneys, not as a twice yearly cleanse as I usually do, but as daily support for my organs and have noticed a marked difference, even in just two weeks.
Herbs I am taking daily are milk thistle (for liver) and several kidney supporting herbs as well. These include:
Uva Ursi
Buchu Leaves
Celery seed
Parsley
In the two weeks that I have been taking these herbs daily, my skin has become clearer and softer, less splotchy, eczema has completely cleared up. Also frequent urination, which I have had almost my whole life, that I had become accustomed to, (thought I just had a small bladder) seems to have been cured. I can go to bed at night and not have to wake several times for a bathroom break. This is a welcome and unexpected side effect of the kidney herbs.
So a little personal evidence to support the research already presented. I can't recommend these herbs strongly enough -- invaluable preventive medicine!