I haven't read the Martha Christi book but I do follow a belief known as Shivambu which believes that spirit exists within the urine and the more you can recycle the less is lost from your body as apana or outflow. This aid's regeneration and recovery of your zest of life. I started off just small amounts mixing it with juices to make it taste better - now I generally average 8-10 glasses a day - 9 months down the track and I have a lot more energy, goto the gym sometimes 7 days a week and my marks at uni have improved. My hair is getting lighter plus some of the greys are dissappearing. Some people say I look younger.
Small amounts are beneficial but I think if you want to start recovering that zest of life the larger amount are the go. The smaller amounts are for the use of the antibodies and antigens that help with disease / viruses / bacteria that can be causing you problems.