Explain the Urinary excretion of Ascorbic Acid?

The urinary excretion of ascorbic acid falls when the dietary intake is low. Since the tissues are not saturated, a greater part of the test dose of ascorbic acid will be retained by the tissues and only a small part will be excreted in urine. In contrast, when the daily intakes are high, a greater part of the test dose will be excreted. A normal saturated person excretes 50 percent of the test dose while a person on a deficient diet excretes only about 35 percent.