An ionic foot detox is said to work by pulling the toxins out of your body through your feet. Take, for example, the popular foot detox bath IonCleanse. Advertised as a safe and relaxing way to clear out the body, the ionizing machine works to ionize the foot bath water.
This process is said to give the hydrogen in the water a positive charge. The positive charge is said to attract the negatively charged toxins in your body. The ions in the foot bath water supposedly hold a charge that enables them bind to any heavy metals and toxins in your body, similar to how a magnet works. This allows the toxins to be pulled out through the bottoms of your feet.