There is no constant measurable current flow beyond the instant equalisation charge transferred to the body when a person makes bare skin contact with the ground or some type of Earthing product.
Once the body is grounded, the body will continue to absorb enough electrons needed to maintain the same electrical potential as the Earth and to restore what is lost as a result of metabolic processes. As long as a person continues to be grounded, the body can use the Earth as a natural reservoir/power-source from which to draw electrons to maintain a “topped up” homeostatic level that compensates for any loss of internal electrons.