Current societies include an unarguable degree of toxicity toward aspects that are related to the human organism. So, having a toxicity rate, the rational precaution is to apply another for detoxification. Several elements cannot be eliminated with the usual habits and the organism acts day after day like a storage unit, increasing the probability of experiencing health problems.
The clay action has a scientific explanation and a chance of success while it doesn't have side-effects if the user follows the necessary precautions. Some specific kind of clay has micro particles that absorb certain elements. Like activated carbon, they have the ability to be like a magnet and help the organism in the task of eliminating residues. That's the theory.
This technique is used at hospitals in cases of intoxication, normally with activated carbon. Like another ones, this is a tool that could help. It seems that these properties of different clays were used in other times, and for sure also in the current state of the evolution. It shouldn't be too risky to give it a try!
Some detailed info here.