I am not an expert but it seems to me that it is probably the magnesium in Epsom Salts is what causes those muscles to relax and expand. So if this drink has magnesium, I would imagine it would be the same. I am kind of skeptical on this part of the flush. If you drink the oil and the whole organ is contracting forcefully, I find it hard to believe that anything in that area would be "relaxed". I may be wrong though.
To me, the Epsom Salts seem like they would grease the skids so to speak in the digestive tract so all that gunk flow out faster.