According to Daniel Reid, author of The Tao of Detox, magnesium sulfate, commonly known as Epsom salts, is rapidly excreted through the kidneys and therefore difficult to assimilate. This would explain in part why the effects from Epsom salt baths do not last long and why you need more magnesium sulfate in a bath than magnesium chloride to get similar results. Magnesium chloride is easily assimilated and metabolized in the human body.[i] Epsom salts are used by parents of children with autism because of the sulfate, which they are sometimes deficient in; sulfate is also crucial to the body and is wasted in the urine of autistic children.
Dr. Jean Durlach et al, at the Université P. et M. Curie, Paris, wrote a paper about the relative toxicities between magnesium sulfate and magnesium chloride. They write, “The reason of the toxicity of pharmacological doses of magnesium using the sulfate anion rather than the chloride anion may perhaps arise from the respective chemical structures of both the two magnesium salts. Chemically, both MgSO4 and MgCl2 are hexa-aqueous complexes. However MgCl2 crystals consist of dianions with magnesium coordinated to the six water molecules as a complex, [Mg(H2O)6]2+ and two independent chloride anions, Cl-. In MgSO4, a seventh water molecule is associated with the sulphate anion, [Mg(H2O)6]2 +[SO4. H2O]. Consequently, the more hydrated MgSO4 molecule may have chemical interactions with paracellular components, rather than with cellular components, presumably potentiating toxic manifestations while reducing therapeutic effect.”
MgSO4 is not always the appropriate salt in clinical therapeutics.
MgCl2 seems the better anion-cation association to be used in many clinical and pharmacological indications.[ii] Dr. Jean Durlach et al
These researches also studied ionic fluxes in the two directions between the mother and the fetus. They found that there was a greater positive effect when MgCl2 was used and that MgSO4 could not guarantee the fetal needs in sodium and potassium exchange like MgCl2 could. Dr. Durlach summarized saying, “MgCl2 interacts with all exchangers while the interaction of MgSO4 is limited to paracellular exchangers, and MgCl2 increases the flux ratio between mother to fetus while MgSO4 decreases it.”
Dropping levels of magnesium during pregnancy leads to premature contraction and this has been treated by allopathic medicine mostly with magnesium sulfate. But high-dosage, tocolytic magnesium sulfate administered to pregnant women during preterm labor can be toxic, and sometimes lethal, for their newborns.[iii] A Medline’s search found MgSO4 had 53 reports of its use in prematures,[iv] whereas MgCl2 had only 4 papers of its use. The paper sited just above showed the results of sever overdose of the mothers, 50 grams or more of MgSO4. Clearly too much is toxic, but other studies show safety and efficacy at lower doses. Magnesium sulfate given to women immediately before very preterm birth may improve important pediatric outcomes. No serious harmful effects have been seen at lower dosage levels.
Chloride is required to produce a large quantity of gastric acid each day and is also needed to stimulate starch-digesting enzymes. We may use magnesium as oxide or carbonate but then we need to produce additional hydrochloric acid to absorb them. Many aging individuals, especially with chronic diseases who desperately need more magnesium cannot produce sufficient hydrochloric acid and then cannot absorb the oxide or carbonate.
Sulfate is also important and has an influence over almost every cellular function. Sulfate attaches to phenols and makes them less harmful, and sets them up for being excreted from your kidneys. A lot of these potentially toxic molecules are in food. Sulfate is also used to regulate the performance of many other molecules. Many systems in the body will not function well in a low-sulfate environment. Sulfur is so critical to life that the body will apparently borrow protein from the muscles to keep from running too low.
Though magnesium sulfate will save your life in emergency situations as quickly and easily as magnesium chloride, magnesium chloride fits the bill as a universal medicine, magnesium sulfate does not. Magnesium sulfate is a close cousin whose effect, form and toxicity demands it be used in special applications when the sulfur is needed.
...."both magnesium as well as chloride have other important functions in keeping us young and healthy. Chloride, of course, is required to produce a large quantity of gastric acid each day and is also needed to stimulate starch-digesting enzymes. Magnesium is the mineral of rejuvenation and prevents the calcification of our organs and tissues that is characteristic of the old-age related degeneration of our body.
Using other magnesium salts is less advantageous because these have to be converted into chlorides in the body anyway. We may use magnesium as oxide or carbonate but then we need to produce additional hydrochloric acid to absorb them. Many aging individuals, especially with chronic diseases who desperately need more magnesium cannot produce sufficient hydrochloric acid and then cannot absorb the oxide or carbonate. Epsom salt is magnesium sulphate. It is soluble but not well absorbed and acts mainly as a laxative. Chelated magnesium is well absorbed but much more expensive and lacks the beneficial contribution of the chloride ions. Orotates are good but very expensive for the amount of magnesium that they provide and both orotates and chelates seem to lack the infection-fighting potential of the magnesium chloride.".... Where to buy Magnesium Chloride