Glycerophosphates are the salts of glycerophosphoric acid, H₂[C₃H₅(OH)₂]PO₄. This acid is produced by the interaction of glycerin and phosphoric acid. In general, only sodium glycerophosphate, Na₂[C₃H₅(OH)₂]PO₄ + 5-1/2H₂O, and calcium glycerophosphate, Ca[C₃H₅(OH)₂]PO₄ + H₂O, are used in medicine, though the glycerophosphates of lithium, potassium, manganese, magnesium, iron, quinin and strychnin are claimed as constituents of proprietary preparations. At a time when certain disorders were assumed to be due to a deficiency of phosphorus in the nerve structure in the body, glycerophosphates were introduced as “nerve foods” and “tonics” on the theory that they would be assimilated more readily than hypophosphites or ordinary phosphates. What led to this assumption was the fact that the lecithins, which form a part of the nerve structure, were known to contain the glycerophosphate radical in the molecule. The belief that inorganic phosphates cannot supply the body’s need of phosphorus is implied or expressed in most of the “literature” devoted to proprietary phosphorus preparations. Thus, Schering and Glatz quote G. Meillière as saying that “the organism is incapable of assimilating inorganic forms of phosphorus.” Again, when exploiters of glycerophosphates admit that the body can synthesize its phosphorus compounds from inorganic phosphates, they attempt to counterbalance the admission by contending that the use of organic compounds “spares” the system the necessity of making such synthesis. This assumption rests on the theory that the organic phosphorus compounds are absorbed and stored as such. This theory is contradicted by evidence which has been presented[97] that the organic phosphorus compounds are split up into inorganic phosphates before absorption. [97] McCollum and Hart, Grosser and Husler, Plimmer, and Bayliss and Plimmer, quoted by Marshall (Note 2). The Council requested E. K. Marshall, Jr., to review the evidence for and against the therapeutic value of organic phosphorus compounds. Marshall’s study[98] brings out the following points: [98] Marshall, E. K.: The Therapeutic Value of Organic Phosphorus Compounds, J. A. M. A., Feb. 13, 1915, p. 573. 1. In various tissues of the animal body, enzymes have been found which hydrolyze complex organic phosphorus compounds so as to liberate the phosphorus in the form of inorganic phosphates. 2. Metabolism studies of the phosphorus balance with diets containing inorganic phosphorus compounds, as compared with diets containing organically bound phosphorus, are somewhat conflicting in their results. The balance of evidence, however, is in favor of the view that there is no difference between organically combined phosphorus and inorganic salts with respect to the phosphorus balance. 3. Experiments indicate that the organism thrives on and supplies its phosphorus needs quite as well from inorganic phosphorus compounds as from organically bound phosphorus. Marshall concludes: