Relationship and Interaction between Sodium and Potassium

Abstract

Compared with the Stone Age diet, the modern human diet is both excessive in NaCl and deficient in fruits and vegetables which are rich in K⁺ and HCO₃⁻-yielding organates like citrate. With the modern diet, the K⁺/Na⁺ ratio and the HCO₃⁻/Cl⁻ ratio have both become reversed. Yet, the biologic machinery that evolved to process these dietary electrolytes remains largely unchanged, genetically fixed in Paleolithic time. Thus, the electrolytic mix of the modern diet is profoundly mismatched to its processing machinery. Dietary potassium modulates both the pressor and hypercalciuric effects of the modern dietary excess of NaCl. A marginally deficient dietary intake of potassium amplifies both of these effects, and both effects are dose-dependently attenuated and may be abolished either with dietary potassium or supplemental KHCO₃. The pathogenic effects of a dietary deficiency of potassium amplify, and are amplified by, those of a dietary excess of NaCl and in some instances a dietary deficiency of bicarbonate precursors. Thus, in those ingesting the modern diet, it may not be possible to discern which of these dietary electrolytic dislocations is most determining of salt-sensitive blood pressure and hypercalciuria, and the hypertension, kidney stones, and osteoporosis they may engender. Obviously abnormal plasma electrolyte concentrations rarely characterize these dietary electrolytic dislocations, and when either dietary potassium or supplemental KHCO₃ corrects the pressor and hypercalciuric effects of these dislocations, the plasma concentrations of sodium, potassium, bicarbonate and chloride change little and remain well within the normal range.