Vol. 22, No. 3 (October2013)
Potassium and Magnesium Important Metabolic Relationship
Magnesium and potassium are involved in many critical functions throughout the body. As many studies have pointed out, there is strong metabolic interplay between the two. Both are involved in the ontraction and relaxation of skeletal, smooth, and cardiac muscle. Sports nutrition plays some homage to these two, when it comes to energy needed for skeletal muscle contraction, as well as in the prevention of cramps during extreme exercise. As far back as 1982 (Whang R, et al:J Am Coll Nutr), a study of 1000 ambulatory patients showed a significant incidence of hypomagnesemia and hypokalemia. In the group with hypomagnesemia and hypokalemia, the researchers noted that the group with hypomagnesemia (not hypokalemia alone), required a greater number of antihypertensive medications than the group who were normomagnesemic.
The average human adult contains about 25 grams of magnesium, of this, 30-40% is in muscles and soft tissue, about 1% in extracellular areas, and the rest is in bone. The soft tissue magnesium is a co-factor in many enzymes that are involved in energy metabolism, protein synthesis, RNA and DNA synthesis, and the maintenance of electrical potential of nervous tissues and cell membranes. The potassium content of the average adult is around 120 grams. Potassium cations are important in neurons (brain and nerve function) and in influencing the osmotic balance between cells and the interstitial fluid, with their distribution mediated by the Na+/K+ ATPase pump. Of particular importance, here are the dangerous effects that magnesium depletion plays in regulating potassium fluxes. Magnesium depletion depresses both cellular and extracellular potassium and exacerbates the effects of low potassium diets on cellular potassium content. Muscle potassium becomes depleted as magnesium deficiency develops, and tissue repletion of potassium has been seen to be virtually impossible unless magnesium status is restored to normal (The Human Vitamin and Mineral Requirements, FAO Corp. Document Repository 2013).
Note on Magnesium Intake
It is important to note that the dietary intake of magnesium in the US, as well as in most developed nations is less than health officials would like. In the latest USDA survey, as reported in Magnesium in Sports Physiology and Performance (Kies and Driskell, CRC 1995), the average dietary intake of magnesium in the USA is only 76% of the RDA, and has been on a steady decline. Furthermore, the survey showed that 75% of the US populace was getting suboptimal amounts of magnesium in their diets. So 75% were suboptimal, but more startling is the fact that 39% were taking in less than 70% of the RDA. At less than 70%, this segment of the populace is truly magnesium deficient, and opens to a vast array of metabolic induced problems, including metabolic syndrome, strokes, heart disease, and more. Since only about one third of the dietary intake of magnesium is absorbed, even marginal deficiencies may be compounded.
Worsening the magnesium status problem of the modern day, is the fact that there are over 113.4 million prescriptions written for proton pump inhibitors per year, let alone all of the top selling OTC proton pump inhibitors. Proton pump inhibitors have been shown to lead to hypomagnesemia. In a case report [American Journal of Kidney Diseases, vol 56, No 1 (July), 2010 pp112-116], the researchers show that PPI induced hypomagnesemia may occur within a single year of PPI therapy, and was associated with hypokalemia - leading to electrocardiogram abnormalities. The hypokalemia was a result of the kaliuresis caused by hypomagnesemia. Hypomagnesemia is a real health hazard in the USA.
Stress has been seen to be another factor that enhances the need for magnesium. Strenuous exercise has been seen to have an impact here. In a study entitled “Repolarization Perturbation and Hypomagnesemia after Extreme Exercise” [Med Sci Sports Exerc 2012 Sep;44(9): 1637-43] the electrolyte and inflammatory status of 198 healthy men were looked at one week prior, and at 0, 24, and 72 hours after participating in a marathon. The researchers saw significant associations between ECG alterations and inflammatory or electrolyte concentrations. Cardiac repolarization was significantly altered immediately after a marathon, coincident with hypomagnesemia and hypokalemia. More investigation needs to be done here. It could be that pre-screening for key electrolytes should be considered.
In the two charts below are the Food and Nutrition Centers’ recommended intakes for magnesium and potassium:
Reason That Hypomagnesemia Leads to Refractory Hypokalemia
As stated, medical practitioners have known for some time that you can’t successfully replete a potassium depleted patient if they have low magnesium levels. The question is for what reason? What is the mechanism that leads to this? A paper by Huang and Kuo (JASN October 2007, Vol 18, No. 10 pp 2649-2652) comes up with a very strong explanation. The authors suggest that magnesium deficiency aggravates hypokalemia and renders it refractory to treatment with potassium. The magnesium deficiency exacerbates potassium wasting by increasing distal potassium excretion. Decreases in intracellular magnesium (as seen in magnesium deficiency) release the magnesium mediated inhibition of renal outer medullary potassium channels (ROMK), and increases potassium secretion. So low magnesium levels lead to low potassium levels. High intracellular levels of magnesium block the ROMK channel pore and prevents potassium from effluxing. Conversely, low intracellular magnesium would allow for high ROMK efflux activity and result in potassium wasting. Other factors that could help lead to this include high aldosterone and increased sodium uptake.
Potassium and magnesium deficiencies often coexist, so supplementation with extra potassium alone, cannot always correct the potassium deficiency. Studies have shown that supplementation with magnesium can correct the potassium deficiency. One such study [J Med Assoc Thai; 2004; 87(12):1506-12] focused on changes in erythrocyte contents of potassium, sodium and magnesium, as well as Na/K-pump activities subsequent to the administration of potassium and magnesium.One of the treatments was with Albion’s Magnesium Bisglycinate Chelate Buffered. The administration of this chelated magnesium alone caused a significant increase in plasma potassium, erythrocyte potassium, sodium, and magnesium. The researchers concluded that the chelated magnesium increased the erythrocyte content of magnesium, potassium, and sodium could be accounted for by the magnesium loading effect and the increase in cellular magnesium content causing a further increase in Na, K cotransporter activity. As has been seen, magnesium and potassium have a strong metabolic connection. It is very difficult to treat hypokalemia without adequate magnesium. Oftentimes, just treating the hypomagnesemia will take care of the hypokalemia. To be safe, supplementing both seems the most conservative method. Albion’s chelated magnesium ingredients have been shown to be effective in certain instances of hypokalemia.
For magnesium and potassium supplementation, look to Albion for the finest in both.