Mineral Balance: Sodium-Potassium
Like children on a see-saw, some minerals work to balance each other in the body. Almost everything in nature is about balance. In humans and animals it’s called homeostasis, which is the property of the body to maintain its internal environment in a stable, constant condition. Occasionally, mainstream medicine overlooks the balance aspect and tends to look at isolated parts and actions of the body. One of these oversights involves sodium and its relationship with potassium, working together as the sodium-potassium pump, which is the mechanism of active transport by which sodium and potassium ions are moved across the cell membrane, into and out of the cell. With the help of ATP as the source of energy, sodium is extruded from the cell and potassium is invited in. This energetic display is necessary for protein biosynthesis, maintenance of osmotic equilibrium, initiation of nerve impulses and transport of some other molecules, such as glucose, across the membrane. To clarify, ATP is a high-energy phosphate compound used by the body to get things done, including muscle contractions and enzyme metabolism, among others.
Sodium (Na) and potassium (K) are essential minerals and electrolytes. As the latter, they dissociate into ions (charged particles), allowing them to conduct electricity. In order for the body to function the right way, they need to be regulated on both sides of the cell membrane. The recommended intake of sodium had been 2300 milligrams a day, but is now 1500 mg/d; that for potassium being unchanged at 4700 mg/day. The sodium:potassium ratio, therefore, has moved from 1:2 to almost 1:3, which is closer to what is believed to be the body’s ideal. In plants, of which humans eat too few, the natural ratio of Na to K is about 1:10.
Sodium is the chief ion outside the cell, potassium inside. Inside the cell, sodium concentrations are ten times lower than outside. Potassium concentration inside are about thirty times higher than outside. The difference across the membrane creates an electrochemical gradient known as membrane potential, which uses a lot of the body’s energy to maintain itself. Without this tight control, muscles would suffer, especially the heart. In the typical American diet, intake of sodium (as sodium chloride) is three times higher than potassium, just the opposite of what it should be. The dietary guidelines for sodium consumption are currently being met by only a tiny percent of the population (Drewnowski, 2012)
Table salt is about 39% sodium. A simple explanation is that one teaspoon of salt, which has a mass about 6200 mg, contains approximately 2400 mg of sodium.
The National Health and Nutrition Examination Survey (NHANES), first conducted in the early 70’s, reported in 2012 that more than 90% of adults consumed more than 2300 mg/d of sodium a day, and less than 2%--that’s two percent—met the recommendation for potassium (Cogswell, 2012). It’s no small surprise that high blood pressure is rampant (Wenberger, 1986) (Elliot, 1991, 1996) (Dyer, 1995) (He, 2004) (Levings, 2012) Of course, you could argue that the relationship of sodium intake to hypertension is a genetic matter, but do you know your genes?
Increasing potassium and reducing sodium intake will help to reduce blood pressure. But be careful not to overdo it by using supplements without strict supervision, since potassium overload is almost as bad as potassium deficiency. After all, potassium is used to stop the heart in lethal injections. Aiming for the recommended 4700 mg a day means that vegetables and fruit intake needs to go up, while intake of cakes, cookies and prepared foods needs to go down. Overdosing potassium from foods is almost impossible…you can’t eat that much food.
If less than 2% of Americans get the recommended amount of potassium, how much do we get? From data collected in 2009-2010, women get about 50% of the RDI, men about 81% (USDA, 2012). Besides supporting coronary health, potassium seems to lower the risk of stroke (Ascherio, 1998) (Larsson, 2011). If you’ve got abnormally high urinary calcium levels, you might be looking at kidney stones in your future, something we wouldn’t wish on anyone. Increasing dietary potassium levels by increasing fruit and vegetable intake has been found to decrease urinary calcium excretion. Taking a supplement under supervision will do the same thing. It has been found that getting more than 4000 mg of potassium a day reduces risk of kidney stones (Curhan, 2004).
Diuretics may lower potassium levels, but not all do, so check with your doctor to find out if your diuretic is potassium-sparing or not. Laxatives, caffeine, tobacco and lots of sugar may also compromise potassium stores. Physical and mental stress interferes with potassium metabolism. If you haven’t already, try to increase potassium foods, including sweet potatoes, bananas, tomatoes, oranges, beans, squashes, nuts and seeds, green foods, avocados, garlic and a host of other produce. Look here for a list: http://www.health.gov/dietaryguidelines/dga2005/document/html/appendixb.htm.
Look at both sodium and potassium in the context of what you eat every day and try to balance foods before you consider a potassium supplement. You know where most of the salt comes from (processed foods and the salt shaker), but you’ll have to read labels to find the rest. If you can maintain a ratio of one to one, you’ll be better off than most, but trying to get two to one, potassium to sodium, is preferred. Limiting sodium to about 500 mg in a meal is a virtuous endeavor. Look at some soup cans and you’ll see more than that in a tiny serving’s worth. Even certain “light” soups have 650 mg of sodium in a 1-cup serving. Potassium values of these products are half that, which is the opposite of what it should be. If the whole can is consumed, sodium-potassium balance needs to be addressed at other meals. Seeing kids unbalanced on a see-saw can be amusing. Viewing sodium-potassium balance from a gurney is not.
Arcand J, Steckham K, Tzianetas R, L'Abbe MR, Newton GE. Evaluation of Sodium Levels in Hospital Patient Menus Arch Intern Med. 2012;172(16):1261-1262.
Ascherio A, Rimm EB, Hernán MA, Giovannucci EL, Kawachi I, Stampfer MJ, Willett WC. Intake of potassium, magnesium, calcium, and fiber and risk of stroke among US men. Circulation. 1998 Sep 22;98(12):1198-204.
Barri YM, Wingo CS. The effects of potassium depletion and supplementation on blood pressure: a clinical review. Am J Med Sci. 1997 Jul;314(1):37-40.
Centers for Disease Control and Prevention (CDC). Usual sodium intakes compared with current dietary guidelines --- United States, 2005-2008. MMWR Morb Mortal Wkly Rep. 2011 Oct 21;60(41):1413-7.
Cogswell ME, Zhang Z, Carriquiry AL, Gunn JP, Kuklina EV, Saydah SH, Yang Q, Moshfegh AJ. Sodium and potassium intakes among US adults: NHANES 2003-2008. Am J Clin Nutr. 2012 Sep;96(3):647-57.
Curhan GC, Willett WC, Knight EL, Stampfer MJ. Dietary factors and the risk of incident kidney stones in younger women: Nurses' Health Study II. Arch Intern Med. 2004 Apr 26;164(8):885-91.
Denton D, Weisinger R, Mundy NI, Wickings EJ, Dixson A, Moisson P, Pingard AM, Shade R, Carey D, Ardaillou R, et al. The effect of increased salt intake on blood pressure of chimpanzees. Nat Med. 1995 Oct;1(10):1009-16.
Drewnowski A, Maillot M, Rehm C. Reducing the sodium-potassium ratio in the US diet: a challenge for public health. Am J Clin Nutr. 2012 Aug;96(2):439-44.
Dyer AR, Stamler R, Elliott P, Stamler J. Dietary salt and blood pressure. Nat Med. 1995 Oct;1(10):994-6.
Elliott P Observational studies of salt and blood pressure. Hypertension. 1991 Jan;17(1 Suppl):I3-8.
Elliott P, Stamler J, Nichols R, Dyer AR, Stamler R, Kesteloot H, Marmot M. Intersalt revisited: further analyses of 24 hour sodium excretion and blood pressure within and across populations. Intersalt Cooperative Research Group. BMJ. 1996 May 18;312(7041):1249-53.
He FJ, MacGregor GA. Effect of longer-term modest salt reduction on blood pressure. Cochrane Database Syst Rev. 2004;(3):CD004937
Hoorn EJ, Betjes MG, Weigel J, Zietse R. Hypernatraemia in critically ill patients: too little wat er and too much salt. Nephrol Dial Transplant. 2008 May;23(5):1562-8.
Krishna GG, Chusid P, Hoeldtke RD. Mild potassium depletion provokes renal sodium retention. J Lab Clin Med. 1987 Jun;109(6):724-30.
Krishna GG. Role of potassium in the pathogenesis of hypertension. Am J Med Sci. 1994 Feb;307 Suppl 1:S21-5.
Larsson SC, Virtamo J, Wolk A. Potassium, calcium, and magnesium intakes and risk of stroke in women. Am J Epidemiol. 2011 Jul 1;174(1):35-43.
Levings J, Cogswell M, Curtis CJ, Gunn J, Neiman A, Angell SY. Progress toward sodium reduction in the United States. Rev Panam Salud Publica. 2012 Oct;32(4):301-6.
National Institute of Health Jan. 26, 2009 Sodium/Potassium Ratio Linked to Cardiovascular Disease Risk http://www.nih.gov/researchmatters/january2009/01262009hypertension.htm
Akira Okayama; Katsuyuki Miura; Tomonori Okamura; Nagako Okuda; Shigeyuki Saitoh; et al Abstract MP077: Dietary Sodium Potassium Ratio as a Risk Factor for Stroke, Cardiovascular Diseases and All-cause Death Among Japanese: Nippondata80. Circulation. 2012; 125: AMP077
Quanhe Yang, PhD; Tiebin Liu, MSPH; Elena V. Kuklina, MD, PhD; et al. Sodium and Potassium Intake and Mortality Among US AdultsProspective Data From the Third National Health and Nutrition Examination Survey FREE Arch Intern Med. 2011;171(13):1183-1191.
Lynn D. Silver, MD, MPH; Thomas A. Farley, MD, MPH Sodium and Potassium Intake: Mortality Effects and Policy ImplicationsComment on “Sodium and Potassium Intake and Mortality Among US Adults” Arch Intern Med. 2011;171(13):1191-1192.
Stofan JR, Zachwieja JJ, Horswill CA, Murray R, Anderson SA, Eichner E Sweat and sodium losses in NCAA football players: a precursor to heat cramps? Int J Sport Nutr Exerc Metab. 2005 Dec;15(6):641-52.
U.S. Department of Agriculture, Agricultural Research Service. 2012. Total Nutrient Intakes: Percent Reporting and Mean Amounts of Selected Vitamins and Minerals from Food and Dietary Supplements, by Family Income (as ! of Federal Poverty Threshold) and Age, What We Eat in America, NHANES 2009-2010. Available: www.ars.usda.gov/ba/bhnrc/fsrg. USDA, Agricultural Research Services
USDA Dietary Guidelines for Americans 2005 Appendix B-1. Food Sources of Potassium http://www.health.gov/dietaryguidelines/dga2005/document/html/appendixb.htm
USDA. Downloadable pdf Tables. What We Eat in America, 2009-2010. http://www.ars.usda.gov/Services/docs.htm?docid=18349
Weinberger MH, Miller JZ, Luft FC, Grim CE, Fineberg NS. Definitions and characteristics of sodium sensitivity and blood pressure resistance. Hypertension. 1986 Jun;8(6 Pt 2):II127-34.
*These statements have not been evaluated by the FDA. These products are not intended to treat, diagnose, cure, or prevent any disease.