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.

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