Potassium is a metal like lithium, but no one builds batteries out of it because it’s evil:
Well, the human body is mostly water – why don’t we explode after eating a banana or taking a supplement?
That doesn’t happen because the pure metal those scientists are playing with doesn’t exist in nature – they made it in the lab.
Potassium oxidizes very quickly (the tarnishing that one scientist mentions), turning into a positively charged ion that’s actually water-soluble and quite stable.
It substitutes nicely with ions of other elements to form minerals (for example, switching places with plagioclase’s sodium ions to form orthoclase).
There’s another connection between potassium and sodium ions that is vital to all living beings, including you and me. It’s called the sodium-potassium pump.
How does my body use potassium?
There is a lot of potassium in rocks (it makes up almost 3% of Earth’s crust by weight) and soil. It gets absorbed into plants, from which we human beings get it directly (that banana, for example) or indirectly (dairy products as well as all meats and fish).
All living cells need potassium in order to work.
In an animal cell like the one above – the kind you and I have – there are positively charged potassium and sodium ions on either side of the cell’s protective outer membrane (in with the blue and red stuff or out there with the green supporting structures).
Let’s say the cell is floating around in some of the water that accounts for about 60 percent of your adult body weight.
It can’t survive without interacting with the environment, so it uses proteins to build some pumps to get things across the membrane.
These pumps are not complicated structures. The sodium-potassium pump, for example, works simply because potassium ions are bigger than sodium ions.
This process sets up the electrical gradient that all of your muscles, including the heart, need in order to contract. Your nervous system also needs that gradient to function.
A chemical gradient is also established, since more sodium than potassium is pumped out of the cell. Sodium ions move back into the cell, away from the higher concentration outside, via other proteins (like that yellow thing in the video above), bringing in with them glucose and amino acids.
None of this would happen without potassium, which makes lots of other wonderful things possible, too, including:
- Building protein
- Breaking down carbohydrates and using them
- Maintaining normal body growth (PDF)
- Controlling the acid-base balance
How much daily potassium do I need?
The World Health Organization recommends (PDF) that adults take at least 3,510 mg daily. They don’t recommend a specific intake for children, suggesting only that the adult dose be scaled down “based on the energy requirements of children relative to those of adults.”
Most healthy adults get all the potassium they need from their diet.
However, it does require a balance with other electrolytes like sodium and magnesium.
That balance is easily be thrown out of kilter when the amount of fluid in your body increases or decreases, or if the other electrolyte concentrations change.
Hypokalemia (low potassium) is rarely caused by diet. The Mayo Clinic lists common causes for it as chronic kidney disease, diabetic ketoacidosis, diarrhea, excessive alcohol or laxative use, excessive sweating, folic acid deficiency, prescription diuretic use, primary aldosteronism, vomiting, or the use of some antibiotics.
The most serious thing that either too little or too much potassium does is affect your heart rhythm. It also causes weakness, fatigue, and muscle cramps.
There are lots of potassium-rich foods to turn to, but see a doctor before popping a potassium supplement pill, since the causes of hypokalemia can be complex and you might have something else going on that needs treatment.
Potassium keeps your body running. It makes your muscles and nervous system work, and helps maintain a good heart beat. It’s not really evil, after all, but rather a very useful and abundant natural nutrient.
More information:
- Potassium and the Diet. Colorado State University Extension
- The Sodium-Potassium Pump. Georgia State University
- Potassium in diet. Medline
- Potassium. Oregon State University
- Potassium. University of Maryland Medical Center
- Potassium in biology. Wikipedia
Flight To Wonder 