Like magnesium and calcium, potassium is a mineral that’s important for your heart, nerves, kidneys and digestive system. One of its most important functions is balancing out water levels in our body. This means it plays a very important role in your body’s pH balance and blood pressure. One of its most important roles, however, takes place in your nerves.
Potassium and Your Nerves
All of our nerves use a combination of minerals to create a charge that travels down the nerve cell, creating a “signal” or nerve impulse that can tell the brain, spine or other nerves to do something. Potassium and sodium help form the impulse, which is called an action potential.
The concentration of sodium outside of a nerve cell is about 10 times higher than it is inside the cell. The concentration of potassium inside the nerve cell is about 20 times higher than it is outside the cell. Therefore, potassium wants to go out of the cell to balance itself out while sodium wants to go in the cell to balance itself out. However, our nerve cells actually work to keep potassium and sodium apart like this preventing them from balancing out, creating a difference in charges. The cell has a negative charge on the inside, while the outside of the cell has a positive charge. This imbalance keeps the cell ready to fire a signal by allowing sodium to rush into the cell causing a change in the voltage inside the cell.
Channels called voltage-gated ion channels generate the action potential. These channels only allow potassium and sodium in or out of the cell. A nerve is at rest when the charge inside the nerve cell is negative (about -70mV) and the charge outside the cell is positive.
When a stimulus occurs, the channels open. If the stimulus is large enough, the flood gates open and sodium rushes into the nerve cell making the charge inside the cell more positive (depolarization). The channels open in sync down the axon of the nerve causing a wave of depolarization to travel down the nerve’s axon. Once the charge inside the cell reaches about +40 mV the channel closes. The nerve re-balances itself by pumping potassium out of the cell to bring the charge inside the cell back down to -70mV (Repolarization). The charge briefly drops below -70mV during this time (Refractory period) because potassium balance point is at a lower voltage than sodium. The nerve then begins to pump sodium out of the cell and potassium back in. This brings the cell back to its resting state.
Here is a video explaining how the action potential works
This is one of the major reasons why potassium is so important to have in our bodies and why we should get a relatively hefty dose of it as adults.
We can easily lose potassium because it’s so involved with balancing out fluids. When we have bouts of diarrhea, vomiting, excessive sweating or urinating…etc we lose potassium (and sodium), this may interfere with the functioning of your nerves and organs because they are so involved with the functioning of your nerves.
Signs of deficiency
Some of the sign include muscle weakness, fatigue, irregular heartbeat, nausea and vomiting, mood swings, high blood pressure. More severe signs include chronic fatigue, cramping, muscle paralysis and abnormal heartbeat.
Any kind of excessive fluid loss will cause your potassium levels to drop so it’s important to get enough potassium when you lose a lot of fluids. Strong anti-inflammatory medications like Prednisone can cause you to lose potassium as well as non-steroidal anti-inflammatory drugs (NSAID’s) like Ibuprofen and Naproxen. ACE-inhibitors may also cause you potassium levels to drop. Diuretic medications and laxatives can cause you to lose potassium as well as some chemotherapy medications. It may be necessary to take a potassium supplement or eat more potassium rich foods when you are taking medication. It’s important to discuss taking potassium supplements with you doctor if you are taking any of these kinds of medications.
How much Potassium?
Adequate Intakes (AI) of Potassium
|0 -6 Months||400 mg||400 mg|
|7 -12 Months||700 mg||700 mg|
|1 – 3 Years||3,000 mg||3,000 mg|
|4 – 8 Years||3,800 mg||3,800 mg|
|9 – 13 Years||4,500 mg||4,500 mg|
|14 – 18+ Years||4,700 mg||4,700 mg||4,700 mg||5,100 mg|
Most processed foods in the American diet are filled with sodium (salt) and we take in more sodium than we do potassium. The average American takes in twice as much sodium as they do potassium.
Foods High in Potassium
These tomatoes contain about 960 mg of potassium in one ounce (28 grams). This is roughly 27% of the daily recommendation for adults. However, sun-dried tomatoes also contain about 25% of your daily recommendation of sodium as well.
Dried apricots are an excellent source of potassium. 1 cup of these fruits contain about 2,200 mg of potassium, which is almost 50% of the recommended daily intake for adults. In addition, it contains virtually no sodium. It does contain, however, 300% of your daily value of vitamin A in 1 cup. Limit the amount of dried apricots you eat daily in order to avoid getting too much vitamin A.
Palm Hearts (Hearts of Palm)
Palm Hearts contain about 500 mg of potassium in one ounce. A can or container of palm hearts usually has about 14 ounces of palm hearts in it.
Believe it or not, bananas only have about 480 mg of potassium in one large banana (8- 9 inches long). Medium (7-8 inches long) and small sized bananas (6-7 inches long) contain 420mg and 360 mg of potassium respectively. 1 cup of mashed bananas, however, has just over 800 mg of potassium.
1 cup of chopped and cooked swiss chard has about 960 mg of potassium. It also has over 700% of your daily value of vitamin K and over 200% of your daily value of vitamin A so limit the amount you eat daily.
- Institute of Medicine, Dietary reference intakes: electrolytes and water. Located at http://www.iom.edu/~/media/Files/Activity%20Files/Nutrition/DRIs/DRI_Electrolytes_Water.pdf