Potassium – cellular transport, nerve & muscle function


Potassium in a nutshell:
Potassium often works in conjunction with sodium for transport of nutrients into cells.  It is vital for good muscle and nerve function.

Best source of potassium for Juicers
Potassium deficiency is rare, but if you need a boost, you can find it in parsley, chard, garlic, spinach, broccoli, carrots, celery & cauliflower to name a few.  You could also grab a handful of pistachio nuts to nibble on Winking smile

Potassium powers every cell in every living organism. Most people need more potassium in their diets, but potassium supplements are tightly regulated.

Alternative names: Potassium. Nutritional supplements such as K-Dur, K-Lor, K-Tab, Kaon CL, Klotrix, K-Lyte CL Klorvess, SlowK, and Ten-K usually contain potassium chloride.

What Is Potassium?

Along with sodium, potassium is one of the two major electrolytes in all living things. Potassium is usually more concentrated inside cells (up to 30 times more concentrated in the cell than in the fluids outside the cell) and sodium is usually more concentrated outside cells (up to 10 times more concentrated in the fluids outside the cell than in the cell itself).

parsleyPotassium and sodium both form ions with a charge of +1, but the potassium ion is larger than the sodium ion. Not as many potassium ions fit inside a cell. That helps every cell maintain a slightly negative electrical gradient across its outer cell membrane, more positive charges staying outside the cell than in it, that enables it to attract and absorb negatively charged nutrients and hormones.

Positively charged sodium ions are needed to carry certain negatively charged molecules, such as glucose, into the cell. The cell has to pump sodium out and potassium in to maintain the right electrical gradient across its outer membrane. Too much sugar and too much salt (sodium chloride) can literally “tire out” the cell so that it cannot absorb nutrients and cannot remove water and sodium.

What Does Potassium Do in the Human Body?

In humans, maintaining the right amount of potassium is critical for maintaining muscle tone. Muscle tone is partly a matter of electrical charge. Muscles need to absorb and release potassium to change their charge as they contract and release. Muscles that don't have enough potassium become loose and weak, while muscles that have too much potassium become “twitchy.”

Potassium is also critical for maintaining fluid balance in the body. The nerves and muscles work by changing potassium and sodium levels inside their cells to change electrical charge. For their processes to work predictably, the watery plasma surrounding them has to have sodium and potassium maintained within a very narrow range.chard-xs

The kidneys regulate the sodium and potassium concentration of blood plasma (the watery fluid of the blood other than the red and white blood cells it carries). They keep sodium concentrations in the bloodstream at about 145 milliequivalents (3.45 grams of sodium per liter of blood) and potassium concentrations in the bloodstream at about 150 milliequivalents (4.8 grams of potassium per liter of blood). The kidneys have to excrete almost exactly the amount of sodium and potassium absorbed from food and supplements in order to maintain the an environment in which nerves and muscles can operate.

The way the kidneys regulate potassium and sodium is by pumping blood plasma through a series of tubules. As the tubules clean the blood, they allow potassium to flow passively through the kidney so that almost all of it (except the 1 to 10 mg absorbed from food each day) flows right back into the bloodstream. The kidneys remove a far greater amount of sodium to keep the blood in nearly perfect balance.

What Happens When We Don't Get Enough Potassium?

Potassium deficiency results in a condition called hypokalemia. This relatively rare medical problem results from insufficient intake of potassium or excessive excretion of potassium.

brocolliThe people at greatest risk for not getting enough potassium for nerve and muscle function are elderly persons living alone who cannot obtain fruits and vegetables or who cannot cook them, or people who cannot swallow.

Excessive excretion is most commonly a side effect of old-style thiazide diuretics (such as HCTZ or hydrochlorothiazide), which are still prescribed for high blood pressure and various kinds of swelling because they are extremely cheap. Excessive excretion can also occur after dehydration, vomiting, or diarrhea.

There is very little potassium in the digestive tract itself. Potassium is not lost during the vomiting or diarrhea itself but rather during the dehydration that follows. Dehydration shrinks the volume of blood and plasma flowing through the body. The kidneys have to maintain a constant concentration of potassium in the bloodstream, so they will pump out potassium so that the heart muscle, the intercostal muscles that empower breathing, and the brain can continue to function.

Potassium deficiency can also occur when excessive amounts of potassium are stored in cells rather than in blood plasma. This can be caused by the use of large amounts of insulin to regulate blood sugar levels or by the use of certain medications.

The medically treatable form of potassium deficiency known as hypokalemia is diagnosed by a blood test showing a potassium concentration of 3.0 milliequivalents (meq) or less. Who is at greatest risk of hypokalemia?

  • Up to 50% of people who use diuretics that do not spare potassium, such as hydrochlorothiazide or spironolactone. People of African descent and women are at greater risk of hypokalemia after using non-potassium sparing diuretics.
  • Up to 20% of people with AIDS also have hypokalemia, often because of diarrhea and vomiting.spinach
  • Up to 13% of alcoholics who are deficient in magnesium, since magnesium is necessary to protect the regulate kidney function and prevent excessive excretion of potassium.
  • Many people who have had gastric bypass surgery have hypokalemia.
  • Most people who have anorexia have hypokalemia.
  • Models, cheerleaders, and wrestlers often develop hypokalemia at some point in their careers.

People who have hypokalemia almost always suffer severe fatigue. They may develop constipation with a resulting rounded pot belly, and they may lose muscle strength and even have trouble breathing.

It only takes about a week of complete potassium deprivation to develop hypokalemia. But it only takes a few hours to treat it if treatment is begun in time.

How to Make Sure You Get Enough Potassium

Most scientific studies have found that consuming 4700 mg of potassium per day is about the level at which there is never a problem with hypokalemia and the benefits of potassium accrue. Women who are breastfeeding may need more potassium, about 5400 mg a day, while teens and children need less.

  • Teens aged 14 to 18 need 4700 mg of potassium per day, like adults.
  • Children aged 9 to 13 need 4500 mg of potassium per day. Since they have lower calorie requirements, this means that they actually need to proportionally more fruits and vegetables than adults.
  • carrotsChildren aged 4 to 8 need 3800 mg of potassium per day. They also need proportionally more fruits and vegetables than adults.
  • Children aged 1 to 3 need 3000 mg of potassium per day. They especially need fruit and vegetables, even more than older children.
  • Infants need 700 to 1000 mg of potassium per day. They typically can get this amount of the mineral from formula or breast milk, however.

While there are dozens of potassium supplements on the market, American potassium supplements are strictly limited to 99 mg of potassium. Contrast this to the 4000 to 7000 mg of potassium experts tell us we need every day for good health, and you can quickly see the downside to relying on potassium supplements to prevent potassium deficiency.

The only practical way to avoid potassium deficiency is to eat foods that are rich in potassium. And it's best to eat enough to these foods to get at least 4000 mg of potassium every day.

  • A 3-1/2 ounce (100 gram) serving of dried daikon radish contains 3490 of potassium.
  • A 3-1/2 ounce (100 gram) serving of sun-dried tomatoes contains 3472 of potassium.
  • A 3-1/2 ounce (100 gram) serving of cocoa mix (no sugar) contains 2702 of potassium.
  • A 3-1/2 ounce (100 gram) serving of Marmite (yeast spread) contains 2600 of potassium.
  • A 3-1/2 ounce (100 gram) serving of dehydrated carrots contains 2540 of potassium.
  • A 3-1/2 ounce (100 gram) serving of dried apricots contains 1850 of potassium.
  • A 3-1/2 ounce (100 gram) serving of instant mashed potatoes contains 1848 of potassium.cauliflower
  • A 3-1/2 ounce (100 gram) serving of potato chips contains 1642 of potassium.
  • A 3-1/2 ounce (100 gram) serving of whitefish contains 1080 of potassium.
  • A 3-1/2 ounce (100 gram) serving of pitted prunes contains 1058 of potassium.
  • A 3-1/2 ounce (100 gram) serving of pistachio nuts contains 1042 of potassium.
  • A 3-1/2 ounce (100 gram) serving of dried peaches contains 996 of potassium.
  • A 3-1/2 ounce (100 gram) serving of boiled beet greens contains 902 of potassium.
  • A 3-1/2 ounce (100 gram) serving of dried persimmons contains 802 of potassium.
  • A 3-1/2 ounce (100 gram) serving of seedless golden raisins contains 749 of potassium.
  • A 3-1/2 ounce (100 gram) serving of chunky peanut butter contains 742 of potassium.
  • A 3-1/2 ounce (100 gram) serving of baked yams contains 670 of potassium.
  • A 3-1/2 ounce (100 gram) serving of pinto beans contains 642 of potassium.
  • A 3-1/2 ounce (100 gram) serving of falafel contains 685 of potassium.
  • A 3-1/2 ounce (100 gram) serving of boiled Swiss chard contains 592 of potassium.
  • A 3-1/2 ounce (100 gram) serving of baked potato with skin contains 573 of potassium
  • A 3-1/2 ounce (100 gram) serving of honey-roasted almonds contains 582 of potassium.
  • A 3-1/2 ounce (100 gram) serving of raw spinach contains 580 of potassium.
  • A 3-1/2 ounce (100 gram) serving of French fries contains 542 of potassium.
  • A 3-1/2 ounce (100 gram) serving of grapefruit juice contains 484 of potassium.
  • A 3-1/2 ounce (100 gram) serving of pineapple juice contains 472 of potassium.
  • A 3-1/2 ounce (100 gram) serving of orange juice contains 354 of potassium.
  • A 3-1/2 ounce (100 gram) serving of fresh bananas contains 300 of potassium.
  • A 3-1/2 ounce (100 gram) serving of most fresh vegetables contains 200 to 250 of potassium.
  • A 3-1/2 ounce (100 gram) serving of boiled broccoli (previously frozen) contains 180 of potassium.
  • A 3-1/2 ounce (100 gram) serving of canned tomatoes, green beans, onions, English peas, or corn contains 100 to 130 of potassium.celery-xs

Fresh oranges and bananas are the foods most of us associated with potassium, but many other foods are much better sources of the nutrient. (Dried banana chips, however, contain about 1400 mg of potassium per serving.) Dried fruits and dried roots have the highest potassium content. The canning process removes over half the potassium in fresh fruits and vegetables, and boiling canned vegetables removes even more.

Using Potassium to Lower Blood Pressure

Some experts will tell you that all you really need to lower your blood pressure is to eat more fruits and vegetables to get more potassium. This advice is simply not true.

People who already have normal blood pressure cannot lower their blood pressure by increasing their consumption of potassium. People who eat Western diets who have been diagnosed with high blood pressure usually can lower their systolic blood pressure (the first number) by about 5 points (mm Hg) if they start eating enough fruits and vegetables to get about 3,000 mg of potassium per day. People who eat extremely high-salt diets, however, can get the same result from taking just 125 mg of potassium per day.

If your blood pressure is 180/130 and you need to get it down to 100/80, 5 points may not seem like a lot. Many medications, however, only lower blood pressure about 5 points, and fruits and vegetables don't have side effects if they are eaten in moderation.

Fruits and Vegetables for Preventing Osteoporosis

Scientists have found that women who consume the highest amounts of potassium, about 6,000 mg a day or more, have only 30% as great a risk of developing osteoporosis as women who consume the lowest amounts of potassium, about 2,000 mg a day. It's the fruits and vegetables that provide the potassium that make the difference rather than the potassium itself.

High-potassium plant foods are also rich in compounds that become bicarbonates in the small intestine when they are digested. These bicarbonates buffer the urine so that the kidneys need less calcium from the bones to keep the blood at the right pH. (Strictly speaking, a diet rich in protein foods does not cause acidity in the body. It just makes the kidneys use more calcium and glutamine to prevent acidity in the body.)

Eating 9 servings of fruits and vegetables every day ensures getting the bicarbonates the kidneys need to keep the body alkaline—and keeps calcium and other minerals in bone.

Fruits and Vegetables for Preventing Kidney Stones

Scientists have also linked greater consumption of potassium with lower risk of kidney stones. As is the case with osteoporosis, fruits and vegetables actually provide the protection against kidney stones, not the potassium they contain.

When the kidneys have to use calcium to keep the blood relatively alkaline, they secrete the used calcium into the urine. This calcium forms stones. Fruits and vegetables provide the bicarbonates the body needs to avoid the need for calcium that prevents the formation of kidney stones.

What Happens When You Get Too Much Potassium?

The opposite of hypokalemia is hyperkalemia, too much potassium in the bloodstream. It is extremely unusual to develop hyperkalemia solely as a result of eating too many fruits and vegetables, although eating about a pound (around 500 g) of dried fruit might cause hyperkalemia in children or adults of small body size. Taking about 18000 mg of potassium supplements in a single day—which is never recommended—can also cause hyperkalemia. Making pickles with potassium chloride salt substitute can also create a toxic product.

People who take certain blood pressure medications, however, and people who consume very large amounts of caffeine or theophylline (the active ingredient in the asthma medication Theo-Dur, also found in iced tea) can develop hyperkalemia after consuming smaller amounts of potassium.

The first sign of hyperkalemia is usually chest palpitations. There may also be tingling in the hands and feet and uncontrollable twitching of the eyebrows. The pulse can become irregular and muscle weakness can set in quickly. In extreme cases, hyperkalemia can cause sudden death due to irregular rhythms of the heart.

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About Andy Williams

In a processed food culture, simply eating may not be enough. Andy Williams, B.SC., Ph.D. is a scientist with a strong interest in Juicing and how it can supply the body with the nutrients it needs to thrive in modern society. You can subscribe to his free daily paper called Juicing The Rainbow and follow him on Facebook orTwitter. You can also follow me on Google +

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