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Special K

Potassium Is More Important to Your Muscles and Health Than You Realize

The ride from the competitors’ hotel to the venue of the Arnold Classic in Columbus, Ohio, isn’t a long one. But for Mike Matarrazo that ride must have felt like a thousand miles. Or so it seemed, judging by the expression on the veteran pro bodybuilder’s face that cold day in March several years ago. The normally ebullient Matarrazo seemed unusually quiet and tense. He looked to be heading to his own execution, not a bodybuilding contest. When asked how he felt, Matarrazo’s terse reply was simply, ‘I feel like I’m going to die.’

Although he didn’t realize it at the time, Mike’s discomfort was self-inflicted. Since competitors at the major contests are judged heavily on muscular definition, Matarrazo and his fellow competitors resorted to various techniques in an effort to lose every bit of extraneous water under their skin. Water retention obscures muscular definition, and a highly defined look often separates the winners from the losers in top shows.

Mike had done what many body’builders have done: He’d taken pharmaceutical diuretics. The one he used in preparation for this contest was known as a potassium-sparing diuretic. While most such drugs eliminate several minerals known to retain water in the body, especially sodium, potassium-sparing drugs, as the name implies, not only prevent the loss of potassium at the expense of sodium but also retain potassium in the body.

Under normal circumstances drug-induced potassium retention isn’t a problem. The hidden danger, though, is combining such diuretics with potassium supplements, and that was Matarrazo's mistake. He’d taken large doses of potassium with potassium-sparing diuretic drugs because he had been told that diuretics cause loss of all minerals. Losing potassium, calcium and magnesium can lead to muscle cramps, the last thing you’d want to experience during a posing routine onstage.

Mike’s malaise was later found to be hyperkalemia, or excess potassium in his blood. While the condition is easily treatable, your heart can stop beating if it isn’t caught in time. In fact, the lethal injection given in capital punishment contains a certain dose of potassium. Injected directly into the heart, potassium can stop the heart like a bullet. For those with normal kidney function, it’s difficult to overdose on potassium because a large dose leads to nausea, vomiting and rapid excretion by the kidneys.

On the other hand, without sufficient potassium you couldn’t contract your muscles, your nervous system couldn’t function, and you wouldn’t be able to store glycogen, the complex carbohydrate that fuels bodybuilding workouts. Nor could you secrete anabolic hormones, including testosterone.

Estimates are that prehistoric man ate up to 10 grams of potassium a day on average, or about five times more than most people get today.1 Sodium was rare in that period, and the human body evolved to conserve sodium and eliminate potassium. The kidneys regulate the process, which is why those with failing kidneys must be aware of their potassium intake. Aldosterone, a hormone secreted by the adrenal glands, helps retain sodium while eliminating potassium.2 Potassium-sparing diuretics, such as the one Matarrazo used, block the effects of aldosterone.

Although it represents a mere 5 percent of the body’s mineral content, potassium is the major intracellular electrolyte. It has a yin-yang relationship with sodium and chloride: As potassium exits a cell, sodium enters it. Those reactions, which are powered by the sodium-potassium ATP pump, are involved in several important mechanisms, including nerve conduction, water balance and muscle contraction. ALL Cells need potassium for normal growth and protein synthesis. That alone should make the mineral of extraordinary interest to anybody who wants to build muscle. Lesser known functions include its involvement in glycogen synthesis and the process that degrades glycogen into glucose to release energy. People on low-carbohydrate diets often experience weakness and fatigue due to a low-potassium intake combined with the natural diuretic effects associated with low-carb diets. Those effects lead to general water loss, especially notable during the initial stages of the diet. But along with water, various minerals, including sodium and potassium, are also lost from the body.

Heart patients on pharmaceutical diuretics that treat heart failure and hypertension, or high blood pressure, are also often prescribed potassium supplements to replace what’s lost. The heart cannot properly function without potassium; it’s vital for the electrical conduction system that regulates heartbeat. Too much potassium, however, can lead to equally serious disturbances.

Several studies have demonstrated potassium’s benefits. It appears to help prevent the most common form of stroke.3 By opposing the action of sodium, potassium helps lower elevated blood pressure, a major cause of stroke. In addition, potassium functions as an antioxidant, limiting the activity of a destructive free radical called superoxide.4 Free radicals, by-products of oxygen metabolism, cause the major damage to brain neurons after a stroke. The vital sodium-potassium pump mechanism sets off an electrical charge that leads to a series of reactions that send nerve impulses from brain to body and back. Without the sodium-potassium pump, glands couldn’t secrete any hormones, including testosterone and growth hormone.

You’ve likely heard that the popular food supplement creatine is best absorbed when taken with simple sugar, which causes a release of insulin. The insulin, in turn, positively influences the actions of the sodium-potassium pump, which then powers the transport protein that actually pushes creatine into muscle.

Certain hormones influence potassium activity in the body. So-called sympathetic hormones, such as epinephrine, promote the entry of potassium into cells. Users of the drug clenbuterol, structurally similar to sympathetic hormones, have often noticed such side effects as hand cramps and muscle twitching; clenbuterol lowers blood levels of potassium and pushes it into cells. The temporary imbalance that results leads to nerve conduction and muscle contraction abnormalities, hence the side effects.

Any drugs that either mimic or promote the release of sympathetic hormones, such as epinephrine, can lower blood potassium levels. Many drugs used to treat asthma, besides clenbuterol, lower potassium. The most popular inhaler for treating asthma attacks, albuterol, lowers blood potassium for four hours, though not to dangerously low levels. The OTC decongestant pseudoepinephrine also lowers potassium levels, as does ephedrine, the popular fat-loss ingredient that was removed from sale last year. Caffeine, a common ingredient in fat-loss supplements and the active ingredient in coffee, lowers potassium. An overdose of the asthma drug theophylline, which is sometimes included in fat-loss supplements, can cause severe hypokalemia. Even eating lots of black licorice will result in potassium excretion and sodium retention’an aldosteronelike effect.

Insulin potently promotes the entry of potassium into cells. One standard treatment of hyperkale’mia is a dose of insulin, which rapidly pushes potassium from the blood into cells. The pH’acidity or alkalinity’of the blood also influences potassium levels. High acidity, which you get on a high-protein diet devoid of alkaline foods like fruits and vegetables, pushes potassium out of cells, while an alkaline state favors cellular sodium retention.

Recent animal studies show that excessive acidity blunts protein synthesis. In fact, high acidity can lead to muscle catabolism, or breakdown. Potassium is an effective buffer against the effects of excess acidity caused by a high protein diet. One study published a few years ago showed that when women following a high-protein diet took potassium bicarbonate, which contains two buffer substances, muscle protein breakdown and calcium losses were inhibited. Dietitians frequently warn that a high-protein diet is hazardous to health because it promotes calcium loss. The culprits here are amino acids, mainly the ones containing sulfur, such as methionine and cysteine. The body compensates for the increased blood acidity by releasing various buffers, including calcium, which disappears from the body during the process. When the subjects of some studies increased their fruit and vegetable intake from 3.6 to 9.5 daily servings, however, calcium excretion decreased by 30 percent. Much of the protective effect is due to the alkalinizing effects of the potassium found in fruits and vegetables.

Compared to most other minerals, potassium is easily absorbed into the body and at about 90 percent efficiency; potassium is highly water-soluble. There is, however, a flag on the play. Because of the dangers associated with high-po’tassium intake, es’pecially in relation to heart function, the government prohibits direct over-the-counter potassium supplements from providing more than 99 milligrams per dose. That doesn’t mean you can’t get higher amounts of potassium in other food supplements, such as meal-replacement products. Another form of potassium, which combines potassium with chloride, is sold as a salt substitute.

The most popular food sources of potassium are bananas and baked potatoes, both of which contain respectable levels of potassium minus excessive sodium. Other potassium-rich foods include fruits, vegetables, almonds, raisins, avocado, figs, dates, yams and dairy products. Since potassium is ubiquitous, it seems unlikely that you’ll suffer from a deficiency of the mineral’unless you resort to some extreme measure, like diuretics.

Most Americans get 2.9 to 3.2 grams of potassium daily, which is below the acceptable intake of 4.7 grams a day. That pales in comparison to the 10 grams our Stone Age ancestors took in. Diets that eliminate the best food sources of potassium’fruits and vegetables’could lead to problems. That’s particularly true of high-protein, low-carb plans that call for no fruits and vegetables. Such diets tend to produce high acidity in the body, which can lead to muscular weakness during exercise and suppression of protein synthesis.

As a diet low in natural potassium continues, the kidneys become less effective at conserving the mineral, and the body excretes more of it. That occurs when you consistently take in less than 1,000 milligrams daily. Eventually some form of hypokalemia, or low potassium, may occur. Symptoms include muscular weakness, heart rhythm disturbances and glucose intolerance, all of which add up to lousy workouts.

Taking OTC potassium pills isn’t the best way to deal with a potassium-deficient diet. Such supplements, which often contain potassium chloride, have a caustic effect on the lining of the gastrointestinal tract and may even cause a type of ulceration and perforation.5 Fortunately, healthy kidneys eliminate excess potassium, so it’s difficult to suffer a potassium overdose unless you have some type of kidney failure.

Bodybuilders often use potassium supplements because of the notion that they prevent muscle cramps. There’s some truth to that, since potassium is vital for muscle contraction and nerve conduction, each of which plays a role in the onset of muscle cramps. Besides potassium, however, a sensible supplemental cocktail should also include magnesium and calcium. Without magnesium, your cells can’t retain potassium.6

One thing to avoid is taking a potassium supplement on an empty stomach. That signals the adrenal glands to secrete aldosterone, which helps the kidneys excrete potassium and retain sodium.7 Then human evolution kicks in and leads to edema, or water retention. Maintaining a higher ratio of potassium to sodium promotes the excretion of excess sodium, which equals less water retention.

You should aim for about five grams of potassium a day to help maintain an alkaline state in your body, thereby reducing muscle catabolism, and replenish muscle glycogen for better workouts. The easiest way to get your potassium quota is to eat at least five (nine is better) servings of fruits and vegetables daily.


1 Frassetto, L.A., et al. (2001). Diet, evolution and aging: the physiopathologic effects of postagricultural inversion of the potassium-to-sodium and base-to- chloride ratios in the human diet. Eur J Nutr. 40:200-213.
2 Meneton, P., et al. (2004). Sodium and potassium handling by the aldosterone-sensitive distal nephron: the pivotal role of the distal and connecting tubule. Am J Physiol. 287:F593-F601.
3 Khaw, K.T., et al. (1987). Dietary potassium and stroke-associated mortality: a 12-year prospective population study. New Eng J Med. 316:235-40.
4 McCabe, R.D., et al. (1994). Potassium inhibits free radical formation. Hypertension. 2:77-82.
5 Debs, A., et al. (1988). Perforation of the small intestine caused by tablets of potassium chloride. Press Med. 17:696-97.
6 Kobrin, S.M., et al. (1990). Magnesium deficiency. Semin Nephrol. 10:525-35.
7 Field, M.J., et al. (1985). Hormonal control of renal potassium excretion. Kidney Int. 27:379-87. IM

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