With hindsight, given that the kind of nutrition a “good mom” was supposed to serve her children was made up mostly of sweetened cereal, fruit juices, plenty of chicken noodle soups, mac and cheese, peanut butter and jelly sandwiches on good old Wonder bread, and burgers, supplementing with vitamins and minerals was indeed the best thing to do.
Moms today may still feed their children the same junk SAD (Standard American Diet), now amended by soft drinks and plenty of candy. So for some people, supplementation is essential. However, some minerals should never be supplemented, and potassium is one of them. In this article I hope to open many eyes.
While there are many vitamins and minerals I could have picked for this discussion—and I may discuss some of the others in later blogs—here I focus on potassium. My reason for doing so is because this mineral is likely the least understood and the most misused. Hardly a day goes by without someone proudly telling me that they supplement potassium. Similarly, hardly a day goes by when I am not attacked when I explain they probably should not be supplementing potassium. Clearly, there is a gap between scientific knowledge and public belief, and this chasm can be harmful.
In order to be sure I provide the proper explanation, I have contacted an emergency cardiac surgeon friend by email, whom I have known for a couple of years. I asked several questions about potassium and its use in the hospital. My comments and explanation to the answers he gave are started with *** so you can distinguish my thoughts on his answers. I use square brackets in some places that provide explanation of a few terms used by the doctor and to replace medical jargon for clarity.
Questions and Answers about Potassium
Dear M, I have been studying potassium for some time. I would like to ask you to help me clarify a few things. Many people supplement potassium and I always tell them to stop. I believe that potassium supplementation is harmful—particularly by the general public that knows nothing about the side effects.
Q: What is potassium?
A: K [Potassium] is an intracellular ion that shifts with pH [acidity level]. So we look for the underlying cause: if [potassium] is elevated – acidosis, renal failure; if [potassium] is reduced – alkalosis. [Potassium] supplements can be potentially harmful in the setting of impaired elimination (renal failure, acidosis) but within reasonable dosing they should not be.
***Potassium is important in our diet—a mineral that is necessary in our electrolyte. If we look at the USDA recommendation for potassium, we find that the RDA is age and gender dependent. For adult males it is 3400 mg a day and 2600 mg for females. How much is 3400 mg potassium? Hmmmmm great question. According to the USDA database, 100 gr (3.5 oz) of a California avocado has 507 mg potassium, 100 gr Florida avocado 351 mg, 100 gr wild Atlantic salmon has 490 gr, 100 gr rib eye steak has 305 gr, 100 gr baked russet potato with skin has 550 gr, and a glass (8 oz) of whole milk has 322 mg potassium. This should give you a good idea of what it takes to incorporate a high potassium diet into your life.
In contrast to the USDA RDA, this is what the Mayo Clinic suggests:
“Because lack of potassium is rare, there is no RDA or RNI for this mineral. However, it is thought that 1600 to 2000 mg (40 to 50 milliequivalents [mEq]) per day for adults is adequate”, which you can find here.
Of course, food sources are not the only means by which you can take potassium. There are potassium supplements and foods that are enriched with added potassium; those are also considered supplements.
Q: In the ER setting, do you (by you I mean your facility) ever give potassium to a patient?
A: Yes. If they are low [in potassium] by IV [intravenous solution] or PO [taken as pill]. IV if we hydrate with Normal Saline (NS), we add 20 mEq of KCL [potassium chloride] per liter on NS plus lidocaine [a medication that is used as anesthetic and also as an anti-arrhythmic] because potassium burns veins.
***20 mEq of KCL is approximately 800 mg potassium equivalent in pill.
Q: If it is supplemented, why so?
A: Because if they are truly low, because of chronic use of diuretics, they need [potassium] replacement. They can be falsely low because of intracellular shifts caused by alkalosis (respiratory or metabolic). Then we try to fix the underlying cause. [Potassium] is not to treat hypertension but to replace [potassium] washed out by diuretics used for treatment of hypertension: furosemide and HCTZ (Hydrochlorothiazide) in particular.
***Looking at it logically, if A > B and if B > C, then A > C. Thus, when anti-diuretics are given for hypertension, they always wash potassium out to such extent that potassium has to be replaced, therefore potassium is given in the treatment of hypertension.
You may want to listen to this podcast with Dr. Paul Saladino. While the discussion is not about hypertension, at about the 40-minute mark, Saladino discusses the importance of salt and problems with supplementing potassium. He says—and this is true—that the FDA limits potassium supplements to be <100 mg because of the often serious side effects. Some of the side effects are vomiting, nausea, upset stomach, gas, diarrhea, and tingling in the hands or feet. Hyperkalemia can also cause serious heart arrhythmias (hyperkalemia is too much potassium). In spite of the FDA regulations, while most supplement providers do only provide 99 mg potassium per serving as supplemental potassium, not all do. This link takes you to one company that disobeys the FDA rules. So be careful about what you purchase.
Q: Is it ever considered in the ER that potassium may cause heart arrhythmia?
A: But of course. Hyperkalemia is a true emergency. It causes VT [ventricular tachycardia]. We fight it with insulin and glucose, calcium gluconate to stabilize cardiac membranes etc. albuterol, hydroxylate
***I found this answer extremely interesting and important. Calcium is the main mineral that is necessary for the heart to beat, hydroxylate to provide a hydroxylation chemical reaction that increases the pH, which results in a temporary potassium shift from the extracellular to the intracellular environment, pulling potassium out of the blood; insulin and glucose for heart, which allows the heart to quickly uptake glucose, causes an intracellular shift of potassium because glucose entering the cells causes a sodium and water efflux, thereby potassium floods into the cell(1) and this too pulls potassium out of the blood and into the cells. Albuterol (β2-adrenergic agonists, same as epinephrine) is also used for asthma. It too induces cellular reuptake of potassium by the release of epinephrine—meaning, it too pulls potassium out of the blood and into the cells. This is how much work and medicines are required to overcome hyperkalemia, which can cause heart failure and death.
I was particularly surprised by the need for insulin administration, but a renal physiology book explained the many connections between insulin and potassium. Interestingly, treatment with insulin is sometimes necessary and not just from supplementation but also as a result of a potassium-rich meal, which can cause hyperkalemia in some populations:
“The importance of insulin is illustrated by two observations. First, the rise in plasma [potassium] after a [potassium]-rich meal is greater in patients with diabetes mellitus… than in healthy people. Second, insulin (and glucose to prevent insulin-induced hypoglycemia) can be infused to correct hyperkalemia. Insulin is the most important hormone that shifts [potassium] into cells after the ingestion of [potassium]… Aldosterone, like catecholamines and insulin, also promotes [potassium] uptake into cells. A rise in aldosterone levels (e.g., primary aldosteronism) causes hypokalemia [too low potassium], whereas a fall in aldosterone levels (e.g., in persons with Addison disease) causes hyperkalemia… aldosterone also stimulates urinary [potassium] excretion. Thus aldosterone alters the plasma [potassium] by acting on [potassium] uptake into cells and by altering urinary [potassium] excretion”(2)
This implies, that supplementing potassium by a person with type 2 diabetes (T2D) has more serious consequences than for a metabolically healthy person. For a person with T2D, even a high-potassium meal may cause hyperkalemia, requiring serious countermeasures. It also means that people with reduced adrenaline or cortisol (the so called “adrenal fatigue”) may have high potassium. Both of these conditions are adrenal disorders. One way to regulate high potassium is by increasing sodium in the diet—this explains the salt cravings of those with adrenal insufficiency (aka adrenal fatigue). This electrolyte disturbance is represented by salt wasting and potassium sparing in the body, which can be remedied by the consumption of excess salt.
Q: A reduced sodium diet will necessarily reduce potassium (by the RAAS system) and will cause problems. Would it not make more sense to increase sodium in order for the kidneys to retain more potassium? I mean, a homeostatic balance (osmolality homeostasis) must always be achieved, so a reduced sodium diet, by default, should be causing problems with potassium.
A: A reduced sodium activates RAAS [Renin–angiotensin system] to retain sodium by exchanging it for potassium in proximal tubules [in the kidneys]. Osmolality is addressed by pituitary ADH [antidiuretic hormone, such as vasopressin] in distal tubules [in the kidneys].
***So let’s take this answer apart:
- “reduced sodium activates RAAS to retain sodium” because of the osmolality of the electrolyte, discussed in the next point, must remain constant. This is an important point here that is relevant in reduced sodium diets that are recommended for the general population and particularly for those with hypertension. However, if reduced dietary sodium initiates the body’s safety system to retain sodium, then does a reduced sodium diet make sense for hypertension? It appears to achieve the opposite: reduced sodium diet increases blood pressure as a result of the RAAS system.
- “by exchanging potassium for sodium in proximal tubules” in the kidneys means that a reduced sodium diet reduces potassium from the blood.
- “osmolality is addressed by pituitary ADH in distal tubules”—this refers to water sparing (retaining) or wasting (eliminating), depending on the circumstance. In order to keep the correct balance (osmolality) between sodium, potassium, and water, in addition to wasting excess potassium, water volume will also be reduced in order to retain sodium and increase its relative density, re-establishing homeostasis.
All in all, a reduced sodium diet prevents the elimination of sodium. Potassium is eliminated as sodium is retained. This is the opposite of the desired outcome of a reduced sodium diet. Because of the careful balancing of the RAAS and ADH systems, a diet with excess potassium will necessarily lead to reduced potassium, increased sodium, and reduced water volume. In other words, the body controls for minerals by releasing extra amounts, retaining those in too small amount, and by reducing water in order to retain the osmolality homeostasis.
The main function of the supplemented potassium, according to the ER doctor above, is to work with diuretics that reduce blood pressure, and also reduce potassium in the electrolyte. However, if one is not taking a diuretic and has no high blood pressure, what does supplemental potassium do? Unlike potassium that is consumed in food, and which – together with sodium – becomes part of electrolyte slowly, potassium that is supplemented absorbs at once in large quantity and can negatively affect the heart and the muscles.
A sudden increase of potassium in supplemental form is a medical emergency for the body. The renal function will handle it the following way: Our kidneys are in charge of the osmolality of blood plasma. Plasma osmolality refers to our electrolyte water balance between its solute (particles and elements dissolved) concentration and the volume of solvent (the liquid in which something is dissolved). Of course, in this case the solvent is water, and the solutes are all the electrolyte minerals that are in the water and form the plasma electrolyte fluid.
When the plasma suddenly contains more potassium than it does in homeostasis, the kidneys have to change the other solute amounts to neutralize the excess potassium to ideal osmolality. The ideal osmolality is between 275 and 295 milliosmoles per kilogram (mOsm/kg) and if this is increased as a result of the extra potassium, a critical renal task is to change it back to homeostasis. The kidneys now will waste (urinate out) potassium and water but retain sodium. This helps regain the same concentration of homeostasis before the arrival of extra potassium—with one caveat. Since the kidneys waste water and potassium, the blood volume changes: it is reduced. Reduced blood volume is indicative of dehydration similarly to a diuretic action.
Although technically potassium is not a diuretic, because supplemented potassium reduces blood volume, it is equivalent in its outcome to having taken a diuretic.
Should You Ever Supplement Potassium?
Probably not, as it can be harmful. Many people drink lots of potassium-rich drinks, such as sport drinks, juices, and green smoothies. Drinking potassium-rich electrolyte during exercise may be harmful. Studies show that during heavy exercise potassium levels increase in the blood naturally as muscles release more potassium. The function of potassium at the potassium/sodium pumps is to operate the electrical activities of the cells. When potassium rushes out of the cells, as it does during heavy exercise, this is a sign that sodium has rushed into the cells. When sodium rushes into the cells, the cell is generating an action potential—an electrical activity. It goes without saying that exercise increases electrical activity in cells, and as such, there will be more potassium in the blood, outside of the cells and more sodium inside of them. Even without supplementing potassium during an exercise, hyperkalemia, caused by the exercise itself, has claimed victims not infrequently in the past. Taking additional potassium increases potassium in the blood, causing hyperkalemia, which can be fatal, even from Low-sodium salt alternatives(3,4). Morton’s Lite-Salt contains 50% less sodium than regular salt, and incorporates 350 mg potassium per ¼ teaspoon salt–over 3.5 times RDA maximum for supplemented potassium per quarter teaspoon.
Nothing beats a healthy diet full of macro and micro nutrients. Although our modern food environment is not as healthy as it should be and we are at risk of potentially missing some minerals or vitamins from our diet, we must consider what the nutrients we wish to supplement will actually do in the body and how. Potassium is not a mineral to supplement without medical prescription and supervision. It may cause more harm than good. If you wish to increase potassium in your diet, eat whole foods and avoid processed foods. It is that simple.
Please consult your physician before making changes to your supplement regimen.
- Longo, D. L. et al. Harrison’s Manual of Medicine 18th Edition. (McGraw Hill Medical, 2013).
- Koeppen, B. M. & Stanton, B. A. in Renal Physiology (Fifth Edition) (eds Bruce M. Koeppen & Bruce A. Stanton) 115-130 (Mosby, 2013).
- Hultgren, H. N., Swenson, R. & Wettach, G. Cardiac arrest due to oral potassium administration. The American Journal of Medicine 58, 139-142, doi:10.1016/0002-9343(75)90545-8 (1975).
- Restuccio, A. Fatal hyperkalemia from a salt substitute. The American Journal of Emergency Medicine 10, 171-173, doi:10.1016/0735-6757(92)90058-6 (1992).
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