Potassium

What it is

Potassium is a mineral that the body uses as a dissolved, positively charged ion. Approximately 98 percent of total body potassium is inside cells, and keeping that gradient across the cell membrane is needed to set the membrane potential, contract muscles, control heart conduction and pass nerve signals.^[1] The body holds blood potassium in a narrow range by shifting it between the inside and outside of cells and by adjusting how much the kidneys excrete.^[1] Potassium also interacts with sodium: low potassium intake causes the kidney to hold on to more sodium.^[1]

Food provides almost all of it. In US survey data from 2009–2010, fruits and vegetables were the largest single category, supplying 20 percent of potassium intake, followed by milk and milk drinks at 11 percent and meats and poultry at 10 percent.^[3] In one national analysis of people aged 4 and older, multivitamin and mineral supplements added only about 11 mg a day to an estimated usual intake of 2,606 mg.^[3]

In supplements potassium comes as a salt: chloride, citrate, bicarbonate and others. Replenish uses tripotassium citrate, the potassium salt of citric acid, beside sodium in the matching citrate form.

How much adults need

Source: National Academies of Sciences, Engineering, and Medicine, Dietary Reference Intakes for Sodium and Potassium (2019), Table S-1.^[2] AI = Adequate Intake. UL = Tolerable Upper Intake Level; ND = not determined, because no toxicological indicator specific to excess potassium intake was found. No Chronic Disease Risk Reduction Intake was set for potassium.

Amount in Replenish: confirmed at launch

These are Adequate Intakes, not RDAs. Balance studies were too small and incomplete to estimate a median requirement, and there was no evidence of potassium deficiency in the population, so the committee set each AI at the highest median intake seen across two national surveys.^[2] That has a consequence for reading your own diet: because it is unknown how the AI relates to actual requirements, intake below it cannot be interpreted as inadequate.^[3] It is a reference point, not a minimum. Between one-quarter and one-half of US and Canadian adults eat more than the AI.^[3] There is no UL either; the committee found insufficient evidence of toxicity in the apparently healthy population to set one.^[2] That is not the same as saying any amount is safe for everyone, as the safety section explains.

What the evidence says

Blood pressure. The 2019 National Academies review found moderate strength of evidence that potassium supplementation lowers systolic and diastolic blood pressure, particularly among adults with hypertension.^[2] It still did not set a chronic disease intake, because the trials were heterogeneous, no intake–response relationship could be established, and the evidence on cardiovascular disease outcomes themselves was low or insufficient.^[2]

More is not always better. A 2020 dose-response meta-analysis of 32 randomized trials lasting at least 4 weeks, mostly in adults with hypertension and with supplement doses of 30 to 140 mmol a day, found a U-shaped relationship. The blood pressure reduction weakened above a difference in potassium excretion of about 30 mmol a day, and blood pressure rose above roughly 80 mmol a day. The effects were stronger in people with hypertension and in those eating more sodium, and the rise at high intakes appeared in people already treated with blood pressure drugs.^[4] The authors caution that the high-intake estimates rest on few trials.^[4]

Salt substitutes. In a cluster-randomized trial of 20,995 adults in rural China who had a history of stroke, or were 60 or older with high blood pressure, replacing regular salt with a substitute of 75% sodium chloride and 25% potassium chloride lowered stroke from 33.65 to 29.14 events per 1,000 person-years over a mean 4.74 years. Serious adverse events attributed to high blood potassium were not significantly different: 3.35 versus 3.30 per 1,000 person-years.^[5] Because that substitute lowers sodium and raises potassium at once, it cannot isolate the effect of potassium alone.

Other outcomes. The National Academies found insufficient evidence of an effect of potassium on kidney stones or on diabetes and blood sugar control, and noted that bone results in supplement trials may depend on the anion, such as citrate or bicarbonate, rather than potassium itself.^[2]

No trial here was in people taking GLP-1 medications. Eating less usually means eating fewer of the fruits, vegetables and dairy foods that supply most potassium; what to eat when you're eating less covers food choices, and electrolytes on a GLP-1 covers the electrolyte picture.

Safety and interactions

In supplementation trials of adults with normal kidney function, potassium may raise blood levels slightly, but there was no evidence that it caused hyperkalemia, defined as serum potassium above 5.5 mmol/L.^[2] Those trials systematically excluded people at risk.^[6] Case reports show that very large doses of potassium supplements can cause dangerous heart rhythm changes and death.^[2] Stomach upset was reported occasionally in trials, but rarely, and no dose threshold could be identified.^[6]

The National Academies say caution against high supplemental potassium is warranted for people with, or at high risk of, reduced kidney function.^[2] They list chronic kidney disease, end-stage renal disease, diabetes, severe heart failure and adrenal insufficiency as conditions that can impair potassium excretion.^[6]

ACE inhibitors and angiotensin receptor blockers (ARBs). These blood pressure drugs have potassium-sparing effects, and people taking them may be at higher risk of hyperkalemia on a potassium-rich diet.^[3] The prescribing information for potassium chloride says to monitor for hyperkalemia with drugs that inhibit the renin-angiotensin-aldosterone system, which include ACE inhibitors, ARBs, spironolactone, eplerenone and aliskiren.^[7]

Potassium-sparing diuretics. The same label warns that combining potassium with triamterene or amiloride can produce severe hyperkalemia.^[7]

NSAIDs. Nonsteroidal anti-inflammatory drugs may cause potassium retention, and the label advises monitoring.^[7]

Other diuretics. Many diuretics that are not potassium-sparing do the reverse and increase potassium lost in urine.^[3]

If you take prescription medicine, ask your pharmacist or prescriber before adding a supplement.

In Replenish

Replenish provides potassium as tripotassium citrate, one of its 4 electrolyte minerals plus zinc, alongside sodium, magnesium and calcium. Potassium is the main electrolyte inside cells, and the formula as a whole supports hydration.^† The amount per serving is published with the Supplement Facts panel. See Replenish.