August/September 2021 Issue
Supplements: Potassium Supplementation
By Joanna Foley, RD, CLT
Vol. 23, No. 7, P. 18
Under what circumstances should it be indicated?
Potassium has been a nutrient of concern for many years. Together with dietary fiber, calcium, and vitamin D, it has been among the top four nutrients of public health concern for Americans for more than a decade. According to a study from The American Journal of Clinical Nutrition, less than 2% of US adults are estimated to be getting enough potassium.1 In addition, a recent study on about 50,000 Americans found that potassium deficiency increased by 7.3 percentage points from 1999 to 2016.2
An increased intake of processed foods and a decline in fruit and vegetable consumption are believed to be contributing factors to rising potassium deficiency; furthermore, certain medications, incidences of vomiting and diarrhea, and restrictive diets can make it difficult to meet potassium intake requirements.
Inadequate potassium can have major health effects, such as higher blood pressure, increased risk of kidney stones, and weakened bones. In addition to recommending greater intake through diet, should supplementation be considered?
Potassium Defined and Its Functions in the Body
Dietitians know that potassium is an important mineral and electrolyte in the body. It’s present in all body tissues and is required for normal cellular function. About 90% of the potassium individuals eat is absorbed, which is high compared with other minerals such as magnesium that have only about a 30% to 40% absorption rate.3 The kidneys filter excess potassium, and the body removes it via urine and stool, with a small amount lost through sweat.
Potassium plays a critical role in human health, working together with other minerals (eg, sodium, calcium) to maintain many bodily processes.4 Some of potassium’s most important functions include conducting nerve impulses, contracting muscles, helping maintain fluid and blood volume in the body, supporting bone health by preserving calcium stores, regulating blood pressure to support heart and kidney health, and helping control blood glucose levels by playing a role in insulin secretion.
Research shows that diets rich in potassium are associated with a reduced risk of serious health conditions such as stroke, CVD, and osteoporosis, and may help delay the progression of kidney disease.5
How Much Potassium Do Clients Need?
According to the National Institutes of Health, the Adequate Intake for potassium for Americans depends on age and pregnancy and lactation status (see Table 1).
While these amounts are believed to ensure nutritional adequacy, the recommended DV for potassium is 4,700 mg for people aged 4 and older. As of 2016, the FDA began requiring the percent DV for potassium to be listed on the Nutrition Facts panel to help increase awareness of requirements among consumers.6
Who’s at Risk of Potassium Deficiency?
Most adults don’t get enough potassium in their diets, but few are considered deficient. Regardless, evidence suggests inadequate potassium intake, even without a true deficiency, can lead to negative health consequences such as higher blood pressure, increased risk of kidney stones, greater losses of calcium in the urine, bone turnover, and salt sensitivity.
A significant potassium deficiency is called hypokalemia, defined as blood levels of less than 3.5 mmol/L, and often is caused by excessive potassium losses from the body.7 People most at risk of hypokalemia are patients on dialysis, individuals who take certain diuretics (eg, furosemide [Lasix]), those who have persistent diarrhea or vomiting, and malnourished patients experiencing refeeding syndrome, which can occur in the eating disorders setting.8,9 For these patients, increasing potassium intake via diet and/or supplementation can benefit overall health and decrease the risk of hypokalemia complications.
Kelsey Peterson, MS, RD, CEDRD, a dietitian specializing in eating disorders and co-owner of Restore Family Therapy, Inc, in San Diego, says, “Supplementing with potassium, especially when someone has a history of purging, can be beneficial under the supervision of a medical doctor. It is vitally important to check lab work first to verify the need, dosage, and frequency of potassium supplementation, as incorrect usage can put a patient at risk of a cardiac event.”
Risks of Too Much Potassium
Conversely, ingesting too much potassium via supplementation can lead to hyperkalemia—high potassium levels in the blood—and pose major health risks. Hyperkalemia is defined as a blood level greater than 5.5 mmol/L and can lead to irregular heartbeats and cardiac arrest, which can be fatal.10,11 People who are most at risk of hyperkalemia include patients with end-stage renal disease (ESRD), type 1 diabetes, congestive heart failure, adrenal insufficiency, and liver disease, and those taking certain medications such as potassium-sparing diuretics.
Fortunately, there’s no evidence that consuming potassium from foods contributes to hyperkalemia in people with normal kidney functioning. This is why a Tolerable Upper Intake Level for potassium in the diet hasn’t been set.12 However, hyperkalemia is more likely to occur in people who take potassium supplements. “If a potassium supplement is prescribed to a dialysis patient, it is critical to monitor serum potassium,” says Kerri Sarzynski, RD, a renal dietitian for DaVita in Orange County, California. “In ESRD, potassium can accumulate between dialysis treatments and may result in a cardiac event.”
Most over-the-counter dietary supplements contain less than 100 mg potassium per serving and therefore usually don’t provide a significant source of the mineral. However, some products contain several hundred milligrams of potassium and thus warrant further caution for individuals taking them.
When Are Supplements Needed?
Potassium supplementation may be necessary for people at risk of or who have a potassium deficiency, or for those not getting enough through their diet. Supplementing with potassium always should be done under a doctor’s supervision and only when clinically indicated to prevent complications from hyperkalemia. (See Table 2 for several examples of high-quality potassium supplements.)
Here’s what RDs should know when clients ask about potassium supplementation:
• Research shows potassium supplementation can lead to side effects such as damage to the digestive tract, diarrhea, stomach pain, nausea, vomiting, and gas.13 While taking the supplement with food may lessen some of these symptoms, long-term potassium supplementation should be avoided.
• Several types of medications can interfere with potassium status in ways that can be dangerous. People taking potassium-sparing diuretics (eg, spironolactone), angiotensin-converting enzyme inhibitors for blood pressure (eg, captopril), and trimethoprim-sulfamethoxazole antibiotics shouldn’t take potassium supplements without medical supervision. People who use salt substitutes, which are composed of potassium chloride and contribute to overall potassium load, also should proceed with caution.
• Not all forms of potassium act the same way in the body. Potassium chloride, the most common form in supplements, has been shown to benefit blood pressure levels, but may have no effect on bone health. Potassium phosphate may benefit people prone to kidney stones by decreasing excess calcium in the urine.14 RDs should refer clients to their primary care physicians, who should determine which form of potassium supplement they should take.
Ultimately, most people don’t need to take potassium supplements, and there are some, including those with ESRD or congestive heart failure, and individuals taking certain medications such as potassium-sparing diuretics, who may need to avoid them altogether.15 RDs should continue to recommend a food-first approach to increasing potassium intake to reap the mineral’s associated health benefits. Good sources of potassium include avocados, potatoes, tomatoes, bananas, citrus, dried fruits, leafy greens, dairy products, fish, beans, and lentils.16 Research has shown that dietary modification to increase potassium is a safe and effective alternative to taking potassium supplements for most people.13
RDs always should assess a client’s risk factors for both hypo- and hyperkalemia and advise those who are interested in potassium supplements to use caution and seek medical guidance before taking them.
— Joanna Foley, RD, CLT, is a freelance health and nutrition writer, cookbook author, and health coach based in southern California. She has worked in a number of health care settings including hospital, outpatient dialysis centers, and private practice. Visit her at joannafoleynutrition.com.
1. Cogswell ME, Zhang Z, Carriquiry AL, et al. Sodium and potassium intakes among US adults: NHANES 2003–2008. Am J Clin Nutr. 2012;96(3):647-657.
2. Sun H, Weaver CM. Rising trend of hypokalemia prevalence in the US population and possible food causes. J Am Coll Nutr. 2021;40(3):273-279.
3. Magnesium. National Institutes of Health Office of Dietary Supplements website. https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/. Updated March 29, 2021. Accessed May 10, 2021.
4. Potassium. National Institutes of Health Office of Dietary Supplements website. https://ods.od.nih.gov/factsheets/Potassium-HealthProfessional/#h5. Updated March 26, 2021. Accessed May 10, 2021.
5. Weaver CM. Potassium and health. Adv Nutr. 2013;4(3):368S-377S.
6. What's new with the Nutrition Facts label. FDA website. https://www.fda.gov/food/new-nutrition-facts-label/whats-new-nutrition-facts-label. Updated March 11, 2020. Accessed May 13, 2021.
7. Lederer E. Hypokalemia. Medscape website. https://emedicine.medscape.com/article/242008-overview. Updated January 8, 2021. Accessed May 13, 2021.
8. Grasso S, Ferro Y, Migliaccio V, et al. Hypokalemia during the early phase of refeeding in patients with cancer. Clinics. 2013;68(11):1413-1415.
9. Managing potassium during eating disorder refeeding. ACUTE website. https://www.acute.org/resource/managing-potassium-eating-disorder-refeeding. Updated February 26, 2021. Accessed May 14, 2021.
10. Hyperkalemia (high potassium). American Heart Association website. https://www.heart.org/en/health-topics/heart-failure/treatment-options-for-heart-failure/hyperkalemia-high-potassium. Updated October 31, 2016. Accessed May 14, 2021.
11. Viera AJ, Wouk N. Potassium disorders: hypokalemia and hyperkalemia. Am Fam Physician. 2015;92(6):487-495.
12. Turck D, Bresson J-L, Burlingame B, et al. Dietary reference values for potassium. EFSA J. 2016;14(10):e04592.
13. Hainsworth AJ, Gatenby PA. Oral potassium supplementation in surgical patients. Int J Surg. 2008;6(4):287-288.
14. Heller HJ, Reza-Albarrán AA, Breslau NA, Pak CY. Sustained reduction in urinary calcium during long-term treatment with slow release neutral potassium phosphate in absorptive hypercalciuria. J Urol. 1998;159(5):1451-1456.
15. Cooperman T. Potassium supplements review. ConsumerLab.com website. https://www.consumerlab.com/reviews/potassium-supplements-review/potassium/. Published May 1, 2021. Accessed May 14, 2021.
16. Potassium. Harvard T.H Chan School of Public Health website. https://www.hsph.harvard.edu/nutritionsource/potassium/. Published January 29, 2021. Accessed May 14, 2021.