Potassium is a very important mineral for the proper function of all cells, tissues and organs in the human body. An electrolyte—a substance that conducts electricity in the body, along with sodium, chloride, calcium and magnesium—potassium is crucial to heart function and plays a key role in skeletal and smooth muscle contraction, making it important for normal digestive and muscular function.1
Having too much potassium in the blood is called hyperkalemia; having too little is known as hypokalemia. Keeping the right potassium balance in the body depends on the amount of sodium and magnesium in the blood. Too much sodium—common in Western diets that use a lot of salt—may increase the need for potassium.
Diarrhea, vomiting, excessive sweating, malnutrition, malabsorption syndromes (such as Crohn’s disease) can also cause potassium deficiency, as well as use of a kind of heart medicine called loop diuretics.1
Most people who eat a healthy diet should get enough potassium naturally. Good natural food sources of calcium include bananas; avocados; nuts (like almonds and peanuts); citrus fruits and juices; leafy, green vegetables, lima beans; milk; potatoes; salmon, cod, chicken and other meats. (It should be noted that some types of cooking, such as boiling, can destroy the potassium in some foods.)2 However, many Americans don’t get enough potassium from their diets due to a preference for—or access to—processed foods over whole foods. So the average U. S. intake of potassium is lower than it should be.
Low potassium is associated with a risk of high blood pressure, heart disease, stroke, arthritis, cancer, digestive disorders and infertility. For people with low potassium, doctors sometimes recommend improved diets— or potassium supplements—to prevent or treat some of these conditions.2
The Institute of Medicine has set an adequate intake for potassium. Getting this amount of potassium from diet, with or without supplements, should be enough to keep individuals healthy. The U. S. Food and Drug Administration (FDA) has determined that foods that contain at least 350mg of potassium can bear the following label: “Diets containing foods that are good sources of potassium and low in sodium may reduce the risk of high blood pressure and stroke.”2
Studies show a positive link between a diet rich in potassium and bone health, particularly among elderly women, suggesting that increasing consumption of foods rich in potassium may play a role in osteoporosis prevention. More research is needed to determine whether a diet high in potassium can reduce bone turnover in people.1,2
Research appearing in the Journal of the American Society of Nephrology showed older women who take potassium citrate supplements can increase their bone density, reducing the risk of osteorperosis.3
Hoping to prove that potassium citrate— a base chemical—could raise acidic body pH in participants, which is generally caused by poor lifestyle and dietary choices, Dr. Reto Krapf of the University of Basel in Switzerland and colleagues conducted a study of 161 post-menopausal women whose average age was 59. Krapf split the women into two groups: The first received a daily supplement of potassium citrate for up to 12 months, and the second (control group) was given a daily supplement of potassium chloride for up to 12 months. (Potassium chloride was used in the control group because it is a neutral chemical that does not affect body pH.)3
After six to 12 months, the researchers conducted bone mineral density tests on the participants’ lower spine and hips.
The group taking the potassium citrate (base) supplements experienced a one percent increase in bone mineral density in the lumbar spine area, as well as a one percent increase in bone density in the hips. Conversely, the group taking the potassium chloride (neutral) experienced a one percent loss of bone density at both test sites.3
The researchers also found that the women taking potassium citrate lost less calcium through their urine than those taking potassium chloride.3
Combating High Blood Pressure
Some studies have linked low levels of potassium in the diet with high blood pressure. And there is some evidence that potassium supplements might cause a slight drop in blood pressure. Other studies show that increasing potassium intake reduces the risk of dying from cardiovascular disease. Researchers suspect this is largely due to potassium’s blood pressure lowering effects. But not all studies agree—two large studies found no effect on blood pressure. It may be that taking potassium helps lower blood pressure only if one is not getting enough of this mineral to start with. Before taking potassium or any supplement for high blood pressure, it is recommended a doctor be consulted.1
In 1997, a meta-analysis of 33 randomized controlled trials including 2,609 individuals assessed the effects of increased potassium intake, mostly in the form of potassium chloride (KCl) supplements, on blood pressure.5 Increased potassium intake (2,300- 3,900mg/day) resulted in slight but significant blood pressure reductions that averaged 1.8/1.0mm Hg in people with normal blood pressure and 4.4/2.5mm Hg in people with hypertension. Subgroup analysis indicated that the blood pressure-lowering effect of potassium was more pronounced in individuals with higher salt intakes and in trials where black individuals were a majority of the participants. A clinical trial in 150 Chinese men and women with borderline to mild hypertension found that moderate supplementation with 500mg/day of potassium chloride for 12 weeks resulted in a significant 5mm Hg reduction in systolic blood pressure compared to placebo; no changes in diastolic blood pressure were observed in this study.5 Like many Western diets, the customary diet of this population was high in sodium and low in potassium. A cross-over trial in 14 hypertensive individuals reported that supplementation with potassium citrate was equally as effective in lowering blood pressure as potassium chloride.6
A more recent cross-over trial in 42 adults with mild, untreated high blood pressure compared the effects of supplemental potassium chloride or potassium bicarbonate with a placebo.7 Supplementation with potassium chloride slightly decreased ambulatory systolic blood pressure but had no effect on office systolic blood pressure, while supplementation with potassium bicarbonate did not affect blood pressure measurements. Both supplements resulted in improved endothelial function and other cardiovascular benefits.7
However, a cross-over trial in 48 adults with early hypertension (defined as a diastolic blood pressure of greater than 80mm Hg but less than 100mg Hg), who were not taking anti-hypertensive medication, reported that increased potassium intake through dietary or supplemental (potassium citrate) means did not improve blood pressure or vascular function.8 Increasing potassium intake by consuming a diet rich in fruits and vegetables may help lower blood pressure and may have other health benefits. Supplemental potassium might help lower blood pressure in some individuals, but potassium supplements should only be used in consultation with a medical provider.4
At normal doses, potassium is fairly safe. Gastrointestinal symptoms are the most common side effects of potassium supplements, including nausea, vomiting, abdominal discomfort and diarrhea. Intestinal ulceration has been reported after the use of enteric-coated potassium chloride tablets. Taking potassium with meals or taking a microencapsulated form of potassium may reduce gastrointestinal side effects.4
Some people have allergies to potassium supplements, and they may not be safe for those who take drugs for diabetes or heart disease. People with kidney disease, diabetes, heart disease, Addison’s disease, stomach ulcers or other health problems should not take potassium supplements without talking to a doctor first.2 VR
1 University of Maryland Medical Center; “Potassium” (http://www.umm.edu/altmed/articles/ potassium-000320.htm)
2 WebMd; “Vitamins and Supplements Lifestyle Guide (http://www.webmd.com/vitamins-and-supplements/ lifestyle-guide-11/supplement-guide-potassium)
3 Jehle S, Zanetti A, Muser J, Hulter HN, Krapf R. “Partial neutralization of the acidogenic Western diet with potassium citrate increases bone mass in postmenopausal women with osteopenia.” J Am Soc Nephrol. 2006 Nov;17(11):3213-22. Epub 2006 Oct 11.
4 Linus Pauling Institute; “Potassium;” (http://lpi.oregonstate.edu/infocenter/minerals/potassium/) 5 Whelton PK, He J, Cutler JA, et al. Effects of oral potassium on blood pressure. Meta-analysis of randomized controlled clinical trials. JAMA. 1997;277(20):1624-1632.(PubMed)
6 He FJ, Markandu ND, Coltart R, Barron J, MacGregor GA. Effect of short-term supplementation of potassium chloride and potassium citrate on blood pressure in hypertensives. Hypertension. 2005;45(4):571-574. (PubMed)
7 He FJ, Marciniak M, Carney C, et al. Effects of potassium chloride and potassium bicarbonate on endothelial function, cardiovascular risk factors, and bone turnover in mild hypertensives. Hypertension. 2010;55(3):681-688.(PubMed)
8 Berry SE, Mulla UZ, Chowienczyk PJ, Sanders TA. Increased potassium intake from fruit and vegetables or supplements does not lower blood pressure or improve vascular function in UK men and women with early hypertension: a randomised controlled trial. Br J Nutr. 2010:1-9. (PubMed)