Potassium is an essential mineral that is needed by all tissues in the body. It is sometimes referred to as an electrolyte because it carries a small electrical charge that activates various cell and nerve functions. Potassium is found naturally in many foods and as a supplement. Its main role in the body is to help maintain normal levels of fluid inside our cells. Sodium, its counterpart, maintains normal fluid levels outside of cells. Potassium also helps muscles to contract and supports normal blood pressure.
The U.S. Dietary Reference Intakes state that there is not enough evidence to establish a Recommended Dietary Allowance (RDA) for potassium. However, the National Academy of Medicine has established an Adequate Intake (AI) for potassium. 
- For women 14-18 years of age, the AI is 2,300 mg daily; for women 19+, 2,600 mg. For pregnant and lactating women, the AI ranges from 2,500-2,900 depending on age.
- For men 14-18 years of age, the AI is 3,000 mg; for men 19+, 3,400 mg.
It is estimated that the average daily intake of potassium in adults is about 2,320 mg for women and 3,016 mg for men. 
Potassium and Health
The functions of sodium and potassium in the body are closely related and often studied together.
The interplay of potassium and sodium
A study in the Archives of Internal Medicine found that:
- People who ate high-sodium, low-potassium diets had a higher risk of dying from a heart attack or any cause. In this study, people with the highest sodium intakes had a 20% higher risk of death from any cause than people with the lowest sodium intakes. People with the highest potassium intakes had a 20% lower risk of dying than people with the lowest intakes. But what may be even more important for health is the relationship of sodium to potassium in the diet. People with the highest ratio of sodium to potassium in their diets had double the risk of dying of a heart attack than people with the lowest ratio, and they had a 50% higher risk of death from any cause. 
- People can make a key dietary change to help lower their risk: Eat more fresh vegetables and fruits, which are naturally high in potassium and low in sodium, but eat less bread, cheese, processed meat, and other processed foods that are high in sodium and low in potassium.
- Observational studies of large groups of people show that sodium and potassium in the diet are associated with blood pressure.  Many Americans tend to eat too much salt or salty foods and not enough potassium, a dietary pattern that places some people at risk for hypertension, or high blood pressure. A review of randomized controlled trials found that the DASH diet (Dietary Approaches to Stop Hypertension) that is low sodium and high potassium was effective at lowering blood pressure in those with existing hypertension.  This same review found that potassium also had a blood-pressure-lowering effect in people with normal blood pressure, either from a higher intake of fruits and vegetables, or with a potassium supplement.
- The Agency for Healthcare Research and Quality issued a report on the effects of sodium and potassium on chronic disease risk based on clinical trials and cohort studies.  They found that potassium supplements (containing 782 to 4,692 mg taken daily) and replacing table salt with potassium salt substitutes significantly decreased blood pressure compared with a placebo, especially in those with hypertension. However there was not enough evidence or there was conflicting evidence of their effects on lowering overall risk of hypertension, kidney stones, cardiovascular diseases including stroke, and kidney disease.
- A meta-analysis of randomized controlled trials and cohort studies looking at increased potassium intake on cardiovascular risk factors found that higher potassium intakes (from food and supplements) reduced blood pressure in people with hypertension, and was associated with a 24% lower risk of stroke.  Another meta-analysis of cohort studies found a dose-response inverse association between potassium intake and stroke risk, meaning that the higher the intake, the lower the risk; potassium intakes of at least 3,500 mg daily were associated with the lowest risk of stroke. 
Calcium is one of the most important nutrients required for bone health. A condition called “negative calcium balance” occurs when calcium losses from the body are greater than the amount of calcium that is absorbed, which can lead to bone loss. This most often happens when a diet is too low in calcium or vitamin D, or in individuals with digestive problems that interfere with the absorption of the calcium. People with thyroid or kidney problems may lose too much calcium in their urine.
According to another theory called “acid-base balance” or “acid-alkaline theory” a high dietary acid load (such as that caused by a high meat and low fruit/vegetable intake) may lead to bone loss if calcium is pulled from bones to help neutralize the acid. It is believed that the breakdown of animal proteins and grains that are high in phosphorus and sulfates generates acid in the body. This causes the kidneys to flush out acid and calcium in the urine.
Potassium-rich foods might offer a buffering “alkalinizing” effect because they contain compounds that can be metabolized to bicarbonate, which helps to neutralize acids in the body and may protect bone. Observational studies have found that a high potassium intake from fruits and vegetables is associated with higher bone density.  However, observational studies have not shown that a high protein intake negatively affects bone health or fracture risk; in fact, in the elderly a higher protein intake appears to protect from fractures. So the acid-alkaline theory on bone health is not yet clear.
The high-potassium DASH diet, rich in fruits, vegetables, and low-fat dairy, has been found to lower markers of bone turnover. [10,11] However, there are other dietary factors of DASH (low sodium, adequate calcium) that may contribute to this result and not just potassium. Animal studies have shown that active plant chemicals and polyphenols in fruits and vegetables may also play a role in bone health.
Randomized controlled trials giving postmenopausal women potassium supplements or a placebo have not consistently found a benefit of less bone fractures or increased bone mineral density with higher potassium intake from supplements. [12,13]
The National Academy of Medicine report concluded that there may be certain components of potassium-rich foods such as its production of bicarbonate that may improve bone mineral density; however, these foods may contain other nutrients and plant chemicals beneficial to bone health that make it difficult to conclude that potassium alone has an effect on bone health. 
A diet rich in potassium helps to prevent calcium from being excreted in the urine, and may also help to prevent calcium from being released from bone into the blood. Calcium that is not reabsorbed is excreted in the urine, which may increase the risk of crystals forming that can lead to kidney stones.
A review of three large prospective cohort studies, the Health Professionals Follow-up Study and the Nurses’ Health Studies I and II, found that a higher potassium intake was associated with a lower risk of stones in all three cohorts. The higher intake was associated specifically with a higher citrate concentration in urine and urine volume (from increased water obtained from fruits and vegetables), both protective factors against stones. 
The Agency for Healthcare Research and Quality and the American College of Physicians conducted a review of randomized controlled trials looking at medical management to prevent repeated kidney stones.  The review found that people with past kidney stones who increased their intake of potassium through potassium citrate supplements significantly lowered the risk of developing further stones, given that they also increased their fluid intake.
Is there any research behind Acid-Alkaline Diet claims?
However, there is some truth that the metabolism of certain foods can create bicarbonates, which neutralizes acids in the body.  Potassium-rich foods that have an alkalizing effect include fruits, vegetables, almonds, and lentils. One theory suggests that a long-term high intake of protein foods such as meats, poultry, fish, dairy, and eggs, as well as cereal grains may create a condition called low-grade metabolic acidosis due to their high sulfate and phosphate content. [10,16] This occurs particularly if the diet does not contain enough counterbalancing potassium-rich foods. The condition is sometimes referred to as the ‘‘acid-ash hypothesis,’’ which may cause a very slight drop in blood pH, though still falling within a normal range. Theories suggest that even a small change such as this may increase one’s risk of developing conditions like kidney stones and bone loss.
BOTTOM LINE: Although theories in this area are compelling, the evidence is still inconsistent and it has not been shown in controlled trials that diet can significantly change blood pH in healthy people. Therefore it is too early to make specific recommendations based on this theory.
- Dried fruits (raisins, apricots)
- Beans, lentils
- Winter squash (acorn, butternut)
- Spinach, broccoli
- Beet greens
- Oranges, orange juice
- Coconut water
- Dairy and plant milks (soy, almond)
- Cashews, almonds
Signs of Deficiency and Toxicity
The kidneys work to maintain normal blood levels of potassium by flushing out excess amounts through urine. Potassium can also be lost through stool and sweat. At least 400-800 mg daily from food is needed because of normal daily losses. Any conditions that increase fluid losses beyond normal such as vomiting, diarrhea, and certain medications like diuretics can lead to a deficiency, called hypokalemia. Hypokalemia is most common in hospitalized patients who are taking medications that cause the body to excrete too much potassium. It is also seen in people with inflammatory bowel diseases (Crohn’s disease, ulcerative colitis) that may cause diarrhea and malabsorption of nutrients.
It is rare for a potassium deficiency to be caused by too low a food intake alone because it is found in so many foods; however an inadequate intake combined with heavy sweating, diuretic use, laxative abuse, or severe nausea and vomiting can quickly lead to hypokalemia. Another reason is a deficiency of magnesium, as the kidneys need magnesium to help reabsorb potassium and maintain normal levels in cells.
- Muscle cramps or weakness
- Muscle paralysis and irregular heart rate (with severe hypokalemia)
Too much potassium in the blood is called hyperkalemia. In healthy people the kidneys will efficiently remove extra potassium, mainly through the urine. However, certain situations can lead to hyperkalemia: advanced kidney disease, taking medications that hold onto potassium in the body (including NSAIDs), or people who have compromised kidneys who eat a high-potassium diet (more than 4,700 mg daily) or use potassium-based salt substitutes. Symptoms of hyperkalemia:
- Weakness, fatigue
- Nausea, vomiting
- Shortness of breath
- Chest pain
- Heart palpitations, irregular heart rate
Did You Know?
- The chemical symbol for potassium is “K,” not to be confused with vitamin K.
- Salt substitutes are sometimes made from potassium chloride, which replaces some or all of the sodium chloride in table salt. Although those on salt-restricted diets may benefit from its much lower sodium content, potassium salt has a bitter aftertaste when heated so it is not recommended for cooking. Check with your doctor before trying a potassium salt, because extra potassium can be dangerous for people who have trouble eliminating excess amounts or who are taking medications that can increase potassium levels in the bloodstream.
- National Academy of Medicine. Dietary Reference Intakes for Sodium and Potassium. Washington (DC): National Academies Press (US); 2019 Mar.
- National Institutes of Health; Office of Dietary Supplements. Potassium: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Potassium-HealthProfessional/. Accessed 5/20/2019.
- Brown IJ, Tzoulaki I, Candeias V, Elliott P. Salt intakes around the world: implications for public health. International journal of epidemiology. 2009 Apr 7;38(3):791-813.
- Dietary Guidelines for Americans Scientific Advisory Committee. Report of the Dietary Guidelines Advisory Committee on the Dietary Guidelines for Americans, 2010, to the Secretary of Agriculture and the Secretary of Health and Human Services. 2010.
- Yang Q, Liu T, Kuklina EV, Flanders WD, Hong Y, Gillespie C, Chang MH, Gwinn M, Dowling N, Khoury MJ, Hu FB. Sodium and potassium intake and mortality among US adults: prospective data from the Third National Health and Nutrition Examination Survey. Archives of internal medicine. 2011 Jul 11;171(13):1183-91.
- Aaron KJ, Sanders PW. Role of dietary salt and potassium intake in cardiovascular health and disease: a review of the evidence. InMayo Clinic Proceedings 2013 Sep 1 (Vol. 88, No. 9, pp. 987-995). Elsevier.
- Newberry SJ, Chung M, Anderson CA, Chen C, Fu Z, Tang A, Zhao N, Booth M, Marks J, Hollands S, Motala A. Sodium and Potassium Intake: Effects on Chronic Disease Outcomes and Risks. Rockville (MD): Agency for Healthcare Research and Quality (US); 2018 Jun. Report No.: 18-EHC009-EF.
- Aburto NJ, Hanson S, Gutierrez H, Hooper L, Elliott P, Cappuccio FP. Effect of increased potassium intake on cardiovascular risk factors and disease: systematic review and meta-analyses. BMJ. 2013 Apr 4;346:f1378.
- Vinceti M, Filippini T, Crippa A, de Sesmaisons A, Wise LA, Orsini N. Meta‐analysis of potassium intake and the risk of stroke. Journal of the American Heart Association. 2016 Oct 6;5(10):e004210.
- Hanley DA, Whiting SJ. Does a high dietary acid content cause bone loss, and can bone loss be prevented with an alkaline diet?. Journal of Clinical Densitometry. 2013 Oct 1;16(4):420-5.
- Lin PH, Ginty F, Appel LJ, Aickin M, Bohannon A, Garnero P, Barclay D, Svetkey LP. The DASH diet and sodium reduction improve markers of bone turnover and calcium metabolism in adults. The Journal of nutrition. 2003 Oct 1;133(10):3130-6.
- Macdonald HM, Black AJ, Aucott L, Duthie G, Duthie S, Sandison R, Hardcastle AC, Lanham New SA, Fraser WD, Reid DM. Effect of potassium citrate supplementation or increased fruit and vegetable intake on bone metabolism in healthy postmenopausal women: a randomized controlled trial. The American journal of clinical nutrition. 2008 Aug 1;88(2):465-74.
- Gregory NS, Kumar R, Stein EM, Alexander E, Christos P, Bockman RS, Rodman JS. Potassium citrate decreases bone resorption in postmenopausal women with osteopenia: A randomized, double-blind clinical trial. Endocrine Practice. 2015 Dec 1;21(12):1380-6.
- Ferraro PM, Mandel EI, Curhan GC, Gambaro G, Taylor EN. Dietary protein and potassium, diet–dependent net acid load, and risk of incident kidney stones. Clinical Journal of the American Society of Nephrology. 2016 Oct 7;11(10):1834-44.
- Fink HA, Wilt TJ, Eidman KE, Garimella PS, MacDonald R, Rutks IR, Brasure M, Kane RL, Monga M. Recurrent nephrolithiasis in adults: comparative effectiveness of preventive medical strategies. Rockville (MD): Agency for Healthcare Research and Quality (US); 2012 Jul. Report No.: 12-EHC049-EF.
- Carnauba RA, Baptistella AB, Paschoal V, Hübscher GH. Diet-induced low-grade metabolic acidosis and clinical outcomes: a review. Nutrients. 2017 Jun;9(6):538.
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