Potassium is a mineral required for normal cell function. It regulates the heartbeat, ensures proper function of the muscles and nerves, and is vital for synthesizing protein and metabolizing carbohydrates.

Potassium is known to have a positive effect on bone health. Observational studies suggest that increased consumption of potassium from fruits and vegetables is associated with increased bone mineral density. (1) The underlying mechanisms are unclear, but according to a hypothesis, potassium can help protect bone through its effect on acid-base balance. (2) Alkaline components in the form of potassium salts from food or potassium supplements might counter this effect and help preserve bone tissue. In the Framingham Heart Study, for example, higher potassium intake was associated with significantly greater bone mineral density in 628 elderly men and women. (3) One study found that participants that took in 5,266 milligrams of potassium per day maintained an average of 3.6 more pounds of lean tissue mass than those with a potassium intake 50 percent lower. Some studies also show an increase in bone density with high potassium intake. (4) In another study with 994 healthy premenopausal women, scientists found that those who ingested the most potassium had more bone mass in their lower back and hip bones. (5) In addition, Potassium helps calcium retention and causes calcium balance. The administration of 60 mmol/d of potassium bicarbonate (KHCO3) to healthy adults reduced urinary calcium excretion by 0.9 mmol/d and caused calcium balance to become equivalently more positive. (6) 

Potassium also helps to balance sodium levels. Having the right potassium-sodium ratio is important for electrolyte balance, which is essential for proper muscle contraction, nerve transmission, and fluid balance, which promotes normal blood pressure and acid-base balance for preservation of bone strength. In a study published in Archives of Internal Medicine, researchers found that the higher the ratio of sodium to potassium, the greater the chance of having a heart attack or stroke, needing bypass surgery or angioplasty, or dying of cardiovascular disease after 10 to 15 years of post-trial follow-up. (7) 

Potassium also relaxes the walls of the blood vessels, lowering blood pressure and protecting against muscle cramping. (8) A number of studies have shown an association between low potassium intake and increased blood pressure and a higher risk of stroke. An analysis of 33 studies found that when people with high blood pressure increased their potassium intake, their systolic blood pressure decreased by 3.49 mmHg, while their diastolic blood pressure decreased by 1.96 mmHg. In another study including 1,285 participants aged 25–64, scientists found that people who ingested the most potassium had reduced blood pressure in a follow-up examination compared to people who ingested the least. 

(9) Those who consumed the most had systolic blood pressure that was 6 mmHg lower and diastolic blood pressure that was 4 mmHg lower, on average. 

Higher potassium intakes have been associated with a decreased risk of stroke and possibly other cardiovascular diseases (CVDs). A meta-analysis of 11 cohort studies in 247,510 adults found that a 1,640 mg per day higher potassium intake was associated with a significant 21% lower risk of stroke as well as nonsignificant lower risks of coronary heart disease and total CVD. (11) Similarly, the authors of a meta-analysis of 9 cohort studies reported a 24% lower risk of stroke with higher potassium intakes and a reduction in coronary heart disease and CVD risk. (9) In one study, those who consumed 4,069 mg of potassium per day had a 49 percent lower risk of death from ischemic heart disease compared with those who consumed about 1,000 mg per day. (12) 

References: 

1. Hanley DA, Whiting SJ. Does a high dietary acid content cause bone loss, and can bone loss be prevented with an alkaline diet? J Clin Densitom. 2013 Oct-Dec; 16 (4): 420-5. 

2. Weaver CM. Potassium and health. Adv Nutr. 2013 May 1; 4 (3): 368-377S 

3. Tucker KL, Hannan MT, Chen H, Cupples LA, Wilson PW, Kiel DP. Potassium, magnesium, and fruit and vegetable intakes are associated with greater bone mineral density in elderly men and women. Am J Clin Nutr. 1999 Apr; 69 (4): 727-36. 

4. Dawson-Hughes B, Harris SS, Ceglia L. Alkaline diets favor lean tissue mass in older adults. Am J Clin Nutr. 2008 Mar; 87 (3): 662-5. 

5. New SA, Bolton-Smith C, Grubb DA, Reid DM. Nutritional influences on bone mineral density: a cross-sectional study in premenopausal women. Am J Clin Nutr. 1997 Jun; 65 (6): 1831-9. 

6. Lemann J Jr, Pleuss JA, Gray RW. Potassium causes calcium retention in healthy adults. J Nutr. 1993 Sep; 123 (9): 1623-6. 

7. Nancy R. Cook, Eva Obarzanek, Jeffrey A. Cutler, Julie E. Buring, Kathryn M. Rexrode, Shiriki K. Kumanyika, Lawrence J. Appel, Paul K. Whelton. Joint Effects of Sodium and Potassium Intake on Subsequent Cardiovascular Disease: The Trials of Hypertension Prevention (TOHP) Follow-up Study Arch Intern Med. 2009 Jan 12; 169 (1): 32-40. 

8. Potassium lowers blood pressure Harvard Health. 2005 Jul; 

9. 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 3; 346:f1378. 

10. Rodrigues SL, Baldo MP, Machado RC, Forechi L, Molina Mdel C, Mill JG. High potassium intake blunts the effect of elevated sodium intake on blood pressure levels. J Am Soc Hypertens. 2014 Apr; 8 (4): 232-8. 

11. D'Elia L, Barba G, Cappuccio FP, Strazzullo P. Potassium intake, stroke, and cardiovascular disease a meta-analysis of prospective studies. J Am Coll Cardiol. 2011 Mar 8; 57 (10): 1210-9. 

12. Rodriguez CJ, Bibbins-Domingo K, Jin Z, Daviglus ML, Goff DC Jr, Jacobs DR Jr. Association of sodium and potassium intake with left ventricular mass: coronary artery risk development in young adults. Hypertension. 2011 Sep; 58 (3): 410-6.