More Dietary Potassium Can Reduce Occurrence of Hypertension, Amount of Drugs Needed for Its Treatment

Health Letter, July 2015

Sidney M. Wolfe, M.D.

We frequently read that excessive salt (sodium) intake can cause or worsen hypertension (high blood pressure) and heart disease. Much less attention has been given to the extremely important, well-established role of the dietary consumption of potassium — a different type of salt naturally present in many fruits and vegetables — in decreasing the risk of hypertension. Evidence from multiple studies shows that large increases in dietary potassium — above the generally inadequate amounts currently consumed — can significantly lower blood pressure and reduce the occurrence of hypertension and one of its most serious consequences: strokes.

Potassium intake guidelines

In their 2010 joint dietary guidelines, the Department of Health and Human Services and the Agriculture Department stated, "Because consumption of vegetables, fruits, whole grains, milk and milk products, and seafood is lower than recommended, intake by Americans of some nutrients is low enough to be of public health concern. These are potassium, dietary fiber, calcium, and vitamin D."

These guidelines currently recommend a daily intake of 4,700 milligrams, or 4.7 grams (gm), of potassium.[1] Most estimates in the United States, however, find that actual average daily intake of potassium is only about 50 percent of this recommended level.

Potassium and cardiovascular risk

A 2014 review of studies on large populations, in a journal article linking nutrition with cardiovascular disease, explored the connection of dietary potassium intake to subsequent strokes, and further substantiates the role of potassium. The authors found that an average increased potassium intake of 1.5 gm per day was associated with a 20 percent decreased risk of stroke.[2]

Discussing the international public health impact of increasing dietary potassium intake, the authors state:

The World Heart Federation reported over 5.5 million deaths a year from stroke worldwide.[3] Given these data and the results of this updated meta-analysis, an increase in population dietary [potassium] intake of 1.5 [gm/day] could avert over one million deaths from stroke per year on a worldwide scale and is expected to produce overall health benefits by reducing the impact of consequent disabilities.

Potassium and blood pressure

Other evidence supports the link between increased dietary potassium intake and decreased high blood pressure.

A 1991 small clinical trial was the first to show that increasing dietary potassium intake reduces the need for antihypertensive medication. People using drugs to treat high blood pressure were randomly selected to either receive dietary advice on how to increase their potassium intake from natural foods or keep their regular diet. After one year, 81 percent of those in the potassium-enhanced diet group were able to control their high blood pressure with less than one-half of the drugs they were previously taking, compared with only 29 percent in the regular diet group. This improvement occurred without differences in sodium, calories or alcohol intake between the groups and was thus attributable to the increased potassium intake.[4]

In 2001, a more elaborate randomized study was published. It examined the blood pressure effects of varying the amounts of dietary sodium and of eating a diet enhanced with more potassium-containing foods — known as a Dietary Approaches to Stop Hypertension (DASH) diet. The study supported that there was a progressive lowering of blood pressure with decreasing sodium intake in either diet.

But the combined effects of the DASH diet and low sodium intake on lowering blood pressure were substantial, greater than either intervention alone, and estimated by the researchers to be "equal to or greater than those of single-[blood pressure]-drug therapy."[5] Compared with the control diet with a high sodium level, the low-sodium DASH diet led to an average systolic blood pressure decrease of 7.1 units in subjects without hypertension, and of 11.5 units in subjects with hypertension.

The most recent study was based on a nationally representative survey published in 2013 by researchers from the Centers for Disease Control and Prevention and Iowa State University. This study used dietary and blood pressure information on more than 10,000 people over age 20 who were not taking antihypertensive medication or on a low-sodium diet.[6] The study found a significant increase in blood pressure in people with higher dietary sodium consumption but a significant decrease in blood pressure in those consuming more potassium. The researchers concluded that the "results provide population-based evidence that concurrent higher sodium and lower potassium are associated with hypertension." The study also showed that the effect of potassium intake on decreasing blood pressure appeared to be stronger among older age groups.

What You Can Do

A 2013 review of multiple randomized trials on the effect of dietary salt intake reduction or increased potassium intake stated:

Modest dietary salt restriction accompanied by increasing potassium intake serves as a broad-spectrum strategy to prevent or control hypertension and decrease cardiovascular morbidity and mortality. As outlined by current guidelines in the United States, population-wide sodium intake reduction and recommended increases in dietary potassium intake provide an essential public health effort to reduce rates of hypertension and prevent kidney disease, stroke, and cardiovascular disease.[7]

Many high-potassium foods (fruit, vegetables and dairy products) also are rich in fiber, calcium or other healthy nutrients, often in combination. (See table for some high-potassium foods.) Start routinely eating more of these foods and, before you know it, both your potassium intake and your health will increase.

High-Potassium Foods

The following table of foods rich in potassium is based on the Department of Agriculture 2009 dietary guidelines:[8]

Food Standard portion size Calories Potassium (milligrams; 1,000 milligrams=1 gram)
Potato, baked, flesh and skin 1 small potato 128 738
Prune juice, canned 1 cup 182 707
Tomato paste ¼ cup 54 664
Beet greens, cooked ½ cup 19 654
White beans, canned ½ cup 149 595
Plain yogurt, nonfat or lowfat 8 ounces 127-143 531-579
Sweet potato, baked in skin 1 medium 103 542
Clams, canned 3 ounces 126 534
Orange juice, fresh 1 cup 112 496
Halibut, cooked 3 ounces 119 490
Soybeans, green, cooked ½ cup 127 485
Evaporated milk, nonfat ½ cup 100 425
Banana, raw 1 medium 105 422
Spinach, cooked ½ cup 21-25 370-419

References

[1] Department of Health and Human Services. Dietary Guidelines for Americans, 2010. http://www.health.gov/dietaryguidelines/2010.asp.

[2] D'Elia L, Iannotta C, Sabino P, Ippolito R. Potassium-rich diet and risk of stroke: Updated meta-analysis. Nutr Metab Cardiovasc Dis. 2014;24(6):585-587.

[3] World Health Organization. World Health Report 2002: Reducing Risks, Promoting Healthy Life. https://www.citizen.org/sites/default/files/whr02_en.pdfua1.

[4] Siani A, Strazzullo P, Giacco A, Pacioni D, Celentano E, Mancini M. Increasing the dietary potassium intake reduces the need for antihypertensive medication. Ann Intern Med. 1991;115:753-759.

[5] Sacks F, Svetkey L, Vollmer W, et al. Effects on blood pressure of reduced dietary sodium and the dietary approaches to stop hypertension (DASH) diet. N Engl J Med. 2001; 344, 3-10.

[6] Zhang Z, Cogswell ME, Gillespie C, et al. Association between usual sodium and potassium intake and blood pressure and hypertension among U.S. adults: NHANES 2005-2010. PLoS ONE. 2013;8(10):e75289. doi:10.1371/journal.pone.0075289

[7] Aaron KJ, Sanders PW. Role of Dietary Salt and Potassium Intake in Cardiovascular Health and Disease: A Review of the Evidence. Mayo Clin Proc. 2013;88(9):987-995.

[8] Department of Health and Human Services. Dietary Guidelines for Americans, 2010. http://www.health.gov/dietaryguidelines/2010.asp.