Potassium: the Heart keeper!

Potassium is an important mineral to the body and plays roles at both the cellular and electrical level. Potassium is the principal positively charged ion (cation) in the fluid inside of cells, while sodium is the principal cation in the fluid outside of cells. Potassium concentrations are about 30 times higher inside than outside cells, while sodium concentrations are more than ten times lower inside than outside cells. Together with sodium, they maintain the cell membrane potential (to read more on this read the article on sodium).

Because of the control of membrane potential is very important for muscular contraction of the soft tissue and regulation of heart rhythm.

There are a limited number of enzymes that require the use of potassium for production and activity, according to the Linus Pauling Institute at Oregon State University. For instance, the use of adenosine triphosphate (ADT) in the production of energy requires the presence of both sodium and potassium.

Potassium deficiency (hypokalemia)

The symptoms of hypokalemia are related to alterations in membrane potential and cellular metabolism. They include fatigue, muscle weakness and cramps, and intestinal paralysis, which may lead to bloating, constipation, and abdominal pain. Severe hypokalemia may result in muscular paralysis or abnormal heart rhythms (cardiac arrhythmias) that can be fatal.

Hypokalemia is most commonly a result of excessive loss of potassium, like from prolonged vomiting, the use of some diuretics, and some forms of kidney disease.

There are some conditions that may increase the risk of hypokalemia:

  • The use of potassium-wasting diuretics (thiazide diuretics or furosemide)
  • Alcoholism
  • Severe vomiting or diarrhea
  • Overuse or abuse of laxatives
  • Anorexia nervosa or bulimia
  • Magnesium depletion
  • Congestive heart failure

Food and Nutrition Board of the Institute of Medicine established an adequate intake level (AI) for potassium based on intake levels that have been found to lower blood pressure, reduce salt sensitivity, and minimize the risk of kidney stones.

Table 1. Adequate Intake (AI) for Potassium
Life Stage Age Males
(mg/day)
Females
(mg/day)
Infants 0-6 months 400 400
Infants 7-12 months 700 700
Children 1-3 years 3,000 3,000
Children 4-8 years 3,800 3,800
Children 9-13 years 4,500 4,500
Adolescents 14-18 years 4,700 4,700
Adults 19 years and older 4,700 4,700
Pregnancy 14-50 years 4,700
Breast-feeding 14-50 years 5,100

Food sources

The richest sources of potassium are fruit and vegetables.

The next table shows some food sources of potassium and how much potassium they hold.

Table 2. Some Food Sources of Potassium
Food Serving Potassium (mg)
Banana 1 medium 422
Potato, baked with skin 1 medium 926
Prune juice 6 fluid ounces 528
Plums, dried (prunes) ½ cup 637
Orange juice 6 fluid ounces 372
Orange 1 medium 237
Tomato juice 6 fluid ounces 417
Tomato 1 medium 292
Raisins ½ cup 598
Raisin bran cereal 1 cup 362
Artichoke, cooked 1 medium 343
Lima beans, cooked ½ cup 485
Acorn squash, cooked ½ cup (cubes) 448
Spinach, cooked ½ cup 420
Sunflower seeds 1 ounce 241
Almonds 1 ounce 200
Molasses 1 tablespoon 293

Blood pressure

The epidemiological data suggest that a modest increase in fruit and vegetable intake (rich sources of dietary potassium), especially in those with hypertension and/or relatively low potassium intakes, could significantly reduce the risk of stroke.

Increasing potassium intake by consuming a diet rich in fruit 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.

Potassium supplements

Multivitamin supplements contain potassium but doses higher than 99 mg are prescribed to prevent and treat potassium depletion and hypokalemia. Intake of very high doses of potassium, as a part of a treatment of hypokalemia, must be prescribed by a doctor which will monitor  serum potassium levels. Because of possible serious side effects, before taking potassium supplements consult your healthcare provider.

Hyperkalemia

Hyperkalemia occurs when potassium intake exceeds the capacity of the kidneys to eliminate it.

Conditions that increase the risk of hyperkalemia are:

  • acute or chronic renal (kidney) failure,
  • the use of potassium-sparing diuretics,
  • insufficient aldosterone secretion (hypoaldosteronism).

Gastrointestinal symptoms are the most common side effects of potassium supplements, including nausea, vomiting, abdominal discomfort, and diarrhea. Taking potassium with meals or taking a microencapsulated form of potassium may reduce gastrointestinal side effects. The most serious adverse reaction to potassium supplementation is hyperkalemia.

Linus Pauling Institute recommends increasing potassium intake to at least 4.7 grams/day by increasing consumption of potassium-rich foods, especially fruit, vegetables, and nuts.

 

 

 

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