Potassium in diet

Definition

Potassium is a mineral involved in electrical and cellular body functions. In the body, potassium is classified as an electrolyte.

Overview & Functions

Potassium is a very important mineral to the human body. It has various roles in metabolism and body functions and is essential for the proper function of all cells, tissues, and organs:

• It assists in the regulation of the acid-base balance.
• It assists in protein synthesis from amino acids and in carbohydrate metabolism.
• It is necessary for the building of muscle and for normal body growth.

Food Sources

Many foods contain potassium. All meats (red meat and chicken) and fish such as salmon, cod, flounder, and sardines are good sources of potassium. Soy products and veggie burgers are also good sources of potassium.
Vegetables including broccoli, peas, lima beans, tomatoes, potatoes (especially their skins), sweet potatoes, and winter squashes are all good sources of potassium.


Fruits that contain significant sources of potassium include citrus fruits, cantaloupe, bananas, kiwi, prunes, and apricots. Dried apricots contain more potassium than fresh apricots.
Milk and yogurt, as well as nuts, are also excellent sources of potassium.
People on dialysis for kidney failure should avoid consuming too many of these potassium-rich foods. These people require specialized diets to avoid excess potassium in the blood

Recommendations

The Food and Nutrition Center of the Institute of Medicine has established the following recommended dietary intakes for potassium:
Infants

• 0 - 6 months: 0.4 grams a day (g/day)
• 7 - 12 months: 0.7 g/day

Children and Adolescents

• 1 - 3 years: 3 g/day
• 4 - 8 years: 3.8 g/day
• 9 - 13 years: 4.5 g/day
• 14 - 18 years: 4.7 g/day

Adults

• Age 19 and older: 4.7 g/day

Women who are producing breast milk need slightly higher amounts (5.1 g/day). Ask your doctor what amount is best for you.
Persons who are being treated for hypokalemia need potassium supplements. The doctor will develop a supplementation plan based on each individual's specific needs.

Side Effects

Having too much or too little potassium in the body can have very serious consequences.
Because so many foods contain potassium, too little potassium (potassium deficiency) is rarely caused by inadequate diet. However, even a moderate reduction in the body's potassium levels can lead to salt sensitivity and high blood pressure. The recommended dietary intake of 4.7 gm or higher can slightly lower blood pressure.


A deficiency of potassium (hypokalemia) can happen in people with certain diseases or as a result of taking diuretics (water pills) for the treatment of high blood pressure or heart failure. Additionally, many medications -- such as diuretics, laxatives, and steroids -- can cause a loss of potassium, which occasionally may be very severe. You should have your blood levels of potassium checked from time to time if you take any of these medicines. Diuretics are probably the most common cause of hypokalemia.

A variety of conditions can cause potassium loss from the body. The most common are vomiting and diarrhea. Several rare kidney and adrenal gland disorders may also cause low potassium levels.

For more information on potassium deficiency, see the article on hypokalemia.
Too much potassium in the blood is known as hyperkalemia. Some common causes of this are reduced renal (kidney) function, an abnormal breakdown of protein, and severe infection. The most common cause of hyperkalemia is reduced kidney function, especially in people receiving dialysis for kidney failure. Certain medicines affect the body's ability to get rid of potassium. These include potassium sparing diuretics and angiotensin converting enzyme (ACE) inhibitors.
For more information on increased potassium levels, see the article on hyperkalemia.

References

Panel on Dietary Reference Intakes for Electrolytes and Water, Standing Committee on the Scientific Evaluation of Dietary Reference Intakes. Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. Washington, DC: The National Academies Press; 2004.
U.S. Department of Health and Human Services (HHS) and U.S. Department of Agriculture (USDA). Dietary Guidelines for Americans 2005: Chapter 8 -- Sodium and Potassium. Accessed June 23, 2008.