Family Doctor notes that potassium helps your body regulate blood pressure while magnesium supports the function of your heart and arteries. A balanced diet normally provides a sufficient intake to meet your body's requirements. The U.S. Department of Agriculture's 2005 Dietary Guidelines for Americans states that, in general, American adults need to increase their intakes of both potassium and magnesium. The USDA also recommends that you eat more mineral-rich foods instead of using supplements to improve your diet.
Daily Intake Recommendations
The Institute of Medicine's Adequate Intake table suggests 400 mg of magnesium daily for adult males up to age 30 and 420 mg after age 30. For women, the IOM suggests 310 mg through age 30 and 320 mg from ages 30 to 70. The IOM has set the daily intake level for potassium at 4.7 g for adult males and females from age 19 to 70. Pregnancy and lactation may affect the amount of potassium or magnesium that you need daily.
Magnesium
The 2005 Dietary Guidelines for Americans notes that fish, nuts, vegetables and some beans are food sources that have at least 10 percent of your suggested daily intake of magnesium. A 1 oz. serving of pumpkin seeds has 151 mg of potassium. An ounce of Brazil nuts and 1 oz. of 100 percent bran cereal, at 107 mg and 103 mg, have approximately 20 percent of your daily requirements.
The U.S. Office of Dietary Supplements states that you can get 20 percent of your daily requirement for magnesium from a 3 oz. serving of halibut, which provides 90 mg. Almonds and cashews, at 85 mg and 75 mg, give you 20 percent of the adequate intake for each 1-oz. serving. Cooked foods that contain 20 percent of your daily intake include 1/2 cup servings of soybeans and spinach.
Potassium
You can obtain potassium from fruits, vegetables, beans, dairy products and fish. Sweet potatoes rank first on the USDA's list of food sources of potassium. The 694 g of potassium in one sweet potato gives you almost 15 percent of your daily intake. Two ounces of tomato paste provide 664 g and 1/2 cup of cooked beet tops have 655 g. A baked white potato has 610 g of potassium.
Family Doctor recommends a variety of foods that have at least 10 percent of your body's daily potassium requirement. An 8 oz. serving of nonfat yogurt, at 579 mg, or low-fat yogurt, at 531 mg, exceeds 10 percent. A 3 oz. serving of yellowfin tuna has 484 mg. Soybeans and lima beans provide 485 and 484 mg each per 1/2 cup serving. Among fruits, bananas have the highest potassium content, but the 422 mg that a medium banana provides falls below 10 percent of the daily adequate intake.
Potassium and Magnesium Food Sources
The USDA defines high-content foods as those with 20 percent or more of recommended daily intake of specific nutrients. The USDA charts do not list any foods with a high content of both potassium and magnesium. To increase your intake of both minerals simultaneously, choose foods that contain at least 10 percent of each mineral and others that provide 20 percent of one.
A 3-oz. serving of halibut has more than 10 percent of your daily potassium needs. It also provides over 20 percent of your recommended daily magnesium intake. Lima beans, white beans or soybeans provide more 10 percent of your daily needs for both minerals in a 1/2 cup serving. Three oz. of yellowfin tuna also provides 10 percent of your daily potassium and magnesium needs.
References
- U.S. Department of Agriculture: 2005 Dietary Guideline for Americans, Chapter 2 Adequate Nutrients Within Calorie Needs
- Institute of Medicine: Dietary Reference Intakes (DRIs): Recommended Intakes for Individuals, Elements
- U.S. Department of Agriculture: Dietary Guidelines for Americans, Appendix B-1 Food Sources of Potassium
- U.S. Department of Agriculture: Dietary Guidelines for Americans, Appendix B-7 Food Sources of Magnesium
- FamilyDoctor.org: Vitamins and Minerals: How to Get What You Need
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