Phosphorus

In addition to food and water, your body needs certain vitamins and minerals to survive. Calcium and phosphorus are two of the most important minerals in the human body, working together to build strong bones and teeth. Phosphorus makes up about 1 percent of total body weight, so if you weigh 150 pounds you have a pound and a half of phosphorus in your body. Most of the phosphorus in your body (about 85 percent) is in your bones and teeth, where it combines with calcium to make bones hard and strong. The rest is in your cells and other tissues. In the kidneys, phosphorus is important in filtering out wastes. It also helps maintain the acid-base (pH) balance in your blood. Phosphorus controls the flow of energy in your body and helps reduce muscle pain after a hard workout. Your body needs phosphorus for the growth, maintenance, and repair of all your tissues and cells, and for the production of DNA and RNA. You also need phosphorus to make use of other vitamins and minerals, including vitamin D, calcium, iodine, magnesium, and zinc.

Uses

We do not normally need to take phosphorus supplements because the foods we eat contain a lot of phosphorus. In some cases, however, such as in a person with kidney disease, a health care provider may prescribe phosphorus supplements. Sometimes athletes use phosphate supplements before competitions or heavy workouts to help reduce muscle pain and fatigue. Phosphorus and calcium can be used together to help heal bone fractures and to treat vitamin D deficiencies such as osteomalacia and rickets.

Dietary Sources

Red meat and poultry contain significant amounts of phosphorus. Other sources include dried milk and milk products, hard cheeses, canned fish, nuts, eggs, and soft drinks.

Other Forms

Elemental phosphorus, a white or yellow waxy substance that burns on contact with air is highly toxic and no longer used in medicine (although it is used in some homeopathic treatments and should be taken under the care of a qualified practitioner). Instead, health care providers may recommend using one or more of the following inorganic phosphates, which are not toxic.

• Dibasic potassium phosphate
• Monobasic potassium phosphate
• Dibasic sodium phosphate
• Monobasic sodium phosphate
• Tribasic sodium phosphate

How to Take It

If you are under 24 years old, or are pregnant or breastfeeding, you need 1,200 mg of phosphorus daily. For everyone else, 800 mg is the recommended dietary allowance (RDA) of phosphorus. Because most people get enough phosphorus from food, you don't normally need to worry about taking supplements. It is more important to pay attention to what you eat and to make sure that you get a good balance of calcium and phosphorus in your diet. Cutting down on meats and finding alternatives to soft drinks can help correct any imbalance between calcium and phosphorus in your body. At the same time, it is important to make sure you are getting enough calcium in your diet, which is somewhat more difficult.

Precautions

Phosphates can be toxic at levels over 1 g per day. Too much phosphate can lead to diarrhea and calcification (hardening) of organs and soft tissue, and interfere with the body's ability to use iron, calcium, magnesium, and zinc. If you are an athlete taking supplements that contain phosphate, be sure to use them only occasionally.

Nutritionists recommend a balance of calcium and phosphorus from your diet, but the typical American diet is low in calcium and high in phosphorus, with two to four times as much phosphorus as calcium. It's easy to understand why. Meat and poultry contain 10 to 20 times as much phosphorus as calcium, and carbonated beverages such as colas have as much as 500 mg of phosphorus in one serving. When there is more phosphorus than calcium in your system, your body will draw on the calcium stored in your bones for normal functions. This can lead to reduced bone mass that makes bones brittle and fragile, or to gum and tooth problems. Low calcium to phosphorus ratios (low levels of calcium in relation to levels of phosphorus) may also increase your risk of high blood pressure and colorectal cancer. A balance of calcium and phosphorus in the foods you eat can help reduce stress, reduce the risk of osteoporosis, and relieve the symptoms of osteoarthritis and other problems that are related to the body's ability to use calcium.

Possible Interactions

High doses of insulin may decrease phosphorus levels.

Supporting Research

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Matsumura M, Nakashima A, Tofuku Y. Electrolyte disorders following massive insulin overdose in a patient with type 2 diabetes. Intern Med. 2000;39(2):55-57.

Metz JA, Anderson JJB, Gallagher Jr PN. Intakes of calcium, phosphorus, and protein, and physical activity level are related to radial bone mass in young adult women. Am J Clin Nutr. 1993;58: 537–542.

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Shires R, Kessler GM. The absorption of tricalcium phosphate and its acute metabolic effects. Calcif Tissue Int. 1990;47:142–144.

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