Uses

Phosphates (phosphorus) are used clinically to treat the following:

• Hypophosphatemia, low levels of phosphorus in the body
• Hypercalcemia, high blood calcium levels
• Calcium-based kidney stones

These conditions require a doctor's care.

Phosphates are also used in enemas as laxatives. Most people get plenty of phosphorus in their diets. Sometimes athletes use phosphate supplements before competitions or heavy workouts to help reduce muscle pain and fatigue, although it is not clear how much it helps or if it improves performance.

Dietary Sources

Protein-rich foods are good sources of phosphorus, such as meat, poultry, fish, eggs, dairy products, nuts, and legumes. Other good sources include whole grains, hard potatoes, dried fruit, garlic cloves, and carbonated beverages.

Available Forms

Elemental phosphorus is a white or yellow, waxy substance that burns on contact with air. It is highly toxic and is only used in medicine as a homeopathic treatment. You should only take elemental phosphorus under the guidance of a qualified professional. Instead, health care providers may use one or more of the following inorganic phosphates, which are not toxic at typical doses:

• Dibasic potassium phosphate
• Monobasic potassium phosphate
• Dibasic sodium phosphate
• Monobasic sodium phosphate
• Tribasic sodium phosphate
• Phosphatidyl choline
• Phosphatidyl serine

How to Take It

Most people do not need to take phosphorus supplements. Recommended dietary allowances (RDAs) for dietary phosphorous are as follows:

Pediatric

• Infants, 0 to 6 months: 100 mg daily
• Infants, 7 to 12 months: 275 mg
• Children, 1 to 3 years: 460 mg
• Children, 4 to 8 years: 500 mg
• Children, 9 to 18 years: 1,250 mg

Adult

• Adults, 19 years and older: 700 mg
• Pregnant and breastfeeding females under 18 years: 1,250 mg
• Pregnant and breastfeeding females, 19 years and older: 700 mg

Precautions

Because of the potential for side effects and interactions with prescription and non-prescription medications, you should take dietary supplements only under the supervision of a knowledgeable health care provider.

Too much phosphate can be toxic. It can cause diarrhea and calcification (hardening) of organs and soft tissue, and can interfere with the body's ability to use iron, calcium, magnesium, and zinc. Athletes and others taking supplements that contain phosphate should only do so occasionally and with the guidance and direction of a health care provider.

Nutritionists recommend a balance of calcium and phosphorus in the diet. The typical Western diet, however, contains roughly 2 to 4 times more phosphorus than calcium. Meat and poultry contain 10 to 20 times as much phosphorus as calcium, and carbonated beverages can have as much as 500 mg of phosphorus in one serving. When there is more phosphorus than calcium in the body, the body will use calcium stored in bones. This can cause osteoporosis (brittle bones) and lead to gum and teeth problems. A balance of dietary calcium and phosphorus can lower the risk of osteoporosis.

Possible Interactions

If you are currently being treated with any of the following medications, you should not use phosphorus preparations without first talking with your doctor.

Alcohol: Alcohol may leach phosphorus from the bones and cause low levels in the body.

Antacids: Antacids containing aluminum, calcium, or magnesium (such as Mylanta, Amphojel, Maalox, Riopan, and Alternagel) can bind phosphate in the gut and prevent the body from absorbing it. Using these antacids long term can cause low phosphate levels (hypophosphatemia).

Anticonvulsants: Some anticonvulsants (including phenobarbital and carbamazepine, or Tegretol) may lower phosphorus levels and increase levels of alkaline phosphatase, an enzyme that helps remove phosphate from the body.

Bile acid sequestrants: These drugs lower cholesterol. They can decrease the oral absorption of phosphates from the diet or from supplements. Oral phosphate supplements should be taken at least 1 hour before or 4 hours after these drugs. Bile acid sequestrants include:

• Cholestyramine (Questran)
• Colestipol (Colestid)

Corticosteroids: Corticosteroids, including prednisone or methylprednisolone (Medrol), may increase phosphorus levels in the urine.

Insulin: High doses of insulin may lower blood levels of phosphorus in people with diabetic ketoacidosis, a condition caused by severe insulin insufficiency.

Potassium supplements or potassium-sparing diuretics: Using phosphorus supplements along with potassium supplements or potassium-sparing diuretics may result in too much potassium in the blood (hyperkalemia). Hyperkalemia can be a serious problem, resulting in life threatening heart rhythm abnormalities (arrhythmias). Potassium-sparing diuretics include:

• Spironolactone (Aldactone)
• Triamterene (Dyrenium)

ACE inhibitors (blood pressure medication): Angiotensin converting enzyme (ACE) inhibitors, used to treat high blood pressure, may lower phosphorus levels. These include:

• Benazepril (Lotensin)
• Captopril (Capoten)
• Enalapril (Vasotec)
• Fosinopril (Monopril)
• Lisinopril (Zestril, Prinivil)
• Quinapril (Accupril)
• Ramipril (Altace)

Other drugs: Other drugs may lower phosphorus levels. They include cyclosporine (used to suppress the immune system), cardiac glycosides (digoxin or Lanoxin), heparins (blood thinning drugs), and nonsteroidal anti-inflammatory drugs (NSAIDs, such as ibuprofen or Advil). Salt substitutes contain high levels of potassium and may lower phosphorus levels if used long term.

Supporting Research

Carrasco R, Lovell DJ, Giannini EH, Henderson CJ, Huang B, Kramer S, et al. Biochemical markers of bone turnover associated with calcium supplementation in children with juvenile rheumatoid arthritis: results of a double-blind, placebo-controlled intervention trial. Arthritis Rheum . 2008 Dec;58(12):3932-40.

Dietary Guidelines for Americans 2005 . Rockville, MD: US Dept of Health and Human Services and US Dept of Agriculture; 2005.

Elliott P, Kesteloot H, Appel LJ, Dyer AR, Ueshima H, Chan Q, Brown IJ, Zhao L, Stamler J; INTERMAP Cooperative Research Group. Dietary phosphorus and blood pressure: international study of macro- and micro-nutrients and blood pressure. Hypertension . 2008 Mar;51(3):669-75. Erratum in: Hypertension . 2008 Apr;51(4):e32.

Goldman. Goldman's Cecil Medicine . 24th ed. Philadelphia, PA: Elsevier Saunders; 2011.

Heaney RP, Nordin BE. Calcium effects on phosphorus absorption: implications for the prevention and co-therapy of osteoporosis. J Am Coll Nutr . 2002;21(3):239-244.

Kastenberg D, Chasen R, Choudhary C, et al. Efficacy and safety of sodium phosphate tablets compared with PEG solution in colon cleansing: two identically designed, randomized, controlled, parallel group, multicenter phase III trials. Gastrointest Endosc . 2001;54(6):705-713.

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.

Noori N, Sims JJ, Kopple JD, Shah A, Colman S, Shinaberger CS, Bross R, Mehrotra R, Kovesdy CP, Kalantar-Zadeh K. Organic and inorganic dietary phosphorus and its management in chronic kidney disease. Iran J Kidney Dis . 2010;4(2):89-100.

Pinheiro MM, Schuch NJ, Genaro PS, Ciconelli RM, Ferraz MB, Martini LA. Nutrient intakes related to osteoporotic fractures in men and women--the Brazilian Osteoporosis Study (BRAZOS). Nutr J . 2009 Jan 29;8:6.

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Sim J, Bhandari S, Smith N, et al. Phosphorus and risk of renal failure in subjects with normal renal function. Am J Med . 2013;126(4):311-8.

Shuto E, Taketani Y, Tanaka R, Harada N, Isshiki M, Sato M, Nashiki K, Amo K, Yamamoto H, Higashi Y, Nakaya Y, Takeda E. Dietary phosphorus acutely impairs endothelial function. J Am Soc Nephrol . 2009;20(7):1504-12.

Smirnov AV, Volkov MM, Dobronravov VA, Rafrafi H. Phosphorus and calcium metabolism and the cardiovascular system status in patients with early stage chronic renal disease. Ter Arkh . 2010;82(6):25-8.

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van Kuijk JP, Flu WJ, Chonchol M, Valentijn TM, Verhagen HJ, Bax JJ, Poldermans D. Elevated preoperative phosphorus levels are an independent risk factor for cardiovascular mortality. Am J Nephrol . 2010;32(2):163-8.