Next to calcium, phosphorus is the most abundant mineral in the body. These 2 important nutrients work closely together to build strong bones and teeth. About 85% of the body's phosphorus is in bones and teeth. Phosphorous is also present in smaller amounts in cells and tissues throughout the body. Phosphorus helps filter out waste in the kidneys and plays an essential role in how the body stores and uses energy. It also helps reduce muscle pain after a workout. Phosphorus is needed for the growth, maintenance, and repair of all tissues and cells, and for the production of the genetic building blocks, DNA and RNA. Phosphorus is also needed to help balance and use other vitamins and minerals, including vitamin D, iodine, magnesium, and zinc.

Most people get plenty of phosphorus in their diets. The mineral is found in milk, grains, and protein-rich foods. Some health conditions, such as diabetes, starvation, and alcoholism can cause levels of phosphorus in the body to fall. The same is true of conditions that make it hard for people to absorb nutrients, such as Crohn disease and celiac disease. Some medications can cause phosphorus levels to drop, including some antacids and diuretics (water pills). Symptoms of phosphorus deficiency include loss of appetite, anxiety, bone pain, fragile bones, stiff joints, fatigue, irregular breathing, irritability, numbness, weakness, and weight change. In children, decreased growth and poor bone and tooth development may occur.

Having too much phosphorus in the body is actually more common and more worrisome than having too little. Too much phosphorus is generally caused by kidney disease or by consuming too much dietary phosphorus and not enough dietary calcium. Several studies suggest that higher intakes of phosphorus are associated with an increased risk of cardiovascular disease. As the amount of phosphorus you eat rises, so does the need for calcium. The delicate balance between calcium and phosphorus is necessary for proper bone density and prevention of osteoporosis.

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.

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.

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

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

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.

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.

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