Next to calcium, phosphorus is the most abundant mineral in the body. These two important nutrients work closely together to build strong bones and teeth. About 85% of phosphorus in the body can be found in bones and teeth, and roughly 10% circulates in the bloodstream. The remaining phosphorus can be found in cells and tissues throughout the body. Phosphorus helps filter out waste in the kidneys and contributes to energy production in the body by participating in the breakdown of carbohydrates, protein, and fats. It also helps reduce muscle pain after a hard 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 metabolize other vitamins and minerals, including vitamin D, iodine, magnesium, and zinc.

Health conditions such as diabetes, starvation, alcoholism, and conditions that can cause abnormal absorption of nutrients (such as Crohn's disease, celiac disease, and radiation damage) can lead to depletion of phosphorus in the body. Phosphorus deficiencies can also be caused by certain prescription medications, including antacids and diuretics (drugs that get rid of excess fluid from the body). Symptoms of phosphorus deficiency include loss of appetite, anxiety, bone pain, bone fragility, stiffness in the joints, fatigue (excessive tiredness), 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 of this mineral. Excessive phosphorus is generally caused by kidney disease or by consuming too much dietary phosphorus relative to dietary calcium. As dietary phosphorus increases, the need for additional calcium rises as well. The delicate balance between calcium and phosphorus is necessary for proper bone density and prevention of osteoporosis.

Phosphates (phosphorus) are used clinically to treat low levels of phosphorus in the body (hypophosphatemia), high blood calcium levels (hypercalcemia), and in the management of calcium-based kidney stones. Phosphates are also used as laxatives. They may also be of some benefit to patients with multiple sclerosis and diabetic ketoacidosis. Because most foods contain sufficient amounts of phosphorus, additional supplementation with this mineral is not generally necessary. 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 bone disorders caused by vitamin D deficiencies, namely osteomalacia and rickets (softening and weakening of the bones in adults and children respectively).

Protein-rich foods, such as meat, poultry, fish, eggs, dairy products, nuts, and legumes are particularly good sources of phosphorus. Other 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. Elemental phosphorus should be taken only under the guidance of a qualified professional. 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
• Phosphatidyl choline
• Phosphatidyl serine

Recommended dietary allowances (RDAs) for dietary phosphorous are listed below:

Pediatric

For infants 0 - 6 months: A dietary phosphorus intake of 100 mg daily is adequate.

For infants 7 - 12 months: A dietary phosphorus intake of 275 mg is adequate.

For children 1 - 3 years: A dietary phosphorus intake of 460 mg is the RDA.

For children 4 - 8 years: A dietary phosphorus intake of 500 mg is the RDA.

For children 9 - 18 years: A dietary phosphorus intake of 1,250 mg is the RDA.

Adult

For adults 19 years and older: A dietary phosphorus intake of 700 mg is the RDA.

For pregnant and breastfeeding females under 18 years: A dietary phosphorus intake of 1,250 mg is the RDA.

For pregnant and breastfeeding females 19 years and older: A dietary phosphorus intake of 700 mg is the RDA.

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

Too much phosphate can lead to 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 very 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, is imbalanced in these minerals. Most people with this type of diet consume roughly 2 - 4 times more phosphorus than calcium. For example, meat and poultry contain 10 - 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 the system, the body will use calcium stored in bones. This can lead to reduced bone mass (osteopenia or osteoporosis), which makes bones brittle and fragile. It can also lead to gum and teeth problems. A balance of dietary calcium and phosphorus can lower the risk of osteoporosis, and relieve the symptoms of osteoarthritis and other problems related to the body's ability to use calcium.

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

Alcohol -- Alcohol (ethanol) may pull out phosphorus from the bones and deplete it from 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 its absorption, potentially leading to low phosphate levels (hypophosphatemia) when used long-term (chronically).

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 -- Bile acid sequestrants are drugs that lower cholesterol and include cholestyramine (Questran) and colestipol (Colestid). They can decrease the oral absorption of phosphates from the diet or from supplements. Therefore, oral phosphate supplements should be administered at least 1 hour before or 4 hours after these drugs.

Corticosteroids -- Corticosteroids, including prednisone (Deltasone) or methylprednisolone (Medrol), may increase urinary phosphorus levels.

Diuretics -- The use of diuretics such as hydrochlorothiazide (Hydrodiuril) or furosemide (Lasix) may increase the elimination of phosphorus from the body in the urine, causing symptoms of phosphorus deficiency.

Insulin -- High doses of insulin may decrease blood levels of phosphorus in people with diabetic ketoacidosis (a condition caused by severe insulin insufficiency). This serious condition is treated in a hospital and replacement of phosphorous takes place under the direction of a doctor.

Potassium supplements or potassium-sparing diuretics -- Using phosphorus supplements along with potassium supplements or potassium-sparing diuretics (including spironolactone or Aldactone and triamterene or Dyrenium) taken together with a phosphate may result in high blood levels of potassium (hyperkalemia). Hyperkalemia can be a serious problem, resulting in life-threatening heart rhythm abnormalities (arrhythmias).

Other drugs -- Drugs called angiotensin-converting enzyme (ACE) inhibitors, normally used for high blood pressure, may decrease phosphorus levels. They include benazepril (Lotensin), captopril (Capoten), enalapril (Vasotec), fosinopril (Monopril), lisinopril (Zestril, Prinivil), quinapril (Accupril), or ramipril (Altace). Other drugs include cyclosporine (used to decrease the immune system), cardiac glycosides (digoxin or Lanoxin), heparins (blood thinning drugs), anti-inflammatory drugs (such as ibuprofen or Motrin). Salt substitutes also contain high levels of potassium which may lower phosphorus levels if used long-term (chronically).

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