What Is Phosphorus?

An Essential Mineral for Bone Health

Phosphorus is an essential mineral found in every cell of the human body. It is the second most abundant mineral next to calcium, accounting for about 1% of your total body weight. Phosphorus is one of 16 essential minerals that your body needs to function properly.

Although the main purpose of phosphorus is to build and maintain bones and teeth, it also plays a major role in the formation of DNA and RNA (the genetic building blocks of the body). Doing so helps ensure that cells and tissues are properly maintained, repaired, and replaced as they age.

Phosphorus also plays a key role in metabolism (the conversion of calories and oxygen to energy), muscle contraction, heart rhythm, and the transmission of nerve signals. Phosphorus is considered a macromineral (along with calcium, sodium, magnesium, potassium, chloride, and sulfur) in that you need more of it than trace minerals like iron and zinc.

A deficiency of phosphorus is usually accompanied by hypophosphatemia, or low blood phosphate levels, which can affect every organ system of the body and may lead to muscle weakness, bone pain, fractures, seizures, and respiratory failure. Unlike certain micronutrients, the body cannot produce phosphorus on its own. You should get it from food first—and especially meat, dairy, oily fish, and seeds—and then, if needed, a dietary supplement.

This article explains how the body uses phosphorus and why many people take it to fight urinary tract infections and osteoporosis. It also discusses the possible side effects of too much potassium, how it interacts with medication, and how problems can be avoided by following the recommended dosage.

Phosphorus health benefits
 Verywell / JR Bee 

What Is Phosphorus Used For?

In the body, phosphorus exists as phosphate, which is a salt of phosphorus. This is partly why healthcare providers are prone to use the terms "phosphorus" and "phosphate" interchangeably. The bones and teeth contain about 85% of the body's total phosphorus.

A phosphate supplement is typically used to prevent a phosphorus deficiency, a condition considered rare in the United States outside of certain high-risk groups. According to a study from Harvard Medical School, phosphorus deficiency is usually seen only in chronic alcoholics and people:

Low phosphorus can also affect people with certain diseases or medical conditions, including Cushing's disease, hypothyroidism, parathyroid disease, vitamin D deficiency, and malnutrition. Hypophosphatemia may also be caused by the overuse of diuretics (water pills) or phosphate-lowering drugs used during kidney dialysis.

Beyond the prevention or treatment of phosphorus deficiency, a phosphate supplement may offer specific health benefits, particularly in older adults and people prone to urinary tract infections (UTIs).

Signs Run the Gamut

Phosphorus deficiencies are rare, but they make their presence known. The warning signs include anemia, bone pain, confusion, coordination problems, and a greater risk of infection.

Urinary Tract Infections

Phosphate supplements are sometimes used to make urine more acidic. It has long been presumed that doing so can help treat certain urinary tract infections or prevent the formation of kidney stones. Recent studies, however, suggest this may not be the case.

According to a study in the Journal of Biochemical Chemistry, urine with a high pH (meaning that it is less acidic) exerted stronger antimicrobial effects compared to urine with low pH/high acidity. However, UTIs are more common in women with hypercalcemia (abnormally high calcium) as the increased urinary calcium promoted bacterial growth. Phosphate supplements may help reverse this risk by binding with free-circulating calcium and clearing it in the stool.

Similarly, kidney stones composed of calcium phosphate tend to develop when the urine pH is more than 7.2 (meaning that it is alkaline). By lowering the pH (and increasing the acidity), phosphate may able to prevent kidney stones in high-risk individuals.

Note that this is not true of all stones. Kidney stones composed of calcium oxalate develop when the urine pH is less than 6.0 (meaning that it is acidic). Increasing the acidity with phosphate may only promote, rather than inhibit, their growth.

UTIs Plague More Females Than Males

There's an explanation for why urinary tract infections are more common in females: Their urethras are shorter and closer to the rectum. This geography makes it easier for bacteria to enter the urinary tract.

Osteoporosis

With most of the body's phosphorus stored in bone, the rest freely circulates in the bloodstream to ease other biological functions. For example, phosphorus works with calcium to help build healthy bones and teeth. These minerals are converted into calcium phosphate salts that stiffen and strengthen bones.

Phosphorus also regulates how much calcium is in the body and how much is excreted in urine, which can prevent excess calcium from being deposited in the blood vessels. This, in turn, can increase the risk of atherosclerosis (hardening of the arteries).

In the past, there was a concern that consuming too much phosphorus could throw off this fine-tuned balance, drawing calcium from bone and increasing the risk of osteoporosis (bone mineral loss). A study published in the Nutrition Journal showed this wasn't the case.

Moreover, increased phosphate intake was not associated with toxicity. Any excess phosphorus in the blood is excreted either in urine or stool.

Nutrients Struggle for Balance

It's a delicate balance, but the school of public health at Harvard University says that "elevated phosphorus levels may disrupt the normal hormonal balance of phosphorus, calcium, and vitamin D that regulates bone health."

Possible Side Effects

Phosphate supplements are considered safe if taken as prescribed. High doses (more than 1,000 milligrams per day) can lead to headaches, dizziness, shortness of breath, swelling in the lower legs or feet, or unusual tiredness or weakness. Call your healthcare if you experience any of these side effects.

Allergies to phosphate are rare, but it's still important to call your provider or seek emergency care if you experience rash, hives, shortness of breath, rapid heartbeat, or swelling of the face, throat, or tongue after taking a phosphate supplement. These could be signs of a potentially life-threatening, whole-body reaction known as anaphylaxis.

A "Multi Approach" May Be Better

An excessive intake of phosphate may interfere with the body's ability to use iron, calcium, magnesium, and zinc. As a result, phosphate is rarely taken on its own but as part of a multivitamin/mineral supplement.

Contraindications

People with chronic kidney disease may need to avoid phosphate supplements. Since the kidneys are less able to clear phosphate from the body, the mineral may accumulate and lead to hyperphosphatemia (excessively high phosphorus levels). Symptoms may include rash, itching, muscle cramps, spasms, bone or joint pain, or numbness and tingling around the mouth.

Excess phosphorus can also affect urine acidity and lead to the dislodgement of a previously undiagnosed kidney stone. Outside of severe kidney dysfunction, hyperphosphatemia is very rare. It is more associated with the failure to clear phosphorus from the body rather than with the use of phosphate supplements.

Drug Interactions

Phosphate may interact with some prescription and over-the-counter medications. Certain drugs may cause decreases in phosphorus levels in the blood, including:

  • Angiotensin-converting enzyme (ACE) inhibitors like Lotensin (benazepril), Capoten (captopril), or Vasotec (enalapril)
  • Antacids containing aluminum, calcium, or magnesium
  • Anticonvulsants like phenobarbital or Tegretol (carbamazepine)
  • Cholesterol-lowering drugs like Questran (cholestyramine) or Colestid (colestipol)
  • Diuretics like Hydrodiuril (hydrochlorothiazide) or Lasix (furosemide)
  • Insulin

Other drugs may cause phosphorus levels to rise excessively, including:

  • Corticosteroids like prednisone or Medrol (methylprednisolone)
  • Potassium supplements
  • Potassium-sparing diuretics like Aldactone (spironolactone) and Dyrenium (triamterene)

If you're being treated with any of these medications, you should not take phosphate supplements without first speaking with your healthcare provider. In some cases, separating the drug doses by two to four hours may help overcome the interaction. In others, a dose adjustment or drug substitution may be needed.

Dosage and Preparation

Phosphate supplements are available in tablet or capsule form under various brand names. Phosphate is also included in many multivitamin/mineral supplements as well as in co-formulated supplements designed specifically for bone health. Doses tend to range from 50 milligrams (mg) to 100 mg.

According to the Food Nutrition Board of the Institute of Medicine, the recommended dietary intake (RDI) of phosphorus from all sources varies by age and pregnancy status, as follows:

  • Children birth to six months old: 100 milligrams per day (mg/day)
  • Children seven to 12 months: 275 mg/day
  • Children one to three years: 460 mg/day
  • Children four to eight years: 500 mg/day
  • Adolescents and teens nine to 18 years: 1,250 mg/day
  • Adults over 18: 700 mg/day
  • Pregnant or lactating women 18 and under: 1,250 mg/day
  • Pregnant or lactating women over 18: 700 mg/day

Injectable phosphate is sometimes used to treat severe hypophosphatemia. Injections are generally indicated when the blood phosphorus level drops below .4 millimoles per liter (mmol/L). The normal range is .87 to 1.52 mmol/L. Phosphate injections are only given in a healthcare setting under the direction of a qualified specialist.

You Can Overdo a Good Thing

Phosphorus dosages exceeding 3,000 to 3,500 mg/day are generally considered excessive and may adversely affect the balance of macro and trace minerals in your blood.

What to Look For

Dietary supplements are not subject to the rigorous testing and research that pharmaceutical drugs are from the U.S. Food and Drug Administration (FDA). Therefore, the quality can vary, and sometimes significantly.

Several groups are trying to fill this space, including ConsumerLab.com, NSF International, and U.S. Pharmacopeia (USP). The most recent addition is UL, a for-profit company known for testing electronics. USP, a nonprofit, has set standards for supplements that Consumer Reports says are the most widely accepted.

Phosphate supplements are vulnerable to extreme heat, humidity, and ultraviolet (UV) radiation. It's always best to store the supplements in their original light-resistant container in a cool, dry room. Throw away supplements that are discolored or deteriorating, no matter what the "use by" date says.

USP Publishes Database

USP publishes the Dietary Supplements Compendium, an online, subscription-based database which provides quality standards for the production of dietary supplements. Supplements that pass USP's quality requirements are awarded a distinction called the USP Verified Mark.

Turn to Food First

Foods that are especially rich in phosphorus include:

  • Pumpkin or squash seeds: 676 mg per 1/4-cup serving
  • Canned sardines in oil: 363 mg per 2.5-ounce serving
  • Cottage cheese: 358 mg per 1-cup serving
  • Sunflower sees: 343 mg per 1/4-cup serving
  • Hard cheese (such as Parmesan): 302 mg per 1.5-ounce serving
  • Milk: 272 mg per 1-cup serving
  • Lentils (cooked): 264 mg per 3/4-cup serving
  • Canned salmon: 247 mg per 2.5-ounce serving
  • Yogurt: 247 mg per 3/4-cup serving
  • Pork: 221 mg per 2.5-ounce serving
  • Tofu: 204 mg per 3/4-cup serving
  • Beef: 180 mg per 2.5-ounce serving
  • Chicken: 163 mg per 2.5-ounce serving
  • Eggs: 157 mg per two eggs
  • Canned tuna in water: 104 mg per 2.5-ounce serving

Protect Your Teeth

You may know that sodas are bad for your teeth, but did you know it's because they contain phosphoric acid or citric acid (or both)? Drinking too much soda will soak your teeth in these acids, which eventually wear down the enamel and make your teeth an easy target for cavities and decay.

Summary

Phosphorus is an essential mineral found in every cell of the human body. It is the second most abundant mineral next to calcium, and its primary function is to build and maintain bones and teeth. Your body needs phosphorus to function properly, with many people presuming that it can be used to help treat certain urinary tract infections or prevent kidney stones and prevent osteoporosis. However, as with other supplements, phosphorus remains a subject under active study, with some efforts confirming its effectiveness and others producing ambivalent findings. One thing is clear: since the body cannot produce phosphorus on its own, you should get it from food first—and especially meat, dairy, oily fish, and seeds—and then, if necessary, a dietary supplement.

A Word From Verywell

You may be worried that your phosphorus level is higher than normal (hyperphosphatemia) or lower than normal (hypophosphatemia). The only way to be certain is to take a phosphorus blood test, which measures the amount of phosphate in the blood. Your healthcare provider may ask you to abstain from taking antacids, laxatives, and water pills before the test, lest they interfere with accurate results. A normal result for an adult usually ranges from 2.8 to 4.5 mg/dL.

Frequently Asked Questions

  • Do I need a phosphorus supplement?

    Most people get all the phosphorus they need from their diet. Unless you have a medical condition that requires supplementation, like alcoholism or chronic obstructive pulmonary disease (COPD), you would be better off eating a healthy, balanced diet rich in macro and trace nutrients.

  • How would I know if I have a phosphorus deficiency?

    The symptoms often include anemia, bone pain, bone disease, confusion, greater risk of infection, muscle weakness, and poor appetite. See your healthcare provider to confirm or debunk your suspicions.

  • How would I know if I have high phosphorus levels?

    In all likelihood, your healthcare provider would diagnose it. Often, high phosphorus is a sign of kidney damage or disease. Whereas healthy kidneys balance phosphorus in your body by removing extra levels from the blood, kidney disease often prevents this purge from occurring.

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11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Brunelli, S, Goldfarb, S. Hypophosphatemia: Clinical consequences and management. JASN. 2007;18(7):1999-2003. doi:10.1681/ASN.2007020143.

  2. National Institutes of Health. Office of Dietary Supplements. Fact sheet for consumers.

  3. Shields-Cutler R, Crowley J, Hung, C, et al. Human Urinary Composition Controls Antibacterial Activity of Siderocalin. J Biol Chem. 2015;290:15949-60. doi:10.1074/jbc.M115.645812.

  4. Centers for Disease Control and Prevention. Urinary tract infection.

  5. Lee, A, Cho, S. Association between phosphorus intake and bone health in the NHANES population. Nutrition J. 2015;14:28. doi:10.1186/s12937-015-0017-0.

  6. Harvard T.H. Chan School of Public Health. Harvard University. Phosphorus.

  7. Mayo Clinic. Phosphate supplement.

  8. Consumer Reports. How to choose supplements wisely.

  9. U.S. Pharmacopeia. What is the U.S. Pharmacopeia?

  10.  Icahn School of Medicine at Mount Sinai. Phosphorus blood test.

  11. American Kidney Fund. High phosphorus.

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