What Is Phosphorus?

Phosphorus is an essential mineral found in every cell of the human body. Like calcium, sodium, magnesium, potassium, chloride, and sulfur, it is a macromineral. This means you need more of it than trace minerals like iron and zinc.

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). Additionally, phosphorus plays a key role in metabolism (the conversion of calories and oxygen to energy), muscle contraction, heart rhythm, and the transmission of nerve signals.

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 phosphorus, how it interacts with medications, and how problems can be avoided by following the recommended dosage.

Uses of Phosphorus

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian, pharmacist, or doctor. No supplement is intended to treat, cure, or prevent disease.

Next to calcium, phosphorus is the second most abundant mineral in the human body, accounting for about 1% of your total body weight. The bones and teeth contain about 85% of the body's total phosphorus.

In the body, phosphorus exists as phosphate, which is a salt of phosphorus. This is partly why healthcare providers often use the terms "phosphorus" and "phosphate" interchangeably.

Unlike certain micronutrients, the body cannot produce phosphorus on its own. You should get it from food first, especially meat, dairy, oily fish, and seeds. If your healthcare provider feels it's necessary, you can also take a phosphate supplement.

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).

Urinary Tract Infections

Phosphate supplements are sometimes used to make urine more acidic. In the past, this was thought to help treat certain urinary tract infections or prevent the formation of kidney stones. More 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/low acidity had stronger antimicrobial effects compared to urine with low pH/high acidity.

However, UTIs are more common in females with abnormally high calcium (hypercalcemia). This is because increased urinary calcium promotes 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 it is alkaline). By lowering the pH and increasing the urine 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.

Osteoporosis

With most of the body's phosphorus stored in bone, the rest freely circulates in the bloodstream for use in 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 strengthen bones.

Phosphorus also regulates how much calcium is in the body and how much is excreted in urine. This can prevent excess calcium from being deposited in the blood vessels. Excess calcium in the arteries can lead to 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.

Phosphorus Deficiency

Phosphate supplements are typically used to prevent a phosphorus deficiency, a condition considered rare in the United States outside of certain high-risk groups.

What Causes a Phosphorus Deficiency?

Phosphorus deficiency is usually seen only in chronic alcoholics and:

• People in intensive care units
• People who have been involved in a major trauma, such as a severe burn
• People who have sepsis, a life-threatening response to an infection

Low phosphorus can also affect people with certain diseases or medical conditions, including:

• Cushing's disease
• Hypothyroidism
• Parathyroid disease
• Chronic obstructive pulmonary disease
• Vitamin D deficiency
• Malnutrition
  

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
• Respiratory failure

Hypophosphatemia may also be caused by the overuse of diuretics (water pills) or phosphate-lowering drugs used during kidney dialysis.

How Do I Know If I Have a Phosphorus Deficiency?

Phosphorus deficiencies are rare and need to be properly identified and diagnosed by a health care provider through blood and urine testing. There are some identifying factors that may signify a deficiency, however. Signs and symptoms may include:

• Anemia
• Bone pain
• Confusion
• Coordination problems
• Greater risk of infection

A long-term phosphorous deficiency may lead to severe health problems, including:

• Rickets, which can cause pain and muscle weakness and delayed growth in children
• Osteomalacia, a softening of the bones
  

What Are the Side Effects of Phosphate?

Phosphate supplements are considered safe if taken as prescribed. Taking any supplement, however, may have potential side effects. These side effects may be common or severe.

Common Side Effects

• Nausea and vomiting
• Diarrhea
• Stomach pain or upset
• Increased thirst
• Bone, joint, or muscle pain
  

Severe Side Effects

Allergies to phosphate are rare, but it's still important to call your provider or seek emergency care if you experience any of the following after taking a phosphate supplement:

• Rash
• Hives
• Shortness of breath
• Rapid heartbeat
• Swelling of the face, throat, or tongue

These could be signs of a potentially life-threatening, whole-body reaction known as anaphylaxis.

Precautions

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
• 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.

Dosage: How Much Phosphorus Should I Take?

Phosphorus doses tend to range from 50 milligrams (mg) to 100 mg.

According to 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 6 months old: 100 milligrams per day (mg/day)
• Children 7 to 12 months: 275 mg/day
• Children 1 to 3 years: 460 mg/day
• Children 4 to 8 years: 500 mg/day
• Adolescents and teens 9 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 0.4 millimoles per liter (mmol/L). The normal range is 0.87 to 1.52 mmol/L. Phosphate injections are only given in a healthcare setting under the direction of a qualified specialist.

What Happens If I Take Too Much Phosphorus?

High doses of phosphorus (more than 1,000 milligrams per day) can lead to side effects such as:

• Headaches
• Dizziness
• Shortness of breath
• Swelling in the lower legs or feet
• Unusual tiredness or weakness

Call your healthcare if you experience any of these side effects.

Phosphorus doses 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.

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 avoid the interaction. In others, a dose adjustment or drug substitution may be needed.

How to Store Phosphorus

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.

Sources of Phosphorus and What to Look For

Most people can get the phosphorous they need from dietary sources. People with certain medical conditions may also need to take phosphate supplements. If you have a phosphorous deficiency, it's important to work with your healthcare provider to find the right treatment plan for your condition.

Food Sources of Phosphorus

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

Phosphorus Supplements

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.

Dietary supplements are not subject to the rigorous testing and research that the FDA requires of pharmaceutical drugs. 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). USP, a nonprofit, has set standards for supplements that Consumer Reports says are the most widely accepted.

Summary

Phosphorus is an essential mineral found in every cell of the human body. It is the second most abundant mineral next to calcium. Its primary function is to build and maintain bones and teeth.

Your body needs phosphorus to function properly. Many people take it to help treat urinary tract infections or prevent kidney stones and prevent osteoporosis. However, as with other supplements, phosphorus remains a subject under active study. Some studies have confirmed its effectiveness, while others have produced ambivalent findings.

One thing is clear: since the body cannot produce phosphorus on its own, you should get it from food first, especially meat, dairy, oily fish, and seeds. If necessary, a dietary supplement can be taken.

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.