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Phosphorus / Phosphate

Evidence Level
Limited
3 Clinical Trials
4 Documented Benefits
2/5 Evidence Score

Phosphorus is an essential mineral and a building block of bones, teeth, DNA, RNA, cell membranes and ATP, the body's main energy molecule. It makes up about 1% to 1.4% of fat-free body mass, and 85% of it sits in bones and teeth as hydroxyapatite together with calcium. It is found in dairy, meat, fish, eggs, nuts, legumes and grains, and phosphate additives in processed foods add more. US adults average about 1,200 to 1,600 mg a day from food, well above the 700 mg RDA, and deficiency is rare and almost always caused by a medical condition. Extra phosphorus is not expected to help bones in people who already get enough, and sports trials of phosphate loading have given mixed results.

Studied Dose Adult RDA 700 mg a day; upper limit 4,000 mg a day (3,000 mg over age 70). Phosphate-loading trials used about 3.5 to 4 g a day of sodium phosphate for 4 to 6 days before an event.
Active Compound Phosphate salts such as sodium, potassium and calcium phosphate; sodium phosphate is the form used in phosphate-loading trials.
Deficiency information View details

Phosphorus deficiency (hypophosphatemia) is rare and almost never caused by a low diet. It usually comes from medical conditions such as hyperparathyroidism, kidney tubule defects, diabetic ketoacidosis and refeeding after severe malnutrition.

Common symptoms

  • Loss of appetite
  • Anemia
  • Muscle weakness, especially near the hips and shoulders
  • Bone pain, and rickets in children or osteomalacia in adults
  • Higher risk of infection
  • Numbness or tingling
  • Loss of coordination
  • Confusion
  • In refeeding syndrome: breathing failure, heart failure, coma and death

At-risk groups

  • People with severe malnutrition who start being fed again (refeeding syndrome), including those with anorexia nervosa, excessive alcohol intake, very low body weight or chronic illnesses such as cancer
  • People recovering from diabetic ketoacidosis
  • People with hyperparathyroidism or kidney tubule defects
  • People taking aluminum hydroxide antacids for 3 months or longer
  • People with rare genetic phosphate disorders such as X-linked hypophosphatemic rickets
  • Very low birthweight preterm infants
When to see a doctor: Low phosphate almost always points to an underlying medical condition, so see a doctor rather than self-supplementing. Anyone recovering from severe malnutrition, anorexia or prolonged fasting needs medically supervised refeeding, because refeeding syndrome can be life threatening.
Explore related deficiencies →
Sources: NIH ODS: Phosphorus Fact Sheet for Health Professionals

Benefits

Part of bone mineral; most diets already supply enough

About 85% of the body's phosphorus is in bones and teeth, bound with calcium as hydroxyapatite, so adequate intake is needed for normal bone. Most adults already eat well above the RDA, so extra phosphorus is not expected to add bone benefit, and some studies link high intakes to adverse bone effects.

Supported by Trial 1

Phosphate loading for endurance performance

Several days of sodium phosphate before an event has been tested with mixed results. In 6 trained cyclists, 4 g a day for 6 days raised power by about 10% in a 16 km time trial. Trials in 11 runners, 13 female cyclists and 16 trained cyclists found no improvement in aerobic capacity or time-trial performance.

Supported by Trial 3, Trial 2

Energy metabolism (ATP)

Phosphate is part of ATP, the molecule cells use to store and spend energy, and of the phospholipids in cell membranes. This is a basic role of the nutrient, not a benefit of taking extra phosphorus when intake is already adequate.

Supported by Trial 1, Trial 3

Acid-base balance

Phosphate helps keep the pH of body fluids in a normal range. This is a basic role of the nutrient, not a demonstrated benefit of phosphorus supplements.

Supported by Trial 3, Trial 1

Mechanism of action

1

Hydroxyapatite in bone

Phosphate and calcium together form hydroxyapatite, the mineral that hardens bone and teeth. Vitamin D and parathyroid hormone regulate both minerals together.

2

2,3-DPG and oxygen release (proposed)

Phosphate loading is proposed to raise 2,3-diphosphoglycerate in red blood cells, helping hemoglobin release oxygen to muscle. In one trial in runners, plasma phosphate rose but red cell 2,3-DPG did not.

3

Phosphorylation and energy

Many proteins and sugars in the body are switched on or off by adding phosphate groups, and phosphate is stored in ATP for energy.

Clinical trials

1
Phosphate Loading in Runners
PubMed

Double-blind crossover trial of calcium phosphate (176 mmol a day) or placebo for 4 days, with a maximal treadmill test on day 3 and a run to exhaustion on day 4. (Bredle et al. 1988, J Appl Physiol)

11 male runners.

Plasma phosphate rose, but red cell 2,3-DPG did not. VO2max and run time to exhaustion did not improve; stroke volume during steady running fell.

2
Sodium Phosphate Loading and 16 km Cycling Time Trial
PubMed

Randomized, double-blind crossover trial of 1 g tribasic sodium phosphate four times a day for 6 days versus a lactose placebo. (Folland et al. 2008, J Sci Med Sport)

6 trained male cyclists.

Mean power was about 9.8% higher and time about 3% faster than placebo, with a trend toward higher oxygen uptake. A very small trial.

3
Phosphate Loading and 30 km Cycling Time Trial
PubMed

Randomized, single-blind crossover trial of 3.5 g a day of dibasic sodium phosphate or a sodium chloride placebo for 4 days before each time trial. (Pope et al. 2023, Int J Sport Nutr Exerc Metab)

16 well-trained cyclists.

No ergogenic benefit: time-trial duration, power output, heart rate and perceived exertion did not differ from placebo.

Side effects and drug interactions

Common Potential side effects

High phosphorus intake rarely causes problems in healthy people, although some studies link intakes of 1,000 mg a day or more to cardiovascular, kidney and bone effects and higher mortality, and others do not.
People with kidney disease often need to limit phosphorus; do not take phosphate supplements without medical advice.
Sodium phosphate laxatives taken above the labeled dose have caused deaths, especially in people with kidney or heart disease or dehydration.
Phosphate additives add phosphorus to processed foods: foods with additives average about 67 mg more phosphorus per serving.

Important Drug interactions

Aluminum hydroxide antacids: bind phosphorus in the gut; use for 3 months or longer can cause low phosphate levels.
Calcium carbonate antacids: reduce absorption of dietary phosphorus.
Sodium phosphate laxatives: can raise blood phosphate; do not exceed the labeled dose.

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Frequently asked questions about Phosphorus / Phosphate

What is phosphorus used for?

Phosphorus is an essential mineral needed for bones and teeth, energy (ATP) and cell membranes. It is rarely supplemented alone because it is plentiful in the diet.

Do I need a phosphorus supplement?

Almost never. Phosphorus is plentiful in dairy, meat, fish, eggs, nuts, legumes and grains, and phosphate additives in processed foods add more, so deficiency is rare and is almost always caused by a medical condition.

How much phosphorus do I need?

The RDA is about 700 mg per day for adults, easily met by diet. There is little reason to take supplemental phosphorus unless directed by a doctor for a specific condition.

Can too much phosphorus be harmful?

People with kidney disease often need to limit phosphorus. In healthy people high intakes rarely cause problems, although some studies link intakes of 1,000 mg a day or more to heart, kidney and bone effects. Taking more sodium phosphate laxative than the label says can be dangerous.

What is Phosphorus / Phosphate?

Phosphorus is an essential mineral and a building block of bones, teeth, DNA, RNA, cell membranes and ATP, the body's main energy molecule. It makes up about 1% to 1.4% of fat-free body mass, and 85% of it sits in bones and teeth as hydroxyapatite together with calcium.

What is Phosphorus / Phosphate used for?

Phosphorus / Phosphate is researched primarily for Bone Health and Athletic Performance. About 85% of the body's phosphorus is in bones and teeth, bound with calcium as hydroxyapatite, so adequate intake is needed for normal bone.

What are the signs of Phosphorus / Phosphate deficiency?

Phosphorus deficiency (hypophosphatemia) is rare and almost never caused by a low diet. It usually comes from medical conditions such as hyperparathyroidism, kidney tubule defects, diabetic ketoacidosis and refeeding after severe malnutrition.

What is the recommended dosage of Phosphorus / Phosphate?

The clinically studied dose is Adult RDA 700 mg a day; upper limit 4,000 mg a day (3,000 mg over age 70). Phosphate-loading trials used about 3.5 to 4 g a day of sodium phosphate for 4 to 6 days before an event. Always follow the product label and check with a healthcare provider for personal advice.

Is Phosphorus / Phosphate safe, and does it have side effects?

For most healthy adults, Phosphorus / Phosphate is well tolerated at studied doses. Reported effects can include: High phosphorus intake rarely causes problems in healthy people, although some studies link intakes of 1,000 mg a day or more to cardiovascular, kidney and bone effects and higher mortality, and others do not. It may also interact with some medications. Phosphorus / Phosphate is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Phosphorus / Phosphate interact with any medications?

Possible interactions include: Aluminum hydroxide antacids: bind phosphorus in the gut; use for 3 months or longer can cause low phosphate levels. Calcium carbonate antacids: reduce absorption of dietary phosphorus. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Phosphorus / Phosphate?

NutraSmarts rates the evidence for Phosphorus / Phosphate as Limited (2 out of 5). It is backed by 3 clinical trials and 9 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(9 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Office of Dietary Supplements, National Institutes of Health. Phosphorus: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements. 2023;Online fact sheet, updated May 4, 2023..SourceUsed to support: Not PubMed-indexed. Phosphorus is a component of bones, teeth, DNA, RNA, phospholipids and ATP; 1% to 1.4% of fat-free mass, 85% in bones and teeth; adult RDA 700 mg and UL 4,000 mg (3,000 mg over 70); US adults average 1,189 mg (women) and 1,596 mg (men) from food; deficiency is rare and caused by medical conditions; refeeding syndrome effects; aluminum hydroxide and calcium carbonate antacids reduce absorption; sodium phosphate laxative warnings; foods with phosphate additives average 67 mg more phosphorus per serving.
  2. Bredle DL, Stager JM, Brechue WF, Farber MO. Phosphate supplementation, cardiovascular function, and exercise performance in humans. J Appl Physiol (1985). 1988;65(4):1821-6. doi: 10.1152/jappl.1988.65.4.1821.PubMedUsed to support: Double-blind crossover trial in 11 male runners: 4 days of calcium phosphate raised plasma phosphate but not red cell 2,3-DPG, and did not improve VO2max or run time to exhaustion; stroke volume fell during steady running.
  3. Folland JP, Stern R, Brickley G. Sodium phosphate loading improves laboratory cycling time-trial performance in trained cyclists. J Sci Med Sport. 2008;11(5):464-8. doi: 10.1016/j.jsams.2007.04.004.PubMedUsed to support: Randomized, double-blind crossover trial in 6 trained cyclists: 4 g a day of tribasic sodium phosphate for 6 days raised 16.1 km time-trial mean power by about 9.8% and cut time by about 3% versus placebo.
  4. Pope H, Davis M, Delgado-Charro MB, Peacock OJ, Gonzalez J, Betts JA. Phosphate Loading Does not Improve 30-km Cycling Time-Trial Performance in Trained Cyclists. Int J Sport Nutr Exerc Metab. 2023;33(2):93-101. doi: 10.1123/ijsnem.2022-0111.PubMedUsed to support: Randomized, single-blind crossover trial in 16 well-trained cyclists: 3.5 g a day of dibasic sodium phosphate for 4 days did not improve 30 km time-trial time or power versus a sodium chloride placebo.
  5. Buck CL, Dawson B, Guelfi KJ, McNaughton L, Wallman KE. Sodium phosphate supplementation and time trial performance in female cyclists. J Sports Sci Med. 2014;13(3):469-75..PubMedUsed to support: Randomized Latin-square trial in 13 female cyclists: three doses of trisodium phosphate for 6 days did not change 500 kJ time-trial performance versus placebo.
  6. Chang AR, Lazo M, Appel LJ, Gutiérrez OM, Grams ME. High dietary phosphorus intake is associated with all-cause mortality: results from NHANES III. Am J Clin Nutr. 2014;99(2):320-7. doi: 10.3945/ajcn.113.073148.PubMedUsed to support: NHANES III cohort of 9,686 healthy US adults: higher phosphorus intake was associated with higher all-cause mortality among those eating more than 1,400 mg a day, with no association below that level. Observational, so it shows association, not cause.
  7. Uribarri J, Calvo MS. Dietary phosphorus excess: a risk factor in chronic bone, kidney, and cardiovascular disease? Adv Nutr. 2013;4(5):542-4. doi: 10.3945/an.113.004234.PubMedUsed to support: Review arguing that excess dietary phosphorus, especially from highly absorbed inorganic phosphate additives, may be a risk factor for chronic bone, kidney and cardiovascular disease.
  8. Calvo MS, Dunford EK, Uribarri J. Industrial Use of Phosphate Food Additives: A Mechanism Linking Ultra-Processed Food Intake to Cardiorenal Disease Risk? Nutrients. 2023;15(16):3510. doi: 10.3390/nu15163510.PubMedUsed to support: Review linking inorganic phosphate additives in ultra-processed foods to cardiorenal disease risk.
  9. Crook MA, Hally V, Panteli JV. The importance of the refeeding syndrome. Nutrition. 2001;17(7-8):632-7. doi: 10.1016/s0899-9007(01)00542-1.PubMedUsed to support: Clinical review of refeeding syndrome, in which low phosphate is a central and dangerous feature, and of the patients at risk.