Phosphorus
Summary
Phosphorus is an essential mineral for bones, teeth and energy metabolism. Most US adults already eat well above the 700 mg RDA, and deficiency is rare. Sodium phosphate loading gave mixed results in four small trials in cyclists (grade D). People with kidney disease are advised to limit phosphorus, and overdosing sodium phosphate laxatives can be dangerous.
Key facts
- An essential mineral; about 85% of the body's phosphorus is in bones and teeth, the rest in cells and blood[1]
- 700 mg/day (1,250 mg/day at ages 9–18)[1]
- 4,000 mg/day from food and supplements (3,000 mg after age 70; 3,500 mg in pregnancy)[1]
- Adults average 1,189 mg/day (women) and 1,596 mg/day (men) from food alone[1]
- Aluminum and calcium antacids; sodium phosphate laxatives[1]
- 5 graded human outcomes on this page
- October 10, 2026
How it works
EstablishedPhosphorus combines with calcium to form hydroxyapatite, the mineral of bone and tooth enamel, and is part of DNA, cell membranes and ATP, the body's energy carrier. The kidneys, bones and gut keep blood phosphate in a narrow range. Sodium phosphate loading is proposed to help exercise by raising red-cell 2,3-DPG and buffering capacity.[1][6]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Prostate | Grade D | Worsened | Observational · n = 47,885 · 2015 | 1 row |
| Endurance | Grade D | No effect | Crossover RCT · n = 20 · 2019 | 3 rows |
| Sprint | Grade D | Improved | RCT · n = 17 · 2015 | 1 row |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Prostate cancer risk with higher dietary phosphorus | Worsened | Grade D | Observational · n = 47,885 · 2015 US male health professionals followed for 24 years Form: Dietary phosphorus from food · Dose: Higher versus lower intake (cut-offs not given in the abstract) · Duration: 1986–2010 Higher phosphorus intake was associated with greater risk of total, lethal and high-grade prostate cancer, independent of calcium and of red meat, white meat, dairy and fish intake. | 25527761 (opens PubMed)Source [7] |
| 20 km cycling time-trial performance | No effect | Grade D | Crossover RCT · n = 20 · 2019 Endurance-trained male cyclists Form: Sodium phosphate · Dose: 50 mg per kg of fat-free mass per day · Duration: 4 days before each trial, 14-day washout No effect on responses to submaximal cycling or on 20 km time (32.8 minutes with both). Ventilation, respiratory exchange ratio, effort ratings and post-trial lactate were higher with sodium phosphate. | 29985679 (opens PubMed)Source [2] |
| Heart and oxygen-delivery responses during exercise at simulated altitude | Improved | Grade D | Crossover RCT · n = 20 · 2021 Trained male cyclists Form: Trisodium phosphate · Dose: 50 mg per kg of fat-free mass per day · Duration: 6 days, 3-week washout During low- and moderate-intensity exercise in hypoxia (about 2,500 m), heart rate fell and stroke volume and oxygen pulse rose; serum phosphate rose 8.7% and serum calcium did not change. Gross efficiency did not change. | 34684557 (opens PubMed)Source [4] |
| Repeated-sprint and time-trial cycling power | Improved | Grade D | RCT · n = 17 · 2015 Trained male cyclists (7 sodium phosphate, 10 placebo) Form: Sodium phosphate · Dose: 50 mg per kg of fat-free mass per day · Duration: 6 days of loading; tested 1 and 4 days later Work and mean power in both the sprint and time-trial efforts rose from baseline 1 and 4 days after loading in the sodium phosphate group; the placebo group did not change. | 25494032 (opens PubMed)Source [3] |
| 500 kJ cycling time trial in women, three doses | No effect | Grade D | Crossover RCT · n = 13 · 2014 Female cyclists of differing fitness Form: Trisodium phosphate dodecahydrate · Dose: 25, 50 or 75 mg per kg of fat-free mass per day, in four split doses · Duration: 6 days per loading phase, about 21-day washout No dose changed time-trial time or average or peak power versus placebo. | 25177171 (opens PubMed)Source [5] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Sodium phosphate (trisodium phosphate) for exercise loading | Varies[2][5] | Six days of loading raised serum phosphate by 8.7% in one trial.[4] | No adverse effects reported in the abstracts; one trial found higher effort ratings and lactate during a time trial.[2][4] | Cycling performance trials (25–75 mg/kg fat-free mass/day) |
| Phosphate salts in supplements (e.g., dipotassium or disodium phosphate) | Varies[1] | About 70% absorbed.[1] | Most products give 10% or less of the Daily Value; a small share give more than 100%.[1] | General supplementation |
| Phospholipids (phosphatidylcholine, phosphatidylserine) | Varies[1] | Absorption of phosphorus from these forms has not been determined in humans.[1] | No phosphorus-specific data in our sources.[1] | Sold mainly for other purposes |
Studied doses, daily needs and limits
Doses studied in human trials ranged from 25 to 75 mg of sodium phosphate per kg of fat-free mass per day, over 4 to 6 days of loading; a review describes typical loading as 3–5 g/day for 3–6 days. These are salt weights, not elemental phosphorus.[2][5][6]
Intake reference: Adult RDA: 700 mg/day, including pregnancy and breastfeeding (ages 19+); 1,250 mg/day at ages 9–18. Adult UL: 4,000 mg/day from food and supplements (3,000 mg after 70; 3,500 mg in pregnancy).[1] The UL is based on intakes associated with normal blood phosphate in healthy people. It does not apply to people given phosphorus under medical supervision. NIH ODS fact sheet (updated May 4, 2023).
Recommended intake and upper limit by age and sex
| Age | Male | Female | Pregnancy | Lactation | Upper limit (UL) |
|---|---|---|---|---|---|
| 0–6 months (AI) | 100 mg | 100 mg | — | — | Not set |
| 7–12 months (AI) | 275 mg | 275 mg | — | — | Not set |
| 1–3 years | 460 mg | 460 mg | — | — | 3,000 mg |
| 4–8 years | 500 mg | 500 mg | — | — | 3,000 mg |
| 9–13 years | 1,250 mg | 1,250 mg | — | — | 4,000 mg |
| 14–18 years | 1,250 mg | 1,250 mg | 1,250 mg | 1,250 mg | 4,000 mg |
| 19–50 years | 700 mg | 700 mg | 700 mg | 700 mg | 4,000 mg |
| 51–70 years | 700 mg | 700 mg | — | — | 4,000 mg |
| 71+ years | 700 mg | 700 mg | — | — | 3,000 mg |
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Medicines
- Aluminum hydroxide antacidsNIH fact sheetBind phosphorus in the gut; use for 3 months or longer can cause low blood phosphate.[1]
- Calcium carbonate antacidsNIH fact sheetReduce absorption of dietary phosphorus.[1]
- Sodium phosphate laxativesNIH fact sheetRaise blood phosphate. FDA warned of serious harm after 13 deaths linked to a single dose above the labeled amount, especially in people with kidney disease, heart disease or dehydration.[1]
Who should be careful
- Chronic kidney disease
- Phosphate builds up as kidney function declines; KDIGO guidelines suggest people with CKD stages 3–5 limit dietary phosphorus.[1]
- Exceeding the UL
- Very high short-term intakes, such as two 6,600 mg doses of sodium phosphate in one day, can cause high blood phosphate.[1]
- Heart disease or dehydration
- FDA warned that sodium phosphate laxatives above the labeled dose are especially dangerous in these groups.[1]
- Infants
- Breast milk, formula and food should be infants' only sources of phosphorus; no UL is set for them.[1]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Safety
Deficiency is rare, and most adults already exceed the RDA.
- Deficiency
- Low phosphate is rare in the US and almost never caused by diet; it usually stems from medical conditions or refeeding after severe malnutrition.[1]
- High intakes
- In NHANES III, intakes of 1,000 mg/day or more were linked to higher death rates, but the meaning is unclear because high intakes may mark otherwise unhealthy diets.[1]
- Exercise loading
- Sodium phosphate loading raised ventilation, effort ratings and lactate during a 20 km time trial without improving time.[2]
Food sources
| Food | Serving | Amount |
|---|---|---|
| Yogurt, plain, low fat | 6-ounce container | 245 mg[1] |
| Milk, 2% milkfat | 1 cup | 226 mg[1] |
| Salmon, Atlantic, farmed, cooked | 3 ounces | 214 mg[1] |
| Chicken breast, roasted | 3 ounces | 182 mg[1] |
| Lentils, boiled | 1/2 cup | 178 mg[1] |
| Cashews, dry roasted | 1 ounce | 139 mg[1] |
- Yogurt, plain, low fat245 mg
- Milk, 2% milkfat226 mg
- Salmon, Atlantic, farmed, cooked214 mg
- Chicken breast, roasted182 mg
- Lentils, boiled178 mg
- Cashews, dry roasted139 mg
How to read the label
- Label dose vs clinical doseMost supplements give 10% or less of the 1,250 mg Daily Value, while US adults already average about 1,200–1,600 mg/day from food.[1]
- Salt weight vs phosphorusAthletic loading trials dosed sodium phosphate by body weight (25–75 mg/kg fat-free mass); that is the salt weight, not elemental phosphorus.[2][5]
- Check the formPhosphate salts are about 70% absorbed; absorption from phospholipid forms has not been measured in humans.[1]
Cost per studied dose, without the sales pitch
Compare any product you already have by the amount it delivers, not by capsule count or front-of-pack weight.
Cost per studied dose
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Frequently asked questions
Do most people need a phosphorus supplement?
Usually not. US adults average 1,189–1,596 mg/day from food, above the 700 mg RDA, and deficiency is rare and usually caused by medical conditions.[1]
Does sodium phosphate improve endurance performance?
Results conflict. Two cycling trials found no time-trial benefit, while two small trials found better power or heart responses after 4–6 days of loading.[2][5][3][4]
What is the upper limit for phosphorus?
4,000 mg/day for adults aged 19–70 and 3,000 mg/day after 70, from food and supplements combined.[1]
Who should be careful with phosphorus?
People with chronic kidney disease, because phosphate builds up as kidney function declines, and anyone using sodium phosphate laxatives, which can harm the kidneys and heart if overdosed.[1]
Which foods are high in phosphorus?
Dairy, meat, fish, lentils and nuts: a 6-ounce low-fat yogurt has 245 mg and 3 ounces of farmed salmon 214 mg.[1]
Is dietary phosphorus linked to prostate cancer?
In a 24-year study of 47,885 US men, higher phosphorus intake was associated with more lethal and high-grade prostate cancer. That is an association, not proof of cause.[7]
Sources
- [1]Phosphorus: Fact Sheet for Health Professionals (updated May 4, 2023). NIH Office of Dietary Supplements, 2023. fact-sheet
- [2]The Effects of Sodium Phosphate Supplementation on Physiological Responses to Submaximal Exercise and 20 km Cycling Time-Trial Performance.. J Diet Suppl, 2019. crossover-RCT
- [3]Effect of sodium phosphate supplementation on repeated high-intensity cycling efforts.. J Sports Sci, 2015. RCT
- [4]The Effects of Sodium Phosphate Supplementation on the Cardiorespiratory System and Gross Efficiency during Exercise under Hypoxia in Male Cyclists: A Randomized, Placebo-Controlled, Cross-Over Study.. Nutrients, 2021. crossover-RCT
- [5]Sodium phosphate supplementation and time trial performance in female cyclists.. J Sports Sci Med, 2014. crossover-RCT
- [6]Sodium phosphate as an ergogenic aid.. Sports Med, 2013. review
- [7]Calcium and phosphorus intake and prostate cancer risk: a 24-y follow-up study.. Am J Clin Nutr, 2015. observational
What changed
- First draft. Every PMID checked against NCBI E-utilities esummary (title and year taken from the record) and abstracts read for the cited rows.
- Adversarial review pass: every evidence row re-read against its PubMed abstract. Official sources opened before citing: NIH ODS Phosphorus fact sheet for health professionals (updated May 4, 2023), whose RDA, UL, food and interaction tables are transcribed here. Industry ties: none declared in the cited trials; the 2021 hypoxia trial was grant-funded and the 2015 cohort NCI-funded; funding for the other trials is not stated in PubMed. Retraction, expression-of-concern, erratum and withdrawn checks on all 6 PMIDs: none flagged. Page set indexable. Independent browser review (4 parallel reviewers, every evidence row checked against its abstract and official sources on the Vercel preview) found: no issues (ODS RDA/UL table, foods and interactions verified).