Phosphorus

A mineral in bones, teeth, DNA and ATP, the body's energy currency. Most Americans get more than they need, partly from phosphate additives in processed food.

How much you need

The official Recommended Dietary Allowance for adults, per day:

Age	Men	Women	Pregnancy	Breastfeeding
19–50 years	700 mg	700 mg	700 mg	700 mg
51–70 years	700 mg	700 mg	—	—
Over 70	700 mg	700 mg	—	—

People aged 18 fall in the official 14–18 group, which needs much more — 1,250 mg a day, including in pregnancy and when breastfeeding. Its upper limit is 4,000 mg, or 3,500 mg in pregnancy. Pregnancy and breastfeeding change what you need — confirm yours with your midwife, obstetrician or doctor.

Upper limit

Age	Men	Women	Pregnancy	Breastfeeding
19–50 years	4,000 mg	4,000 mg	3,500 mg	4,000 mg
51–70 years	4,000 mg	4,000 mg	—	—
Over 70	3,000 mg	3,000 mg	—	—

The upper limit covers phosphorus from food and supplements combined, and is lower in pregnancy and after 70. It is the most that is unlikely to cause harm, not a target, and was based on intakes that keep blood phosphate normal. It does not apply to people taking phosphorus under medical supervision.

What it does

Phosphorus is part of bones, teeth, DNA and RNA, of cell membranes, and of ATP, the body's key energy source ^[1]. It helps regulate gene transcription, activate enzymes, keep the fluid outside cells at a normal pH and store energy inside them ^[1]. About 85% of the body's phosphorus is in bones and teeth ^[1]. Its metabolism is linked with calcium's, through vitamin D and parathyroid hormone ^[1].

Forms

Food contains phosphorus mainly as phosphates; in seeds and unleavened bread it is phytic acid, much of which humans cannot absorb ^[1]. Phosphate additives such as phosphoric acid and sodium phosphate are common in processed food and may provide 300 to 1,000 mg a day — 10% to 50% of intake in Western countries — and their use is rising ^[1]. Supplements usually contain phosphate salts or phospholipids ^[1].

Where it comes from

Yogurt, plain, low fat6-ounce container245 mg
Milk, 2% milkfat1 cup226 mg
Salmon, Atlantic, farmed, cooked3 ounces214 mg
Scallops, breaded and fried3 ounces201 mg
Cheese, mozzarella, part skim1.5 ounces197 mg

How these five were chosen: The five foods with the most phosphorus per serving in the NIH fact sheet's food table. Fortified foods are marked.

How far one serving goes toward a day's phosphorus

How far one serving goes toward a day's phosphorus
Item	Percent of the adult daily amount (700 mg)
Yogurt, low fat	35%
Milk, 2%	32%
Salmon, farmed	31%
Scallops, fried	29%
Mozzarella	28%

Against the recommended daily amount for adults 19 to 50: 700 mg. Where a food varies by brand, the bar shows the lowest figure and the label the full range. Computed from the figures on this page, taken from the NIH fact sheet.

Getting the most from it

The body absorbs 40% to 70% of the phosphorus naturally in food, more from animal than plant sources, and about 70% from phosphate additives and supplement salts ^[1]. Calcium binds some phosphorus in food and prevents its absorption ^[1].

In the United States

Most Americans get more than the recommended amount: in 2015–2016, average intake from food was 1,596 mg a day for men and 1,189 mg for women ^[1]. These surveys may underestimate true intake, because they do not capture phosphate additives ^[1]. Dairy products provide about 20% of the phosphorus Americans eat, and bakery products 10% ^[1].

Who is most likely to run low

People with rare genetic disorders of phosphate regulation, such as X-linked hypophosphatemic rickets ^[1]
People with severe malnutrition — from chronic disease, anorexia nervosa, heavy drinking or other causes — who can develop dangerously low phosphate (refeeding syndrome) when feeding restarts; phosphorus and thiamin given in advance can prevent it ^[1]

What deficiency looks like

Phosphorus deficiency (hypophosphatemia) is rare in the United States and almost never caused by diet ^[1]. It can cause loss of appetite, anemia, muscle weakness, bone pain, rickets and osteomalacia, more infections, tingling, poor coordination and confusion ^[1]. It is usually caused by medical conditions such as hyperparathyroidism, kidney tubule defects and diabetic ketoacidosis ^[1].

What the evidence supports, and what it doesn't

Established. Phosphorus is essential for bones, teeth, DNA and energy metabolism ^[1]. In chronic kidney disease the kidneys cannot remove phosphate efficiently, blood levels rise, and in people on dialysis the highest phosphate levels are linked to a 39% higher risk of death ^[1].

Not supported by trials. There is no evidence on whether restricting phosphorus prevents cardiovascular disease in healthy adults ^[1]. In people with milder chronic kidney disease, higher phosphorus intakes were not linked to higher mortality ^[1].

Mixed. Observational studies link higher blood phosphate with cardiovascular disease and death in healthy adults, but not all agree ^[1]. In U.S. adults, intakes of 1,000 mg a day or more — twice the recommended amount but well below the limit — were linked to higher death rates, which may reflect diets unhealthy in other ways ^[1]. For severe kidney disease, a guideline group weakly recommends limiting dietary phosphorus ^[1].

Too much

High phosphorus intakes rarely harm healthy people ^[1]. Very large amounts over a short time — such as two 6,600 mg doses of sodium phosphate in a day — can cause hyperphosphatemia, which disturbs the hormones that regulate calcium and can calcify soft tissues, especially the kidneys ^[1].

Medicines that interact

Antacids containing aluminum hydroxide bind phosphorus and, used for 3 months or more, can cause low phosphate; calcium carbonate antacids also reduce its absorption ^[1]. Laxatives containing sodium phosphate raise blood phosphate, and after 13 reported deaths from a single dose above the label's, the FDA warned that they are potentially dangerous above recommended doses, especially with kidney disease, heart disease or dehydration ^[1]. If you take any of these regularly, talk to your doctor or pharmacist.