Phosphorus is a mineral that helps us maintain strong bones and teeth. It is the second most abundant mineral in the body (after calcium), and about 85% of the body’s calcium is found in bones.1 Since our bodies cannot produce phosphorus, we must get it through our diet.
Phosphorus is crucial for bone and dental health. It is a major component of hydroxyapatite, a crystal substance that is the foundation of our bones and teeth.2 As a component of hydroxyapatite, phosphorus allows us to form new bone, and it protects against fractures.
Phosphorus also allows us to use and store energy, as it’s a component of adenosine triphosphate, which is considered the energy currency of our cells. Similarly, phosphorus is also found in creatine phosphate, a molecule that provides energy to our muscles.
Phosphorus has many other important functions. It provides structure to our cell membranes, and it’s involved in gene expression, cell signaling, and oxygen transport, among other things.2
Phosphorus is naturally present in protein-rich foods like milk, yogurt, cheese, eggs, fish, meat, poultry, and legumes. It’s also frequently added to processed foods, to enhance the texture or extend the shelf life of these products. Phosphorus additives are found in foods like soda, packaged snacks, condiments, baked goods, and bottled drinks.
Phosphorus can also be taken as a supplement. Phosphorus supplements are rarely needed, however, as most people get enough phosphorus from foods.
The daily Recommended Dietary Allowance (RDA) for phosphorus, or the amount that is likely to meet the needs of most healthy people, is 460 milligrams (mg) for children aged 1-3 years, 500 mg for children aged 4-8 years, 1250 mg for adolescents aged 9-18 years, and 700 mg for adults over the age of 19 years.1
Most people meet their phosphorus requirements very easily, as phosphorus is widely available in food. For reference, a cup of low-fat milk provides about 250 mg of phosphorus, which covers over 30% of an adult's daily phosphorus needs.3
Phosphorus deficiency can have negative consequences on our bones, muscles, and immune system. Symptoms of phosphorus deficiency include muscle weakness, bone pain, confusion, loss of appetite, and frequent infections.1 Phosphorus deficiency can cause serious complications such as bone disease, and it may progress to death in severe cases.
Phosphorus deficiency is very rare. When it does happen, it’s typically caused by other medical conditions like respiratory acidosis or diabetic ketoacidosis.2 It is also seen in people with alcoholism, as well as people who are fed suddenly after periods of not eating much (e.g., anorexia).2
Excessive phosphorus consumption can be dangerous. Phosphorus toxicity can alter levels of hormones involved in calcium regulation.1 This in turn may lead to calcium being deposited in places where it shouldn’t be, like the kidneys or blood vessels.4 Phosphorus toxicity can also cause our bones to become weak and porous, and it can make us more susceptible to kidney damage, fertility issues, and heart disease, among other negative outcomes.4
To prevent toxicity, a Tolerable Upper Intake Level (UL), or a maximum daily amount that is considered safe, has been established for phosphorus. The UL for phosphorus is 3000 mg for children aged 1-8 years, 4000 mg for anyone aged 9-70 years, and 3000 mg for adults over the age of 71.1 For pregnant and breastfeeding women, the UL is 3500 mg.1
Many plant-based foods like grains and legumes contain a substance called phytic acid, which stores phosphorus. Our bodies are unable to break down phytic acid, meaning we have trouble getting phosphorus from these foods. For this reason, we tend to absorb less phosphorus from plant-based foods compared to other sources.5
You may have heard that drinking too much soda can be bad for our teeth. One reason for this is that the added phosphorus found in soda (as phosphoric acid) may weaken our tooth enamel when consumed in large amounts. This in turn can make us more susceptible to cavities and tooth decay.6
This list shows food that are top sources of Phosphorus (P) and the quantity of Phosphorus (P) in 100g of food