Phosphorus is a mineral with several functions in the body. After calcium, it is the second most abundant mineral, accounting for about 1% of a person’s body weight. In the body, phosphorus is almost always found combined with oxygen, where it is known as phosphate. This element is naturally present in many foods and is also available as a dietary supplement.
The Role of Phosphorus in the Body
The primary function of phosphorus is its partnership with calcium to form and maintain bones and teeth. Together, these minerals create a crystalline structure called hydroxyapatite, which provides rigidity and strength to the skeletal system. Approximately 85% of the body’s phosphorus is found within bones and teeth. This relationship is managed by hormones that regulate the balance of both minerals in the blood and bone.
Phosphorus is a component of adenosine triphosphate (ATP), the molecule for storing and transferring energy in cells. Every cellular process, from muscle contraction to nerve signal transmission, relies on the energy released from ATP. When a cell needs energy, one of the phosphate groups is broken off from the ATP molecule, releasing power for the cell to use.
Phosphorus contributes to the structure of all body cells as a component of phospholipids. These fat-based molecules form cell membranes, which enclose the cell’s contents and control what passes in and out. The mineral is also a building block for DNA and RNA, which hold instructions for cellular activity. Alternating sugar and phosphate molecules form the structural backbone of these genetic strands.
Dietary Sources of Phosphorus
Phosphorus is widely available in foods, particularly those high in protein like meats, poultry, and fish. For example, a three-ounce serving of farmed Atlantic salmon contains over 200 milligrams of the mineral. The phosphorus from animal-based foods is more readily absorbed by the body compared to plant-based sources.
Dairy products are another category of phosphorus-rich foods. Milk, yogurt, and cheese contribute to phosphorus intake, with a six-ounce container of plain, low-fat yogurt providing nearly 250 milligrams. Eggs are also a good source, containing the mineral in the yolk. A diet with sufficient protein and calcium often provides enough phosphorus.
Plant-based foods also offer phosphorus, though its availability can be different. Sources include nuts, seeds, beans, lentils, and whole grains. In these plants, phosphorus is often stored as phytic acid, which is more difficult for the digestive system to absorb. The body does not produce the enzyme needed to break down phytic acid efficiently.
A significant amount of phosphorus in modern diets comes from additives in processed foods. These inorganic phosphate additives are used to preserve moisture, enhance flavor, or stabilize products like:
- Processed meats
- Baked goods
- Sodas
- Other bottled beverages
Unlike the naturally occurring phosphorus in whole foods, the phosphorus from these additives is highly absorbable.
Recommended Intake and Imbalances
For adults 19 years and older, the Recommended Dietary Allowance (RDA) for phosphorus is 700 milligrams per day. This amount is met or exceeded by most people, as the mineral is present in many common foods. In the United States, the average daily intake for adults is around 1,400 mg, double the RDA.
A phosphorus deficiency, known as hypophosphatemia, is uncommon in healthy individuals but can occur with severe malnutrition or certain medical conditions. Symptoms of low phosphorus levels can include:
- Bone pain
- Muscle weakness
- Poor appetite
- Fatigue
If intake is low, the kidneys help maintain stable levels by conserving phosphorus and excreting less of it in the urine.
Excess phosphorus, or hyperphosphatemia, is also rare in the general population. The main risk group for high phosphorus levels is individuals with chronic kidney disease (CKD). Healthy kidneys filter extra phosphorus from the blood, but when kidney function is impaired, the mineral can accumulate. This accumulation can disrupt the body’s calcium balance and lead to health complications.