What is the second abundant mineral in the body? An in-depth look at phosphorus

December 30, 2025 •

3 min read

Phosphorus accounts for approximately 1% of a person's total body weight, making it the second most plentiful mineral found in the human body, right after calcium. Although often overshadowed by its more famous counterpart, phosphorus is a critical nutrient involved in a myriad of essential biological processes.

Quick Summary

Phosphorus is the body's second most abundant mineral, after calcium. It is essential for bone and tooth formation, energy metabolism, cellular structure, and nerve signaling. This mineral is found in every cell and plays a vital role in maintaining overall physiological balance and health.

Key Points

Phosphorus is Second: After calcium, phosphorus is the most abundant mineral in the human body, constituting about 1% of total body weight.
85% in Bones: The vast majority of the body's phosphorus is concentrated in the bones and teeth, forming strong calcium phosphate salts.
Essential for Energy: Phosphorus is a crucial component of ATP, the primary molecule for storing and transferring energy within cells.
Key for Cells: Beyond bones, phosphorus is vital for the structure of DNA, RNA, and cell membranes.
Kidney Regulation: The kidneys play a major role in regulating phosphorus levels, and problems can arise in cases of kidney disease.
Balanced with Calcium: A healthy ratio between phosphorus and calcium is necessary for preventing various health complications.

The Second Most Abundant Mineral

While most people associate strong bones with calcium, they often forget about its essential partner: phosphorus. Calcium holds the top spot as the most abundant mineral, but phosphorus is a close second. In the average adult, this mineral makes up about 1% of their total body weight, with approximately 85% of this phosphorus stored within the skeleton and teeth in the form of calcium phosphate salts. The remaining 15% is distributed in soft tissues and extracellular fluids, where it performs equally vital roles. This distribution highlights its structural importance, but also its crucial function beyond just supporting our skeletal frame.

The Diverse Roles of Phosphorus in the Body

Phosphorus is involved in more than just mineralizing bone. Its versatile chemical properties allow it to participate in numerous fundamental biological functions across every cell in the body.

Cellular Energy and Repair

One of the most critical functions of phosphorus is its role in energy production. It is a fundamental component of adenosine triphosphate (ATP), the primary energy currency of all cells. Without phosphorus, the body would be unable to convert food into usable energy, severely impairing all metabolic processes. Furthermore, phosphorus is an integral part of the structure of DNA and RNA, meaning it is essential for genetic replication and the repair of cells and tissues.

Neuromuscular Function

Beyond energy, phosphorus contributes significantly to the proper functioning of the nervous and muscular systems. It is involved in nerve signaling and muscle contraction, helping to regulate these critical processes. For instance, a deficiency can sometimes lead to muscle weakness.

Acid-Base Balance

Phosphorus, in the form of phosphate, plays a key role as a buffer system, helping to maintain a normal acid-base (pH) balance within the body. This balance is crucial for many cellular and metabolic functions, as even small changes in pH can have significant health consequences.

Regulating Phosphorus and Calcium

Maintaining the right balance of phosphorus and calcium is crucial. This balance is tightly regulated by a complex interplay of hormones, including parathyroid hormone (PTH), vitamin D, and fibroblast growth factor 23 (FGF23), and managed by the kidneys, bones, and intestines.

When phosphorus levels are low, the kidneys conserve it and vitamin D absorption is enhanced.
When phosphorus levels are high, the kidneys increase its excretion.

This system ensures that blood phosphorus levels stay within a tight range, though the levels can be influenced by diet and kidney function. In cases of chronic kidney disease, the body struggles to excrete excess phosphorus, which can lead to high blood levels (hyperphosphatemia), causing potential health problems.

Calcium vs. Phosphorus: A Functional Comparison


Feature	Calcium	Phosphorus
Abundance	Most abundant mineral in the body	Second most abundant mineral in the body
Primary Location	Over 99% in bones and teeth	About 85% in bones and teeth
Key Functions	Bone structure, muscle contraction, nerve transmission, blood clotting	Bone structure, energy production (ATP), cell membrane integrity, DNA/RNA formation, nerve signaling
Regulation	Tightly controlled by PTH and vitamin D	Regulated by kidneys, PTH, vitamin D, and FGF23
Dietary Sources	Dairy, fortified foods, leafy greens	Meat, dairy, eggs, nuts, legumes

Excellent Food Sources of Phosphorus

Since the body cannot produce phosphorus, it must be obtained through diet. Fortunately, it is widely available in many common foods.

Meat and Poultry: Chicken, turkey, and beef are rich sources.
Fish and Seafood: Salmon, tuna, and sardines are excellent options.
Dairy Products: Milk, yogurt, and cheese are well-known sources of both calcium and phosphorus.
Eggs: A good source, particularly the yolk.
Nuts and Seeds: Almonds, pumpkin seeds, and sunflower seeds contain significant amounts.
Legumes: Lentils, beans, and chickpeas are great plant-based sources.
Processed Foods: Some processed foods contain phosphate additives, which can increase overall intake.

Conclusion

Phosphorus is undoubtedly the second most abundant mineral in the human body, but its importance extends far beyond its ranking. As a partner to calcium in forming our skeletal structure, and a critical component for cellular energy, genetics, and nerve function, its role is irreplaceable. While deficiency is rare in the general population due to its abundance in food, maintaining a healthy balance is crucial for optimal health, especially concerning kidney function. Ensuring adequate intake from a varied diet is the best way to support the countless physiological processes that depend on this vital mineral. For more detailed information on phosphorus, you can consult resources like the NIH Office of Dietary Supplements.

Frequently Asked Questions

Neither is more important than the other, as they work together synergistically. While calcium is the most abundant, phosphorus is the second, and they combine to form the minerals that give bones and teeth their strength. They are partners in supporting critical bodily functions.

Phosphorus is abundant in protein-rich foods such as meat, fish, poultry, eggs, and dairy products. It is also found in nuts, legumes, and whole grains.

Yes, high levels of phosphorus (hyperphosphatemia) can occur, especially in people with severe kidney disease. Excessively high levels can combine with calcium and cause calcification in soft tissues like muscles and blood vessels.

Phosphorus is essential for proper muscle contraction. It also helps the body use carbohydrates and fats for energy, which is critical for muscle function.

The body's regulation of phosphorus is closely linked to vitamin D. Vitamin D enhances the intestinal absorption of phosphorus, while hormones like PTH and FGF23, which are influenced by vitamin D, help control its levels in the blood and bones.

The majority of the body's phosphorus, about 85%, is stored in the bones and teeth. The rest is found in soft tissues and extracellular fluids.

Individuals with chronic kidney disease (CKD) are at the highest risk for developing high phosphorus levels because their kidneys cannot efficiently excrete the mineral. A high intake of phosphorus additives from processed foods can also contribute to this risk.

Phosphorus deficiency (hypophosphatemia) is rare but can occur due to malnutrition or certain medical conditions. Severe deficiency can lead to muscle weakness, red blood cell hemolysis, and bone deformities.