The Reaction Of Calcium & Phosphate

Calcium and phosphorus are essential nutrients. When combined in your bones, these two elements react to form a calcium phosphate salt called hydroxyapatite, which serves as the mineral matrix for your skeleton. The Linus Pauling Institute at Oregon State University states that 85 percent of your body's phosphorus and 99 percent of your calcium are sequestered in your bones and teeth, with the remainder distributed in your soft tissues and bodily fluids. Although you require both minerals for optimal health, excessive phosphorus in your diet might disrupt your calcium balance.

Calcium Functions

In addition to serving as the principal mineral in your bones, calcium is involved in generating the electrical impulses that allow your muscles, heart and nerves to function properly. By binding to messenger proteins within your cells, calcium helps control hormone secretion, neurotransmitter production and the breakdown of carbohydrate molecules for energy. Because calcium's actions are critical to life, your body maintains its concentrations within a relatively narrow range. Consumption of phosphate-rich meats, soft drinks and processed foods adversely affects the metabolism of calcium in your body.

Phosphorus Roles

Most of the phosphorus in your body exists as phosphate, which is incorporated into many compounds, including the energy molecule, adenosine triphosphate, or ATP. Phosphate is a critical component of your chromosomes, and it is found in the membranes of your cells. Phosphorus is required for activating many enzymes, hormones and other important molecules. It helps maintain your acid-base balance, and it influences the delivery of oxygen to your tissues.

Regulation

Whenever your blood calcium level dips slightly, your parathyroid glands secrete parathyroid hormone, or PTH, which increases the production of activated vitamin D in your kidneys. Vitamin D enhances absorption of both calcium and phosphorus from your intestine, and vitamin D and PTH both stimulate removal of calcium and phosphorus from your bones. In contrast, vitamin D causes your kidneys to hold onto calcium while stimulating the excretion of phosphorus. These combined activities raise your serum calcium level, which eventually "turns off" PTH production.

Interactions

In his book, "Staying Healthy with Nutrition," Dr. Elson Haas reports that the typical American diet, which is high in phosphorus and low in calcium, results in ongoing removal of calcium from your bones and elimination of this important mineral from your body. This eventually leads to bone demineralization and other health problems associated with calcium deficiency. High dietary phosphate interferes with intestinal calcium absorption and encourages the production of PTH, which mobilizes calcium from your bones.

Considerations

High phosphate consumption probably contributes to leaching of calcium from the bones of many Americans, whose dietary phosphorus-to-calcium ratios often approach 5 to 1. The ideal ratio is about 1 to 1, according to Haas. Animal proteins are among the richest dietary sources of phosphorus. The replacement of milk with phosphate-rich soft drinks contributes to a dietary calcium deficiency for many individuals. Adequate intake levels for calcium vary from 210 mg daily for infants to 1,300 mg for adolescents. Ask your doctor for advice about dietary calcium and phosphates.