Dicalcium phosphate is an ionic salt, meaning it's made up of charged particles of calcium and phosphate, both of which humans need in the diet. While dicalcium phosphate isn't as common a nutritional supplement as the more familiar tricalcium phosphate, it still shows up occasionally on nutrition labels as a means of adding calcium to a food.
Dicalcium phosphate has the chemical formula CaHPO4; it's a combination of positively charged particles of calcium, and negatively charged particles of hydrogen phosphate, which is interchangeable with phosphate in the body. As such, it's a source of both the mineral calcium and of phosphate, which you use for a variety of purposes, explains the Linus Pauling Institute. These include producing bone matrix and synthesizing DNA, which is genetic material.
Use of Dicalcium Phosphate
Dicalcium phosphate shows up in some foods as a calcium supplement, but isn't typically used in calcium pills. This is because it's lower in calcium as a percentage of weight than tricalcium phosphate, which has the chemical formula Ca3(PO4)2. It's also sometimes added as an anti-caking agent, because the dry form of the dicalcium phosphate salt can complex with water, forming the salt-hydrate. This removes water from foods that can become stale and helps keep them fresh.
Though dicalcium phosphate isn't the best possible source of calcium because of its low quantity of calcium as a percent of weight, it's still a source of this important mineral. You need calcium to maintain the bone structure, but also use it for a number of other things, explains Dr. Lauralee Sherwood in her book "Human Physiology." Uses of calcium include cell communication, neural signals and muscle contractions.
Dicalcium phosphate is also a source of phosphorus. While humans typically don't need phosphorus supplements, notes the Linus Pauling Institute, many animals do, so dicalcium phosphate has extensive application as a supplement in animal feed, according to Drugs.com. The bioavailability of phosphorus---the amount an animal can actually take up and use---is much higher from dicalcium phosphate than from other phosphorus supplements, making it a valuable addition to feed.