Calcium citrate is calcium salt of citric acid, which is a mild, naturally-occurring acid. The mineral is a cold water-soluble powder that is often used to preserve, flavor, or add texture or substance to food. It can also be found in calcium supplements. Calcium citrate may be used as a water softener as well.
As a food additive, calcium citrate can serve several purposes. It can be used to neutralize or buffer acid and firm or stabilize a product. The mineral can also be used to increase the calcium content of foods. The sour but salty taste of calcium citrate can also flavor food. Some of the products it is used to enhance include soy milk, flour, sweet condensed milk, and powdered milk.
Though calcium carbonate is a less expensive way to add calcium to supplements, some individuals are not able to absorb the compound. Calcium citrate is frequently used as a substitute as it tends to be more readily absorbed by most patients. It is also less likely to cause constipation, gas, and bloating than calcium carbonate, though it can still cause these symptoms. The compound is typically used only when other minerals do not work because more of it is required in order to get the same calcium content as calcium carbonate.
Calcium citrate supplements are often particularly effective in recent gastric bypass surgery patients due to changes in the composition of their digestive systems, such as a lower amount of stomach acid. As a supplement it can also be used to treat individuals who have trouble building and maintaining bone mass, such as osteoporosis patients. It can also help support healthy muscles, nerves, and heart function. The supplement can be problematic for individuals who have had a parathyroid gland disorder or kidney stones.
The mineral can also be purchased in powdered form to be used as a water softener. It is effective for this purpose because it contains ions that chelate, or remove, heavy metals. These compounds increase the toxicity of water.
Calcium citrate can be generated as a part of the fermentation process that makes citric acid. Compounds such as calcium hydroxide and oxide, which neutralize acid, cause the reaction that generates the mineral. It is prepared in a broth solution from which it is filtered, washed, and then dried into solid form. The solid is then often ground to be used in food products or supplements. If the end product is to be citric acid, then the solid will be mixed with dilute sulfuric acid.