- Calcium citrate is a calcium salt derived from citric acid, with the chemical formula Ca₃(C₆H₅O₇)₂·4H₂O. It typically appears as a white, odorless powder or crystalline substance that is highly soluble in water, especially in acidic conditions.
- As one of the most commonly used forms of supplemental calcium, calcium citrate is widely utilized in the nutritional, medical, and food industries due to its high bioavailability, low risk of gastrointestinal side effects, and good absorption profile, even without the presence of stomach acid.
- In dietary supplementation, calcium citrate is highly regarded for its ability to be absorbed efficiently across a wide pH range. Unlike calcium carbonate, which requires an acidic environment for optimal absorption, calcium citrate is well absorbed even by individuals with low stomach acid (a condition more common in older adults or those taking acid-reducing medications). For this reason, it is often recommended for individuals with achlorhydria, gastric bypass patients, or those using proton pump inhibitors (PPIs) or H2 blockers.
- Calcium citrate plays a crucial role in bone health and osteoporosis prevention, as it provides elemental calcium necessary for maintaining bone density and structural integrity. It is often prescribed or recommended for postmenopausal women, older adults, and individuals at risk for osteopenia or osteoporosis. It also contributes to nerve conduction, muscle function, enzyme activity, and blood clotting, as calcium is essential for a range of physiological processes.
- In addition to its health benefits, calcium citrate is used in the food and beverage industry as a firming agent, preservative, and acidity regulator, designated by the food additive code E333. It is added to canned vegetables, jams, beverages, and other processed foods to stabilize pH and enhance texture. Its buffering capacity also makes it useful in pharmaceutical formulations and nutraceutical products.
- Calcium citrate typically provides about 21% elemental calcium by weight, meaning that higher doses may be required compared to more concentrated calcium salts like calcium carbonate to meet daily requirements. However, this is offset by its superior absorption and reduced likelihood of causing constipation, bloating, or gas, which are common side effects of other calcium forms.
- From a safety perspective, calcium citrate is well tolerated and safe for most people when taken within recommended limits. Excessive intake, particularly in conjunction with high levels of vitamin D or other calcium sources, can lead to hypercalcemia (elevated calcium levels in the blood), which may cause symptoms such as nausea, confusion, or kidney stones. People with chronic kidney disease, sarcoidosis, or other conditions that affect calcium metabolism should use calcium supplements under medical supervision.
