There are two main clinical uses for calcium carbonate: one is for calcium supplementation to treat osteoporosis; the other is for patients with renal insufficiency or hyperphosphatemia due to chronic kidney disease, where the calcium in calcium carbonate can be used to bind to phosphoric acid in food, blocking the absorption of phosphoric acid and thus playing a role in lowering blood phosphorus. When calcium carbonate is used as a calcium supplement for the treatment of osteoporosis, calcium carbonate is generally suitable to be taken after meals. Because taking calcium carbonate on an empty stomach will react with hydrochloric acid in the stomach and produce carbon dioxide, causing stomach bloating and stomach pain, calcium carbonate as a calcium supplement should be taken after a meal. When calcium carbonate is used as a combination with phosphate in food to inhibit phosphate absorption and treat hyperphosphatemia, calcium carbonate is suitable to be chewed during meals to fully combine with phosphate in food and thus lower blood phosphorus, which are the two main uses of calcium carbonate.