Middle-aged and elderly people usually eat calcium tablets after 4 hours after meals, when the absorption effect is the best, but specific should be taken according to the instructions. Data show that in fasting, the pH of stomach acid is between 0.9 and 1.8. After eating, the pH of stomach acid rises due to the diluting effect of the amount eaten, up to 5.0. How well calcium carbonate or other calcium products dissolve in stomach acid is critical in determining whether calcium can be absorbed and fully utilized. Acidic environment calcium solubility is high. After 4 hours after a meal, the stomach empties completely and the pH value of the stomach is the lowest, which is favorable for the absorption of calcium tablets. Calcium tablets are used for the prevention and treatment of calcium deficiencies, such as osteoporosis, tetany, osteogenesis imperfecta, rickets, and calcium supplementation for children, pregnant and lactating women, menopausal women, and the elderly. Calcium tablets are contraindicated in patients with hypercalcemia and hypercalciuria. Prohibited for those who are allergic to Calcium Tablets, and used with caution for those with allergic constitution. Use with caution for people with cardiac and renal insufficiency. Calcium supplementation should be in moderation, should be under the guidance of a professional doctor for calcium supplementation, you can also eat more calcium-containing foods such as milk, shrimp, fish and so on.