I. As people age, the absorption of calcium in the intestine decreases for the following reasons: 1. The intestine itself is defective due to age and the absorption of calcium decreases; 2. As we age, the liver and kidney function decreases and the synthesis of active vitamin D decreases, and since active vitamin D is what promotes the absorption of calcium in the small intestine, its decrease causes a decrease in calcium absorption; 3. The decrease in estrogen after menopause also causes a decrease in the absorption of calcium. At the same time, the excretion of calcium from the kidneys increases, making the calcium level in the blood low. All these stimulate the body to increase the secretion of parathyroid hormone, which promotes bone dissolution and increases the release of calcium. Therefore, to maintain calcium balance, older people need more calcium. Adults aged 18 to 50 years old need 800mg of calcium per day, while older people need 1000mg of calcium per day, while the daily calcium intake of Chinese diet is at 400mg, so calcium supplementation becomes very important. Second, calcium supplementation is actually divided into two aspects: 1, balanced diet 2, eat enough calcium-rich foods: dairy products, soy products, seafood, vegetables, nuts 3, from food or sun exposure to take enough vitamin D 4, moderate intake of meat 5, 1-2 fruits a day, orange, citrus, grapefruit, kiwi fruit best There are many diets rich in Calcium, for example, milk 1 ml of milk contains about 1 mg of calcium, drink 200ml ~ 300ml of milk daily, equivalent to 200mg ~ 300mg of calcium, milk in small portions is better, low-fat than pure milk, fat will prevent the absorption of calcium, but if you do not love milk, or drink milk after causing diarrhea, you need to supplement calcium tablets.