The Chinese Nutrition Society recommends that adults between the ages of 25 and 45 should consume 800 to 1000 mg of elemental calcium per day. Adolescence is the second peak of growth acceleration, at this time the elemental calcium intake plays an important role in reaching the ideal peak bone mass, the optimal intake is 1200 mg to 1500 mg per day; pregnant women and lactating mothers, because they are in a special physiological period, require elemental calcium at a higher level than normal people, 1000 mg to 2000 mg per day; postmenopausal women taking estrogen recommended daily elemental calcium intake The recommended daily intake of elemental calcium for postmenopausal women taking estrogen is 1000 mg, for those not taking estrogen is 1500 mg per day, and for elderly people over 65 years old, 1500 mg per day is the best intake. The main calcium supplements currently available on the market are inorganic calcium and organic calcium. Inorganic calcium mainly refers to calcium carbonate, calcium chloride, calcium phosphate and so on. Organic calcium mostly refers to calcium lactate, calcium gluconate, calcium citrate p acetate, calcium aspartate, etc. Although inorganic calcium salts contain high calcium content, but its solubility is low, and its absorption requires the participation of gastric acid, which is irritating to the gastrointestinal tract and can cause heartburn, nausea and slight pain in the stomach after taking, so inorganic calcium is more suitable for patients without gastrointestinal diseases. Children should not use calcium carbonate because of incomplete development of kidney function, which can easily cause acidosis. Organic calcium is relatively well absorbed and does not require the participation of stomach acid in the dissolution process, which is more suitable for some patients with stomach acid deficiency. The choice of calcium should not be based on price, because calcium is not the more expensive the better. Calcium products on the market are in the form of calcium salts, calcium salts can not be absorbed directly by the body, calcium salts into the human body to separate out the calcium ions (elemental calcium) can be absorbed, so when choosing calcium tablets mainly depends on the level of elemental calcium content, and what kind of calcium compounds, because the calcium compounds contain different amounts of calcium, its solubility and absorption rate are different, such as calcium carbonate contains elemental calcium and absorption rate of 40%, respectively p39%; calcium citrate contains elemental calcium and absorption rate of 21% p30%; calcium lactate contains elemental calcium and absorption rate of 13% p32%; calcium gluconate contains elemental calcium and absorption rate of 9% p27%. If Calcium D contains 600 mg of elemental calcium, and 1 gram of calcium carbonate contains 400 mg of elemental calcium, so it takes 2 grams of calcium carbonate a day to reach the 800 mg of elemental calcium content recommended by the Chinese Nutrition Society. Calcium citrate contains less calcium than calcium carbonate, about 21%, so it may be necessary to take two times more tablets to reach the recommended intake. Taking a large amount of calcium at one time can close the receptors, resulting in calcium not being absorbed. Therefore, do not take too large a dose of calcium at a time; take it in divided doses and try not to take more than 500 mg at a time. Calcium tablets supplemented into the body need to be absorbed, which can be promoted by outdoor sun exposure and eating with vitamin D. Faced with the problem of calcium supplementation, there are many sources of calcium in food, and dietary adjustment is the basis. In the daily diet, calcium-rich foods are mainly: 1, dairy foods: such as milk, yogurt, cheese and other dairy and dairy products; 2, soy products: such as tofu, soy milk, dried beans, tofu skin, vegetarian chicken and other soy products; 3, seafood: some fish with bones, such as anchovies and shrimp; 4, nuts: such as almonds, peanuts, pine nuts; 5, vegetables: dark green vegetables, such as broccoli. In life the correct choice of calcium supplements properly, combined with diet and exercise adjustment, can prevent osteoporosis p reduce the incidence of fractures, effective relief of osteoporosis-induced pain in the lower back p legs and joints; can alleviate the harm caused by lack of calcium during pregnancy and lactation; reduce the rate of bone calcium loss in menopausal women, alleviate menopausal syndrome; can regulate blood pressure.