Do you think that if you go to the hospital and have a blood test result that shows normal blood calcium, your body should not be deficient in calcium? In other words, should the gold standard for determining whether your body is deficient in calcium be blood calcium? No! Bone density test is the gold standard to determine whether the body is deficient in calcium. In order to keep the electrolytes in the blood stable, the body will continuously absorb calcium from other parts of the body into the blood, if the absorbed calcium and food intake of calcium is balanced, the body is healthy; if the body absorbs more calcium than the food intake of calcium, the body is calcium deficient, but the blood calcium is still normal, then there may be cramps, back pain, chest tightness and other osteoporosis symptoms. Once the blood calcium decreases, it means that the degree of calcium deficiency in the body is already very serious, and violent convulsions may occur. No matter children or the elderly, it is not too early or too late to start taking calcium supplements. Especially people with low body weight, elderly, menopausal women, smokers, alcohol drinkers, frequent coffee drinkers, low exercise and vitamin D deficient should pay attention to their bone density early. A diet high in calcium and low in salt and adequate in protein is the key to preventing and treating osteoporosis. The best food for calcium is milk, both plain milk and yogurt. 100 ml of milk provides 100 mg of calcium, and it is recommended to drink 300 ml of milk daily to prevent osteoporosis. Other foods with high calcium content include soy products, seafood, and dark green vegetables. Adequate protein intake can assist in the transit and absorption of calcium. Sodium and calcium have a common ion absorption channel, and excessive salt intake can reduce calcium absorption, so eat a light diet. In addition to diet, moderate exercise can help deposit calcium into the bones, and daily sun exposure can help the body produce vitamin D to promote calcium absorption. Even after a fracture, moderate exercise is needed to help bone calcium deposition, not resting; long-term resting can lead to more bone calcium loss and more pronounced pain symptoms, which can lead to a vicious cycle.