Factors that hinder calcium absorption, mainly food, gastrointestinal tract, age, drugs and other aspects, as follows: First, food: If you eat too much spinach, celery, dumplings, bamboo shoots, will affect calcium binding, resulting in calcium insoluble salts, which will reduce the concentration of calcium, thus affecting calcium absorption. Second, the gastrointestinal tract: the gastrointestinal tract absorption on the calcium rate of difference, absorption rate is very large, normal people must eat 400mg of blood calcium every day, so that the intestinal absorption of calcium to reach saturation. If you have had gastrointestinal tract surgery, it will inhibit the absorption of calcium. Third, age: the older you are, the lower the intestinal absorption of calcium will be, so as you age, the absorption of blood calcium is getting slower and slower, especially for postmenopausal women. Fourth, drugs: generally glucocorticoids will affect the absorption of calcium, as well as ethanol, diazepam, phenytoin sodium will affect the absorption of calcium.