Taking calcium tablets on an early morning fast is usually not recommended, as follows. If calcium tablets are taken on an early morning fast, they may cause a certain degree of stimulation to the mucous membrane of the digestive tract, and patients are prone to clinical symptoms such as abdominal pain, bloating and nausea, which can affect the intake of breakfast and make patients malnourished. In addition, taking calcium tablets early in the morning on an empty stomach is not conducive to calcium absorption, which is usually most easily absorbed during the night. If calcium tablets are taken in the morning, the amount of calcium absorption may be significantly reduced and the purpose of calcium supplementation will not be achieved. Therefore, it is best not to take calcium tablets on an empty stomach, but after a meal, preferably at night, to achieve the purpose of significantly replenishing calcium.