There is a saying in China “too much is not enough”, which explains a very simple truth that everything needs to have a degree, more than that is not good. Calcium is also the same, although calcium is an essential mineral for the human body, it has a role in promoting bone development, muscle activity and body metabolism. But if excessive calcium supplementation, its harm is also greater. The main hazards of taking too much calcium are the following: a. Excessive calcium supplementation is likely to induce kidney stones, calcium is the main component of stones, if too much intake for a long time, and the body can not be absorbed properly, is prone to stones. Second, affect the absorption of nutrients, because calcium can adsorb with iron and certain vitamins and form chelates, reducing the absorption concentration and absorption rate of iron and these vitamins in the intestine, so excessive calcium supplementation can lead to iron and vitamin deficiency, inducing anemia and vitamin deficiency, reducing the body’s immune function. The most direct complication of excessive calcium supplementation is hypercalcemia, once it occurs, there will be lethargy, weakness, drowsiness, forgetfulness and other phenomena, which is extremely harmful to the human body. Fourth, excessive calcium supplementation will also affect the absorption of iron, zinc, magnesium, phosphorus, experimental evidence that calcium can significantly inhibit the absorption of iron; calcium and zinc have a mutually antagonistic effect; excess calcium will lead to reduced absorption of magnesium; high calcium will reduce the absorption of phosphorus in the diet. Fifth, easy to cause gastrointestinal adverse reactions, excessive calcium supplementation can stimulate the gastric mucosa to promote rebound gastric acid secretion, resulting in a large amount of gastric acid and gastric juice secretion, can cause mucosal congestion and swelling, mucosal erosion or ulcers. Excessive calcium supplementation can also induce constipation, which can have a negative impact on health. The lack of any nutrient can affect health, what is not good to eat too much, dietary balance is the important principle of health, this must be mastered, they do not understand, we must ask the doctor, never indiscriminate supplementation.