There are many factors that affect the absorption of calcium in humans, such as the amount of calcium intake, the ratio of dietary calcium to phosphorus content, the dissociation state of calcium entering the intestine, the amount and type of protein in food, and the physiological state of the gastrointestinal tract, all of which can affect calcium absorption. There is a correlation between dietary calcium intake: and intestinal calcium absorption rate. In general, as dietary calcium intake increases, the amount of calcium ions absorbed by the intestine also increases accordingly. However, due to the saturation of the active transit process of intestinal absorption, the intestinal calcium ion absorption curve shows a significant upward trend in normal people when they consume about 5 mg of calcium per kg of body weight per day. When the intake of calcium reaches more than 10 mg per kg of body weight per day, the amount of intestinal absorption of calcium ions increases more slowly. Phosphorus: The presence of dietary phosphorus has an effect on the absorption of calcium. Because calcium absorption depends on a reasonable intestinal calcium to phosphorus ratio, proper phosphorus intake is important for calcium absorption. However, when a healthy adult consumes more than 1 gram of phosphorus, the phosphorus will form insoluble calcium phosphate with calcium ions, preventing the absorption of calcium ions in the intestine. For example, milk is very rich in phosphorus, about 3-4 times more than human milk, but due to its high phosphorus content, the ratio of calcium to phosphorus is not appropriate, resulting in a large amount of calcium in milk that is not easily absorbed. Unabsorbed calcium and phosphorus are present in the feces, making the feces dry and caked. Milk-fed infants are prone to calcium deficiency, which can lead to rickets in severe cases. Some of the better dairy products on the market use a series of scientific and clever formula design, so that the calcium and phosphorus ratio is basically 2:1, very close to the calcium and phosphorus ratio in breast milk, it avoids the disadvantages of improper calcium and phosphorus ratio in cow’s milk and low calcium absorption rate, which is conducive to the absorption of calcium in the intestinal tract. Calcium status: The dissociation status of ingested calcium has a significant effect on the intestinal calcium absorption rate. Generally dietary calcium is present in the form of compounds that enter the stomach and are dissociated into ionic calcium by the action of gastric acid and then absorbed in the small intestine. The modern process of activating calcium in vitro in the dissociated state of ionic calcium, i.e. active calcium, has a higher absorption rate in the intestine than dietary calcium or traditional calcium preparations such as calcium carbonate and calcium lactate. The main physiological state of the gastrointestinal tract: the physiological state of the gastrointestinal tract affects intestinal calcium absorption in many ways. Calcium intake through diet is firstly affected by the gastrointestinal function. Gastric acid has the function of dissolving calcium salts, and whether the concentration and quantity of gastric acid secretion are appropriate will have a direct impact on calcium absorption. This is mainly because dietary calcium exists in the form of compounds, and if the first step of calcium salt decomposition in the stomach is not solved, the next step of calcium ion absorption will not be possible. Therefore, when suffering from gastrointestinal disorders and chronic gastritis, gastric ulcer and other organic diseases, if the secretion of gastric acid is insufficient, it will inevitably affect the dissociation of calcium ions in food, directly hindering the digestion and absorption of calcium. The role of pancreatic enzymes in the intestine is mainly to digest fat. If the fat in the diet is too low, the secretion of bile salts is insufficient, which may delay the absorption of exogenous vitamin D. However, when fat is fully digested, fatty acids form insoluble calcium soaps with calcium that are not easily absorbed by the intestine, thus reducing the absorption and utilization of calcium. It is for this reason that any intestinal (mainly small intestine) disorder may interfere with the absorption of inorganic salts, including calcium ions. Other factors: In addition to the above factors can affect the absorption of calcium, there are many other can also affect the absorption of calcium absorption, such as oxalic acid in food and plants can be combined with calcium ions to form insoluble calcium salts and reduce the absorption of calcium; Xu I inorganic salts, such as sodium salts and phosphate, as well as vitamins, antibiotics, anti-epileptic drugs, diuretics and other drugs, can also affect the body’s absorption of calcium. In addition, some physiological factors on the human body to collect calcium also has a significant impact, such as the older the age, the less intestinal absorption of calcium, of which women and more obvious than men. On the other hand, the normal endocrine function also determines how much or how little calcium the body absorbs. Hormones in the body, such as thyroxine, calcitonin, estrogen, adrenocorticotropic hormone, and thyroxine, have a significant effect on the absorption of calcium in the intestine. The most closely related to calcium absorption is vitamin D and its active metabolites, and the relationship between vitamin D and calcium is just like a deep fish-water relationship, interdependent and mutually influential.