Many patients ask me if they should take calcium supplements. My opinion is that if you can supplement calcium through diet and physical exercise, you should not take medication because our daily diet already contains a large amount of calcium in various proportions. However, for many patients with significant calcium deficiency due to osteoporosis, malnutrition, or certain diseases, calcium supplementation is still necessary. So, please look and learn the following rationally and consult your own doctor.
Calcium is an important mineral in the body, 95% of which is found in the bones and teeth, and the remaining 5% is distributed in the blood, nerves and various soft tissues. In skeletal tissue, calcium ions and phosphorus form hydroxyl phosphate lime crystals that are deposited on a matrix of collagen and maintain the solidity of the bone.
When the body is deficient in calcium, on the one hand, the lack of the raw materials that make up bone leads to an intensification of bone metabolism in the direction of osteolysis; on the other hand, a drop in blood calcium to a threshold will lead to hyperparathyroidism (parathyroid hormone raises blood calcium), increasing bone resorption and freeing calcium from the bone tissue into the blood. Both factors can lead to a decrease in bone mass per unit volume, so calcium deficiency is an important cause of osteoporosis.
Whether it is primary osteoporosis (including postmenopausal, senile and idiopathic) or secondary to various other diseases or medications, calcium supplementation can reduce bone loss and is a basic adjunctive treatment. However, in clinical work, calcium supplementation therapy may not be reasonably standardized. So, what do we need to pay attention to for reasonable and standardized calcium supplementation?
Point 1: Reasonable choice of calcium supplements
Case: The patient is a 50-year-old woman with a history of kidney stones. She was given calcium supplementation for “postmenopausal osteoporosis”, and calcium tablets were used for calcium supplementation.
Ans: Based on the physiological and biochemical functions and pharmacological effects of calcium, the preparation with calcium salts as the main component is called calcium agent. There are many kinds of calcium preparations, which can be divided into inorganic calcium and organic acid calcium according to their composition. Inorganic calcium mainly includes calcium oxide, calcium carbonate, calcium hydrogen phosphate, calcium chloride, calcium hydroxide and so on. Organic calcium acids mainly include calcium gluconate, calcium lactate, calcium citrate, calcium citrate, etc. Inorganic calcium has higher calcium content, but most of them have low solubility and great gastrointestinal tract irritation; organic acid calcium generally has better body solubility, but low calcium content.
When choosing calcium supplements, the characteristics of the population and the combined diseases should be taken into account. For example.
1, people lacking stomach acid basically do not absorb inorganic calcium, and elderly people often have reduced stomach acid secretion, so it is recommended that people older than 65 years old and lacking stomach acid take organic acid calcium such as calcium citrate, and that inorganic calcium with high calcium content, such as calcium carbonate, be elected as calcium supplement for the general population.
2, hypoparathyroidism and chronic renal failure patients, often combined with hyperphosphatemia, can not use calcium containing phosphorus (calcium hydrogen phosphate), calcium carbonate, calcium citrate, calcium acetate should be used, not only to supplement calcium, but also as a phosphorus binding agent for hyperphosphatemia, in order to reduce blood phosphorus concentration.
3, calcium citrate increases intestinal aluminum absorption, taking aluminum is prohibited.
4, calcium gluconate is not suitable for diabetic patients.
5, calcium acetate is likely to increase blood pressure, not suitable for patients with hypertension and cardiac insufficiency.
Long-term use of general calcium supplements, such as calcium carbonate in cases, can cause an increase in blood and urine calcium concentrations, which can increase the risk of urinary calcium oxalate crystals and stone formation, which is particularly serious in patients with a history of urinary stones. Calcium citrate has a strong complexation of calcium, and when the concentration of citrate is increased, it can combine to replace calcium oxalate, free calcium ions and calcium phosphate salts, thus forming a complex that is easily soluble in water and inhibiting calcium oxalate supersaturation to precipitate crystals and form stones. Calcium citrate is recommended as a calcium supplement for patients with urinary stones.
Point 2: How to use?
Case: The patient was 68 years old and was taking 600 mg of calcium carbonate in the morning and evening for primary osteoporosis.
The recommended daily intake of calcium for adults is 800 mg, which is the appropriate dose to obtain the ideal bone peak and maintain bone health. The average amount of elemental calcium for postmenopausal women and the elderly should be 500-600 mg per day (e.g., calcium carbonate contains 600 mg of elemental calcium per tablet).
Before determining the dose, the patient’s blood and urine calcium levels should also be measured and considered in conjunction with the patient’s dietary calcium intake to prevent the development of hypercalcemia (as in the case), which increases the risk of kidney stones and cardiovascular disease. The maximum permissible daily intake of calcium for adults in China is 2000 mg.
After calcium supplementation, it is recommended that blood and urine calcium concentrations be tested every 3 months, and that the drug be discontinued if hypercalcemia occurs, and that the dose of calcium be reduced if urine calcium increases.
A large dose of calcium in a single dose is not as well absorbed as a divided dose. The commonly used calcium carbonate is better absorbed in an acidic environment, and when calcium carbonate is taken with food, the stimulation of food increases the secretion of gastric acid, which can increase the absorption efficiency of calcium. Organic calcium does not need to be activated by gastric acid, so it is not necessary to take it with food. Also note that vegetables containing more oxalic acid (spinach, amaranth) reduce the absorption of calcium and avoid using them with calcium supplements as much as possible.
Point 3: Calcium supplementation should be combined with vitamin D
Case: Male, 70 years old, chronic nephritis with uremia and osteoporosis, given only calcium carbonate vitamin D chewable tablets orally.
Ans: Vitamin D promotes calcium absorption, is beneficial for bone health, maintains muscle strength, enhances body balance, reduces falls, and lowers the risk of fractures. Vitamin D deficiency can lead to secondary hyperparathyroidism and increase bone resorption, which can cause or worsen osteoporosis. Vitamin D is indispensable along with calcium supplementation and is the foundation of treatment.
Although some calcium supplements include vitamin D (e.g., cases), the dose is far from adequate. Our guidelines recommend a dose of 800-1200 IU/d for the treatment of osteoporosis, and the conversion of common vitamin D to active vitamin D is necessary for it to be effective, so substitute active vitamin D supplementation, including alpha-skeletriol (0.25-1.0 μg daily) or osteopontin (0.25-0.5 μg daily).
Osteomalacia secondary to renal failure is due to reduced active vitamin D synthesis, but only osteotriol should be supplemented because α-osteotriol requires renal activation and this activating enzyme is reduced in patients with renal failure.
Clinical co-administration of calcium and vitamin D preparations should also be monitored once every 3 months for blood and urine calcium, and dose adjustments should be made as appropriate. It is recommended that serum 25-hydroxyvitamin D concentrations (reflecting vitamin D nutritional status for better supplementation) equal to or above 30 ng/mL (75 nmol/L) be measured as appropriate in hospitals where available to reduce the risk of falls and fractures.