What is the role of calcium in the human body? Calcium is the most abundant mineral element in the human body. Adequate calcium intake is essential for maintaining normal bone density in children and adolescents, achieving high peak bone mass, reducing bone fractures and lowering the risk of osteoporosis in old age. In addition, calcium ions are involved in a variety of physiological functions in the body, such as blood coagulation, maintaining normal excitability and signaling of the heart, muscles, nerves, and the permeability and integrity of cell membranes. Studies have shown that calcium deficiency in the human body increases the risk of various chronic metabolic diseases, such as osteoporosis, hypertension, tumors, diabetes and so on. Are there many people with calcium deficiency? China’s residents dietary calcium intake is generally low, of which the proportion of dietary calcium intake of adolescents aged 11 to 13 years old to reach the appropriate intake of calcium in the dietary nutrient reference intake of Chinese residents (AI) is the lowest. Survey data from the United States also showed that the proportion of children and adolescents aged 8-19 years with dietary calcium intake meeting the AI was the lowest. What factors prevent and promote calcium absorption? Dietary factors that impede calcium absorption include alcohol, caffeine, oxalic acid (which is found in all plants, with spinach and tea being the most abundant), and phytic acid. Fats help in the absorption of dietary calcium. In addition, physical activity is an important determinant of bone health. Moderate weight-bearing exercises such as running and jumping are conducive to skeletal calcium deposition, leading to higher peak bone mass. What foods are rich in calcium? Milk and milk products are the main and best source of calcium in the body; green vegetables, soybeans and their products are also high in calcium and can be used as a supplementary source of calcium; calcium-fortified foods can also provide some calcium. How to recognize calcium deficiency? The diagnosis of calcium deficiency can be based on a combination of risk factors, clinical manifestations, laboratory tests and bone mineral test results. Risk factors 1. Chronic insufficient dietary calcium intake and poor intestinal calcium absorption due to insufficient or deficient vitamin D are the main causes of calcium deficiency. 2, <2 years old infants and adolescents, due to rapid growth, rapid increase in bone mass, the need for calcium is relatively high, is a high-risk group of calcium deficiency. Among them, infancy is the period of life when the proportion of bone calcium deposition is relatively the highest; and during the 3~4 years of rapid growth of youth, adolescents obtain a total of about 40% of their adult bone mass. The rate of skeletal calcium deposition peaks at 12.5 years of age for girls and 14.0 years of age for boys. Inadequate calcium and/or vitamin D intake by the mother during pregnancy, preterm birth/low birth weight, and twin/multiple births result in insufficient calcium storage during the fetal period, causing calcium deficiency in the early years of life. 4, breast milk calcium and phosphorus ratio is appropriate, high absorption rate, insufficient breast milk, not replaced by formula milk or other dairy products after weaning from breast milk and dietary lack of milk and other high-calcium foods, is an important factor leading to children's calcium deficiency. 5, a large number of fruit juice and carbonated beverages affect calcium intake by crowding out milk intake. 6, suffering from diarrhea, gastrointestinal diseases, intestinal calcium absorption and utilization is poor, also easy to cause calcium deficiency. 7, vitamin D insufficiency or deficiency, as well as suffering from liver, kidney disease and affect the activity of vitamin D, is also an important factor causing calcium deficiency. What are the signs of calcium deficiency? Calcium deficiency in children often has no obvious clinical symptoms. A few children may have non-specific symptoms such as growing pains, joint pains, palpitations or insomnia. Severe calcium deficiency leads to impaired bone mineralization and the clinical manifestations of rickets. Temporary parathyroid insufficiency and calcium deficiency in newborns can lead to hypocalcemia, increased neuromuscular excitability, tetany, laryngospasm and even generalized convulsions. What tests can be done to determine calcium deficiency? Blood calcium levels cannot be used to determine the body's calcium nutritional status. Normally, blood calcium levels are tightly regulated and only decrease or increase slightly in cases of extreme calcium deficiency or short-term high calcium intake. Bone mineral content and bone mineral density measured by dual-energy X-ray absorptiometry are rapid, accurate, low in radioactivity, and highly reproducible, and are considered to be ideal indicators that can indirectly reflect the calcium nutritional status of the human body by evaluating its bone mineral content. However, the test is expensive and there is a lack of normal reference data for children. Quantitative ultrasound bone strength testing is gradually increasing in clinical use due to its advantages of being inexpensive, portable and non-radioactive. However, its results are also affected by the elasticity and structure of the bones, so its clinical value has yet to be confirmed. How to prevent calcium deficiency? Encourage breastfeeding. Breastmilk is a good source of calcium for infants, and as long as breastmilk is sufficient, calcium nutrition for infants is adequate. When mothers do not breastfeed or breastmilk is insufficient for various reasons, reasonable formula feeding can still provide adequate calcium nutrition. Preterm/low birth weight, twin/multiple birth infants require additional calcium supplementation, either through breast milk fortification, special preterm infant formula, or the addition of vitamin D and calcium supplements. When vitamin D levels are maintained at an appropriate level, prepubertal children should be able to meet their calcium needs with a daily intake of 500 ml of milk or an equivalent amount of dairy products. Adolescents need 750 ml of milk per day to meet their calcium needs for rapid growth. Soy products, green vegetables and calcium-fortified foods can be used as supplementary sources of calcium. Treatment of Calcium Deficiency Dietary modifications should be made to increase dietary calcium intake. Aggressively search for risk factors and underlying diseases that lead to calcium deficiency and take effective interventions. Use calcium supplements to make up for inadequate dietary intake. Use calcium supplements only when dietary calcium intake is inadequate. The American Dietetic Association recommends a maximum calcium intake of 2.5 g/day of elemental calcium for children aged 1 to 18 years. Children with calcium deficiency and vitamin D deficiency should take vitamin D supplements at the same time. in addition, calcium deficiency in children often coexists with other micronutrients, such as magnesium, phosphorus, and vitamin A, C, and K deficiencies, so it is important to take care of calcium supplements as well as other related micronutrients. How to choose calcium supplements? High-quality calcium preparations should have the following characteristics: high effective calcium content; good chemical and biological activity; safe and reliable; and good taste. Currently, calcium carbonate is considered to be the calcium preparation with the highest effect-price ratio. Commercially available trade names include: Calcium D, Dicor, Nanocard, etc.