Calcium is a vital mineral for the developing infant. The foetal mineral supply is with the help of active transport across the placenta. At birth, this is disrupted leading to drop in calcium levels. There is an increase in phosphorous levels triggering an increase in parathyroid hormone and a succeeding rise in calcitriol (Vit D) which stimulates calcium absorption from intestine and reabsorption at kidney level. 1 Intestinal calcium absorption is initially a passive process facilitated by lactose, which later becomes active and calcitriol-dependent.2
Approximately 99% of the calcium in our bodies is in our bones and teeth. The remaining 1% calcium is present in the blood and soft tissues, where it performs very critical functions3.
Calcium cannot be synthesized by the body and is therefore an essential nutrient3. Also, we lose calcium through our skin, nails, hair, sweat, urine and faeces4. Thus, it is important to get enough calcium from the food especially during infancy which is a crucial period of growth.
Role of Calcium5 :
Bone and tooth formation: The most well-known calcium function is to build and strengthen bones and teeth. During bone mineralization process, there is deposition of calcium phosphates (salts) on the protein matrix. Increased calcium intake helps to increase the mineralized content of bone tissue that corresponds to a greater Bone Mineral Density, and to greater bone strength. This reduces the risk of osteoporosis later in adulthood 6
Nerve impulse transmission:Calcium aids electrical impulse transmission from one nerve cell to another. Calcium helps in release of neurotransmitters into the neural synapses (junction between nerve cells), allowing flow of ions in and out of nerve cells.
Contraction of muscles: Calcium ions flow along the surface of muscle cells and the calcium influx into the muscle cell are important for muscle contraction. Hence, important for functioning of the heart.
Clotting factors: During an injury, the damaged tissue releases specific factors for activating the circulating clotting factors and platelets. Some of these clotting factors require calcium for activation.
Maintaining normal physiology: Calcium has other several minor functions. It helps in release of hormone insulin from cells in the pancreas, breakdown of glycogen in muscles and helps in muscle contraction.
Calcium deficiency reduces the mineral content of bone, causing it to become brittle and weak. This affects skeletal growth and development. It also affects nerve cell function, muscle contraction and relaxation. Infants with low calcium levels may have tremors or twitching. Calcium deficiency could also be a result of Vitamin D deficiency. As discussed earlier, active form of vitamin D called as “Calcitriol” increases calcium absorption in the intestines by producing calcium binding protein and increases calcium deposition in the bone. Hence, Vitamin D also plays an important role in the maintenance of skeletal integrity.7 Calcium (and vitamin D) deficiency in infants can lead to rickets. Rickets is a condition characterised by soft and weak bones, stunted growth, and skeletal deformities. This is preventable by adequate calcium and vitamin D intake.8
The first nutritional source of calcium for infants is breast milk. The bioavailability of calcium from breast milk is greater than that from cow's milk6 . Once weaning starts, calcium can be obtained from sources such as animal milk, curd, paneer, ragi, sesame seeds and green leafy vegetables9
Recommended Dietary Allowance (RDA) for Calcium10
Calcium is a vital mineral component of bone tissue and is therefore essential for adequate bone formation. Vitamin D plays a key role in calcium metabolism. Inadequate dietary intake of these nutrients can negatively impact the skeletal formation and therefore hinders the process of growth and development.
- Ryan BA, Kovacs CS. Calciotropic and phosphotropic hormones in fetal and neonatal bone development. Semin Fetal Neonatal Med. 2020;25(1):101062. doi:10.1016/j.siny.2019.101062
- Kovacs CS. Bone development and mineral homeostasis in the fetus and neonate: roles of the calciotropic and phosphotropic hormones. Physiol Rev. 2014;94(4):1143-1218. doi:10.1152/physrev.00014.2014
- Beto J. A. (2015). The role of calcium in human aging. Clinical nutrition research, 4(1), 1–8. https://doi.org/10.7762/cnr.2015.4.1.1
- Karen Rafferty, Robert P. Heaney, Nutrient Effects on the Calcium Economy: Emphasizing the Potassium Controversy, The Journal of Nutrition, Volume 138, Issue 1, January 2008, Pages 166S–171S, https://doi.org/10.1093/jn/138.1.166S
- Micronutrients Essential for Bone Health- Calcium and Vitamin D. (2020, August 14).https://med.libretexts.org/@go/page/6649
- Baker, S. S., Cochran, W. J., Flores, C. A., Georgieff, M. K., Jacobson, M. S., Jaksic, T., & Krebs, N. F. (1999). American Academy of Pediatrics. Committee on Nutrition. Calcium requirements of infants, children, and adolescents. Pediatrics, 104(5 Pt 1), 1152–1157.
- Hitesh Kumar Bhattarai, Shreya Shrestha, Kabita Rokka, Rosy Shakya, "Vitamin D, Calcium, Parathyroid Hormone, and Sex Steroids in Bone Health and Effects of Aging", Journal of Osteoporosis, vol. 2020, Article ID 9324505, 10 pages, 2020. https://doi.org/10.1155/2020/9324505
- Khadilkar, A., Khadilkar, V., Chinnappa, J. et al. Prevention and treatment of vitamin D and calcium deficiency in children and adolescents: Indian Academy of Pediatrics (IAP) guidelines. Indian Pediatr 54, 567–573 (2017).https://doi.org/10.1007/s13312-017-1070-x
- Dietary guidelines for Indians. National Institute of Nutrition . Retrieved fromhttps://www.nin.res.in/downloads/DietaryGuidelinesforNINwebsite.pdf
- Recommended dietary allowances and estimated average requirements. Nutrient requirements for Indians – 2020, ICMR-National Institute of Nutrition.
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