Calcium

What is calcium used for?

Updated 4 Nov 2026

Short answer

Large reviews found small effects of supplements on bones, and other uses have mixed or limited evidence:

  • Fractures. A 2026 review of 69 trials found little to no effect of calcium, alone or with vitamin D, on fractures or falls.[1]
  • Bone density. In people over 50, calcium raised bone density by 0.7% to 1.8%. The authors judged this gain unlikely to lower fracture risk in a way that matters.[2]
  • Rickets with a low calcium diet. In Nigerian children with rickets, 1,000 mg a day for 24 weeks brought near-complete healing in 61%, against 19% with vitamin D alone.[3]
  • Pre-eclampsia. A 2025 Cochrane review found little to no effect in large trials.[4] The World Health Organization (WHO) still recommends 1.5 to 2.0 g a day in pregnancy where calcium intake is low.[5]
  • Blood pressure. In people with normal blood pressure, more calcium lowered it by about 1.4 mmHg.[6]
  • Premenstrual syndrome. In the largest trial, 1,200 mg a day cut premenstrual symptoms by 48%, against 30% with placebo.[7]
  • After thyroid surgery. In a trial of 106 patients, low blood calcium with symptoms occurred in 1.9% with routine calcium and in 33.9% without it.[8]

Other expected benefits have little support. Calcium may make little or no difference to body weight, on low-certainty evidence.[9] In 34,157 women after menopause, calcium with vitamin D did not change sleep disturbance.[10] A later analysis of a trial in 212 people with prediabetes found better sleep with calcium only in some subgroups.[11] The evidence on leg cramps in pregnancy is unclear.[12]

Not every study of a calcium compound tests a tablet. A 2-year trial in 6,000 children, for example, tested toothpaste with arginine, a calcium compound and fluoride.[13]

Sources (13)

  1. Calcium, vitamin D, or combined supplementation to prevent fractures and falls: systematic review and meta-analysis. Massé O, Mercurio CM, Dupuis S, Al Sahwi M, Arruda A, Dallaire G, et al. BMJ, 2026. PMID 42161415
  2. Calcium intake and bone mineral density: systematic review and meta-analysis. Tai V, Leung W, Grey A, Reid IR, Bolland MJ BMJ, 2015. PMID 26420598
  3. A comparison of calcium, vitamin D, or both for nutritional rickets in Nigerian children. Thacher TD, Fischer PR, Pettifor JM, Lawson JO, Isichei CO, Reading JC, et al. N Engl J Med, 1999. PMID 10451461
  4. Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems. Cluver CA, Rohwer C, Rohwer AC Cochrane Database Syst Rev, 2025. PMID 41330480
  5. Calcium supplementation during pregnancy to reduce the risk of pre-eclampsia. World Health Organization, 2023. www.who.int
  6. Calcium supplementation for prevention of primary hypertension. Cormick G, Ciapponi A, Cafferata ML, Cormick MS, Belizán JM Cochrane Database Syst Rev, 2022. PMID 35014026
  7. Calcium carbonate and the premenstrual syndrome: effects on premenstrual and menstrual symptoms. Premenstrual Syndrome Study Group. Thys-Jacobs S, Starkey P, Bernstein D, Tian J Am J Obstet Gynecol, 1998. PMID 9731851
  8. Prophylactic oral calcium supplementation therapy to prevent early post thyroidectomy hypocalcemia and evaluation of postoperative parathyroid hormone levels to detect hypocalcemia: A prospective randomized study. Arer IM, Kus M, Akkapulu N, Aytac HO, Yabanoglu H, Caliskan K, et al. Int J Surg, 2017. PMID 28039060
  9. Calcium supplementation for people with overweight or obesity. Cormick G, Ciapponi A, Harbron J, Perez SM, Vazquez P, Rivo J, et al. Cochrane Database Syst Rev, 2024. PMID 38721870
  10. Calcium and vitamin D supplementation do not influence menopause-related symptoms: Results of the Women's Health Initiative Trial. LeBlanc ES, Hedlin H, Qin F, Desai M, Wactawski-Wende J, Perrin N, et al. Maturitas, 2015. PMID 26044075
  11. Effects of vitamin D and/or calcium intervention on sleep quality in individuals with prediabetes: a post hoc analysis of a randomized controlled trial. Miao Y, Zhang L, Zhang D, Feng M, Zhang C, Zhao T, et al. Eur J Nutr, 2024. PMID 38366270
  12. Interventions for leg cramps in pregnancy. Luo L, Zhou K, Zhang J, Xu L, Yin W Cochrane Database Syst Rev, 2020. PMID 33275278
  13. Two-year caries clinical study of the efficacy of novel dentifrices containing 1.5% arginine, an insoluble calcium compound and 1,450 ppm fluoride. Kraivaphan P, Amornchat C, Triratana T, Mateo LR, Ellwood R, Cummins D, et al. Caries Res, 2013. PMID 23988908

More about calcium

What is calcium?Which foods contain calcium?Does calcium need vitamin D to work?How much calcium can the body absorb at one time?What happens if you do not get enough calcium?Is calcium safe?

For education; not medical advice. Talk to a doctor before you start, stop or change a supplement.