Calcium

Calcium: How it works?

• Calcium is the most plentiful mineral in the human body, found mainly in bones and teeth.

• It is also found in blood, muscles, and other tissues with a variety of functions within the body. Physical activity such as weight-bearing exercises, loss of calcium via sweat, and the female athlete triad (disordered eating, amenorrhea, and osteoporosis) are all important factors to consider for supplementation as it relates to physical activity.

What is it used for?

• Calcium is involved in a myriad of processes within the human body.

• While its most well-known function is for bone health and prevention of osteoporosis, it is utilized for many other functions within the human body that would be of interest to an athlete.

• It is involved in muscle contraction, regulation of heartbeat, nerve impulse conduction, blood pressure, and balance of water within the body, energy and fat metabolism, and general transport of nutrients across cell membranes.

Evidence for or against its use:

• A large placebo-controlled study involving 33,000 women administered 1000 mg calcium carbonate and 400 mg Vitamin D3 compared to placebo examining physical performance and exercise measures after 1, 2, and 4 years.

• The results showed no improvement in subjective or objective physical function.

• Another study found elevated urinary calcium losses after a high-impact training program, suggesting that calcium is utilized in higher amounts in high-impact physical exercise.

• However, the current literature reviewed did not conclude the need for calcium supplementation greater than what can be obtained via diet.

Safety concerns, side effects, and precautions:

• In a study reviewing randomized control trial evidence of adverse events from calcium supplementation, gastrointestinal events were the most common described.

• This included constipation, abdominal cramping, bloating, upper GI events, GI disease, and severe diarrhea (for calcium there was an incidence of 14.1%, for placebo 10.0%, with a relative risk (RR) of 1.43, and a confidence interval of 1.28–1.59, p < 0.001) [76].

• Two trials also examined self-reported myocardial infarctions with dietary calcium supplementation at 3.6% rate in the calcium supplementation group and 2.1% in the placebo group.

• However, after undergoing an adjudication process by the reviewers, the adjusted rates were 2.4% in the calcium group and 1.6% in the placebo group.

Interactions with other medications:

• An absolute contraindication to being prescribed calcium carbonate is concomitant use of ceftriaxone due to increased risk of end-organ failure and death.

Key Web Sources

• Kunstel K. Calcium requirements for the athlete. Curr Sports Med Rep. 2005;4(4):203–6.

  https://doi.org/10.1097/01.CSMR.0000306208.56939.01.

• Brunner RL, Cochrane B, Jackson RD, Larson J, Lewis C, Limacher M, et al. Calcium, vita-

  min D supplementation, and physical function in the Women’s Health Initiative. J Am Diet

  Assoc. 2008;108(9):1472–9.

• Nemoseck T, Kern M. The effects of high-impact and resistance exercise on urinary calcium

  excretion. Int J Sport Nutr Exerc Metab. 2009;19(2):162–71.

• Lewis JR, Zhu K, Prince RL. Adverse events from calcium supplementation: relationship

  to errors in myocardial infarction self-reporting in randomized controlled trials of calcium

  supplementation. J Bone Miner Res. 2012;27(3):719–22. https://doi.org/10.1002/jbmr.1484.

  PMID: 22139587

• Steadman E, Raisch DW, Bennett CL, Esterly JS, Becker T, Postelnick M, McKoy JM,

  Trifilio S, Yarnold PR, Scheetz MH. Evaluation of a potential clinical interaction between

  ceftriaxone and calcium. Antimicrob Agents Chemother. 2010;54(4):1534–40.