The human body uses calcium to form the teeth and bones, secrete hormones, regulate the transmission of nerve impulses, and dilate and constrict blood vessels. Because of its use in the teeth and bones, calcium plays a role in the prevention of osteoporosis. Reducing the risk of osteoporosis helps prevent fractures of the hips and other bones.
Significance
The body stores 99 percent of its calcium in the bones and teeth, according to the Linus Pauling Institute at Oregon State University. Bone remodeling occurs throughout life because a type of bone cell, called an osteoclast, dissolves bone tissue. Another type of bone cell, called an osteoblast, makes new bone to replace the dissolved bone. Calcium supports this remodeling process, but some people do not get enough calcium in their diets. This causes the amount of bone dissolved to exceed the amount of new bone formed, which in turn results in a weakening of the bones and increases the risk for hip fractures.
Types
Doctors recommend calcium carbonate and calcium citrate for hip fracture prevention. The citrate form of calcium does not require the presence of stomach acid for proper absorption. Calcium carbonate does require the presence of stomach acid for adequate absorption. Someone taking calcium carbonate should take it with a meal or snack, as eating stimulates the production of stomach acid. The body also needs vitamin D to absorb calcium properly. The National Institutes of Health Office of Dietary Supplements reports that calcium and vitamin D supplements effectively reduce the number of hip fractures in the elderly.
Sources
Dairy products represent a major source of calcium. One cup of low-fat yogurt contains 447.37 mg of calcium, according to the World’s Healthiest Foods. For those who struggle with lactose intolerance, some other foods also contain calcium. Non-dairy food sources of calcium include broccoli, sardines, summer squash, celery, green beans, oranges and mushrooms. Over-the-counter calcium supplements also provide a daily dose of calcium.
Research
Researchers from the Institut National de la Sante et de la Recherche Medicale, led by Dr. M.C. Chapuy, conducted a study to determine the efficacy of using calcium to reduce bone loss and prevent fractures. One group of study participants received daily calcium and vitamin D supplements, while the other group received two placebos. Bone density of the femur, or thigh bone, increased by 2.7 percent in the group receiving calcium and vitamin D. Bone density decreased by 4.6 percent in the participants receiving placebos. Investigators determined that the supplements reduce the risk of hip fractures and other types of fractures. The results of the study appeared in the December 1992 issue of “The New England Journal of Medicine.”
Misconceptions
Some people choose not to take calcium supplements because they believe their risk for hip fractures does not justify the expense of the supplements. Adrianne Bendich, Ph.D., and her colleagues found evidence to the contrary. The research team determined that hip fracture patients could have eliminated $2.6 billion in direct care costs in 1995 by taking 1,200 mg of calcium per day. The study, "Supplemental Calcium for the Prevention of Hip Fracture” appeared in the June 1999 issue of “Clinical Therapeutics.” Bendich and her colleagues also found that calcium supplementation reduces the risk of other types of fractures, leading to increased health care savings.
References
- Linus Pauling Institute: Calcium
- Office of Dietary Supplements: What is the Evidence for Supplement Use for Healthy Bones?
- The World's Healthiest Foods: Calcium
- "The New England Journal of Medicine"; Vitamin D3 and Calcium to Prevent Hip Fractures; Chupay; 1992
- "Clinical Therapeutics"; Supplemental Calcium for the Prevention of Hip Fracture; A. Bendich, et al.; June 1999
