Calcium Supplements, Vitamin D, and Osteoporosis

Richard S. Bockman, MD, PhD
Richard S. Bockman, MD, PhD

Attending Physician, Hospital for Special Surgery
Associate Senior Scientist, Hospital for Special Surgery

Background: Calcium and Bone Health

Many studies have shown that calcium is an essential nutrient for bone health. Every day, approximately 10,000 milligrams of calcium move in and out of the skeleton. Much of this movement is part of the active process of bone remodeling, which keeps the skeleton healthy and renews parts that need to be repaired.

Vitamin D is also involved in bone remodeling. It aids the absorption of calcium from the intestine into the bloodstream, and helps calcium in the blood move into bone tissue that is newly formed by cells called osteoblasts. 

The skeleton must have enough calcium to meet the demands of bone remodeling. The amount of calcium that individuals need varies, but adults typically require about 1,200 to 1,500 milligrams daily. Generally, a person’s diet does not provide enough calcium because people do not consume very large amounts of dairy foods, which are the best sources. Therefore, calcium and vitamin D supplements are necessary for many individuals to meet their daily requirements.

Our recommendations for total intake (food source plus supplements) is in agreement with the recent guideline released by the Institute of Medicine and reported in the New York Times on November 29, 2010.

Calcium and vitamin D recommendations as posted in the New York Times on 11/29/10.

Concerns About Calcium Supplements

A recent review article published in the British Medical Journal looked at the results of several studies of calcium supplements and found that calcium supplements taken alone may increase the risk of non-fatal heart attack, or myocardial infarction. However, this review publication was not based on a prospective, randomized clinical trial, which is the gold standard of medical research. Two recently published prospective, randomized clinical trials do not show an increase of heart attacks with calcium supplementation.

The Food and Drug Administration and the American Society for Bone and Mineral Research are continuing to research this important issue. In the meantime, people should be aware that:

  • Numerous large studies of calcium plus vitamin D have not conclusively shown an increased risk of heart problems. 
  • Calcium and vitamin D are essential nutrients for bone health. Though food remains the best source of calcium, some people may need additional calcium in the form of supplements.

A recent report by the Practice Committee of the American Society for Bone and Mineral Research reviewed all available data. Dr. Bockman considers this report to be the definitive word on calcium supplements and cardiovascular events.

People who have concerns about taking calcium supplements should discuss this issue with their doctors.

Suggestions for the Medical Community

Desired Blood values:

Values of 30 ng/mL (75 nmol/L) or higher for 25 OH-Vitamin D are often labeled “sufficient” but it must be stressed that the boundary between sufficiency and insufficiency has not been firmly fixed; a useful reference is Bess Dawson-Hughes Æ Robert P. Heaney, Michael F. Holick Æ Paul Lips Æ Pierre J. Meunier, Reinhold Vieth. (2005) Estimates of optimal vitamin D status, Osteoporos Int (2005) 16: 713–716

Monitoring should be considered in the following settings:

  1. Patients taking medications which either bind vitamin D in the gut or accelerate the breakdown of vitamin D (e.g. cholestyramine; inducers of the cytochrome P450 pathway such as phenytoin and phenobarbital) 
  2. Obesity BMI >30 Kg/m2 or high body mass-  >90 Kg* 
  3. Malabsorption syndromes 
  4. Patients with osteoporosis

It is not necessary for clinicians to routinely monitor 25(OH)D for safety or efficacy when supplementation is within the Guideline recommendations. If clinicians choose to monitor 25(OH)D, they are advised to test after 4 months of supplementation to confirm that appropriate levels have been achieved.

Points to remember about the benefits of Vitamin D supplementation:

  • Aggregate evidence is based on meta-analyses, RCTs, and dosing trials in the target populations
  • Risk of harm: considered low
  • Cost: minimal 
  • Benefit-harm assessment: preponderance of benefit over harm
  • Role of patient preferences: high

Summary by Allyson Collins, MS

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