Is calcium supplement useful in preventing osteoporosis?

From the Guidelines

Calcium supplements can be useful in preventing osteoporosis, but their effectiveness depends on various factors, including the dose and combination with vitamin D.

Key Findings

• A study published in the Journal of Clinical Oncology found that calcium supplements reduced the risk of total fracture and vertebral fracture, but not hip or forearm fracture 1.
• The same study noted that when considering data from high-quality trials with low risk of bias, there was no effect of supplementation on the risk of fracture at any site.
• A Cochrane review found that vitamin D plus calcium resulted in a small reduction in hip fracture risk and a reduction in the incidence of new nonvertebral fractures 1.
• The US Preventive Services Task Force (USPSTF) concludes that the current evidence is insufficient to assess the balance of the benefits and harms of combined vitamin D and calcium supplementation for the primary prevention of fractures in premenopausal women or in men 1.

Important Considerations

• The effectiveness of calcium supplements in preventing osteoporosis may depend on the dose and combination with vitamin D.
• Patients should figure out the calcium content that they get from their dietary sources and then only use supplements to get a total calcium dose of 1,000 to 1,200 mg per day.
• Checking levels of 25-OH vitamin D is strongly recommended, especially in populations with high prevalence of vitamin D deficiency.
• Exercise, particularly high-force exercise such as progressive resistance strength training, may not be sufficient to improve bone health in survivors of cancer, but may have a positive effect on lumbar spine BMD in certain populations.
• The USPSTF recommends against daily supplementation with 400 IU or less of vitamin D3 and 1000 mg or less of calcium for the primary prevention of fractures in noninstitutionalized postmenopausal women 1.

The FDA Drug Labels for calcium (PO) do not address this question.

From the Research

Calcium Supplementation and Osteoporosis Prevention

• Calcium supplementation has been shown to have a positive effect on bone density and fracture risk reduction in older adults 2, 3, 4, 5.
• A meta-analysis of 29 randomized trials found that calcium supplementation, alone or in combination with vitamin D, reduced the risk of fractures by 12% and slowed bone loss by 0.54% at the hip and 1.19% in the spine 2.
• Another study found that combined calcium and vitamin D supplementation increased total bone mineral density, lumbar spine BMD, arms BMD, and femoral neck BMD, and reduced the incidence of hip fracture in postmenopausal women 4.
• Calcium supplementation alone has been shown to have a small positive effect on bone density, with a trend toward reduction in vertebral fractures, but the effect on non-vertebral fractures is unclear 5.

Optimal Dosage and Compliance

• The optimal dosage of calcium supplementation for osteoporosis prevention is at least 1200 mg per day, with or without vitamin D 2, 3.
• Vitamin D doses of 800 IU or more per day have been shown to be more effective than lower doses 2, 3.
• Compliance with calcium supplementation is key to optimizing clinical efficacy, with higher compliance rates associated with greater fracture risk reduction 2, 3.

Potential Controversies and Risks

• There is some controversy surrounding the use of calcium supplements for osteoporosis prevention, with some studies suggesting potential cardiovascular adverse effects 6.
• The increased calcium load in the circulation resulting from supplementation may lead to extraskeletal deposition, including in the coronary arteries 6.