Increasing Calcium Intake Has Minimal Effects on Bone-Mineral Density and Fracture Risk

Year in Review |
December 30, 2015

Increasing Calcium Intake Has Minimal Effects on Bone-Mineral Density and Fracture Risk

  1. Paul S. Mueller, MD, MPH, FACP

Two meta-analyses challenge the widespread practice of promoting high calcium intake.

  1. Paul S. Mueller, MD, MPH, FACP

The Institute of Medicine recommends that adults maintain a daily calcium intake of 1000 to 1200 mg for preventing osteoporosis and reducing fracture risk (J Clin Endocrinol Metab 2011; 96:53). However, average daily calcium intake is 700 to 900 mg. Two recent reviews of published studies (which involved primarily middle-aged and older women) clarify the effects of increased dietary calcium intake and calcium supplements on bone-mineral density (BMD) and fracture risk.

In a meta-analysis of 59 randomized controlled trials, researchers evaluated whether raising dietary calcium intake and taking calcium supplements increases BMD. Increasing dietary calcium intake (by 250–3320 mg daily) increased baseline BMD by 0.6% to 1.0% at the total hip and total body at 1 year and by 0.7% to 1.8% at the total hip, total body, femoral neck, and lumbar spine at 2 years; no changes at the forearm were observed. Calcium supplements (250–2500 mg daily) increased BMD by 0.7% to 1.4% at all five sites at 1 year with little change thereafter. Although statistically significant, these BMD increases do not translate into clinically significant reductions in fracture risk (NEJM JW Gen Med Nov 15 2015 and BMJ 2015; 351:h4183).

In another review, researchers analyzed 58 cohort studies of dietary calcium and fracture risk. Most of the studies (74%), showed no association between dietary calcium intake and risks for total, hip, vertebral, or forearm fractures; positive associations in the remaining studies were weak. In analyses of data from 26 randomized trials, calcium supplements (≥1000 mg daily in most studies) lowered relative risk for total and vertebral fractures by 11% and 14%, respectively. However, corresponding numbers needed to treat to prevent one fracture were high (77 and 489), and calcium supplements did not lower risks for hip fracture or forearm fracture (NEJM JW Gen Med Nov 15 2015 and BMJ 2015; 351:h4580).

These analyses suggest that untargeted increases in calcium intake through dietary sources or supplements have minimal effects on BMD and fracture risk. Furthermore, calcium supplement use is associated with harms, including cardiovascular disease (NEJM JW Gen Med Jun 1 2011 and BMJ 2011; 342:d2040), kidney stones, dyspepsia, constipation, and malabsorption of medication (e.g., thyroid hormone). Patients should maintain the recommended daily allowance (RDA) for calcium (1000−1200 mg) through dietary sources, maintain the RDA for vitamin D (600 IU), and mitigate other osteoporosis risk factors (e.g., sedentary lifestyle, excessive alcohol intake, smoking).

Editor Disclosures at Time of Publication

  • Disclosures for Paul S. Mueller, MD, MPH, FACP at time of publication Consultant / advisory board Boston Scientific (Patient Safety Advisory Board) Editorial boards Medical Knowledge Self-Assessment Program (MKSAP 17 General Internal Medicine Committee); MKSAP 17 General Internal Medicine (author/contributor) Leadership positions in professional societies American Osler Society (Vice President)

Reader Comments (3)

Myers, Yaacov, John B. BSc, MBBCh(Rand), FCP(SA) PHD, FRACP Physician, Hospital Medicine, Private practice, Geriatrician, Outpatients, not hospital based, as well.

The relationship between intake of Vit D, Calcium and magnesium, and serum calcium, Parathyroid hormone, Vitamin D and bone formation and arterial stiffening or cardiovascular risk, which is also affected by glucose level, insulin and other dietary factors that also affect calcium absorption, indicates a more complex scenario than that outlined.
For a start Vitamin D levels need to be measured, as well as each of these relevant parameters, including intra-cellular magnesium, before and after supplemental Vitamin D (Vit. D) in at least two if not three doses (4-500 IU as control, 1000IU and 5000IU, daily, or the latter weekly, plus standard recommended calcium intakes of 1200mg/day and Arterial compliance (Carotid-brachial index, Pulse Wave Velocity) and Cardiovascular morbidity, serum urate and markers of bone turnover and/or urinary calcium and phosphate excretion.
It stands to reason that if serum calcium is high because of inadequate Vit. D and excess calcium intake, vascular calcification will occur. However Vit. D levels sufficient to ensure bone mineralisation would direct calcium movement from plasma to bone and not result in arterial stiffening or CVS risk greater than control. The dose of Vit D taht ensures mineralisation and or no increase in plasma Calcium levels with this level of Ca supplementation, can easily be ascertained in aptients/volunteers on which to base the study dose. Until relevant studies are performed, it would be wise to continue to recommend Vit D 1000IU/day or as required to achieve adequate Vit D levels plus standard does of Calcium (as Carbonate) 1200mg/day, and determine the ionised calcium level after a single calcium dose.
High risk patients for CVS disease need to be treated for that, and one added measure may be to increase level of Vit D. This could be a separate study and one more easily performed to obtain the necessary information this area of practice demands, given the controversy relates to serum level of Vit D and Vit D supplementation.

Jerry Amos BSEE BSME Other, Other, Home

Journal of Gerontology 55 (2000) M585-M592 Frasetto et. al. "A high ratio of vegetable to animal protein consumption was found to be impressively associated with a virtual disappearance of bone fractures (in elderly women)". A more convenient summary and chart is on pages 206-208 of "The China Study" (2006) by Cornell nutritional biochemist prof. T. Colin Campbell. This is a very effective way to really reduce osteoporosis risk. I'm 80, ski, fall hard, no breaks. My wife's recent pelvis and lateral hip xray shows satisfactory bony mineralization. She doesn't usually fall.

Myers, Yaacov, John B. Physician, Hospital Medicine, Private practice, Geriatrician, Outpatients, not hospital based, as well.

See added comment and one typo correction herewith, many thanks.
The relationship between intake of Vit D, Calcium and magnesium, and serum calcium, Parathyroid hormone, Vitamin D and bone formation and arterial stiffening or cardiovascular risk, which is also affected by glucose level, insulin and other dietary factors that also affect calcium absorption, indicates a more complex scenario than that outlined.
For a start Vitamin D levels need to be measured, as well as each of these relevant parameters, including intra-cellular magnesium, before and after supplemental Vitamin D (Vit. D) in at least two if not three doses (4-500 IU, 1000IU and 5000IU, daily, or the latter weekly, plus standard recommended calcium intakes of 1200mg/day and Arterial compliance (Carotid-brachial index, Pulse Wave Velocity) and Cardiovascular morbidity, and markers of bone turnover and/or urinary calcium and phosphate excretion.
It stands to reason that if serum calcium is high because of inadequate Vit. D and excess calcium intake, vascular calcification will occur. However Vit. D levels sufficient to ensure bone mineralisation would direct calcium movement from plasma to bone and not result in arterial stiffening or CVS risk greater than control. Until relevant studies are performed, it would be wise to continue to recommend Vit D 1000IU/day or as required to achieve adequate Vit D levels plus standard does of Calcium (as Carbonate) 1200mg/day.

I also need to add - High risk patients for CVS disease need to be treated for that, and one added measure may be to increase level of Vit D. This could be a separate study and one more easily performed to obtain the necessary information this area of practice demands, given the controversy relates to serum level of Vit D and Vit D supplementation.

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