Vitamin D and Calcium Dietary Supplements: Do They Prevent Bone Fractures?

Vitamins and minerals are essential nutrients that people must consume, ideally through food intake, in order to survive because the human body cannot make them in sufficient quantities. A classic example is vitamin C. Deficiencies in vitamin C are a well-documented cause of the disease scurvy, which killed hundreds of thousands of sailors in the 18th century.[1]

In this article, we discuss whether vitamin D and calcium dietary supplements are useful for promoting bone health. In the early twentieth century, the dreaded childhood disease rickets was rampant in northern cities of the U.S., but by midcentury the disease was largely eradicated following the discovery of vitamin D and widespread use of cod-liver oil, a rich source of the vitamin.[2]

About vitamin D and calcium

Vitamin D is especially important to skeletal health because it maintains normal body levels of calcium and phosphate, minerals necessary for bone growth and strength. Vitamin D also seems to directly promote muscle health and strength.[3]

Osteoporosis is a common condition characterized by very low bone density. It affects many elderly persons, especially women, by placing them at heightened risk of bone fracture. One test used to assess a patient’s susceptibility to fracture is bone mineral density, which is measured by X-ray absorption.

Accordingly, vitamin D and calcium intake via supplementation is a potential strategy to reduce the risk of bone fractures. Dietary vitamin D is available from sources such as fish and chicken livers, eggs and vitamin D-fortified products like milk and orange juice. In addition, vitamin D is produced naturally in the skin by exposure to sunlight (specifically ultraviolet radiation, though such exposure also increases one’s risk of skin cancer). Sources of calcium include dairy products and green leafy vegetables.

Several forms of vitamin D supplements are available for people who clearly have inadequate vitamin D dietary intake and skin production from sun exposure. The most commonly used forms are cholecalciferol, also known as vitamin D3, and ergocalciferol, or vitamin D2.[4]

New research on vitamin D and calcium supplementation

A meta-analysis (a study that analyzes data from multiple clinical trials) published in the Journal of the American Medical Association (JAMA) Network Open in December 2019 found that vitamin D plus calcium supplementation in older adults reduced the risk of any bone fracture by 6% and the risk of hip fracture by 16%.[5] These findings were based on an analysis of data from six randomized, controlled clinical trials that together enrolled more than 49,000 subjects who had an average age of 66. For these six trials, the daily doses of vitamin D ranged from 400 to 800 international units (IU) and the daily doses of calcium ranged from 1,000 to 1,200 milligrams (mg).

These results are important because hip fractures are especially serious, correlating with a 30% increase in death in the year after they occur,[6] and each year more than 300,000 persons in the U.S. age 65 and older are hospitalized for hip fractures.[7]

Similar protection from bone fractures was not found in a separate analysis presented in the JAMA Network Open study of data from 11 other randomized clinical trials that tested supplementation with vitamin D alone in older adults.[8] These 11 trials overall involved more than 34,000 subjects with an average age of 77. The researchers noted, however, that these trials had limitations that prevent any definitive conclusions from being made.

The JAMA Network Open study did not directly assess adverse effects of vitamin D and calcium supplementation in older adults, but the study’s authors did note that high doses of vitamin D may, ironically, increase the risk of fracture. Prior research has suggested that use of very high-dose vitamin D increases the risk of falls.[9] The JAMA Network Open study authors further wrote that adverse consequences of vitamin-D-plus-calcium supplementation may include cardiovascular complications, such as heart attacks, and kidney stones.

What You Can Do

The best approach to reduce the risk of bone fractures remains a balanced diet that includes vitamin D- and calcium-containing products, exercise and minimizing alcohol and tobacco use.[10],[11] If you are 70 or younger, you should try to consume foods that collectively contain 600 IU of vitamin D daily. If you are older, consume 800 IU of vitamin D daily.[12] Depending on your age and sex, you should consume either 1,000 mg or 1,200 mg of calcium daily if you are age 19 or older.[13]

Finally, if you have osteoporosis and a high risk of fracture (meaning your calculated risk of hip fracture is 3% or more over the next 10 years) and you already have experienced a fracture, ask your doctor regarding time-limited (three to five years) use of a bisphosphonate, such as alendronate (BINOSTO, FOSOMAX), ibandronate (BONIVA) or risedronate (ACTONEL, ATELVIA).[14]
 

References

[1] Leigh, A. Randomistas: How radical researchers are changing our world. Yale University Press. New Haven, CT. 2018.

[2] Rajakumar, K.. Vitamin D, cod-liver oil, sunlight, and rickets: a historical perspective. Pediatrics. 2003;112(2): e132-e135.

[3] Bischoff-Ferrari HA. Relevance of vitamin D in muscle health. Rev Endocr Metab Disord. 2012;13(1):71-77.

[4] Dawson-Hughes B. Vitamin D deficiency in adults: Definition, clinical manifestations, and treatment. UpToDate. Last updated September 30, 2019.

[5] Yao P, Bennett D, Mafham M, et al. Vitamin D and calcium for the prevention of fracture: A systematic review and meta-analysis. JAMA Network Open. 2019;2(12):e1917789-e1917789.

[6] Lund CA, Møller AM, Wetterslev J, Lundstrøm LH. Organizational factors and long-term mortality after hip fracture surgery: a cohort study of 6143 consecutive patients undergoing hip fracture surgery. PLoS One. 2014;9 (6):e99308.

[7] Centers for Disease Control and Prevention. Hip fractures among older adults. September 20, 2016. https://www.cdc.gov/homeandrecreationalsafety/falls/adulthipfx.html. Accessed May 31, 2020.

[8] Yao P, Bennett D, Mafham M, et al. Vitamin D and calcium for the prevention of fracture: a systematic review and meta-analysis. JAMA Network Open. 2019;2(12):e1917789-e1917789.

[9] Vitamin D for preventing falls in the elderly: Less Is safer. Worst Pills, Best Pills News. July 2016. /newsletters/view/1043. Accessed May 31, 2020.

[10] National Institutes of Health. Smoking and bone health. December 2018. https://www.bones.nih.gov/health-info/bone/osteoporosis/conditions-behaviors/bone-smoking. Accessed May 31, 2020.

[11] Sampson HW. Alcohol’s harmful effects on bone. Alcohol Health and Research World. 1998;22(3):190-194.

[12] National Institutes of Health. Vitamin D. March 24, 2020. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/. Accessed June 1, 2020.

[13] National Institutes of Health. Calcium. March 26, 2020. https://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/. Accessed May 31, 2020.

[14] A Guide to treatments for osteoporosis. Worst Pill Best Pills News. May 2015. /newsletters/view/960. Accessed May 31, 2020.