Danielle Pavliv & Brandel France de Bravo, MPH; Meg Seymour, PhD: National Center for Health Research
Walking through the grocery store, you may have noticed the phrases “Fortified with calcium and vitamin D,” or “A good source of calcium!” on cartons of juice, boxes of cereal, and even boxes of chocolate pudding mix. People, particularly women, are often recommended to take calcium and vitamin D in order to prevent hip fractures. A fractured hip can take away a person’s independence and even be deadly. What exactly are calcium and vitamin D, and what do they do for the body? Do people need to take supplements of them in order to prevent hip fractures? What are the benefits and the risks of these supplements?
What Do Calcium and Vitamin D Do for the Body?
Calcium can be found naturally in many foods, including dairy products such as milk, yogurt and cheese; dark green leafy vegetables like kale and broccoli; and some nuts and seeds such as pistachios, almonds and sesame seeds. There are also many calcium-fortified foods available, such as orange juice, soy products, oatmeal, and other cereals.1 It is important for people of all ages to consume enough calcium because it helps prevent weak bones. Weak bones are more likely to break, and can even cause you to lose height as you age.2
Vitamin D is also important for bone health because it helps us absorb calcium. It is found naturally in only a small number of foods like fish and egg yolk, and in fortified foods like milk and juice. However, sunlight is a good source of vitamin D. When exposed to sunlight, your skin (where it is not covered in sunscreen) is able to create vitamin D. Of course, that exposure needs to be done carefully to avoid sunburn, which in turn can cause cancer later in life.
Many people have a hard time getting enough vitamin D, including:
- People who do not get enough sun exposure – People who are homebound or people who wear more or heavier clothing due to religious or other reasons, and people in some climates may not get enough sun exposure.
- Breastfed infants – There is not enough vitamin D in human milk, unless women take a vitamin D supplement while they are breastfeeding.
- Elderly people – Over time, the skin loses its ability to produce vitamin D as efficiently as in the past. In addition, elderly individuals tend to spend less time outside.
- Obese people: Having more fat makes vitamin D less available in the body
- People with darker skin – The more melanin you have, the darker your skin is. This reduces your ability to produce vitamin D from sunlight.3
We know that calcium and vitamin D help maintain strong bones, but how does that happen? Over the course of a person’s life, bones are constantly changing. Bones break down, and new bones are made from calcium deposits in the body. During childhood, you are making more new bone than you are losing, but that reverses later in life, leading to bone loss and an increased chance of developing osteoporosis (loss of bone density).4 The National Institutes of Health estimates that more than 53 million Americans have osteoporosis or are at high risk of developing it, and are therefore more likely to fracture their bones than healthy people.5 Most people who develop osteoporosis are post-menopausal women, although men can develop it as well. To read more about the risks and benefits of frequently prescribed treatments for osteoporosis, check out this article.
Calcium and Vitamin D Supplements to Prevent Bone Fractures in Older Adults
Are calcium and vitamin D supplements a helpful way to strengthen bones and prevent them from fracturing? What does the research say?
A 2019 meta-analysis (a study that combines the results of several studies) looked at studies where people were given vitamin D alone, as well as studies where people were given a combination of vitamin D and calcium.6 The analysis included 11 randomized, clinical trials of more than 34,000 people who were given either vitamin D alone or were given a placebo or no treatment. The people taking vitamin D alone were not more or less likely to have a fracture than those taking placebo. In contrast, when the researchers combined 6 randomized, clinical trials of more than 49,000 people who were either given a combination of vitamin D and calcium or were given a placebo or no treatment, the researchers found that people taking daily supplements of both vitamin D and calcium for approximately 6 years were 16% less likely to fracture their hip and 6% less likely to have any type of fracture. Despite these encouraging findings, the researchers caution that more clinical trials are needed to determine how safe and effective these supplements are.
The results of this meta-analysis are different from the results of some older studies, but that is due to differences in how the studies are designed. For example, a study from 2006 looking at more than 36,000 post-menopausal women, ages 50-79, found that taking 1000mg of calcium along with 400 IU of vitamin D was not associated with a decreased risk of hip fractures for those women.7 However, the participants in this study were taking a small dose of vitamin D. Another meta-analysis from 2012 found that taking doses of vitamin D higher than 792 IU helped to prevent fractures in adults 65 and over.8 It is important to note that in the studies they looked at where people were given high doses of vitamin D, people were also given calcium. This means that it was not possible for the researchers of this study to conclude whether high doses of vitamin D alone reduce fractures, or if the combination of vitamin D and calcium is what is beneficial. However, the results of the 2019 meta-analysis suggest that the combination of calcium and high enough doses of vitamin D is what helps.
In 2018, the United States Preventive Services Task Force (USPSTF), a federally funded group that analyses scientific research, issued a statement saying that there is not enough evidence in order to know whether the potential benefits of supplements taken to prevent fractures outweigh the potential risks for men or for pre-menopausal women. The USPSTF has two separate recommendations for post-menopausal women:
- For doses of 400 IU or less of vitamin D with 1000 mg or less of calcium, USPSTF recommends against post-menopausal women taking the supplements, saying that the potential risks outweigh the benefits.
- For doses more than 400 IU vitamin D and 1000 mg of calcium or more, USPSTF says there is not enough evidence in order to know if the risks outweigh the benefits for post-menopausal women.9
It is important to note that these recommendations are based on research that does not include people with osteoporosis or a vitamin D deficiency. Also, these guidelines came out before the 2019 meta-analysis research discussed above, so that newer research was not taken into account when these recommendations were developed. Although the National Center for Health Research had previously advised the USPSTF to recommend against these supplements for preventing fractures, our statement was also written prior to the 2019 meta-analysis.
The Risks of Supplements
Studies also found risks of taking these supplements. The 2006 study, discussed above, found that women assigned to take both vitamin D and calcium supplements were more likely to develop kidney stones, compared to women taking a placebo.7 However, more recent research on vitamin D and calcium supplements has not found this increased risk of kidney stones.10, 11 Researchers have also found that there are some potential risks to taking very high doses of vitamin D. For example, a study of more than 2,000 women over age 70 found that very high doses of vitamin D (taken annually) increased the percentage of women who fell or had fractures.12
A 2012 study also found that people who took calcium supplements were more likely to have a heart attack than those who did not take calcium supplements.13 However, this was not a clinical trial. The researchers did not randomly assign anyone to take supplements, but instead they asked people whether or not they took any supplements. People may have been taking the supplements due to health problems that increased their chances of having a heart attack. When researchers combined data from clinical trials in a meta-analysis, the results did not provide evidence that calcium supplements increased the chances of having a heart attack or developing heart disease.14 And since people often take calcium combined with vitamin D, it is not possible to know whether the combination of calcium and vitamin D is more or less likely to cause a heart attack or heart disease.15 For more information about supplements and heart health, click here.
The Bottom Line
Whether or not you take these two supplements, try to eat a diet rich in calcium and vitamin D because your body absorbs nutrients best when they are delivered through food. In addition, the best way to prevent hip fractures is to prevent falls, by getting rid of area rugs or other things in the house that might cause you to trip, and using a non-slip mat in the bath or shower. You can also talk with your doctor about possible side effects of your medications, both prescription and over-the-counter, because some medications can make you lightheaded and increase your chances of falling. The Surgeon General also recommends regular exercise, such as weight bearing exercises like walking, hiking, or dancing, or tai chi.2
- Miller, G. D., Jarvis, J. K., & McBean, L. D. (2001). The importance of meeting calcium needs with foods. Journal of the American College of Nutrition, 20(2), 168S-185S.
- National Institutes of Health Osteoporosis and Related Bone Diseases National Resource Center. The Surgeon General’s Report on Bone Health and Osteoporosis: What It Means to You. February 2017. Available at: https://www.bones.nih.gov/health-info/bone/SGR/surgeon-generals-report
- Nair, R., & Maseeh, A. (2012). Vitamin D: The “sunshine” vitamin. Journal of Pharmacology & Pharmacotherapeutics, 3(2), 118.
- Clarke, B. (2008). Normal bone anatomy and physiology. Clinical Journal of the American Society of Nephrology, 3(Supplement 3), S131-S139.
- National Institutes of Health Osteoporosis and Related Bone Diseases National Resource Center. Osteoporosis Overview. October 2018. Available at: https://www.bones.nih.gov/health-info/bone/osteoporosis/overview
- Yao P, Bennett D, Mafham M, et al. Vitamin D and Calcium for the Prevention of Fracture: A Systematic Review and Meta-analysis. JAMA Netw Open. 2019;2(12):e1917789. doi:10.1001/jamanetworkopen.2019.17789
- Jackson, R. D., LaCroix, A. Z., Gass, M., Wallace, R. B., Robbins, J., Lewis, C. E., … & Bonds, D. E. (2006). Calcium plus vitamin D supplementation and the risk of fractures. New England Journal of Medicine, 354(7), 669-683.
- Bischoff-Ferrari HA, Willett WC, Orav EJ, Lips P, Meunier PJ, Lyons RA… Dawson-Hughes B. A pooled analysis of vitamin D dose requirements for fracture prevention. New England Journal of Medicine. 2012;367(1):40-49.
- Grossman, D. C., Curry, S. J., Owens, D. K., Barry, M. J., Caughey, A. B., Davidson, K. W., … & Kubik, M. (2018). Vitamin D, calcium, or combined supplementation for the primary prevention of fractures in community-dwelling adults: US Preventive Services Task Force recommendation statement. JAMA, 319(15), 1592-1599.
- Lappe, J., Watson, P., Travers-Gustafson, D., Recker, R., Garland, C., Gorham, E., … & McDonnell, S. L. (2017). Effect of vitamin D and calcium supplementation on cancer incidence in older women: a randomized clinical trial. JAMA, 317(12), 1234-1243.
- Manson, J. E., Cook, N. R., Lee, I. M., Christen, W., Bassuk, S. S., Mora, S., … & Friedenberg, G. (2019). Vitamin D supplements and prevention of cancer and cardiovascular disease. New England Journal of Medicine, 380(1), 33-44.
- Sanders, K. M., Stuart, A. L., Williamson, E. J., Simpson, J. A., Kotowicz, M. A., Young, D., & Nicholson, G. C. (2010). Annual high-dose oral vitamin D and falls and fractures in older women: a randomized controlled trial. JAMA, 303(18), 1815-1822.
- Li, K., Kaaks, R., Linseisen, J., & Rohrmann, S. (2012). Associations of dietary calcium intake and calcium supplementation with myocardial infarction and stroke risk and overall cardiovascular mortality in the Heidelberg cohort of the European Prospective Investigation into Cancer and Nutrition study (EPIC-Heidelberg). Heart, 98(12), 920-925.
- Wang, L., Manson, J. E., & Sesso, H. D. (2012). Calcium intake and risk of cardiovascular disease. American Journal of Cardiovascular Drugs, 12(2), 105-116.
- Chin, K., Appel, L. J., & Michos, E. D. (2017). Vitamin D, calcium, and cardiovascular disease: a “D” vantageous or “D” etrimental? An era of uncertainty. Current Atherosclerosis Reports, 19(1), 5.