By Jordan Long, PharmD Student Cedarville University
For years, calcium has been considered an essential nutrient to have in the daily diet. Intake of calcium is essential for many bodily functions including muscle contraction, nerve transmission, and bone remodeling.1 Some of the benefits from calcium are helping bone growth, prevent loss of bone density, and prevent osteoporosis development.2 But recent reports are questioning the actual efficacy in these different functions and if higher calcium levels could lead to adverse effects due to additional intake through supplementation. These recent studies led the New York Times to post an article in April of 2013 stating that people should be Thinking Twice about Calcium Supplements.3 The article stated that not only is the efficacy of calcium supplementation in it’s prevention of bone fracture questionable, but calcium supplementation might be harmful. The views presented in this article are hard to believe, since calcium is a very common nutrient found in many foods found in the standard diet. However, recent literature is beginning to provide evidence to back up this view.
Studies have shown that calcium is essential for the increase of bone density in prepubescent children.4 Parents should highly encourage their kids to consume calcium in their diet to have strong bones. But the United States Preventative Risk Task Forces stated that there is currently insufficient evidence that the benefits from calcium supplementation over 1,000mg per day is worth the risk for the primary prevention of fracture in healthy, older woman. They also do not recommend taking less than 1,000mg a day of calcium supplementation, because it is not shown to decrease fracture at these low levels but increases risk of kidney stones.5 The National Institutes of Health recommends optimal calcium intake levels varying from 1,000mg to 1,300mg for anyone over the age of four, depending on age.1 Those numbers include the calcium from dietary intake and any calcium taken as a supplement. A lot of these studies are hard to compare and contrast their recommendations because of the high amount of variation in type of calcium supplementation and complementary supplementation, especially with vitamin D, which also plays an important role in the bones ability to absorb calcium.6
One of the primary concerns with calcium supplementation is that the risks of all cause mortality, attributed mostly to cardiovascular disease. A study observing all cause and cardiovascular mortality due to calcium found that there was an associated increase in all cause, cardiovascular, and ischemic heart disease mortality with people with an average intake of calcium above 1,400mg a day, but these results were not conclusive.7 A few other articles looking at the association of calcium and cardiovascular disease mortality found no hard evidence and said that no causality could be confirmed.8,9 Sadly, a limitation to the research of calcium effects is that randomized clinical trials might be unfeasible. The risks of high supplementation of calcium are to high and could be considered unethical to test for. But is the intake of calcium the issue? The National Institutes of Health states that calcium intake is not involved in the prevalence of cardiovascular issues, but the serum concentrations of calcium.1 Calcium serum concentrations are highly regulated by the body to obtain proper homeostatic balance, using the bones as a reservoir for excess calcium.10 But this balance could be thrown off by increased or decreased calcium intake over longer periods of time. Even though there is some evidence that calcium supplementation could be reducing incidence of fractures, evidence is increasing regarding the incidence of cardiovascular issues.11
From the research, I would say that patients should be cautioned when thinking about taking a calcium supplement for an extended period of time. The New York Times pointed out some good points, people should try to stay away from supplements as much as possible.3 If someone is below his or her recommended daily value of calcium, higher intake of high-calcium food should be recommended. Some examples of foods that are high in calcium are milk, cheese, yogurt, kale, and spinach.1 The major thing causing problems in people that are taking calcium supplements is that they most likely have an adequate amount of calcium in there normal diet, and the additional supplement is putting them over the recommended daily amount. The supplements themselves might not be necessarily directly causing the higher risk of cardiovascular disease, but it is increasing the calcium levels above the recommended daily amount. People wanting to take calcium supplements should consult their local pharmacist or primary care provider to make sure it is appropriate. For another great resource, check out Dr. Mercola’s article on the relationship between vitamin K2, vitamin D, and calcium (Link found in references section below). It explains the proper balance of these dietary supplements and how to control your calcium levels through them.12
With all of these risks, do you know what your daily calcium intake is? Maybe it’s time you checked for yourself.
1. Dietary Supplement Fact Sheet: Calcium. Offices of Dietary Supplements of the National Institutes of Health Website. http://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/#en82. Accessed December 4, 2013.
2. Top Foods for Calcium and Vitmain D. WebMD Website. http://www.webmd.com/food-recipes/guide/calcium-vitamin-d-foods. Accessed on December 4, 2013.
3. Thinking Twice about Calcium Supplements. New York Times Website. http://well.blogs.nytimes.com/2013/04/08/thinking-twice-about-calcium-supplements-2/. Accessed December 3, 2013.
4. Johnston, CC; Miller, JZ; Slemenda, CW; Reister, TK; Hui, S; Christian, JC; Peacock, M. Calcium Supplementation and Increases in Bone Mineral Density in Children. NEJM. 1992;327(2):82-87. Accessed December 4, 2013.
5. Vitamin D and Calcium Supplementation to Prevent Fractures in Adults. U.S. Preventative Services Task Force Website. http://www.uspreventiveservicestaskforce.org/uspstf12/vitamind/finalrecvitd.htm. Published February, 2013. Accessed December 4, 2013.
6. Calcium and Vitamin D; What you need to know. National Osteoporosis Website.
http://nof.org/articles/10. Accessed of December 7th, 2013.
7. Michaëlsson, K; Melhus, H; Lemming, EW; Wolk, A; Byberg, L. Long term calcium intake and rates of all cause and cardiovascular mortality: community based prospective longitudinal cohort study. BMJ. 2013;346(228). Accessed December 4, 2013.
8. Bolland, M; Grey, A; Reid, I. Calcium and Cardiovascular Risks. Australian Prescriber. 2013;36(1):5-8. Accessed December 4, 2013.
9. Van Hemelrijck, M; Michaelsson, K; Linseisen, J; Rohrmann, S. Calcium Intake and Serum Concentration in Relation to Risk of Cardiovascular Death in NHANES III. PLOS One. 2013;8(4): 1-9. Accessed December 4, 2013.
10. Marks, AR. Calcium and the heart: a question of life and death. The Journal of Clinical Investigation. 2003;1(5):597-600. Accessed December 4, 2013.
11. Reid, IR. Cardiovascular Effects of Calcium Supplements. Nutrients. 2013;5:2522-2529. Accessed December 4, 2013.
12. What You Need to Know About Vitamin K2, D and Calcium. Mercola.com Website.
http://articles.mercola.com/sites/articles/archive/2012/12/16/vitamin-k2.aspx. Published in December of 2012. Accessed on December 7th, 2013.