Sure, calcium builds strong osteoporosis-resistant bones. But most people don’t know that getting enough of this mineral also helps keep blood pressure in check, improves cholesterol numbers, makes preeclampsia in pregnancy less likely, reduces the risk of colon cancer, and helps with weight maintenance. So you can see, it’s essential you get enough calcium—but what’s the best way? While there are many rich sources of calcium, the most important thing when evaluating your options is to understand how much of it is actually absorbed and used by the body.
The National Academy of Sciences recommends 1,000 mg daily for people ages 19 to 50 and 1,200 mg daily over age 51.
If you’re considering a calcium supplement to bump up your calcium intake, you have your pick of many different forms are available in dietary supplements. Some research has found that certain forms of calcium absorb better than others, but other studies have found they are about the same. So, taking a calcium supplement regularly may be more important than which one you choose:
Whichever form of calcium you choose, they all add to your body’s calcium stores, especially if you take it with a meal. Dinner might be the best choice since supplementing in the evening appears better for osteoporosis prevention than taking calcium in the morning, because of the circadian rhythm of bone loss. However, people supplementing with more than 600 mg per day should divide it up between meals.
Not everyone knows that the body also needs vitamin D in order to properly absorb calcium. And since vitamin D–deficiency is surprisingly common, you might discuss with your doctor whether you should get your levels checked.
1. U.S. Department of Agriculture, Nationwide Food Consumption Survey 1987–1988, PB-92–500016. Washington, DC; U.S. Government Printing Office, 1989.
2. Fleming KH, Heimbach JT. Consumption of calcium in the U.S.: food sources and intake levels. J Nutr 1994;124(8 Suppl):1426S–30S.
3. Heaney RP, Dowell MS, Rafferty K, Bierman J. Bioavailability of the calcium in fortified soy imitation milk, with some observations on method. Am J Clin Nutr 2000;71:1166–9.
4. Mortensen L, Charles P. Bioavailability of calcium supplements and the effect of vitamin D: comparisons between milk, calcium carbonate, and calcium carbonate plus vitamin D. Am J Clin Nutr 1996;63:354–7.
5. Miller J, Smith D, Flora L, et al. Calcium absorption from calcium carbonate and a new form of calcium (CCM) in healthy male and female adolescents. Am J Clin Nutr 1988;48:1291–4.
6. Harvey JA, Kenny P, Poindexter J, Pak CY. Superior calcium absorption from calcium citrate than calcium carbonate using external forearm counting. J Am Coll Nutr 1990;9:583–7.
7. Smith KT, Heaney RP, Flora L, Hinders SM. Calcium absorption from a new calcium delivery system (CCM). Calcif Tiss Int 1987;41:351–2.
8. Dawson-Hughes B, Dallal GE, Krall EA, et al. A controlled trial of the effect of calcium supplementation on bone density in postmenopausal women. N Engl J Med 1990;323:878–83.
9. Nicar MJ, Pak CY. Calcium bioavailability from calcium carbonate and calcium citrate. J Clin Endocrinol Metab 1985;6(2)1:391–3.
10. Harvey JA, Kenny P, Poindexter J, Pak CYC. Superior calcium absorption from calcium citrate than calcium carbonate using external forearm counting. J Am Coll Nutr 1990;9:583–7.
11. Epstein O, Kato Y, Dick R, Sherlock S. Vitamin D, hydroxyapatite, and calcium gluconate in treatment of cortical bone thinning in postmenopausal women with primary biliary cirrhosis. Am J Clin Nutr 1982;36:426–30.
12. Rüegsegger P, Keller A, Dambacher MA. Comparison of the treatment effects of ossein-hydroxyapatite compound and calcium carbonate in osteoporotic females. Osteoporos Int 1995;5:30–4.
13. Heaney RP, Recker RR, Weaver CM. Absorbability of calcium sources: the limited role of solubility. Calcif Tissue Int 1990;46:300–4.
14. Heaney RP, Smith KT, Recker RR, Hinders SM. Meal effects on calcium absorption. Am J Clin Nutr 1989;49:372–6.
15. Blumsohn A, Herrington K, Hannon RA, et al. The effect of calcium supplementation on the circadian rhythm of bone reabsorption. J Clin Endocrinol Metab 1994;79:730–5.