Calcium and diet
Your body doesn't produce calcium, so you must get it through other sources. Calcium can be found in a variety of foods, including:
- Dairy products, such as cheese, milk and yogurt
- Dark green leafy vegetables, such as broccoli and kale
- Fish with edible soft bones, such as sardines and canned salmon
- Calcium-fortified foods and beverages, such as soy products, cereal and fruit juices
Even if you eat a healthy, balanced diet, you may find it difficult to get enough calcium if you:
- Follow a vegan diet
- Have lactose intolerance and limit dairy products
- Consume large amounts of protein or sodium, which can cause your body to excrete calcium
- Have osteoporosis
- Are receiving long-term treatment with corticosteroids
- Have certain bowel or digestive diseases that decrease your ability to absorb calcium, such as inflammatory bowel disease or celiac disease
In these situations, calcium supplements may help you meet your calcium requirements.
Types of calcium supplements
Several different kinds of calcium compounds are used in calcium supplements. Each compound contains varying amounts of the mineral calcium — referred to as elemental calcium. Common calcium supplements may be labeled as:
- Calcium carbonate (40 percent elemental calcium)
- Calcium citrate (21 percent elemental calcium)
- Calcium gluconate (9 percent elemental calcium)
- Calcium lactate (13 percent elemental calcium)
The two main forms of calcium supplements are carbonate and citrate. Calcium carbonate is cheapest and therefore often a good first choice. Other forms of calcium in supplements include gluconate and lactate.
In addition, some calcium supplements are combined with vitamins and other minerals. For instance, some calcium supplements may also contain vitamin D or magnesium. Check the ingredient list to see which form of calcium your calcium supplement is and what other nutrients it may contain. This information is important if you have any health or dietary concerns.
Choosing calcium supplements
To determine which calcium supplement may be best for you, consider these factors:
Amount of calcium
Elemental calcium is key because it's the actual amount of calcium in the supplement. It's what your body absorbs for bone growth and other health benefits. The Supplement Facts label on calcium supplements is helpful in determining how much calcium is in one serving. As an example, calcium carbonate is 40 percent elemental calcium, so 1,250 milligrams (mg) of calcium carbonate contains 500 mg of elemental calcium. Be sure to note the serving size (number of tablets) when determining how much calcium is in one serving.
Calcium supplements cause few, if any, side effects. But side effects can sometimes occur, including gas, constipation and bloating. In general, calcium carbonate is the most constipating. You may need to try a few different brands or types of calcium supplements to find one that you tolerate the best.
What prescriptions you take
Calcium supplements can interact with many different prescription medications, including blood pressure medications, synthetic thyroid hormones, bisphosphonates, antibiotics and calcium channel blockers. Ask your doctor or pharmacist about possible interactions and which type of calcium supplement would work for you.
Quality and cost
Manufacturers are responsible for ensuring that supplements are safe and claims are truthful. Some companies may have their products independently tested by the U.S. Pharmacopeia(USP) or Consumer Labs (CL). Supplements that bear the USP or CL abbreviation meet voluntary industry standards for quality, purity, potency, and tablet disintegration or dissolution. Different types of calcium supplements have different costs. Comparison shop if cost is a factor for you.
Calcium supplements are available in a variety of forms, including tablets, capsules, chews, liquids and powders. If you have trouble swallowing pills, you may want a chewable or liquid calcium supplement.
Your body must be able to absorb the calcium for it to be effective. All varieties of calcium supplements are better absorbed when taken in small doses (500 mg or less) at mealtimes. Calcium citrate is absorbed equally well when taken with or without food and is a form recommended for individuals with low stomach acid (more common in individuals 50 and older, or if taking stomach acid blockers), inflammatory bowel disease or absorption disorders.
Do calcium supplements have risks?
Calcium supplements aren't for everyone. For instance, if you have a health condition that causes excess calcium in your bloodstream (hypercalcemia), you should avoid calcium supplements. If you aren't sure if calcium supplements are appropriate for your situation, talk to your doctor.
It's not definitive, but there may be a link between calcium supplements and heart disease. It's thought that the calcium in supplements could make its way into fatty plaques in your arteries — a condition called atherosclerosis — causing those plaques to harden and increasing your risk of heart attack. More research is needed before doctors know the effect calcium supplements may have on heart attack risk.
There is similar controversy about calcium and prostate cancer. Some studies have shown that high calcium intake from dairy products and supplements may increase risk whereas another more recent study showed no increased risk of prostate cancer associated with total calcium, dietary calcium or supplemental calcium intakes.
As with any health issue, it's important to talk to your doctor to determine what's right for you.
More isn't always better: Too much calcium has risks
Dietary calcium is generally safe, but more isn't necessarily better, and excessive calcium doesn't provide extra bone protection. In fact, if the calcium in your diet and from supplements exceeds the tolerable upper limit, you could increase your risk of health problems, such as:
- Kidney stones
- Prostate cancer
- Calcium buildup in your blood vessels
- Impaired absorption of iron and zinc
If you take calcium supplements and eat calcium-fortified foods, you may be getting more calcium than you realize. Check food and supplement labels to monitor how much calcium you're getting a day and whether you're achieving the RDA but not exceeding the recommended upper limit.
Sep. 28, 2012
See more In-depth
- Dietary Guidelines for Americans, 2010. U.S. Department of Health and Human Services. http://www.cnpp.usda.gov/DGAs2010-PolicyDocument.htm. Accessed July 3, 2012.
- Dietary Reference Intakes for calcium and vitamin D. Institute of Medicine. http://www.iom.edu/vitamind. Accessed July 3, 2012.
- Calcium and vitamin D: Important at every age. National Institutes of Health. http://www.niams.nih.gov/Health_Info/Bone/Bone_Health/Nutrition/default.asp. Accessed July 16, 2012.
- Calcium. Natural Medicines Comprehensive Database. http://www.naturaldatabase.com. Accessed July 16, 2012.
- Calcium quick facts. Office of Dietary Supplements. http://ods.od.nih.gov/pdf/factsheets/Calcium-QuickFacts.pdf. Accessed July 16, 2012.
- Duyff RL. American Dietetic Association Complete Food and Nutrition Guide. 4th ed. Hoboken, N.J.: John Wiley & Sons; 2012:140.
- Rosen HN. Calcium and vitamin D supplementation in osteoporosis. http://www.uptodate.com/home/index. Accessed July 16, 2012.
- Osteoporosis: Handout on health. NIH Osteoporosis and Related Bone Diseases National Resource Center. http://www.niams.nih.gov/Health_Info/Bone/Osteoporosis/osteoporosis_hoh.asp. Accessed July 17, 2012.
- Hwang C, et al. Micronutrient deficiencies in inflammatory bowel disease: From A to zinc. Inflammatory Bowel Disease. In press. Accessed July 17, 2012.
- What people with celiac disease need to know about osteoporosis. NIH Osteoporosis and Related Bone Diseases National Resource Center. http://www.niams.nih.gov/Health_Info/Bone/Osteoporosis/Conditions_Behaviors/celiac.asp. Accessed July 17, 2012.
- Straub D. Calcium supplementation in clinical practice: A review of forms, doses, and indications. Nutrition in Clinical Practice. 2007;22:286.
- Reid IR, et al. Calcium supplementation: Bad for the heart? Heart. 2012;98:895.
- Bolland MJ, et al. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: Meta-analysis. BMJ. 2010;341:3691.
- Bolland MJ, et al. Calcium supplements with or without vitamin D and risk of cardiovascular events: Reanalysis of the Women's Health Initiative limited access dataset and meta-analysis. BMJ. In press. Accessed July 17, 2012.
- Grogan M (expert opinion). Mayo Clinic, Rochester, Minn. July 17, 2012.
- Dietary supplements standards. U.S. Pharmacopeial Convention. http://www.usp.org/dietary-supplements/overview. Accessed July 31, 2012.
- About ConsumerLab.com. ConsumerLab.com. http://www.consumerlab.com/aboutcl.asp. Accessed July 31, 2012.
- Calcium and Cancer Prevention: Strengths and Limits of the Evidence. National Cancer Institute. http://www.cancer.gov/cancertopics/factsheet/prevention/calcium. Accessed July 31, 2012.