How to Choose Good Calcium Supplements

The role of calcium in bone health is indisputable. We’ve previously talked about food sources of calcium and the recommended daily requirements (“RDA’s”) of calcium per age group. This article will review the different forms of calcium supplements and give you tips upon how to select one that is best for you.

Who should consider calcium supplements?

Even when 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 more calcium;
  • Are receiving long-term treatment with corticosteroids; or
  • 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. Talk with your doctor or dietitian about whether calcium supplements are right for you.

How do I know which calcium supplements provide the most calcium?  There are so many kinds – carbonate, citrate, lactate, and gluconate.

The key factor to consider when buying calcium supplements is the amount of elemental calcium that the particular supplement contains. The term “elemental calcium” refers to the amount of calcium in a supplement that’s available for your body to absorb. Common calcium supplements may be labeled as:

  • Calcium carbonate (40% elemental calcium)
  • Calcium citrate (21% elemental calcium)
  • Calcium gluconate (9% elemental calcium)
  • Calcium lactate (13% elemental calcium)

If the amount of elemental calcium isn’t clearly listed on the label, check the Nutrition Facts label. The amount of elemental calcium will be listed in milligrams (mg) according to “serving size” – generally one or two tablets.

The Nutrition Facts label also lists the Percent Daily Value (“% Daily Value”). This indicates how much one serving provides toward the average daily recommended amount of a given nutrient for most people. For calcium, the % Daily Value is 1000 mg of elemental calcium. However, your needs for calcium may vary according to recommendations from your doctor or dietitian.

Additional factors to consider when choosing a calcium supplement:

  •  Tolerability

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. Depending on your medications, you may need to take the supplement with your meals or between meals. 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 have their products independently tested by the U.S. Pharmacopeial Convention (USP), (CL) or NSF International. Supplements that bear the USP, CL or NSF 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.

  • Supplement form

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.

  • Absorbability

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. The two main forms of calcium supplements are carbonate and citrate.

Calcium carbonate is cheapest and therefore often a good first choice. 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 people over 50 or taking acid blockers), inflammatory bowel disease or absorption disorders. 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.

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.

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 total calcium you’re getting a day and whether you’re achieving the RDA but not exceeding the recommended upper limit. Be sure to tell your doctor if you’re taking calcium supplements.


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Author: Michelle Hanson

Michelle Hanson, MA, RD, LD is Fresh & Natural Food’s Registered Dietitian. She received a Bachelor of Science degree in Nutrition and Clinical Dietetics with a minor in Community Health from the University of Minnesota – Twin Cities. She is a registered dietitian and current member of the Academy of Nutrition and Dietetics. Michelle has been a nutrition consultant for numerous years as well as a nutrition research director at the University of Minnesota – Twin Cities.

Michelle is passionate about food and nutrition and believes in helping people find simple, realistic ways to make healthy eating a part of their everyday lifestyle.
If you are interested in meeting Michelle or have questions for her, you can email her at: She will look forward to meeting you!