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Calcium Supplementation

When Your Doctor Advises You To Take A Calcium Supplement

If you find it difficult to obtain the recommended amounts of calcium through diet alone, your physician may recommend a combination of foods rich in calcium and a low dose calcium supplement as a good strategy for you. Calcium supplements are tablets, capsules or liquids containing the mineral calcium from a non-food source. Many brands of calcium supplements are available. When making a choice, take the following factors into consideration:

The Amount Of Calcium Per Tablet Or Dose

The product label should state the amount of elemental calcium in each tablet, e.g., 300 mg of elemental calcium in a 750 mg tablet of calcium carbonate. The amount of elemental calcium is the figure you use to calculate your true daily intake from a supplement.


The most expensive preparations are not necessarily better. Costs will vary among brand name products and similar generic supplements. Prices may also vary with the amount of elemental calcium per tablet. Compare brands and prices.

Side Effects

For some, calcium supplements may cause stomach upset, constipation or nausea. Try different brands or forms, e.g., gelatine capsules, chewable calcium or effervescent tablets, to find a suitable product for you. Calcium citrate may be a good alternative to calcium carbonate.


Specific Canadian standards have been established for lead content, quality, and disintegration; products with DIN (Drug Identification Number) or NPN (Natural Product Number) numbers have passed these tests. If you have any doubts, ask your pharmacist to recommend a good calcium supplement for you.

Tablet Size

Some calcium tablets are very large and may be difficult to swallow. If this is a problem for you and you can’t see the tablet through the bottle, ask your pharmacist or sales person about tablet size. You may wish to inquire about chewable or effervescent tablets or calcium in a gelatine capsule form. In addition, calcium tablets that also contain vitamin D tend to be larger in size. If size matters to you, take your calcium and vitamin D separately rather than in a combined form.

How To Take A Supplement

To maximize the absorption of calcium:

  1. Take calcium carbonate with food or immediately after eating. It is absorbed more effectively when there is food in the stomach. Calcium citrate, calcium lactate and calcium gluconate are well absorbed at any time.
  2. Take calcium with plenty of water.
  3. Take no more than 500-600 mg of elemental calcium at one time. In fact, it is best to take smaller doses more frequently rather than large doses once a day.
  4. Antacids are an acceptable source of calcium. The calcium in these products is calcium carbonate and should be taken at mealtime for better absorption.

Be Sure About Your Dose Of Supplemental Calcium

Only take a calcium supplement if your doctor has advised you to do so. Unless you are very confident that you are taking the correct dose, show your bottle of calcium to your doctor or pharmacist to be sure that you are not taking too much calcium, which may be harmful. If you change the brand of calcium supplement you are taking, you may need to show the new bottle to your doctor or pharmacist again, to make sure that your dose of calcium has not changed.

How Do I Know If I Need A Calcium Supplement?

Osteoporosis Canada strongly recommends that everyone obtain their calcium through nutrition whenever possible. Even if you take excess calcium from your diet, that is not harmful. However, some individuals just can’t seem to get enough calcium in their diet. These persons may need to take a calcium supplement, but this should be discussed with a physician as calcium supplements can have some side effects and have been associated with some risks.

To know whether or not you need to take a calcium supplement, you really need to figure out how much calcium you are getting in your diet. Here is a very simple way to calculate this.

First, give yourself a baseline of 300 mg of calcium simply for eating anything at all. This is because there is a small amount of calcium in a variety of foods such as breads, muffins, oranges, etc. At the end of the day, even without eating any high calcium foods, you can’t help but get about 300 mg of calcium in your daily diet.

Now, add another 300 mg for any of the following high calcium foods:

  • 1 cup (250 ml) of cow’s milk or goat’s milk (including whole milk, 2%, 1%, skim or chocolate milk)

  • 1 cup (250 ml) of fortified soy, almond or rice beverage

  • 1 cup (250 ml) of fortified (or calcium rich) orange juice

  • ¾ cup of yogurt (175 ml)

  • 2 slices of cheese

  • one chunk of cheese (a 3 cm cube)

  • salmon, canned with bones (1/2 can or 107 g) or sardines, canned with bones (7 medium or 84 g)

Three servings of any of the above will give you about 900 mg of calcium, and if you add the 300 mg of baseline calcium for eating anything at all, this will ensure the 1200 mg of calcium you need if you are over 50. Don’t forget to add in any calcium you might be getting from a multivitamin tablet.

If you are already getting close to the recommended amount of calcium for your age group, then you are doing great. Your body needs calcium and you are already getting the calcium you need from your diet.

Extra dietary calcium is not harmful. However, getting more calcium than you need from supplements can be harmful. Excess calcium from supplements has been associated with kidney stones, heart problems, prostate cancer, constipation and digestive problems. Do not take extra calcium from supplements if your diet is already giving you enough calcium.

If you are not getting or cannot get the recommended amount of calcium for your age group from your diet, or if you are not certain if your diet is giving you enough calcium, then you should discuss whether you need to take a low dose calcium supplement with your doctor. You should not just arbitrarily take a calcium supplement on your own. 

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