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Joint Health
Your Complete Guide to Calcium Supplements
Swanson staff • March 8, 2022

Choosing the Right Calcium Supplement

Calcium is one of the minerals nearly everyone associates with strong, healthy bones and many people choose to supplement it.1 Similar to the many different types of magnesium supplements, there are numerous types of calcium to choose from...so how do you know that you’re taking the right type?

Types of Calcium: Comparing the Best Calcium Supplement Forms

You may be surprised to learn that most forms of calcium supplements are quite similar to each other. In contrast to magnesium supplements, most calcium supplements work in very similar ways, which is good news for those worrying that they would to pay a higher price if they wanted a "better" supplement.

Still, here’s an overview of the most popular types of calcium supplements:

A common form of elemental calcium commonly found in rocks, limestone, marine animal shells, pearls, eggshells and snails.2 While it has one of the highest concentrations of elemental calcium (35-40%), it is not high in bioavailability.

This is a popular and economical form of calcium. While calcium carbonate is very alkaline, calcium citrate is more acidic and so requires less stomach acid to break down.3 Fortunately, that means you can take calcium citrate on an empty stomach or at mealtimes without having to worry about an upset stomach. Calcium citrate also has good bioavailability for its value.

  • Calcium Phosphate

This is the main form of calcium found in cow’s milk. Tooth enamel and bones are very high in calcium phosphate.4 However, supplemental forms do not seem to be highly bioavailable.

This form of calcium is complexed with lactic acid (it doesn’t contain lactose).5 Calcium lactate doesn’t cause stomach discomfort like other forms of calcium, and it has good bioavailability.

Microcrystalline hydroxyapatite (MCHA) is a component of our bones and teeth that provides rigidity and strength.6 Calcium Hydroxyapatite as a supplement is typically derived from bovine bone, which is almost identical in structure to human bone.7 This is a moderately bioavailable form of calcium, but studies indicate that it’s especially useful for promoting bone health.

Since this calcium is sourced directly from bone,8 you’ll be supplementing more than calcium alone! MCHA also provides phosphorous, magnesium, collagen and other minerals.

As the name suggests, this type of calcium comes directly from coral. Coral calcium contains calcium carbonate. However, there are additional risks to coral calcium: unless harvested sustainably, these supplements can further endanger coral reefs. If you opt for coral calcium, make sure it is harvested from above-the-sea sources where no living coral is harmed.

Comes from nature’s sources of calcium. There are downsides to this option, though. Most of the calcium from these sources is calcium carbonate, which is not very well-absorbed.

There’s More to It Than the Calcium Type!

Perhaps more important than the type of calcium you take is how much you take, when you take it and what you take it with.

Elemental Calcium

Elemental calcium is key when choosing a calcium supplement. Elemental calcium is what your body absorbs for its health benefit. Luckily, it’s easy to find on the package label; elemental calcium has to be listed in the supplement facts. See below for an example of how elemental calcium is listed on our Calcium Citrate label.

Calcium Supplement Facts

The 200 mg of calcium listed is the elemental calcium contained in each capsule. It’s always important to look at a product’s supplement facts, because the amount of elemental calcium does not always equal the total amount of calcium. Below is another example of a supplement facts label from a coral calcium supplement.

Elemental Calcium Supplement Facts

While the supplement contains 1,000 mg of coral calcium, the total elemental calcium in each capsule is 350 mg. So always look for the elemental calcium on the Supplement Facts label to help you decide on a supplement and how much to take.

When to Take Your Supplements

Calcium is best absorbed in smaller doses of 500 mg or less. Anything over 500 mg will not be absorbed well by the body and will simply be wasted. So, if you need to supplement 1,000 mg of elemental calcium a day, you’ll have to take 500 mg twice a day to for the best absorption.

Since calcium supplements can cause stomach discomfort for some people, many opt to take it at mealtimes to avoid difficulty.

Combine with Other Nutrients for Better Absorption

If you’re not getting enough other vitamins, minerals and trace minerals, you likely won’t absorb calcium as well. For example, if you’re deficient in vitamin D, you’ll only absorb 10% of your calcium instead of the average 30%. So, it’s important to also make sure you’re getting enough vitamin D, magnesium and vitamin K along with calcium.

More Isn’t Always Better

Yes, calcium is an essential mineral for your health, but taking more and more calcium isn’t always a good idea. You can overdo your supplements! The Recommended Daily Intake of calcium is around 1,000 mg, and unless your doctor recommends more there isn’t much of a reason to supplement beyond that.

Food Sources of Calcium

If you’d rather not supplement calcium and rely on your diet, there are many foods that contain calcium. Most well-known is dairy products. However, leafy green vegetables have high amounts of calcium, too.

Always serving our customers,

Your friends at Swanson

*These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.


1. Calcium and calcium supplements. Mayo Clinic. Read source

2. What is calcium carbonate? Industrial Minerals Association. Read source

3. Choosing a calcium supplement. Harvard Health. Read source

4. Calcium phosphate. Science Direct. Read source

5. Calcium lactate. Healthline. Read source

6. Nutritional strategies for skeletal and cardiovascular health. National Library of Medicine. Read source

7. Hydroxyapatite. Science Direct. Read source

8. British Journal of NutritionRead source