6 Types of Calcium for Bone Health

by Melissa Chichester

Calcium is an essential mineral found in many foods, such as dairy products and leafy green vegetables.

Most calcium in your body is stored in the bones and teeth, where it supports skeletal health.** Your muscles and nerves also rely on calcium (and magnesium) to transport messages to the brain.**  Unfortunately, many adults do not receive enough of this essential mineral, which is when supplementation is useful. 

For adults, the Recommended Daily Intake (RDI) for calcium is 1,000 milligrams (mg) daily. If you are over age 50, 1,200 mg per day is the RDI for women. It is the same for men over age 70. The National Institutes of Health Office of Dietary Supplements also notes that age and lifestyle habits play a factor in how well calcium absorbs.

Adequate calcium intake should come from food first, but when that isn’t enough, supplements may help bridge nutritional gaps.**

If your personal healthcare practitioner recommends a calcium supplement, it can be tricky to pick one out due to all of the varieties available. Here are six types of calcium and what they do, so you can decide the best supplement for you! 

Calcium carbonate

More than 4% of the earth’s crust is made of calcium carbonate. This kind of calcium is usually sourced from crushed rocks and limestone; however, it is also found in pearls, eggshells, and other shells (e.g., snails, marine animals). According to the Mayo Clinic, calcium carbonate contains the highest amount of elemental calcium by weight (40%). Calcium carbonate is best known for its use in antacid products. Because it requires stomach acid to adequately absorb, calcium carbonate should be taken with food. 

Calcium carbonate supplements include:

eggshells have calcium in them

Calcium citrate

Calcium citrate is comprised of 21% elemental calcium. It is made when calcium carbonate bonds with citric acid. This type of calcium absorbs more easily than calcium carbonate. Calcium citrate can be taken with or without food because it already contains an acid source. 

Calcium citrate supplements include:

Calcium citrate malate 

Similar to calcium citrate is calcium citrate malate, which is also comprised of 21% elemental calcium. This type of calcium is made by combining calcium carbonate with citric acid and malic acid. It is water-soluble and usually the type of calcium used to fortify fruit juices (e.g., orange juice) and other packaged foods with a source of calcium.

Calcium gluconate 

Calcium gluconate contains 9% elemental calcium. It is composed of calcium carbonate and gluconic acid. According to the American Chemical Society, gluconic acid is an essential building block of sugars and polysaccharides. It is found in foods such as honey and fruits. Calcium gluconate has been used since the 1920s for wellness and is on the World Health Organization’s List of Essential Medicines. 

Calcium gluconate supplements include:

Calcium lactate 

Calcium lactate is usually made by mixing calcium carbonate (or calcium hydroxide) with lactic acid. Calcium lactate consists of 13% elemental calcium and you can find it in aged cheese products, as it is used as a flavor enhancer and firming agent.

Calcium lactate supplements include:

Coral calcium 

When sea coral dies, the hard shell that is left behind is a rich source of minerals, including calcium. Coral calcium is highly absorbable. Most coral calcium supplements are derived from fossilized coral that is collected from above ground, making it an environmentally friendly source or coral calcium. 

Coral calcium supplements include:

Calcium plays an integral role in many systems in your body throughout your lifetime. Knowing the different types of calcium can help you understand how they play a role in your health.