Types of Calcium Used in Food Supplements

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Finding the right calcium supplement for you can be tough.

You start to lose bone at around 40-years-old. And you need calcium, as well as other nutrients, to help reverse the bone loss. But getting enough calcium from your diet alone can be tricky. Ideally, you need a calcium supplement on top of your dietary calcium to counterbalance bone loss and avoid osteoporosis.

But as you may have discovered, there are many different types of calcium. Calcium carbonate, calcium phosphate, and plant-based calcium to name just a few.

But what’s the difference between them? Is one type of calcium better for your bones than the others?

Continue reading and you’ll discover everything you need to know about the different types of calcium!

10 Calcium Types Compared: Calcium Carbonate, Calcium Citrate, Calcium Phosphate, Calcium Gluconate (and more)

We’re going to look at the 10 most popular types of calcium used in calcium supplement formulations. They come from different sources, they can have different side effects on your body, and they provide different amounts of calcium.

A Word on Elemental Calcium

Now, that last point may surprise you. You’d think that 400 mg of calcium carbonate and 400 mg of any other type of calcium would provide the same amount of calcium, right? But you need to take the “elemental calcium” value into account (that’s the middle column in the table below).

You see, elemental calcium is the amount of pure calcium a calcium type contains. And this pure calcium bonds with other elements. Let’s take calcium carbonate as an example. Calcium carbonate contains elemental calcium bonded with elemental carbon and elemental oxygen. When you consume calcium carbonate, these elements break away from one another, and this is when you get the pure calcium– 40% in the case of calcium carbonate.

It’s important to be aware of the elemental value of each calcium type. But it’s not the be-all-and-end-all. In the United States and Canada the labeling laws require the manufacturer to list the elemental calcium amount on the label– so no need to bring your calculator. If the calcium carbonate label says “400 mg”, it means you’re getting 400 mg of elemental calcium. But there are other factors that come into play (as you’ll see a little further down).

Type of Calcium Elemental Calcium (approximate value) What’s The Source?
Calcium Carbonate 40% Rock-derived: marble, limestone
Calcium Phosphate 38.7% Rock-derived. Also found in cow’s milk
Plant-Based Calcium
(a complex of 4 calcium molecules pre-processed by a plant source; calcium hydroxide, calcium chloride, calcium sulfate and calcium carbonate.)
30% Marine Algae: Lithothamnion superpositum
Microcrystalline Hydroxyapatite (MCHC Calcium) 25% Animal bones
Calcium Citrate 21% Rock-derived. Calcium sourced from marble or limestone bound with citric acid (think citrus fruits like lemons and limes)
Calcium Citrate Malate 21% Rock-derived. Calcium sourced from marble or limestone bound with citric acid and malic acid
Calcium Lactate 13% Rock-derived. Calcium sourced from marble or limestone bound with lactic acid. Also found in foods like aged cheese
Calcium Ascorbate 10% Rock-derived. Calcium sourced from marble or limestone bound with ascorbic acid
Calcium Gluconate 9% Rock-derived. Calcium sourced from marble or limestone bound with gluconic acid
Dolomite, Oyster Shell, and Bone Meal Calcium Varies drastically depending on the particular source Dolomite rock, oyster shell, bone meal

You may have noticed a theme in the Sources above– many types of calcium are derived from marble or limestone and are bound with some form of acid.

See, calcium is never found in its isolated state in nature, but exists instead in compounds, which are called “calcium salts,” even though they don’t contain any salt. And one of the most common compounds is calcium carbonate, which is found in rocks like marble and limestone. More often than not, calcium carbonate is used as the “base” for other calcium compounds.

Let’s take calcium citrate as an example. Calcium citrate isn’t a natural form of calcium, it’s just a calcium compound (calcium carbonate) bound with citric acid. These other calcium compounds can offer different benefits, but the real source of the calcium is still rock (marble or limestone) which the human body wasn’t designed to consume.

Types of Calcium

Calcium Carbonate

Calcium carbonate is one of the most common types of calcium you’ll find in calcium supplements. This is because it’s a rock-based calcium compound, which is cheap to source and produce. And yes, “rock-based” literally means the calcium comes from ground-up rocks like marble and limestone! But calcium carbonate can be found in other sources too…

Calcium carbonate is the main component of pearls, and the shells of marine animals, snails, and eggs. Maybe you’ve heard of “eggshell calcium”? People crush eggshells into a powder to make a homemade calcium supplement. But it’s still calcium carbonate. In fact, a lot of other calcium types are actually a modified version of calcium carbonate. Remember, isolated calcium isn’t found in nature. It binds to another element to form a compound, and calcium carbonate is one of the most abundant calcium compounds there is.

How much elemental calcium does calcium carbonate contain?
Approximately 40%

Pros of Calcium Carbonate Cons of Calcium Carbonate
Cheap to source and produce, so calcium carbonate supplements are often cheap for the consumer Sourced from rock like marble and limestone– your body isn’t designed to consume rock!
High level of elemental calcium Rock-based calciums only provide you with calcium and whichever element the calcium is bound with. They don’t provide the entire matrix of nutrients you need to absorb the calcium and support your bones. What’s more, consuming high amounts of calcium on its own can cause gastrointestinal issues like constipation
Can only slow bone loss

 

Calcium Phosphate

Calcium phosphate is the calcium salt of phosphoric acid. It’s the primary form of calcium in cow’s milk. And if you check the ingredients on your toothpaste tube, you may well find calcium phosphate there too! See, the primary mineral of tooth enamel is calcium phosphate (in hydroxyapatite form– we’ll cover this a little later on), and research suggests calcium phosphate-based paste promotes tooth enamel.

When it comes to calcium supplements, you’ll commonly find calcium phosphate as tricalcium phosphate or microcrystalline hydroxyapatite (MCHC – we’ll cover this in just a moment.) Tricalcium phosphate supplements tend to source their calcium from phosphate rock– that’s any rock with a high concentration of phosphate. And remember, your body isn’t designed to digest rock.

How much elemental calcium does calcium phosphate contain?

Approximately 38.7% (Microcrystalline Hydroxyapatite has a different value)

 

Pros of Calcium Phosphate Cons of Calcium Phosphate
High level of elemental calcium Commonly sourced from rocks– your body isn’t designed to consume rock!
Rock-based calciums only provide you with calcium and whichever element the calcium is bound with. They don’t provide the entire matrix of nutrients you need to absorb the calcium and support your bones. What’s more, consuming high amounts of calcium on its own can cause gastrointestinal issues like constipation
Can only slow bone loss

 

Plant-Based Calcium

Plant-based calcium is exactly what it sounds like… calcium sourced from plants! You may know that leafy greens like broccoli and collard greens provide calcium (check out our “Top Calcium-Rich Foods” page for some other great sources). But, one very special source of plant-based calcium is concentrated enough to be used in a calcium supplement. And this calcium has accomplished something no other calcium supplement ever has: Increased bone mineral density in older adults.

That doesn’t mean reduced bone loss. It means brand new bone as measured by a DEXA bone scan! So what’s this special plant-based calcium behind the new bone? It’s a unique strain of marine algae called Lithothamnion superpositum.

Lithothamnion superpositum contains a complex of at least 4 calcium molecules. But the most fascinating thing about this plant-based calcium source, is that the calcium it contains is part of a natural matrix along with lots of other bone-building nutrients. In fact, Lithothamnion superpositum provides all 13 minerals essential for building bone– in the optimal balance for humans.

As well as their bone-building properties, you need some of these minerals to properly utilize calcium. Plus, they provide other health benefits of their own too. The best part though? The calcium and other nutrients are pre-digested by the algae. That means they’re basically “pre-approved” to get to work in your body when you consume them, and will cause no nasty side-effects either.

So, how do you get this superfood calcium source? In AlgaeCal Plus. AlgaeCal Plus is the calcium supplement we alluded to a little earlier. The only calcium supplement (and the only plant-based calcium) in history that’s clinically proven to increase bone density. Yes, increase bone density, not just slow down bone loss!

What’s more, studies show AlgaeCal Plus is guaranteed to increase bone density in as little as six months when combined with strontium (they’re available together in the Bone Builder Pack).

How much elemental calcium does plant-based calcium provide?

Approximately 30%

Pros of Plant-Based Calcium Cons of Plant-Based Calcium
Organic, sustainable, renewable resource Because calcium supplements that use plant-based calcium provide a whole matrix of nutrients alongside calcium, they can cost a little more than their rock-based counterparts.
Natural form of body-friendly calcium. Because the calcium in plant-based sources is part of a nutrient matrix, you get everything you need to absorb it and utilize it properly, with no side effects
Lithothamnion superpositum (a plant-based calcium source) doesn’t just provide calcium. It provides an extra 12 minerals too, and they all play a role in supporting strong, healthy bones.
AlgaeCal Plus (a calcium supplement which sources calcium from Lithothamnion superpositum) is guaranteed to increase bone density when you take it with Strontium Boost
Less is more when it comes plant-based calcium. The matrix of “helper nutrients” that help your body absorb and use the calcium mean you don’t need to take as much of this calcium each day as you would with other types of calcium

 

Microcrystalline Hydroxyapatite Calcium (MCHC)

Hydroxyapatite is a mineral complex derived from cow bones. In hydroxyapatite, calcium is bound with phosphorus which is the principal form of storage for calcium in bone. That sounds positive for dealing with bone loss, but when you consume calcium, no matter what it’s bound with, the calcium is freed from that compound before it’s absorbed. So in the case of hydroxyapatite, the calcium is separated from the phosphorus, and you absorb more phosphorus than you ideally want to.

Research shows too much dietary phosphorus can be a risk factor for cardiovascular and kidney diseases. What’s more, one study found the risk of fractures increased by 9% for every 100 mg of phosphorus intake. That’s worrying news, especially as the general population is already consuming more than enough phosphorus in processed foods and food additives.

How much elemental calcium does MCHC contain?

Approximately 25%

Pros of MCHC Cons of MCHC
Provides other minerals and proteins that support bone, such as magnesium, potassium, zinc, trace minerals, collagen, and osteocalcin The calcium in MCHC is bound to phosphorus. And consuming too much phosphorus can be a risk factor for cardiovascular and kidney diseases, and fracture
It’s expensive
No studies show it’s more effective than other calcium types at lessening bone loss
It’s derived from animal bones, so isn’t suitable for vegetarians or vegans

 

Calcium Citrate

Calcium citrate is another of the more common calcium types used in calcium supplements. It’s derived from rock calcium bound with citric acid (think citrus juices, especially lime and lemon).

Calcium citrate has an acidic base, so it doesn’t require hydrochloric acid for absorption. This means calcium citrate is particularly beneficial for people taking certain medications that reduce stomach acid, or people that have had gastric bypass surgery. And because you don’t need stomach acid to consume calcium citrate, you can take it with or without food.

How much elemental calcium does calcium citrate contain?

Approximately 21%

Pros of Calcium Citrate Cons of Calcium Citrate
Can be taken with or without food Rock-derived– your body isn’t designed to consume rock!
People on certain medications or who have had gastric bypass surgery can only absorb this type of calcium Low elemental calcium, so you’d have to take a lot of capsules a day to reap any real benefit
Can only slow bone loss

 

Calcium Citrate Malate

It may sound a lot like calcium citrate, but calcium citrate malate is a little different. Calcium citrate malate contains the calcium salt of citric acid and malic acid, and was first patented in the late 1980s. It’s a water-soluble calcium, which means it dissolves without the need for stomach acid. That means you can take it with or without food.

And if you’ve ever seen fruit juices and other drinks that say they’re “calcium-fortified” on the label, the added calcium is often calcium citrate malate.

How much elemental calcium is in calcium citrate malate?

Approximately 21%

Pros of Calcium Citrate Malate Cons of Calcium Citrate Malate
Can be taken with or without food Rock-derived– your body isn’t designed to consume rock!
Relatively low elemental calcium value, so you’d have to take a lot of capsules a day to reap any real benefit
Can only slow bone loss

 

Calcium Lactate

Calcium lactate is a salt that consists of two lactate anions (atoms that have gained electrons) for each calcium. Calcium lactate is made for commercial use by mixing lactic acid with calcium carbonate or calcium hydroxide. In a commercial sense, calcium lactate is used as a thickener, firming agent, and flavor enhancer. And you can also find it in some of your favorite aged cheeses!

Calcium lactate supplements offer a very small amount of elemental calcium. So like we saw with calcium citrate malate, you’d have to consume a lot of capsules each day to reap any benefit.

How much elemental calcium does calcium lactate contain?

Approximately 13%

Pros of Calcium Lactate Cons of Calcium Lactate
Can be used as an additive to extend the shelf life of food products Rock-derived– your body isn’t designed to consume rock!
Very low level of elemental calcium, so you’d have to take a lot of capsules a day to reap any benefit
Can only slow bone loss

 

Calcium Ascorbate

Calcium ascorbate is the combination of calcium and ascorbic acid (that’s the fancy name for vitamin C). While it’s convenient to get both calcium and vitamin C from one type of calcium, calcium ascorbate supplements provide far more vitamin C than calcium. So from the perspective of supporting your bone health, you’d have to consume a lot of capsules a day to reap any real bone-health benefit.

How much elemental calcium does calcium ascorbate contain?

Approximately 10%

Pros of Calcium Ascorbate Cons of Calcium Ascorbate
Provides vitamin C along with calcium. Vitamin C helps to make the calcium more soluble Rock-derived– your body isn’t designed to consume rock!
Low level of elemental calcium, so you’d have to consume a lot of capsules a day to reap any real benefit
Can only slow bone loss

 

Calcium Gluconate

Calcium Gluconate is the calcium salt of gluconic acid. The most common use of calcium gluconate is in a supersaturated injection, which is used to treat low blood calcium, high blood potassium, and magnesium toxicity.

Fun fact: Calcium gluconate was a conventional treatment for black widow spider bites! Calcium was thought to stabilize nerve membrane permeability, resulting in decreased neurotransmitter release. (However, studies have cast doubt over the effectiveness of calcium gluconate treatment for black widow bites, and it’s since fallen out of favor).

When it comes to a supplement form, calcium gluconate has a very low level of elemental calcium (the lowest of all the calcium types on this list). That means you’d have to take a lot of capsules each day to reach the recommended daily intake of calcium and reap any real benefit.

How much elemental calcium does calcium gluconate contain?

Approximately 9%

Pros of Calcium Gluconate Cons of Calcium Gluconate
In injection form it can treat low blood calcium, high blood potassium, and magnesium toxicity Rock-derived– your body isn’t designed to consume rock!
Very low elemental calcium level, so you’d have to take a lot of capsules a day to reap any real benefit
Can only slow bone loss

 

Dolomite, Oyster Shell, and Bone Meal Calcium

The calcium in dolomite (a rock-forming mineral), oyster shell, and bone meal isn’t a unique chemical type of calcium. It’s actually mainly calcium carbonate. But calcium from dolomite, oyster shell, and bone meal warrants a separate mention on this list as it carries health implications you should be aware of…

Advocates of dolomite, oyster shell, and bone meal calcium will point to the fact they’re natural sources (although something being naturally occuring and natural to consume are two very different matters). Besides, these types of calcium are not advised for consumption because studies show they contain dangerous levels of lead. Consuming toxic levels of lead can cause abdominal pain, vomiting, muscle weakness, and even seizures.

How much elemental calcium is in dolomite, oyster shell, and bone meal calcium?

Depending on the source, the amount of elemental calcium can vary quite drastically.

Pros of dolomite, oyster shell, and bone meal calcium Cons of dolomite, oyster shell, and bone meal calcium
Can be viewed as natural Contains high levels of lead
Not suitable for vegetarians and vegans depending on the source

 

The Takeaway

There are a whole host of calcium types out there. And that can make choosing a calcium supplement tricky.

To make things trickier still, there are lots of different supplements, containing lots of different calcium types, claiming to do lots of different things. But as you can see from the information on this page, the negatives often outweigh any benefits. Especially when it comes to bone loss…

Many of the calcium types on this page can help you slow the rate of your bone loss when you take them in supplement form. But only one calcium supplement can stop it altogether, and actually help you build more bone than you lose– plant-based AlgaeCal Plus.

AlgaeCal Plus uses natural, body-friendly calcium sourced from Lithothamnion superpositum. And it’s the only calcium supplement in the world that’s clinically proven to increase your bone density.