Calcium Supplements: History, Benefits, Myths, Dangers and More!

Did you know around 43% of the American population uses a calcium supplement?

It’s true! As you know, calcium is essential for maintaining strong, healthy bones and preventing debilitating bone loss. But getting enough calcium from your diet alone is tough work.

That’s why so many people turn to calcium supplements as an easy, convenient way to reach their target daily calcium intake.

It’s not just your bones that benefit from calcium and calcium supplements though! Calcium offers a whole host of other health benefits, (some of them might surprise you.)

Keep reading to discover everything you need to know about calcium supplements. Including; the health benefits, common misconceptions, the calcium supplement side effects you may have read about and advice on how to choose the right calcium supplement for you.

A Brief History of Calcium Supplements

Calcium has been used in a medicinal sense since the middle of the 19th century, when it was first recognized in science.

Since then, most research into calcium supplementation has been building on the original findings on calcium therapy.

And while the purpose of calcium supplementation has remained largely the same for the last few decades, a debate over the best source of calcium is still ongoing.

Early use of calcium chloride was criticized for its unpleasant, salty taste and tendency to cause indigestion. And calcium carbonate derived from oyster and mussel shells, crab’s eyes, pincers, and even coral wasn’t highly marketable or environmentally friendly. These marine-based calciums were outsold in the early 20th century by carbonates made from natural chalk and PCC, a synthetic carbonate similar to limestone or marble.

In recent years, the drive has been towards plant-based calcium. Highly-digestible plant-based calcium has fewer side effects than alternative calciums and is far more usable once digested. We’ll cover all of these points in just a moment, but first let’s see if you could benefit from a calcium supplement.

Who Should Consider Calcium Supplements?

Consuming enough calcium from your diet alone can be tricky, so calcium supplements are a good idea for anyone that struggles to reach their recommended dietary allowance.

But calcium supplements are particularly beneficial for anyone that:

  • Has low bone density – As calcium is the cornerstone of bone health, calcium supplements are a common option for people with low bone density to slow the rate of bone loss, strengthen their bones, and improve their bone density– especially if the supplement contains other bone-building nutrients besides calcium (more on that in just a moment).
  • Wants to take preventative measures against bone loss – At around age 40, your natural bone remodeling process begins to remove more bone than it forms, causing gradual bone loss which can lead to dangerously low bone density. But by consuming enough calcium, and other bone-building nutrients, you can create a “bone bank account” that you can withdraw from when your natural bone remodeling process becomes unbalanced. And if you choose your calcium supplement wisely, you can even increase your bone density!
  • Is lactose intolerant or limits dairy products – Dairy products are among the highest sources of dietary calcium, so if you aren’t consuming them in your diet, calcium supplements will help make up for any calcium shortfall.
  • Eats a vegan diet – It’s not impossible to consume enough calcium a day eating a vegan diet, but it’s harder to reach the daily target without animal sources of calcium.
  • Has a digestive disease or issue – Celiac disease, irritable bowel syndrome and other digestive diseases can prevent your body from properly absorbing calcium and other nutrients effectively. So people with a digestive disease may need to give their bodies a helping hand in the form of supplementation.

The Benefits of Calcium

If you’re thinking about taking a calcium supplement, odds are you have your bone health in mind. Calcium is the cornerstone of bone health after all.

But did you know calcium provides a whole host of other health benefits too? Check out the list below– some of these benefits may surprise you!

Balances Your Blood Pressure
Reduces Your Risk of Colorectal Cancer
Combats Kidney Stones
Promotes Weight Loss
Eases PMS Symptoms
Promotes Healthy Teeth

As you can see, calcium is far from a one trick pony. If you’d like to discover more about the surprising health benefits of calcium and calcium supplements, head over to our “The Top Science-Backed Calcium Benefits” page.

Types of Calcium Supplements

When it comes to choosing a calcium supplement it’s not quite as simple as settling on the first one you come across…

See, there are several different calcium compounds used in calcium supplements. And these different calcium compounds contain different amounts of calcium, are derived from different sources, and have different levels of success as far as building bone with no side effects is concerned.

Below are the most common forms of calcium used in calcium supplements:

  • Plant-Based Calcium
  • Calcium Carbonate
  • Calcium Citrate
  • Calcium Gluconate

These are the four most common calcium compounds you’ll find in calcium supplements, but there are a whole host of others too! To discover the 10 most prominent calcium compounds, how much elemental calcium they contain, and the pros and cons of each type (including the four above) visit our dedicated “Types of Calcium” page.

Calcium Supplement Myths

Unfortunately, there’s a lot of misinformation surrounding calcium supplements. Maybe you’ve read conflicting or confusing information online before?

But don’t worry, because in this section we’re going to set the record straight on three of the most common calcium supplement myths.

Myth #1: Your Calcium Comes from an Edible Source

The majority of calcium supplements use calcium derived from rocks. Yes, rocks! Calcium carbonate, calcium citrate and most other calcium compounds come from rock like marble or limestone.

The rock is ground into a powder and the powder is ultimately what you consume in the calcium supplement. So if you read the label of a calcium supplement and see calcium carbonate or another of the rock-derived calcium compounds, the supplement is not an edible source of calcium. That’s not to say that these calcium supplements won’t provide any benefit at all. They’re proven to slow annual bone loss a little. But your body won’t recognize the calcium as a food source, so very little actually ends up in your bones. There are more body-friendly calcium sources which are discussed in the “How To Choose A Calcium Supplement” section below.

Myth #2: Most Formulations are Complete

One of the main reasons people use calcium supplements is to improve their bone health. But not all formulations are created equal.

Obviously, calcium is an important factor in the bone health puzzle, but there are other nutrients you need to support healthy bones too. Now, you might see some calcium supplements that contain vitamin D and/or magnesium (two important nutrients for bone health) as well as calcium. But these three nutrients are still not enough…

The truth is, there are 13 minerals your bones need, plus three vitamins. They are:

The 13 Essential Bone-Supporting Minerals

The Supporting Cast Of Vitamins

For a calcium supplement to truly be considered complete– at least from a bone health perspective – it needs to provide all the nutrients listed above. Most calcium supplement companies won’t include all these nutrients as it would make their supplement more expensive to source and produce and would eat into their profit margins.

Myth #3: Absorption is Important

Perhaps the biggest misconception surrounding calcium supplements is the issue of absorption.

Marketing efforts by many companies tout their supplement as the “most absorbable calcium supplement” or something similar. But in reality, all calcium salts are absorbed at very similar rates– around 23% to 37% when taken with food. (Note: calcium citrate is a slight exception as it doesn’t need to be taken with food. But the absorption rate of calcium citrate is still very similar to other types of calcium when they’re taken with food.)

Where those marketing efforts go wrong is by confusing absorption with dissolution. Before your body can use the calcium in any calcium supplement, it needs to be dissolved in your stomach first. Now, calcium salts are generally very soluble (they dissolve well) in water and stomach acid. That’s why it’s recommended to take your calcium supplement with food, to ensure there’s adequate stomach acid to dissolve the supplement. So when a company claims their calcium supplement is “super-absorbable,” what they actually mean is that it’s well dissolved, and that’s a moot point as all calcium salts are well dissolved when taken with food. But what you really care about is the dissolved calcium getting to your bones.

As far as absorption is concerned, all calcium salts are absorbed at very similar rates. So, does that mean you can opt for the cheapest calcium supplement and still give your bones the greatest benefit? No, it doesn’t.

Here’s the thing; dissolving a calcium supplement, and absorbing it (into your small intestine) is not the end of the story. The calcium in your body needs to be bioavailable– your body needs to be able to use it for it to have active effect. So, in the case of bone health, you need a calcium that your bones can use and that can have an active effect on them. Beyond absorbing the calcium then, it needs to enter your bloodstream and be directed to your bones where it can get to work. And in order to do that, you need a calcium supplement that provides the complementary nutrients that help calcium on its journey from your stomach to your bones, and that help it carry out its bone-building duties when it arrives.

If you want to read more about the absorption of calcium supplements, check out our dedicated “Calcium Absorption” page.

Calcium Supplement Side Effects

We covered– and debunked –three common myths about calcium supplements in the previous section. But what we haven’t touched on just yet are the side effects associated with calcium supplements.

After all, you may have heard about some worrying calcium supplement side effects. Side effects like an increased risk of a heart attack and stroke. And even increased rates of bone loss. So is it true?

Well, these shocking side effects are all associated with “The Calcium Paradox.” (A paradox is a statement or statistic that’s contradictory, but could be possible). In recent history, The Calcium Paradox referred to a strange finding in countries with high calcium intake like Finland and Sweden. These countries boast some of the highest calcium consumption rates per capita in the world. But they also have higher rates of bone loss than average. A rather contradictory– or paradoxical –statistic!

A researcher named MJ Bolland fuelled the fire surrounding The Calcium Paradox further with his 2010 study. Bolland’s paper investigated whether calcium supplements increase the risk of cardiovascular events. His conclusion? Calcium supplements increase the risk for a heart attack and stroke.

Naturally, these findings fuelled international concern amid the subsequent media attention and sensationalized headlines. But Bolland made a glaring oversight that renders his study pretty much obsolete…

The Role of Vitamins D and K2

Both of the examples above fail to take the role of vitamins D and K2 into account.

If you recall in the “Calcium supplement myths” section, we outlined the importance of a complete formulation. To build on that point further, it’s vital to consume enough vitamin D and vitamin K2 to properly utilize the calcium you consume. Here’s why:

Vitamin DSpecifically vitamin D3 (as research shows it’s the superior form of vitamin D) helps your body absorb calcium. Without vitamin D, you can only absorb 10-15% of the calcium you consume, whether that’s from a food or supplement source.

Vitamin K2Vitamin K2 activates two proteins called osteocalcin, and matrix gla protein. Osteocalcin directs calcium to where you need it– your bones and teeth. While matrix gla protein prevents calcium from depositing in your arteries, heart, and soft tissue. Think of these proteins as your body’s traffic signs for calcium!

So, let’s take another look at the findings in Sweden and Finland. The higher than average rate of bone loss can be explained by a deficiency of vitamin D and/or vitamin K2. Not by the fact that there’s a higher consumption of calcium. Remember, you can consume as much calcium as you want, but without vitamin D you can only absorb 10-15% of it.

The same can be said of Bolland’s paper. By failing to take the role of vitamin D and vitamin K2 into account, the ‘findings’ are wildly misleading. Without vitamin K2, in particular, directing the calcium to where it’s needed, it could be deposited in your blood vessels, causing them to harden or calcify. And that will increase your risk for a heart attack or stroke, which is what Bolland saw. But Bolland’s claims that calcium increases the risk of heart attack and stroke have since been refuted.

The takeaway here is that calcium supplements are safe and beneficial, as long as you get the “helper nutrients” too. That’s why it’s so important to choose a calcium supplement that also provides vitamins D and K2 at the very least. And preferably, one that provides all 13 bone-supporting minerals and 3 vitamins too.

Other Calcium Supplement Safety Considerations

There are a few potential interactions and safety concerns to take into consideration with calcium supplements.

If you’re currently taking a prescription medication, you may need to schedule taking your calcium supplement at a different time of day to avoid any potential interactions. It’s always best to discuss this with your doctor who will advise you on a schedule for taking all your supplements and medications.

There are some health conditions that could complicate the use of calcium supplements too. For example, people with hypercalcemia have too much calcium in their blood, so calcium supplements could be an issue. Again, it’s always best to discuss health conditions that may affect calcium supplements with your doctor.

How to Choose a Calcium Supplement

Now you know who should consider a calcium supplement, the potential benefits of taking a calcium supplement, the types of calcium supplement available, and the truth behind some common myths.

But how do you know which calcium supplement is right for you? Well, you can use the points below as a starting point to form your ideal calcium supplement checklist.

How Much Calcium Does It Provide?

Each calcium compound contains a different amount of elemental calcium– that’s the amount of pure calcium you’re getting (you can see exactly how much elemental calcium each calcium compound contains on our “Types of Calcium” page.) Now, some people think a calcium supplement that contains the most calcium will be the most beneficial, but this isn’t necessarily the case.

For example, calcium carbonate contains more elemental calcium than the plant-based calcium used in AlgaeCal Plus– the only calcium supplement supported to increase bone density. In other words, the rock-based calcium supplement provides more calcium than the plant-based calcium supplement but the plant-based calcium is more effective.

Remember, there are other factors that come into play with calcium supplements. The calcium needs to be readily usable and ideally accompanied by the other nutrients that help it reach your bones and get to work when it arrives. So don’t get too hung up on the amount of calcium a calcium supplement provides. The old saying “quality over quantity” is very applicable to calcium supplements!


Will It Be Tolerable For You?

You’ll want to make sure your calcium supplement isn’t going to cause any undesirable side effects. After all, nobody wants to endure stomach cramps or constipation for the sake of supplementing.

You’ll want to make sure your calcium supplement isn’t going to cause any undesirable side effects. After all, nobody wants to endure stomach cramps or constipation for the sake of supplementing.

Now, there are two main factors that will cause a calcium supplement to cause constipation or other gastrointestinal issues:

  1. Too Much Calcium – It’s true, a calcium supplement can actually provide too much calcium. Remember, you’ll still be consuming some calcium from your diet so ideally your calcium supplement won’t contain more than 1,000 mg of calcium (your body can only absorb 500 mg of calcium at a time anyway.) If you start consuming too much calcium, it could upset your stomach. This is a common problem for people who take rock-based calcium supplements. The calcium in rock-based calcium supplements isn’t as effective as plant-based calciums, meaning you’ll often have to consume more of it, which is where the gastrointestinal issues can start to occur.

Alternatively, by opting for a pre-digested, plant-based calcium, you won’t need such a high dose of elemental calcium to gain the benefits and won’t suffer any nasty side effects as a result.

  1. Not enough magnesium – You may remember from the myths section above that magnesium is one of the 13 key minerals you need for healthy bones. And magnesium works very closely with calcium in multiple processes around your body. One of the ways these minerals work together is by contracting and relaxing tissue, including in your intestines. So you can see why it’s important that your levels of calcium and magnesium are balanced in order to avoid digestive issues like constipation, right? Ideally, you want to look for a calcium supplement that provides a 2:1 ratio of calcium to magnesium– the natural balance in a healthy human body.

What Form Is It In?

As you’re probably aware, calcium supplements come in a variety of different forms, including tablets, capsules, gummies, and liquids.

Understandably, some people don’t like swallowing large capsules, but there are a few important things to note on calcium supplement forms.


Tablets may be smaller and easier to swallow than capsules, but they also tend to be much harder for your stomach to dissolve. Here’s the thing; in the interest of making a tablet as small and easy to swallow as possible, manufacturers will compress the ingredients under immense pressure and even use glue to keep the tablet from crumbling. This makes the tablet far more difficult for your body to dissolve, and it’s not unheard of for tablets to remain fully intact after being digested. That’s literally flushing your money down the toilet!


Calcium supplements in gummy form were originally designed for kids, but the sweet taste and chewy texture have made them increasingly popular amongst adults in recent years too.

Now, gummies are a handy alternative for children (and adults) who don’t like swallowing pills, but there are certain drawbacks to be aware of. The reason gummies look and taste so good is because, more often than not, they contain artificial colors and sugar. This is problematic for two reasons:

  1. Calcium supplement gummies look and taste like candy, so it can be very easy to consume them like candy. But as we’ve already covered, consuming too much calcium presents gastrointestinal issues and can also impact your levels of other key minerals.
  2. Sugar is not good for your bones. So consuming it in a supplement that is geared towards protecting your bone health is a little counterintuitive.

Does It Provide More Than Just Calcium?

Remember, calcium is the cornerstone of bone health, but it’s only one cog in the bone health machine.

Your bones need a total of 13 minerals and 3 vitamins (listed in the second point of the myth section on this page) to stay strong and healthy. So ideally, your calcium supplement will provide them all.

Read the ingredients on the label of any calcium supplement you consider. It may be time consuming, but doing your due diligence will pay dividends in the long run.

What Is The Quality Like, and How Much Does It Cost?

Obviously, you’ll need to take your budget in to consideration when you’re comparing calcium supplements. It may be tempting to opt for the cheaper option, but it’s important to remember that, like a lot of things in life, you tend to get what you pay for when it comes to calcium supplements.

In the long run, spending a little extra on a calcium supplement that provides all the vitamins and minerals you need to support strong, healthy bones can save you thousands of dollars, and the stress, of potential complications like fractures further down the line. The same isn’t true of a cheaper calcium supplement that only provides calcium and vitamin D.

View your bone health as if you were building a house. You could use cheap materials like wood or straw to save money and you would in essence have a house. But further down the line, a strong gust of wind (or the huff and puff of a big bad wolf) would blow the house down and you’d have to spend more money to rebuild your house, and deal with any other issues it may cause.

But if you spend a little more money in the first place to buy strong materials like brick and mortar, your house would withstand the gust of wind, and you wouldn’t have to shell out on rebuilding your house from scratch.

Is It Clinically Supported to Increase Bone Density?

What it all boils down to, is what you’re hoping to achieve by taking a calcium supplement. For a lot of people, that is to stop bone loss, increase bone density, and escape the fear and paranoia of low bone density.

So how do you know if a calcium supplement can deliver those results? Well, the best way is to determine whether scientific studies have confirmed the effectiveness of a calcium supplement.

Tip: Studies have shown that many rock-based calcium supplements can slow down the rate of bone loss, but only one calcium supplement has been supported to increase bone density. You’ll find a little extra information on this supplement below the considerations section…

The Only Calcium Supplement Clinically Supported To Increase Bone Density

In recent years, plant-based calcium supplements have snatched the limelight from traditional rock-based calcium supplements. And it’s not hard to see why…

Plant-based calcium comes from a natural, edible food source that won’t cause any nasty side effects. Plant-based calcium is far more usable in your body than rock-based calcium. And one unique plant-based calcium supplement has been clinically supported to do what no other calcium supplement (rock- or plant-based) has ever been able to do… increase bone density!

That calcium supplement is AlgaeCal Plus.

What makes AlgaeCal Plus so special is the strain of marine algae, Lithothamnion superpositum, that it sources it’s calcium from.

See, this marine algae contains all 13 of the essential minerals you need to support healthy bones. Plus, the algae contains these minerals in very similar levels to those found in human bone. And the best part? The algae pre-digests the minerals to use in its own bony structure. So when you take AlgaeCal Plus, they’re already prepped and ready to get to work in your body! Three crucial vitamins are then added (vitamin D3, K2, and C) to make AlgaeCal Plus a complete, bone-building calcium supplement!

As far as the checklist for choosing a calcium supplement is concerned, AlgaeCal Plus ticks all the boxes!