The Best Calcium Supplement Brands Compared

The Best Calcium Supplements Compared

First thing’s first, let’s clear the air.  

Yes, AlgaeCal is a calcium supplement manufacturer. And yes, we’re reviewing calcium supplements including our own on this page. So why trust our review?  

Because there’s only one calcium supplement that’s clinically supported to INCREASE bone density.

Traditional calcium supplements do slow annual bone loss. But you probably prefer to increase your bone density, not just slow bone loss, right? (After age 40, you normally lose 1% of your bone density every year until death… so slowing that loss is valuable, but building brand new bone is even better!)

Sure, we have an undeniable bias. But the facts are also undeniable: the science, the clinical studies, and the 1000s of people who’ve increased their bone density. And when you look at the facts, one calcium brand stands above the crowd.

Best Calcium Supplement: The Scientists’ Choice

Science iconIt’s a common misconception that “calcium is calcium”.
That’s because hundreds of studies have looked into the effect of calcium supplements on bone density. And the popular conclusion is that all calcium supplements can slow bone loss a little.

Here’s the catch: the research mainly looks at calcium carbonate and calcium citrate.

Now, these types of calcium are derived from rock, so they’re cheap to source and produce. That’s why they’re by far the most common types of calcium used in supplements.

So it’s rare to find a calcium brand that has its own studies. After all, it’s already well-established that calcium carbonate and calcium citrate only slow bone loss.

But one plant-sourced calcium supplement has such a unique formulation that new studies were commissioned to determine its effects. And the results were unprecedented — this calcium supplement actually increased bone density!

In this category, we’ll take a closer look at this special type of calcium and compare it to other calcium brands based on science. We asked the following questions:

  • Is the calcium supplement scientifically formulated to support EVERY aspect of building bone?
  • Are there clinical studies that show its efficacy and safety?

By answering these questions, we narrowed it down to the top three calcium supplement brands in this category. Here’s how they ranked and why:

Brand: AlgaeCal

Is the calcium supplement scientifically formulated to support EVERY aspect of building bone?

Yes, AlgaeCal Plus is scientifically formulated to support every aspect of bone building! It doesn’t just contain calcium, or calcium and vitamin D, or even calcium, magnesium, and vitamin D…

It contains all 13 essential minerals and three vitamins you need to build strong, new bone.

AlgaeCal Plus provides a natural form of plant-based calcium and 12 other bone-supporting minerals from a strain of marine algae called Lithothamnion superpositum. What’s fascinating about this algae is that it uses these minerals to support its own bony structure. So not only are the calcium and minerals present in the perfect proportions for healthy bones, they’re also “pre-approved” for your body to use!

The “Plus” in AlgaeCal Plus refers to added vitamins D3, K2, C and extra boron and magnesium to complete the list of everything you need to build bone.

Vitamin D helps you absorb calcium. Vitamin K2 directs calcium to your bones once it’s absorbed. And vitamin C fights bone-damaging inflammation and promotes collagen formation (an essential component of healthy bone!).

Finally, the extra boron delivers the ideal daily dose for strong bones. And the extra magnesium ensures you get the ideal 2:1 ratio of calcium to magnesium. A balanced ratio of these two minerals is key because they work together to support many essential functions like bone-building and digestion. This also explains why traditional calcium supplements without magnesium can cause side effects like bloating and constipation.

So AlgaeCal Plus delivers every single nutrient your bones crave. This multi-nutrient approach is the reason AlgaeCal is more effective than any other calcium supplement on the market!

How do we know? Three clinical studies support it.

Are there clinical studies that show its efficacy and safety?

Yes, AlgaeCal Plus is the only calcium supplement brand clinically supported to increase bone density in three peer-reviewed human clinical studies!

The first study followed over 200 women and men who took AlgaeCal formulations for six months. Researchers measured participants’ bone density at the beginning and at the end of the six months. They found an unprecedented result… participants increased their bone density across the board!

The second study followed 414 post-menopausal women who took AlgaeCal formulations for 12 months. The result? The smallest average increase in bone density was 1.3%. Once again, this result was totally unprecedented.

Finally, the third study investigated what would happen with long-term use of AlgaeCal. The results stunned the medical community, earning the study the Ragus Research Award in 2016 from the prestigious Journal of the American College of Nutrition. Participants increased their bone density on average 1.04% every year, for seven years… that’s a total average increase of 7.3%!

What’s more, the safety of AlgaeCal was established in all three of these studies by way of rigorous blood panel testing. No adverse effects were found in these blood chemistry tests, and participants reported no adverse side effects.

When you consider most people lose 1% bone density each year after age 40, these results are even more impressive. Not only did AlgaeCal successfully slow bone loss, it accomplished something no supplement ever has before… it increased bone density.

That’s why AlgaeCal Plus deserves the first spot in this list. Because when you get down to it, isn’t the end result of taking a calcium supplement what matters most?

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#2 – Citracal Maximum Plus

Brand: Citracal

Is the calcium supplement scientifically formulated to support EVERY aspect of building bone?

No, Citracal Maximum Plus isn’t formulated to support every aspect of bone building. It provides a few of the nutrients needed to support bone health, but not all of them.

Specifically, it contains vitamin D3, copper, manganese, and zinc. So, vitamin K2, vitamin C, and magnesium are missing. It’s also lacking other essential minerals like boron, silica, and vanadium to name a few! Remember, 13 minerals and three vitamins are involved in building new bone.

In terms of calcium, this supplement contains calcium citrate. As we mentioned earlier on, calcium citrate is a common type of calcium used in supplements because it’s derived from rock and cheap to source.

On the plus side, calcium citrate has an acidic base, so it doesn’t require hydrochloric acid for absorption. This means calcium citrate supplements can be taken with or without food— a fact that makes this type of calcium a better option for people who’ve had gastric bypass surgery.

But remember, calcium citrate has only been shown to slow annual loss, not increase bone density.

Are there clinical studies that show its efficacy and safety?

There are no clinical studies for Citracal Maximum Plus.

#3 – Os-cal® Calcium + D3

Brand: Os-cal

Is the calcium supplement scientifically formulated to support EVERY aspect of building bone?

No, Os-cal’s Calcium + D3 formula isn’t formulated to support every aspect of bone building. It only provides two of the nutrients important for bone health: calcium and vitamin D3.

Now, calcium and vitamin D3 are a good start. Vitamin D3 helps you absorb the calcium you consume. But science tells us there are many other nutrients your bones crave!

In particular, this formula lacks vitamin K2, which is critical for directing calcium to your bones once you’ve absorbed it. It’s also missing magnesium, which is a key component of your bone structure and helps prevent bone loss. And as we noted earlier, calcium and magnesium work together to support many of the body’s functions, including digestion.

So if you’re not getting the optimal ratio of 2:1 calcium to magnesium, you may end up suffering unpleasant side effects like constipation.

It’s also worth noting the calcium in Os-cal comes from oyster shells. This type of calcium is called calcium carbonate. And as we’ve covered, it’s the most common form of calcium used in supplements because it’s cheap to source.

Are there clinical studies that show its efficacy and safety?

There’s one study that shows postmenopausal women over the age of 50 who took Os-cal reduced their risk of hip fracture by 29%.

Now, that may seem like an impressive number. But there are a few important things to bear in mind…

Number one: the participants in this study didn’t increase their bone density. The group that took Os-cal had slightly better hip bone density compared to the group that took a placebo, but they still lost bone density while on this product.

So, at best, Os-cal may slow annual bone loss, but it won’t increase bone density.

Number two: the reported 29% reduced risk of hip fracture is based on something called “hazard ratio”. Now, hazard ratio is a bit like relative risk. But instead of measuring risk over the entire course of a study, hazard ratio measures risk at any given moment.

Here’s the thing: measurements like relative risk and hazard ratio may seem impressive. But taken out of context, these percentages can appear more significant than they really are. That’s why absolute risk is a more accurate measurement. Absolute risk simply compares the difference between two sets of data.

Let’s take this Os-cal study as an example:

  • In the group that took a placebo, there were 199 hip fractures.
  • In the group that took Os-cal, there were 175 hip fractures.

Based on this data, absolute risk for hip fracture would be:

  • 199 of 18,176 participants = 0.16
  • 175 of 18,106 participants = 0.14

So the difference in absolute risk is a mere .02 points. Can you see what a distorted picture presenting only hazard ratio paints?

That’s why in the study’s actual conclusion, the researchers found that Os-cal “did not significantly reduce hip fracture.”

The Scientists’ Choice for Best Calcium Supplement Scoreboard

Scientist’s Choice Ingredients Clinical Studies

#1 AlgaeCal Plus

Plant-based calcium, 12 essential bone-supporting minerals, vitamins D3, K2, and C

3 clinical studies where AlgaeCal Plus increased bone density

#2 Citracal Maximum Plus

Calcium citrate, vitamin D3, copper, manganese, zinc

No clinical studies

#3 Os-cal Calcium + D3

Calcium carbonate, vitamin D3

1 clinical study where Os-cal Calcium + D3 had an insignificant impact on hip fracture risk

Best Calcium Supplement: The People’s Choice

People iconThere are so many unsubstantiated claims and bold statements about calcium supplements on the internet.
It’s natural to be skeptical, and even disbelieving at times.

That’s why finding real proof is so important. And what better proof than other people, just like you, who’ve successfully reclaimed their bone health?

So for this category, we examined calcium brands based on the experiences of real people. We searched for the leading calcium supplement brands, and rated them based on two measures:

  • Product reviews on a brand’s website
  • Video success stories on a brand’s website

And one calcium supplement stood out above the rest— both in terms of the quality and legitimacy of its product reviews, and the thousands of video success stories!

Here is the people’s choice for best calcium supplement…

Brand: AlgaeCal

Product reviews

There are over 400 product reviews for AlgaeCal Plus on the AlgaeCal website, with an average rating of 5 stars (at the time of writing). Thousands of these reviews tell inspiring stories of women and men successfully increasing their bone density with this product! Here’s a sample of what people are saying:

“I have been taking AlgaeCal for a number of years now and my BMD has improved. There finally is a product that is safe, natural and has no side effects. Thank you!” — Dennis

“Have been taking AlgaeCal for almost 3 months and my last bone density was normal. My previous bone density doctor said that I have [low bone density] and been taking calcium supplement but no improvement. Since I started taking AlgaeCal, my bone density improved. I am glad AlgaeCal can help my bone density to be normal!” — Purita

“I think it has been more like nine months since I started and I recently had another bone scan. Spine is improved by almost 10% and hip is improved by about 5%[…] The technician who did the scan was so amazed she had me write down the name of the product so she can tell others about it. My endocrinologist said, “Let’s stick with this regimen”. — Denise

Success stories

There are over 120 video testimonials on the AlgaeCal website. The women and men in these videos are among the many who’ve increasedtheir bone density with AlgaeCal, and are actively enjoying their lives again!

At one point, these women and men were suffering with low bone density, and bone loss. But they’ve finally found a product that works, and now, they want you to share their success.

Click on the video below to see what they have to say for yourself:

#2 – Swanson® Calcium Citrate & Vitamin D

Brand: Swanson

Product reviews

Swanson’s Calcium Citrate & Vitamin D has over 120 reviews on their website, with an average rating of 4.7 stars (at the time of writing). The feedback on this product is positive on the whole. But the reviews mostly refer to the pricing and quality of the supplement with some concerns about the formulation.

The formulation itself delivers only calcium citrate and vitamin D with a bunch of other ingredients unnecessary for bone health. So it makes sense there are no reports of increased bone density in the comments.

Here’s a sample of what people are saying:

“I am feeling healthy so hopefully this supplement is part of feeling my best.” — Kats

“100% calcium citrate plus some vitamin D to boot? At this price? It doesn’t get better than this. I hope it meets Dr. Hulda Clark’s standards for pollution free supplements.” — Mary

“Sadly this would be a good product except for all the additives in it. No thank you. Swanson we expect better of you.” — Mdbiker

Success stories

There are no video testimonials on the Swanson website.

#3 – GNC Calcium Plus® 1000

Brand: GNC

Product reviews

GNC Calcium Plus 1000 has over 50 reviews on their website, with an average rating of 4.7 stars (at the time of writing). That said, the comments are mostly vague statements about liking the product, or refer to pricing and shipping.

There’s no mention of anyone improving their bone density with this product which is unsurprising given the formulation. This product contains calcium carbonate, vitamin D, and magnesium, but it’s lacking vitamin K2 and all the other essential bone-supporting minerals.

Here’s a sample of what people are saying:

“Order this product online and get it fast. Good quality and will buy again.”
— Stephanie

“Good for condition.” — Inhwan

“Like it. Easy to take.” — Taylor

Success stories

There are no video testimonials on the GNC website.

The People’s Choice for Best Calcium Supplement Scoreboard

People’s Choice Product Reviews Success Stories

#1 AlgaeCal Plus

Over 400 reviews with an average rating of 5 stars

Yes, over 120 video testimonials of women and men who increased their bone density with AlgaeCal

#2 Swanson Calcium Citrate & Vitamin D

120 reviews with an average rating of 4.7 stars


#3 GNC Calcium Plus 1000

54 reviews with an average rating of 4.7 stars


Best Calcium Supplement: AlgaeCal Plus

Natural iconAfter learning they have low bone density, many people prefer to look for a natural solution.

Now, natural supplements from whole-food sources are easier for your body to digest and utilize. On the other hand, traditional rock-based supplements are much more difficult for your body to tolerate. That’s because they rarely contain any of the complementary nutrients your body (and your bones!) need.  

That’s why this category is all about the source of the ingredients calcium brands use. We asked the following questions:

  • Does it use a body-friendly calcium source?
  • Does it contain all 13 essential bone-supporting minerals naturally?
  • Is it harvested in an ecologically-friendly manner?

These questions helped us narrow it down to the top three natural calcium supplement brands. Here’s how they stacked up:

Reading ingredients on AlgaeCal Plus bottle

Brand: AlgaeCal

Does it use a body-friendly calcium source?

Yes, as we discussed a little earlier, AlgaeCal contains natural, plant-based calcium. The source? A unique strain of red ocean algae found on the shores of South America called Lithothamnion superpositum.

Once the algae washes up on shore, it’s sustainably hand-harvested, cleaned with fresh ionized water, and sun-dried. Afterwards, it’s milled down to powder form. This powder is the raw version of AlgaeCal.

Then, the powder is tested for microbial activity and mineral content to ensure the utmost quality and safety. There are no additives or chemicals used during manufacturing. There’s no sieving process and no extractions that might dilute mineral content.

AlgaeCal’s calcium source is 100% natural and body-friendly.

Does it contain all 13 essential bone-supporting minerals naturally?

Yes, AlgaeCal Plus contains all 13 essential bone-supporting minerals naturally! These minerals are:

  • Boron
  • Calcium
  • Copper
  • Magnesium
  • Manganese
  • Nickel
  • Potassium
  • Phosphorus
  • Selenium
  • Silica
  • Strontium
  • Vanadium
  • Zinc

This is what makes AlgaeCal truly exceptional. The algae it’s sourced from has a nearly identical mineral composition to human bone. So, AlgaeCal Plus delivers all the minerals your bones crave in the ideal proportions to build healthy, new bone!

What’s more, since these minerals are “pre-digested” by the algae, they’re extra bio-available. In other words, your body has to do a lot less work to break down and use these minerals.

In essence, you’re eating a plant— a natural wholefood— which is why AlgaeCal Plus has no adverse side effects. This also explains why traditional rock-based supplements are so difficult to tolerate! It’s plain and simple: what’s more natural for your body to digest… rocks or plants?

Is it harvested in an ecologically-friendly manner?

Absolutely. Here’s why…

The algae this product uses has a 180-day lifecycle. First, it attaches itself to seaweed on the ocean floor where it grows for around six months. Once it’s around the size of a kiwi, the algae detaches from the seaweed and washes up on shore.

Note that the algae washes up onto the beach naturally. This means it doesn’t have to be dredged up out of the ocean like other algae calcium sources. This is key because dredging unsettles the ocean floor and disrupts marine life.

Once the algae washes up on shore, it’s hand-harvested by a team of locals within 48 hours to protect it from sun exposure and preserve its mineral content.

Finally, the team of harvesters follows a careful beach to beach rotation to conserve the natural cycle of marine algae.

This careful process is why AlgaeCal’s calcium source is certified organic. A third-party organization called IBD Certificacoes is responsible for certifying that harvesting is conducted in a sustainable and environmentally-friendly manner.

IBD Certificacoes reports to the United States Department of Agriculture (USDA) to ensure the quality and purity of AlgaeCal’s calcium source.

AlgaeCal’s calcium source is also certified as kosher through Natural Food Certifiers.

#2 – New Chapter Bone Strength Take Care™

Brand: New Chapter

Does it use a body-friendly calcium source?

On first glance, New Chapter’s Bone Strength Take Care (BSTC) looks a lot like AlgaeCal Plus. Both of these supplements source their calcium from red ocean algae. So, BSTC does use a natural, body-friendly calcium source.

But if you look a little closer, there are crucial differences between the two. First off, the calcium used in BSTC is from a variety of algae harvested from the ocean floor in Iceland. Note that no clinical studies show this source of calcium can increase bone density.

Second, the formulations differ in critical ways which we’ll go over next…

Does it contain all 13 essential bone-supporting minerals naturally?

Since BSTC is harvested from algae, it does contain many of the minerals found in AlgaeCal Plus. The product contains the following minerals:

  • Calcium
  • Magnesium
  • Strontium
  • Silica
  • Vanadium

That’s five minerals total. It’s unclear whether BSTC contains the eight other bone-supporting minerals.

The magnesium content in BSTC is also a lot lower than the content in AlgaeCal Plus. BSTC contains 58 mg of magnesium which isn’t enough to balance the 770 mg of calcium it provides. That’s because studies show the ideal ratio of calcium to magnesium is 2:1. Remember, not getting the right balance of magnesium to calcium is also the reason many people experience constipation. (Note that AlgaeCal Plus provides the ideal ratio of these minerals).    

In addition, there’s no mention of boron in BSTC’s formula. As you may know, boron is one of the key bone-supporting minerals— which is why there’s extra boron in AlgaeCal Plus.

Finally, the vitamin content of BSTC is lacking compared to AlgaeCal Plus. BSTC only provides 1000 IU of vitamin D3 per day whereas AlgaeCal delivers 1600 IU. The same goes for vitamin K2… BSTC provides 45 mcg per day; AlgaeCal Plus delivers 100 mcg per day. And BSTC doesn’t contain vitamin C while AlgaeCal Plus provides 50 mg per day.

So, even though there are surface similarities between the two products, when you break it all down, it’s clear which supplement is superior.

Is it harvested in an ecologically-friendly manner?

BSTC claims their algae is “sustainably harvested from Iceland”. But they don’t provide any details about the harvesting process on their website.

#3 – Jarrow Formulas Bone-Up®

Brand: Jarrow Formulas

Does it use a body-friendly calcium source?

Yes and no.

Bone-Up uses a calcium we haven’t discussed yet— microcrystalline hydroxyapatite. It sounds complicated, but hydroxyapatite is simply a mineral complex derived from cow bones. In hydroxyapatite, calcium is bound with phosphorus.

Now, phosphorus is the principal form of storage for calcium in bone, but when you consume hydroxyapatite, the calcium is separated from the phosphorus, and you absorb more phosphorus than you ideally want.

See, research shows too much dietary phosphorus can be a risk factor for cardiovascular and kidney diseases. Plus, the general population is already consuming more than enough phosphorus in processed foods and food additives!

That’s why— even though this calcium source is natural— it’s less body-friendly than calcium from algae. It’s also not clinically supported to increase bone density like AlgaeCal Plus. Studies show that even though hydroxyapatite is more effective at slowing bone loss than other forms of calcium, it still only slows annual bone loss.

Does it contain all 13 essential bone-supporting minerals naturally?

On top of calcium, Bone-Up provides boron, copper, magnesium, manganese, potassium, and zinc. That’s not a bad portfolio, but it’s still missing several of the 13 bone-supporting minerals.

Bone-Up also contains vitamins D3 and K2— albeit in smaller quantities than AlgaeCal Plus. Specifically, it provides 1,000 IU of vitamin D3 and 45 mcg of vitamin K2. (Remember, AlgaeCal Plus offers 1,600 IUs of vitamin D3 and 100 mcg of vitamin K2.)

Is it harvested in an ecologically-friendly manner?

The calcium in Bone-Up comes from free-range New Zealand calves.

But it’s difficult to say how ecologically-friendly this calcium source is since there are no details regarding the manufacturing process on the website.

The Natural Choice for Best Calcium Supplement Scoreboard

Natural Choice Body-Friendly Calcium Source 13 Essential Minerals Ecologically-friendly

#1 AlgaeCal Plus

Yes, plant-based calcium from algae clinically supported to increase bone density



#2 New Chapter Bone Strength Take Care

Yes, plant-based calcium from algae



#3 Jarrow Formulas Bone-Up

Yes, calcium from cow bone



Best Calcium Supplement Takeaways

What’s the most important thing you want out of your calcium supplement?

If you have low bone density or are experiencing bone loss, the answer is simple: to increase your bone density.

So, which calcium supplement is best for you is also simple: the one that increases your bone density.

And there’s only one calcium supplement on the planet that’s clinically supported to increase bone density, safely and naturally: AlgaeCal Plus.

The facts are clear. AlgaeCal’s formula supports every aspect of bone-building. Participants increased their bone density in three clinical studies by taking AlgaeCal! And 1000s of people have successfully built new bone with AlgaeCal.

So if you’re looking for a natural approach to bone loss, AlgaeCal Plus is the only calcium supplement for you. And the best part? With our money-back guarantee, you have nothing to lose!