It all comes down to source and absorption.

Rock-based calcium

Most conventional calcium supplements are made by grinding up rocks such as limestone or marble. Chemically, this produces calcium carbonate or calcium citrate—forms that are essentially purified stone. And because humans are not designed to digest rock, these supplements:

- Absorb poorly in the digestive tract, especially if stomach acid is low (which becomes more common with age).

- Provide only calcium and little else, leaving out the dozens of trace minerals your bones need to increase bone density

- Often require high daily doses (1,000–1,200 mg) to have even a modest effect—and even then, clinical studies show they merely slow bone loss rather than increase bone density.

Plant-based calcium

Plant calcium comes from living organisms—for example, the marine algae used in AlgaeCal (Mesophyllum superpositum). This algae absorbs a wide spectrum of ocean minerals as it grows, creating a natural mineral matrix similar to human bone.

Key advantages include:

- Better absorption: Your body recognizes plant minerals as food, allowing more efficient uptake even at lower doses (the 720 mg in AlgaeCal was the exact amount used in clinical trials that stopped bone loss).

- Complete mineral profile: Along with calcium, the algae naturally provides magnesium, boron, silica, zinc, and other trace minerals proven to support new bone formation.

- Clinical evidence: Human studies show plant-based AlgaeCal not only slows bone loss, but can stop bone loss—something no other calcium has ever demonstrated.

Bottom line

Rock-based calcium is literally ground stone. Hard to absorb and incomplete. Plant-based calcium is food for your bones: easier to digest, naturally balanced with essential co-factors, and clinically shown to help your bones grow stronger

AlgaeCal isn’t just another algae calcium. It’s the only one of its kind.

- Exclusive Source:

AlgaeCal has the worldwide exclusive rights to a rare red marine algae called Mesophyllum superpositum. No other supplement company can use this species. This unique algae naturally absorbs a complete spectrum of 13 bone-supporting minerals in ratios that closely match human bone.

- Clinically Supported:

AlgaeCal is the only calcium supplement—of any kind—that is supported by published human clinical studies showing actual increases in bone density.

Other algae-based calciums may provide plant calcium, but none have peer-reviewed research demonstrating measurable bone gains.

Because of this exclusive species and unmatched clinical evidence, AlgaeCal stands alone as the only algae-based calcium that is both unique in source and supported to strengthen bones.

Every serving of AlgaeCal delivers a whole-food mineral complex harvested from the exclusive marine algae Mesophyllum superpositum—plus added vitamin D3 to help your body absorb it. Together, these nutrients create the complete mineral matrix clinically supported to stop bone loss:

Naturally Occurring Minerals (from the algae)

- Calcium – the primary structural mineral of bone

- Magnesium – helps activate vitamin D and supports new bone formation

- Boron – aids calcium and magnesium absorption and supports bone-protective hormones

- Zinc – essential for collagen production and bone tissue repair

- Copper – strengthens collagen cross-links for resilient bones

- Manganese – assists in cartilage and connective tissue formation

- Selenium – antioxidant that protects bone cells from oxidative stress

- Strontium – supports bone formation and reduces bone breakdown

- Silica (Silicon) – promotes collagen production and mineralization

- Vanadium – helps regulate enzymes involved in bone growth

- Nickel – trace mineral involved in bone and cartilage enzyme function

- Phosphorus – partners with calcium to form the mineral crystals that harden bone

- Potassium – helps maintain a pH balance that prevents mineral loss from bone

Added Nutrient

- Vitamin D3 – enhances calcium absorption so minerals reach your bones

Take AlgaeCal to STOP bone loss. Take AlgaeCal Plus to INCREASE bone density. Both products begin with the same foundation: plant-based calcium from our exclusive red marine algae (Mesophyllum superpositum), which naturally provides all 13 essential bone-supporting minerals. 

AlgaeCal is ideal for people who cannot take vitamin K2, such as those using older anticoagulant (blood-thinning) medications like warfarin or Coumadin, because it delivers the complete mineral matrix with vitamin D3 and without vitamin K2. 

AlgaeCal Plus contains everything in AlgaeCal but goes a step further by adding vitamin C for collagen formation and vitamin K2-7 (MK-7) to guide calcium safely into bones and away from soft tissues, while also providing slightly more vitamin D3, magnesium, and boron for even stronger bone support. 

Clinical studies show that AlgaeCal Plus produces the greatest improvements in bone density, so if you’re not on an older blood thinner—or if you’ve switched to a newer anticoagulant that doesn’t interact with K2—AlgaeCal Plus is the best choice for maximum bone-building benefits.

Real increases in bone mineral density, related to AlgaeCal, have been shown in women over age 40. This is certainly preferred over merely slowing down bone loss. However, the increase takes longer and is not as great as the recommended combination of AlgaeCal Plus and Strontium Boost.

AlgaeCal Plus contains vitamin K2, which is contraindicated for those taking older classes of anticoagulant prescriptions. Two newer types of blood thinners, XA Inhibitors and Direct Thrombin Inhibitors, don’t interact with vitamin K. However, for those unable to switch, we recommend AlgaeCal as the best option.

For the greatest bone-health benefits, patients should take 3 AlgaeCal capsules a day. That’s the dose used by clinical study participants who saw small increases in their bone density after one year.

We recommend splitting the daily 3 capsule dose into 3 servings throughout the day. And it’s best to take AlgaeCal with food for better absorption.