Home Ingredients AlgaeCal® (Plant-Sourced Calcium — Lithothamnion)
Bone Health

AlgaeCal® (Plant-Sourced Calcium — Lithothamnion)

Lithothamnion superpositum
Evidence Level
Moderate
1 Clinical Trial
3 Documented Benefits
3/5 Evidence Score

AlgaeCal® is a plant-sourced calcium derived from the marine red algae Lithothamnion, which absorbs calcium, magnesium, and dozens of trace minerals from seawater as it grows. Unlike rock-based calcium carbonate, it delivers calcium alongside its naturally occurring mineral cofactors, and the AlgaeCal Plus formula adds magnesium, boron, and vitamins D3 and K2. It is best known for a multi-year longitudinal study reporting increased, rather than merely maintained, bone mineral density.

Studied Dose Around 720 mg of elemental plant calcium per day, taken with the accompanying magnesium, trace minerals, vitamin D3, and vitamin K2.
Active Compound Whole-algae calcium from Lithothamnion, naturally containing magnesium, boron, and 70-plus trace minerals; the AlgaeCal Plus formula adds vitamin D3 and vitamin K2 (MK-7).

Benefits

Bone mineral density

In a multi-year study, adults taking the plant-calcium complex showed increases in bone mineral density over time, a notable result since most calcium supplements aim only to slow bone loss rather than reverse it.

Supported by Trial 1

Mineral cofactors for bone

Calcium works best with partners. The complex supplies magnesium, boron, vitamin D3, and vitamin K2, the cofactors that help direct calcium into bone rather than soft tissue.

Supported by Trial 1

Plant-based and food-form

As a whole-algae, food-form mineral, it offers a plant-based alternative to rock-derived calcium carbonate for people who prefer that source.

Supported by Trial 1

Mechanism of action

1

Bioavailable plant calcium

Calcium is delivered in a porous, food-bound algal matrix alongside trace minerals, which the manufacturer's research links to favorable absorption and bone outcomes.

2

Vitamin K2 and D3 cofactors

Vitamin D3 supports calcium absorption while vitamin K2 activates osteocalcin and matrix Gla protein, helping deposit calcium in bone and keep it out of arteries.

Clinical trials

1
Plant Calcium and Bone Density — 7-Year Study
PubMed

A 7-year longitudinal study of the safety and efficacy of the AlgaeCal plant-calcium plus vitamin and mineral program on bone mineral density. (Kaats et al. 2016, Journal of the American College of Nutrition). Note: open-label longitudinal design, not placebo-controlled.

Adults supplementing for bone health.

Participants showed annual increases in bone mineral density over the multi-year period with a good safety profile, an unusual finding for a calcium program. Because the study was open-label, results should be read with that limitation in mind.

Side effects and drug interactions

Common Potential side effects

Generally well-tolerated — mild digestive symptoms such as bloating or constipation can occur, as with any calcium.
Taking it with food and splitting the dose improves comfort and absorption.
Excess total calcium from all sources should be avoided; stay within recommended daily limits.

Important Drug interactions

Thyroid medication (levothyroxine) — calcium can reduce absorption; separate by at least 4 hours.
Certain antibiotics (tetracyclines, fluoroquinolones) — calcium binds them; separate dosing.
Bisphosphonates — calcium interferes with absorption; take at a different time.

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Frequently asked questions about AlgaeCal® (Plant-Sourced Calcium — Lithothamnion)

What is AlgaeCal?

AlgaeCal® is a plant-sourced calcium derived from the marine red algae Lithothamnion, which absorbs calcium, magnesium, and dozens of trace minerals from seawater as it grows.

What is AlgaeCal used for?

AlgaeCal is researched primarily for Bone Health. In a multi-year study, adults taking the plant-calcium complex showed increases in bone mineral density over time, a notable result since most calcium supplements aim only to slow bone loss rather than reverse it.

What is the recommended dosage of AlgaeCal?

The clinically studied dose is Around 720 mg of elemental plant calcium per day, taken with the accompanying magnesium, trace minerals, vitamin D3, and vitamin K2. Always follow the product label and check with a healthcare provider for personal advice.

Is AlgaeCal safe, and does it have side effects?

For most healthy adults, AlgaeCal is well tolerated at studied doses. Reported effects can include: Generally well-tolerated — mild digestive symptoms such as bloating or constipation can occur, as with any calcium. Taking it with food and splitting the dose improves comfort and absorption. It may also interact with some medications. AlgaeCal is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does AlgaeCal interact with any medications?

Possible interactions include: Thyroid medication (levothyroxine) — calcium can reduce absorption; separate by at least 4 hours. Certain antibiotics (tetracyclines, fluoroquinolones) — calcium binds them; separate dosing. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for AlgaeCal?

NutraSmarts rates the evidence for AlgaeCal as Moderate (3 out of 5). It is backed by 1 clinical trial and 1 cited reference summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(1 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Kaats GR, Preuss HG, Stohs S, et al. A 7-Year Longitudinal Trial of the Safety and Efficacy of a Vitamin/Mineral Enhanced Plant-Sourced Calcium Supplement. J Am Coll Nutr. 2016;35(2):91-9..PubMedUsed to support: Longitudinal evidence of increased bone mineral density (bone-density benefit).