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Calcium

4.6
★ ★ ★ ★ ★
(97 ratings)
Calcium 1000 mg
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Score65

Substantial algae-derived calcium with some magnesium offers useful coverage, though the large dose, pill burden, and missing vitamin D are notable trade-offs.

How scoring works
Capsule
Quantity:120 Capsule(s) • (30 servings)
Goals:
Bone Health

Score 65

Substantial algae-derived calcium with some magnesium offers useful coverage, though the large dose, pill burden, and missing vitamin D are notable trade-offs.

How scoring works
$47.35($1.57 per serving)
iHerb
$ 47.35
Vitacost
$ 52.09
Pure Formulas
$ 47.35
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Analysis

The algae-derived ingredient supplies substantial calcium and some magnesium in one source. That offers broader mineral coverage than calcium alone, although magnesium remains modest relative to calcium.

A large daily calcium amount should be split when possible to improve absorption and tolerance. The formula does not include vitamin D or vitamin K, so those nutrients must come from diet, sunlight, or a separately planned supplement.

Multiple capsules are needed for the full serving, adding pill burden. The algae source may appeal to users avoiding oyster shell, but it does not remove the need to match the dose to dietary calcium.

Who is it for
  • Adults seeking algae-derived calcium
  • People avoiding oyster-shell calcium
  • Users willing to divide a multi-capsule dose
Best for
  • Large calcium gaps
  • Algae-based mineral supplementation
  • Calcium with modest magnesium

Pros

  • Algae-derived calcium source
  • Includes magnesium
  • Substantial calcium amount
  • Source amount is clearly stated

Cons

  • Large daily calcium amount
  • Multi-capsule serving
  • No vitamin D or vitamin K
  • Magnesium is modest

Warnings

  • Separate calcium from levothyroxine and certain antibiotics according to medication guidance.
  • High supplemental calcium requires guidance with kidney stones, high blood calcium, or kidney disease.
  • Check total dietary and supplemental calcium before using the full serving.

Nutrient quality

77 High impact

The algae-derived mineral source and companion magnesium provide useful bone-focused ingredients. The large calcium amount exceeds efficient single-dose absorption and lacks vitamin D support.

Ingredient transparency

65 High impact

Calcium and magnesium totals are disclosed, but the branded algae complex is not fully characterized. Intake directions and non-active capsule ingredients are not included in the supplied facts.

Customer satisfaction

64 Moderate impact

The aggregate rating is strong and has a useful response base. No review text is supplied, so repeated complaints and purpose-specific experiences cannot be verified.

Value for money

49 Lower impact

A premium algae source supports quality, but the large dose pattern and narrow cofactor coverage weaken price justification. The high ongoing cost compares poorly with simpler calcium options.

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Goals

Bone Health
Bone Health
Impact
High effect
B+ Goal FitA- Strength of SupportC CoverageB Formula Quality
Magnesium · 100 mgCalcium · 1000 mg

A full gram of calcium provides strong structural-mineral support, with magnesium as a useful companion. The algae-derived source is clearly identified and supplies a focused mineral complex.

No vitamin D, vitamin K, or matrix protein is listed, so mineral transport and protein-matrix pathways remain uncovered. Strong calcium depth makes the formula useful but not comprehensive.

Study evidence
Calcium Supportive 144 studies
Magnesium Supportive 48 studies

Ingredients

IngredientAmount per serving
Calcium (Certified Organic AlgaeCal)
 1000 mg
Magnesium (Certified Organic AlgaeCal)
 100 mg
certified organic AlgaeCal
3333 mg
Gluten Free Adults 18–50 Vegan Dairy Free Organic Vegetarian
Report overview
Calcium (Certified Organic AlgaeCal) · 1000 mg OverallScore70
A+ Active Ingredient Quality & BioavailabilityC Dose, Safety & Label TransparencyF Value

Certified organic algae-derived calcium provides a premium mineral source. The 1,000 mg serving exceeds the efficient per-dose absorption window, so divided intake would be more useful. Cost per serving provides poor value for the calcium delivered.

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Loading alternative details
88 Performance

Calcium Hydroxyapatite Caps

NOW
<p>Hydroxyapatite supplies a practical calcium amount with naturally paired phosphorus and clear dosing. Clearer forms and stronger calcium focus improve practical usefulness compared with the original formula.</p>
85 Performance

Cal/Mag 500 mg/250 mg

NaturesPlus
<p>Chelated calcium and magnesium provide a balanced mineral formula with strong form quality. Broader mineral and vitamin coverage gives it more bone-support depth than the original focused calcium formula.</p>
82 Performance

Ultra BoneUp

Jarrow Formulas
<p>Calcium, vitamin D3, magnesium, MK-7, silicon, boron, and cartilage collagen cover several bone pathways. Broader mineral and vitamin coverage gives it more bone-support depth than the original focused calcium formula. Magnesium oxide is a weakness, and vitamin K2 needs caution with warfarin-type medicines.</p>
84 Budget

600 Calcium Supplement

21st Century
<p>A straightforward 600 mg calcium carbonate tablet provides a focused serving without unrelated actives. It lowers routine cost while maintaining direct calcium support, although carbonate still works best with food.</p>
85 Budget

Calcium Carbonate

NOW
<p>A pure calcium carbonate powder supplies a substantial dose with simple active disclosure. It lowers routine cost while maintaining direct calcium support, although carbonate still works best with food.</p>
84 Budget

Calcium 600 with Vitamin D3

Nature's Bounty
<p>Calcium carbonate and vitamin D3 provide a direct bone-support pairing in a focused formula. It lowers routine cost while maintaining direct calcium support, although carbonate still works best with food.</p>
88 Value

Calcium Citrate Pure Powder

NOW
<p>Calcium citrate powder provides a substantial, well-absorbed dose with flexible use and strong serving value. Clearer forms and stronger calcium focus improve practical usefulness compared with the original formula. It does not include vitamin D, vitamin K, or magnesium.</p>
82 Value

Calcium Citrate

Nature's Way
<p>Citrate and malate improve absorption flexibility within a practical mixed-calcium serving at strong value. Clearer forms and stronger calcium focus improve practical usefulness compared with the original formula.</p>
85 Value

600+D3

21st Century
<p>A reasonably sized calcium carbonate serving with vitamin D3 provides focused bone support at very low routine cost. Clearer forms and stronger calcium focus improve practical usefulness compared with the original formula. Calcium should be separated from levothyroxine and tetracycline or quinolone antibiotics.</p>
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Sources

Published studies used for the product analysis and the top-ranked studies for each ingredient and goal.

  1. Calcium supplementation during pregnancy and maternal and offspring bone health: a systematic review and meta-analysis.
    Tihtonen K; Korhonen P; Isojärvi J; Ojala R; Ashorn U; Ashorn P; Tammela O · Annals of the New York Academy of Sciences · 2022
    Meta-analysis1,566 participants7 studies pooledBone Health forCalcium
  2. Calcium supplementation and bone mineral density in postmenopausal women using estrogen replacement therapy.
    Haines CJ; Chung TK; Leung PC; Hsu SY; Leung DH · Bone · 1995
    Randomized trialBone Health forCalcium
  3. Calcium supplementation provides an extended window of opportunity for bone mass accretion after menarche.
    Rozen GS; Rennert G; Dodiuk-Gad RP; Rennert HS; Ish-Shalom N; Diab G; Raz B; Ish-Shalom S · The American journal of clinical nutrition · 2003
    Randomized trial100 participantsBone Health forCalcium
  4. Relationship between bone mineral density changes and risk of fractures among patients receiving calcium with or without vitamin D supplementation: a meta-regression.
    Rabenda V; Bruyère O; Reginster JY · Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA · 2011
    Meta-analysis47,365 participants15 studies pooledBone Health forCalcium
  5. Treatment with alendronate plus calcium, alendronate alone, or calcium alone for postmenopausal low bone mineral density.
    Bonnick S; Broy S; Kaiser F; Teutsch C; Rosenberg E; DeLucca P; Melton M · Current medical research and opinion · 2007
    Randomized trial701 participantsBone Health forCalcium
  6. What is the impact of daily oral supplementation of vitamin D3 (cholecalciferol) plus calcium on the incidence of hip fracture in older people? A systematic review and meta-analysis.
    Manoj P; Derwin R; George S · International journal of older people nursing · 2023
    Meta-analysis12,620 participants7 studies pooledBone Health forCalcium
  7. Calcium supplementation prevents seasonal bone loss and changes in biochemical markers of bone turnover in elderly New England women: a randomized placebo-controlled trial.
    Storm D; Eslin R; Porter ES; Musgrave K; Vereault D; Patton C; Kessenich C; Mohan S; Chen T; Holick MF; Rosen CJ · The Journal of clinical endocrinology and metabolism · 1998
    Randomized trial60 participantsBone Health forCalcium
  8. The effects of calcium supplementation (milk powder or tablets) and exercise on bone density in postmenopausal women.
    Prince R; Devine A; Dick I; Criddle A; Kerr D; Kent N; Price R; Randell A · Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research · 1995
    Randomized trial168 participantsBone Health forCalcium
  9. The efficacy of calcium supplementation alone in elderly Thai women over a 2-year period: a randomized controlled trial.
    Rajatanavin R; Chailurkit L; Saetung S; Thakkinstian A; Nimitphong H · Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA · 2014
    Randomized trial404 participantsBone Health forCalcium
  10. Calcium-enriched foods and bone mass growth in prepubertal girls: a randomized, double-blind, placebo-controlled trial.
    Bonjour JP; Carrie AL; Ferrari S; Clavien H; Slosman D; Theintz G; Rizzoli R · The Journal of clinical investigation · 1997
    Randomized trial149 participantsBone Health forCalcium
  11. Association between Serum Magnesium and Fractures: A Systematic Review and Meta-Analysis of Observational Studies.
    Dominguez LJ; Veronese N; Ciriminna S; Pérez-Albela JL; Vásquez-López VF; Rodas-Regalado S; Di Bella G; Parisi A; Tagliaferri F; Barbagallo M · Nutrients · 2023
    Meta-analysis119,755 participants4 studies pooledBone Health forMagnesium
  12. Bioabsorbable Magnesium-Based Materials Potential and Safety in Bone Surgery: A Systematic Review.
    Hung CH; Kwok YC; Yip J; Wong HH; Leung YY · Craniomaxillofacial trauma & reconstruction · 2025
    Systematic review386 participants8 studies pooledBone Health forMagnesium
  13. Vascularized bone grafting fixed by biodegradable magnesium screw for treating osteonecrosis of the femoral head.
    Zhao D; Huang S; Lu F; Wang B; Yang L; Qin L; Yang K; Li Y; Li W; Wang W; Tian S; Zhang X; Gao W; Wang Z; Zhang Y; Xie X; Wang J; Li J · Biomaterials · 2016
    Randomized trial48 participantsBone Health forMagnesium
  14. An update on magnesium and bone health.
    Rondanelli M; Faliva MA; Tartara A; Gasparri C; Perna S; Infantino V; Riva A; Petrangolini G; Peroni G · Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine · 2022
    Narrative reviewBone Health forMagnesium
  15. Sex-specific differences in the association of magnesium intake with femoral neck bone mineral density among older adults.
    Wang B; Tan X; Yao X; Zhu Z · Endocrine connections · 2025
    Cross-sectional study1,343 participantsBone Health forMagnesium