Mineral
Calcium
Also known as: Ca, Calcium ion
Essential mineral for bone health, muscle function, nerve signaling, and blood clotting.
Last reviewed June 2026 · Evidence graded from peer-reviewed research, not editorial opinion. Educational only — not medical advice.
Every Calcium product we have scored
| # | Product | Score | Per serving |
|---|---|---|---|
| 1 | Nutricost Calcium Citrate | 97 A | $0.28 |
| 2 | Thorne Protein Isolate - Chocolate | 96 A | $1.47 |
| 3 | Thorne Whey Protein Isolate - Vanilla | 96 A | $1.47 |
| 4 | NutraBio Whey Protein Isolate Powder | 96 A | $2.50 |
| 5 | Nutricost Calcium Citrate Powder | 95 A | $0.19 |
| 6 | Transparent Labs Grass-Fed Whey Protein Isolate | 95 A | $2.00 |
| 7 | Nutricost Calcium Citrate + Magnesium Citrate Powder | 94 A | $0.63 |
| 8 | Nutricost Calcium Citrate + Vitamin D | 93 A | $0.30 |
| 9 | Nutricost Calcium + Vitamin D3 Tablets | 92 A | $0.15 |
| 10 | Pure Encapsulations Calcium K/D | 92 A | $0.53 |
| 11 | Pure Encapsulations Calcium Magnesium (citrate/malate) | 92 A | $0.62 |
| 12 | Pure Encapsulations Calcium Magnesium (citrate) | 92 A | $0.57 |
Scored on dose accuracy, form, label transparency and third-party testing. Per-serving cost is list price divided by servings per container. No brand pays to be listed or ranked.
Common questions
How much Calcium should I take?
The typical range is 500-1200mg daily. Long-term
When should I take Calcium?
Divided doses. Carbonate yes, citrate optional.
Which form of Calcium is best?
Citrate — Well absorbed. Other forms in the catalog: Carbonate.
Is Calcium safe?
Commonly reported: Constipation, Gas. Serious warnings: Excess may increase cardiovascular risk. Caution in kidney disease
Which Calcium supplement scores highest?
Nutricost Calcium Citrate, at 97/100. Scored on dose accuracy, form, label transparency and third-party testing — no brand pays to be listed or ranked.
Daily target & upper limit
1300 mg / day · UL 2500 mgCalcium has an established daily reference intake. See best forms, label synonyms, upper-limit warnings, and top-scoring supplements:
Calcium dosage reference →Primary uses
- Bone health
- Muscle function
- Nerve signaling
What systematic reviews concluded
Outcomes that systematic reviews of Calcium reached a verdict on: 5 with a benefit, 1 with no effect. Each is quoted from a review and linked to it on PubMed. How these were read.
Reviews found a benefit (5)
“Perioperative calcium combined with vitamin D is the most effective strategy for preventing post-thyroidectomy hypocalcaemia and reducing intravenous calcium use, supporting routine postoperative implementation despite heterogeneity in supplementation protocols.” PMID 42397982
“calcium (OR=0.77, 95% CI 0.65, 0.91) were more effective in preventing preeclampsia” PMID 42397815
“Supplementation of vitamin D and/or calcium reduces the recurrence rate of BPPV in patients with low serum vitamin D levels.” PMID 42259062
“Dairy products fortified with calcium and vitamin D have a favorable effect on bone mineral density.” PMID 33237064
“Combined calcium and vitamin D supplementation could prevent osteoporosis hip fracture in postmenopausal women.” PMID 33237064
Reviews found no effect (1)
“this review found little to no benefits from use of calcium, vitamin D, or combined supplementation on the prevention of fractures and falls.” PMID 42161415
1 finding from reviews in specific patient groups (such as cancer, pregnancy or surgery) is not shown here.
How it works
- Structural component of bones/teeth
- Required for muscle contraction
- Nerve impulse transmission
Dosage
- Typical range
- 500-1200mg daily
- Timing
- Divided doses
- With food
- Carbonate yes, citrate optional
- Duration
- Long-term
- Special populations
- Post-menopausal women
Forms
- Citrate
- Carbonate
Safety
Common side effects
- Constipation
- Gas
Contraindications
- Hypercalcemia
Products containing Calcium
Top-scoring supplements in our catalog that list Calcium on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.
Known interactions
- Warningwith iron
Calcium significantly reduces iron absorption
- Cautionwith magnesium
High calcium can impair magnesium absorption
- Cautionwith zinc
Calcium may reduce zinc absorption
- Synergywith vitamin d
Vitamin D enhances calcium absorption
- Infowith antacids
Antacids reduce calcium absorption
- Warningwith thyroid medication
Calcium blocks thyroid medication absorption
Evidence notes
Essential mineral with strong evidence for bone health
Grade A: Multiple well-designed human trials support the main claims.
Cited research for Calcium
Clinical studies referenced across Formulate guides that mention calcium. Each links to the full study page with PubMed source + the guides that cite it.
- Bolland et al. (2015)BMJ
Calcium intake and risk of fracture: systematic review
- Hurrell R, Egli I (2010)American Journal of Clinical Nutrition
Iron bioavailability and dietary reference values
- Hallberg and Hulthén (2000)American Journal of Clinical Nutrition
Prediction of dietary iron absorption: an algorithm for calculating absorption and bioavailability
Related in Mineral
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Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider. Individual needs and risks vary — consult a professional before starting, stopping, or combining supplements, especially if you are pregnant or nursing, taking medication, or managing a health condition.