21st Century Calcium 500 + D3, 15 mcg (600 IU), 90 Tablets supplement bottle
21st Century

Calcium 500 + D3, 15 mcg (600 IU), 90 Tablets

What We Researched
2 active ingredients analyzed · 9 inactive ingredients decoded · 2 brand certifications checked · 2 retailers compared · Last updated: Mar 2026
83
Product Score Good
76
Brand Score Fair

Product Analysis

Transparency Excellent

Supplement Facts

IngredientAmount% DV
Vitamin D3 (as Cholecalciferol) (600 IU) 15 mcg 75%
Calcium (from Oyster Shell) 500 mg 38%
Bioavailability Excellent

Absorption Rating

  • Vitamin D3 (as Cholecalciferol) (600 IU) Good
  • Calcium (from Oyster Shell) Good
Other Ingredients Fair

Fillers & Additives

  • Maltodextrin
  • Croscarmellose Sodium
  • Cellulose
  • Magnesium Silicate
  • Magnesium Stearate
  • PEG Medium
  • Polyvinyl Alcohol
  • Stearic Acid
  • Titanium Dioxide High
Efficacy Excellent

Dosage Analysis

  • Vitamin D3 (as Cholecalciferol) (600 IU) 15 mcg Effective
  • Calcium (from Oyster Shell) 500 mg Effective

Supplement Facts

Ingredient Amount % Daily Value
Vitamin D3 (as Cholecalciferol) (600 IU) 15 mcg 75%
Calcium (from Oyster Shell) 500 mg 38%

Other Ingredients

Inactive ingredients used in manufacturing. All rated for safety.

Maltodextrin Generally_safe

Helps carry and stabilize active ingredients. Provides bulk.

Croscarmellose Sodium Safe

Helps tablets break apart and dissolve quickly in the stomach.

Cellulose Safe

Provides bulk and structure in tablets and capsules.

Magnesium Silicate Generally_safe

It is used to improve powder flow and prevent clumping.

Magnesium Stearate Safe

Prevents ingredients from sticking to manufacturing equipment during tableting.

PEG Caution

It is used as a binder, coating, or emulsifier.

Polyvinyl Alcohol Generally_safe

It is used as a coating for tablets or capsules.

Stearic Acid Safe

Helps ingredients flow smoothly through manufacturing equipment.

Titanium Dioxide Caution

Used as a whitening agent in tablet coatings and capsules.

Price Comparison

Price History

Tracked across major retailers. Updated periodically.

$7$6$5$4$3 Mar 12 $5.49
iHerb

Prices shown at time of last check. Click a retailer to see current price. GoodSupp is not affiliated with any retailer.

Brand Trust Report
21st Century

Founded 1991 · Tempe, Arizona, United States · 231 products · 21stcenturyvitamins.com/

Certifications

2 certifications
Consumerlab Verified
Nsf Gmp Verified Source

Transparency

4 claims
Third Party Testing Claim — Claimed Source
Testing Lab Disclosure — Verified Source
In House Testing — Verified Source

Violation History

4 incidents
Prop 65 Lead2021-06-22Source
Recall Vitamin D3 5000 IU Tablets2021-05-19Source
Lawsuit False advertising of Glucosamine/Chondroitin supplements.2012Source
Prop 65 Lead2008-12-23Source
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Frequently Asked Questions
Is 21st Century Calcium 500 + D3, 15 mcg (600 IU) a good supplement?

21st Century Calcium 500 + D3, 15 mcg (600 IU), 90 Tablets received a product quality score of 83/100 in GoodSupp's independent analysis, indicating strong overall quality. The product contains 2 active ingredients Of the 9 inactive ingredients, 4 are rated safe and 2 are flagged for review. The manufacturer, 21st Century, holds a brand trust score of 76/100 with 2 verified certifications including Consumerlab, Nsf Gmp.

What are the ingredients in 21st Century Calcium 500 + D3, 15 mcg (600 IU)?

21st Century Calcium 500 + D3, 15 mcg (600 IU) contains 2 active ingredients: Vitamin D3 (as Cholecalciferol) (600 IU) (15 mcg), Calcium (from Oyster Shell) (500 mg). Each ingredient's dosage, form, and safety rating is analyzed independently in GoodSupp's full product breakdown.

Is 21st Century Calcium 500 + D3, 15 mcg (600 IU) safe to take?

21st Century Calcium 500 + D3, 15 mcg (600 IU), 90 Tablets has been analyzed for ingredient safety across all its components. Of 9 inactive ingredients, 4 are rated safe. 2 ingredients are flagged for review: PEG, Titanium Dioxide. 'Caution' doesn't mean dangerous — it indicates the ingredient has some considerations worth being aware of, such as potential sensitivities or ongoing research. Always consult your healthcare provider before starting any new supplement, especially if you take medications or have underlying health conditions.

Is 21st Century a trustworthy supplement brand?

21st Century receives a brand trust score of 76/100 based on GoodSupp's independent analysis of certifications, regulatory history, and transparency practices. Founded in 1991 and headquartered in Tempe, Arizona, United States, the company offers 231 products in their lineup. They hold 2 verified certifications including Consumerlab, Nsf Gmp. Third-party certifications are independently verified and indicate the brand meets specific quality, purity, and manufacturing standards. Note: 21st Century has 4 historical regulatory incidents on record, which are factored into the trust score.

What is magnesium good for?

Magnesium Good For is a topic many supplement consumers ask about. In the context of dietary supplements, understanding magnesium good for helps you make more informed choices about what you put in your body. The quality and form of ingredients matters significantly — two products listing the same ingredient can differ dramatically in bioavailability and effectiveness. GoodSupp analyzes over 250,000 supplement products to help consumers understand exactly what's in their supplements and whether the formulation meets quality standards.

How much magnesium per day?

The optimal dosage depends on your individual health needs, age, sex, and current nutrient levels. Recommended daily amounts are established by health authorities but may vary from therapeutic doses used in clinical research. It's important to check the Supplement Facts label for the exact amount per serving and compare it against the % Daily Value. Some supplements provide mega-doses well above the Daily Value, which may not be necessary and in some cases could be harmful — particularly for fat-soluble vitamins (A, D, E, K) that accumulate in the body. GoodSupp's efficacy analysis evaluates whether a product's dosages align with clinically studied amounts. Always consult your healthcare provider for personalized dosage recommendations.

What is zinc good for?

Zinc Good For is a topic many supplement consumers ask about. In the context of dietary supplements, understanding zinc good for helps you make more informed choices about what you put in your body. The quality and form of ingredients matters significantly — two products listing the same ingredient can differ dramatically in bioavailability and effectiveness. GoodSupp analyzes over 250,000 supplement products to help consumers understand exactly what's in their supplements and whether the formulation meets quality standards.

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Disclaimer: GoodSupp provides independent supplement quality analysis for informational purposes only. Scores are generated algorithmically based on ingredient profiles, brand certifications, and public records. This is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Product data is sourced from manufacturer labels and public databases. GoodSupp is not affiliated with any supplement brand.