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Calcium 500+D3

21st Century
4.8
(10464 ratings)
Calcium 500 mg
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Score96

A natural oyster-shell calcium supplement with D3 for affordable and simple bone support.

How scoring works
Quantity:90 Tablet(s)(90 servings)
Goals:
Bone Health

Score 96

A natural oyster-shell calcium supplement with D3 for affordable and simple bone support.

How scoring works
$5.49($0.06 per serving)
iHerb
$ 4.67
iHerb
$ 4.67
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Analysis

Using oyster shell provides a natural source of calcium carbonate, which can help maintain the mineral matrix of your bones. The addition of vitamin D3 assists with the absorption process to make the supplement more effective. It is a moderate 500mg dose, which is generally very well-tolerated by most people.

This fits well for someone looking for a simple, nature-derived mineral supplement at a very low price. The tablets are easy to take and provide the foundational support needed for skeletal strength. It's a practical choice for everyday mineral repletion.

Pros

  • Natural marine-derived calcium
  • Includes Vitamin D3
  • Very budget-friendly
  • Moderate 500mg serving size
  • Easy to swallow compared to higher doses

Cons

  • Avoid if you have shellfish allergies
  • Vitamin D dose is relatively low
  • Requires food for proper absorption

Warnings

  • Take with a full meal
  • Avoid if you are sensitive to seafood
  • Store in a cool, dry place

Nutrient quality

88 Highest impact

Inclusion of vitamin D3 enhances the utility of the calcium carbonate source for skeletal support. While bioavailability of the mineral is moderate, the synergistic pairing is appropriate for maintenance.

Ingredient transparency

99 Highest impact

Labeling clearly identifies the oyster shell source and quantifies the active components. Consumer transparency is supported by clear intake instructions and disclosure of excipients.

Customer satisfaction

97 Highest impact

High ratings across a massive user base confirm the product's reliability and perceived benefit. Feedback indicates the supplement is well-tolerated and effective for routine bone support.

Value for money

100 Highest impact

Pricing is exceptionally low for a synergistic mineral and vitamin supplement. High serving value makes this a top choice for budget-conscious users seeking skeletal support.

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Goals

Impact
High effect
A Goal FitB Strength of SupportC- CoverageA- Formula Quality

Calcium derived from oyster shells is provided here as the primary building block for the skeletal mineral matrix. Vitamin D3 is included at a low maintenance dose of 5 mcg to assist with the intestinal absorption of the calcium provided.

While aligned with structural goals, the 500 mg dose of calcium carbonate is most effective when taken with meals to ensure proper solubility. The formula lacks magnesium and trace minerals, which are necessary cofactors for high-quality bone formation.

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Ingredients

IngredientAmount per serving
Vitamin D3 (Cholecalciferol)
5 mcg
Calcium (Oyster)
500 mg
Gluten Free Adults 18–50
Report overview
Calcium (Oyster) · 500 mg OverallScore70
C+ Active Ingredient Quality & BioavailabilityC Dose, Safety & Label TransparencyA+ Value
This oyster shell-based calcium supplement provides a standard dose with Vitamin D3. It is incredibly affordable, though the oyster shell source is essentially calcium carbonate and may carry risks for those with seafood sensitivities.
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