Metagenics Magnesium L-Threonate
vs
21st Century Calcium Magnesium Zinc + D3
Supplement Comparison

  • Magnesium: 21st Century Calcium Magnesium Zinc + D3 has 4.1× more
  • The image below shows:
    • Side-by-side charts with label nutrient amounts, per serving
    • Nutrient forms as listed on the label
    • 8 nutrients compared
Bar chart: per-serving label amounts and listed forms for Metagenics Magnesium L-Threonate vs 21st Century Calcium Magnesium Zinc + D3.

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Frequently asked questions

Which active ingredients does Metagenics Magnesium L-Threonate have?

  • Magnesium appears as Magtein Magnesium L-Threonate

Which active ingredients does 21st Century Calcium Magnesium Zinc + D3 have?

  • Vitamin D appears as Cholecalciferol (D3)
  • Calcium appears as Calcium Carbonate
  • Magnesium appears as Magnesium Oxide
  • Zinc appears as Zinc Oxide

Which categories do Metagenics Magnesium L-Threonate and 21st Century Calcium Magnesium Zinc + D3 belong to?

  • Single Mineral
  • Mineral Complex

What health concerns do Metagenics Magnesium L-Threonate and 21st Century Calcium Magnesium Zinc + D3 address?

  • Muscle Support
  • Brain, Focus & Cognitive Function
  • Sleep Quality
  • Stress Management
  • Eye Health
  • General Health
  • Heart & Cardiovascular Health
  • Immune System Support
  • Joint & Bone Health
  • Men's Health
  • Skin, Hair & Nail Health

Which product has a higher amount of Magnesium per serving?

  • 21st Century Calcium Magnesium Zinc + D3 has the highest total amount of Magnesium: 400 mg per serving

How do the serving sizes compare between the two supplements?

  • Serving size:
    • Metagenics Magnesium L-Threonate: 2 capsules
    • 21st Century Calcium Magnesium Zinc + D3: 3 tablets
  • Vitamin D
    • This supplement has 400 IU
    • Recommended Dietary Allowance in men: 600 IU
    • Recommended Dietary Allowance in women: 600 IU
    • Tolerable Upper Intake Level: 4000 IU
  • Calcium
    • This supplement has 1000 mg
    • Recommended Dietary Allowance in men: 1000 mg
    • Recommended Dietary Allowance in women: 1000 mg
    • Tolerable Upper Intake Level: 2500 mg
  • Zinc
    • This supplement has 15 mg
    • Recommended Dietary Allowance in men: 11 mg
    • Recommended Dietary Allowance in women: 8 mg
    • Tolerable Upper Intake Level: 40 mg

Last updated: February 4, 2026

  • Sources & Methodology: Nutrient data and forms are taken directly from Supplement Facts labels. Reviewed and standardized by the VIOscan Research Team. Learn more on the Methodology page.
  • We show the Recommended Dietary Allowance (RDA) when available. If no RDA exists, we show the Adequate Intake (AI). Tolerable Upper Intake Levels (UL) are used for upper limits. Unless otherwise noted, RDAs shown correspond to healthy adults aged 19–50 years and are sex-specific. Separate values exist for 51–70 years and >70 years, and pregnancy and lactation are excluded. All values come from the Dietary Reference Intakes (DRIs) published by the National Academies of Sciences, Engineering, and Medicine (NASEM), Food and Nutrition Board (FNB).
  • Transparency: We’re funded by our users. We don’t have sponsors or affiliate links, and we don’t sell supplements.
  • Editorial standards: we provide independent, impartial and objective data analysis.
  • This analysis is for educational purposes only. It is not a substitute for medical advice.
  • Questions? Read our Frequently Asked Questions or contact us, we’re here to help.
  • See an error? Report it through our Contact page.
  • Author: VIOscan Research Team