Swanson Vitamin B12
vs
21st Century Vitamin B-12 1000 mcg
Supplement Comparison

  • Vitamin B12 (Cobalamin): 21st Century Vitamin B-12 1000 mcg has 2.0× more
  • The image below shows:
    • Side-by-side charts with label nutrient amounts, per serving
    • Nutrient forms as listed on the label
    • 3 nutrients compared
Bar chart: per-serving label amounts and listed forms for Swanson Vitamin B12 vs 21st Century Vitamin B-12 1000 mcg.

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Frequently asked questions

Which active ingredients does Swanson Vitamin B12 have?

  • Vitamin B12 (Cobalamin) appears as Cyanocobalamin

Which active ingredients does 21st Century Vitamin B-12 1000 mcg have?

  • Vitamin B12 (Cobalamin) appears as Cyanocobalamin
  • Calcium appears as Calcium Carbonate

Which categories do Swanson Vitamin B12 and 21st Century Vitamin B-12 1000 mcg belong to?

  • Single Vitamin

What health concerns do Swanson Vitamin B12 and 21st Century Vitamin B-12 1000 mcg address?

  • Energy & Metabolism
  • Metabolic Support
  • Heart & Cardiovascular Health
  • General Health

Which product has a higher amount of Vitamin B12 (Cobalamin) per serving?

  • 21st Century Vitamin B-12 1000 mcg has the highest total amount of Vitamin B12 (Cobalamin): 1000 mcg per serving

How do the serving sizes compare between the two supplements?

  • Serving size:
    • Swanson Vitamin B12: 1 capsule
    • 21st Century Vitamin B-12 1000 mcg: 1 tablet
  • Vitamin B12 (Cobalamin)
    • This supplement has 500 mcg
    • Recommended Dietary Allowance in men: 2.4 mcg
    • Recommended Dietary Allowance in women: 2.4 mcg
    • Tolerable Upper Intake Level: Not established
  • Vitamin B12 (Cobalamin)
    • This supplement has 1000 mcg
    • Recommended Dietary Allowance in men: 2.4 mcg
    • Recommended Dietary Allowance in women: 2.4 mcg
    • Tolerable Upper Intake Level: Not established
  • Calcium
    • This supplement has 100 mg
    • Recommended Dietary Allowance in men: 1000 mg
    • Recommended Dietary Allowance in women: 1000 mg
    • Tolerable Upper Intake Level: 2500 mg

Last updated: February 18, 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.
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  • Author: VIOscan Research Team