Thorne Ferrasorb
vs
21st Century Vitamin C
Supplement Comparison

  • Vitamin C: 21st Century Vitamin C has 33× more
  • The image below shows:
    • Side-by-side charts with label nutrient amounts, per serving
    • Nutrient forms as listed on the label
    • 11 nutrients compared
Bar chart: per-serving label amounts and listed forms for Thorne Ferrasorb vs 21st Century Vitamin C.

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Frequently asked questions

Which active ingredients does Thorne Ferrasorb have?

  • Vitamin C appears as Ascorbic Acid
  • Vitamin B6 (Pyridoxine) appears as Pyridoxal 5-Phosphate
  • Vitamin B9 (Folate) appears as L-5-Methyltetrahydrofolate
  • Vitamin B12 (Cobalamin) appears as Methylcobalamin
  • Iron appears as Ferrochel Ferrous Bisglycinate Chelate (Albion)

Which active ingredients does 21st Century Vitamin C have?

  • Vitamin C appears as Ascorbic Acid
  • Calcium appears as Calcium Carbonate

Which categories do Thorne Ferrasorb and 21st Century Vitamin C belong to?

  • Single Mineral
  • Single Vitamin

What health concerns do Thorne Ferrasorb and 21st Century Vitamin C address?

  • Energy & Metabolism
  • Women's Health
  • Antioxidant Support
  • Immune System Support

Which product has a higher amount of Vitamin C per serving?

  • 21st Century Vitamin C has the highest total amount of Vitamin C: 500 mg per serving

How do the serving sizes compare between the two supplements?

  • Serving size:
    • Thorne Ferrasorb: 1 capsule
    • 21st Century Vitamin C: 1 tablet
  • Vitamin C
    • This supplement has 15 mg
    • Recommended Dietary Allowance in men: 90 mg
    • Recommended Dietary Allowance in women: 75 mg
    • Tolerable Upper Intake Level: 2000 mg
  • Vitamin B6 (Pyridoxine)
    • This supplement has 5 mg
    • Recommended Dietary Allowance in men: 1.3 mg
    • Recommended Dietary Allowance in women: 1.3 mg
    • Tolerable Upper Intake Level: 100 mg
  • Vitamin B9 (Folate)
    • This supplement has 667 mcg DFE
    • Recommended Dietary Allowance in men: 400 mcg DFE
    • Recommended Dietary Allowance in women: 400 mcg DFE
    • Tolerable Upper Intake Level: 1000 mcg DFE
  • Vitamin B12 (Cobalamin)
    • This supplement has 300 mcg
    • Recommended Dietary Allowance in men: 2.4 mcg
    • Recommended Dietary Allowance in women: 2.4 mcg
    • Tolerable Upper Intake Level: Not established
  • Iron
    • This supplement has 36 mg
    • Recommended Dietary Allowance in men: 8 mg
    • Recommended Dietary Allowance in women: 18 mg
    • Tolerable Upper Intake Level: 45 mg
  • Vitamin C
    • This supplement has 500 mg
    • Recommended Dietary Allowance in men: 90 mg
    • Recommended Dietary Allowance in women: 75 mg
    • Tolerable Upper Intake Level: 2000 mg
  • Calcium
    • This supplement has 30 mg
    • Recommended Dietary Allowance in men: 1000 mg
    • Recommended Dietary Allowance in women: 1000 mg
    • Tolerable Upper Intake Level: 2500 mg

Last updated: February 9, 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