NOW Foods Vitamin D-3 10000 IU
vs
21st Century Vitamin D3 2000 IU
Supplement Comparison

  • Vitamin D: NOW Foods Vitamin D-3 10000 IU has 5.0× more
  • The image below shows:
    • Side-by-side charts with label nutrient amounts, per serving
    • Nutrient forms as listed on the label
    • 1 nutrients compared
Bar chart: per-serving label amounts and listed forms for NOW Foods Vitamin D-3 10000 IU vs 21st Century Vitamin D3 2000 IU.

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Frequently asked questions

Which active ingredients does NOW Foods Vitamin D-3 10000 IU have?

  • Vitamin D appears as Cholecalciferol (D3)

Which active ingredients does 21st Century Vitamin D3 2000 IU have?

  • Vitamin D appears as Cholecalciferol (D3)

Which categories do NOW Foods Vitamin D-3 10000 IU and 21st Century Vitamin D3 2000 IU belong to?

  • Single Vitamin

What health concerns do NOW Foods Vitamin D-3 10000 IU and 21st Century Vitamin D3 2000 IU address?

  • Brain, Focus & Cognitive Function
  • General Health
  • Heart & Cardiovascular Health
  • Immune System Support
  • Joint & Bone Health

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

  • NOW Foods Vitamin D-3 10000 IU has the highest total amount of Vitamin D: 10000 IU per serving

How do the serving sizes compare between the two supplements?

  • Serving size:
    • NOW Foods Vitamin D-3 10000 IU: 1 softgel
    • 21st Century Vitamin D3 2000 IU: 1 softgel
  • Vitamin D
    • This supplement has 10000 IU
    • Recommended Dietary Allowance in men: 600 IU
    • Recommended Dietary Allowance in women: 600 IU
    • Tolerable Upper Intake Level: 4000 IU
  • Vitamin D
    • This supplement has 2000 IU
    • Recommended Dietary Allowance in men: 600 IU
    • Recommended Dietary Allowance in women: 600 IU
    • Tolerable Upper Intake Level: 4000 IU

Last updated: February 14, 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