21st Century Vitamin D3 5000 IU
vs
Klean Athlete Klean-D 5000 IU
Supplement Comparison

  • Vitamin D: same total amount on both labels
  • 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 21st Century Vitamin D3 5000 IU vs Klean Athlete Klean-D 5000 IU.

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Frequently asked questions

Which active ingredients does 21st Century Vitamin D3 5000 IU have?

  • Vitamin D appears as Cholecalciferol (D3)
  • Calcium appears as Calcium Carbonate

Which active ingredients does Klean Athlete Klean-D 5000 IU have?

  • Vitamin D appears as Cholecalciferol (D3)

Which categories do 21st Century Vitamin D3 5000 IU and Klean Athlete Klean-D 5000 IU belong to?

  • Single Vitamin

What health concerns do 21st Century Vitamin D3 5000 IU and Klean Athlete Klean-D 5000 IU address?

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

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

  • Both products list the same total amount of Vitamin D per serving

How do the serving sizes compare between the two supplements?

  • Serving size:
    • 21st Century Vitamin D3 5000 IU: 1 tablet
    • Klean Athlete Klean-D 5000 IU: 1 tablet
  • Vitamin D
    • This supplement has 5000 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 90 mg
    • Recommended Dietary Allowance in men: 1000 mg
    • Recommended Dietary Allowance in women: 1000 mg
    • Tolerable Upper Intake Level: 2500 mg
  • Vitamin D
    • This supplement has 5000 IU
    • Recommended Dietary Allowance in men: 600 IU
    • Recommended Dietary Allowance in women: 600 IU
    • Tolerable Upper Intake Level: 4000 IU

Last updated: February 5, 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