Doctor's Best Vitamin D3 2000 IU
vs
Douglas Laboratories Sereniten Plus
Supplement Comparison

  • Vitamin D: Doctor's Best Vitamin D3 2000 IU has 20× more
  • The image below shows:
    • Side-by-side charts with label nutrient amounts, per serving
    • Nutrient forms as listed on the label
    • 5 nutrients compared
Bar chart: per-serving label amounts and listed forms for Doctor's Best Vitamin D3 2000 IU vs Douglas Laboratories Sereniten Plus.

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Frequently asked questions

Which active ingredients does Doctor's Best Vitamin D3 2000 IU have?

  • Vitamin D appears as Cholecalciferol (D3)

Which active ingredients does Douglas Laboratories Sereniten Plus have?

  • Vitamin D appears as Cholecalciferol (D3)
  • L-Theanine appears as Suntheanine L-Theanine
  • Casein appears as Lactium Casein Decapeptide (containing bioactive decapeptide)

Which categories do Doctor's Best Vitamin D3 2000 IU and Douglas Laboratories Sereniten Plus belong to?

  • Single Vitamin
  • Herbal Extract

What health concerns do Doctor's Best Vitamin D3 2000 IU and Douglas Laboratories Sereniten Plus address?

  • General Health
  • Heart & Cardiovascular Health
  • Immune System Support
  • Joint & Bone Health
  • Mood Support
  • Stress Management

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

  • Doctor's Best Vitamin D3 2000 IU has the highest total amount of Vitamin D: 2000 IU per serving

How do the serving sizes compare between the two supplements?

  • Serving size:
    • Doctor's Best Vitamin D3 2000 IU: 1 softgel
    • Douglas Laboratories Sereniten Plus: 1 capsule
  • 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
  • Vitamin D
    • This supplement has 100 IU
    • Recommended Dietary Allowance in men: 600 IU
    • Recommended Dietary Allowance in women: 600 IU
    • Tolerable Upper Intake Level: 4000 IU

Last updated: February 2, 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