NOW Foods Calcium & Magnesium
vs
Douglas Laboratories Sereniten Plus
Supplement Comparison

  • Vitamin D: NOW Foods Calcium & Magnesium has 4.0× 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 NOW Foods Calcium & Magnesium vs Douglas Laboratories Sereniten Plus.

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Frequently asked questions

Which active ingredients does NOW Foods Calcium & Magnesium have?

  • Vitamin D appears as Cholecalciferol (D3)
  • Calcium appears as Calcium Carbonate and Citrate
  • Magnesium appears as Magnesium Oxide and Citrate
  • Zinc appears as Zinc Oxide

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 NOW Foods Calcium & Magnesium and Douglas Laboratories Sereniten Plus belong to?

  • Mineral Complex
  • Single Mineral
  • Herbal Extract

What health concerns do NOW Foods Calcium & Magnesium and Douglas Laboratories Sereniten Plus address?

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

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

  • NOW Foods Calcium & Magnesium has the highest total amount of Vitamin D: 400 IU per serving

How do the serving sizes compare between the two supplements?

  • Serving size:
    • NOW Foods Calcium & Magnesium: 2 softgels
    • Douglas Laboratories Sereniten Plus: 1 capsule
  • Vitamin D
    • This supplement has 400 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 667 mg
    • Recommended Dietary Allowance in men: 1000 mg
    • Recommended Dietary Allowance in women: 1000 mg
    • Tolerable Upper Intake Level: 2500 mg
  • Zinc
    • This supplement has 25 mg
    • Recommended Dietary Allowance in men: 11 mg
    • Recommended Dietary Allowance in women: 8 mg
    • Tolerable Upper Intake Level: 40 mg
  • 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 15, 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