21st Century Melatonin 5 mg
vs
Metagenics Ultra Potent-C® 1000 Vitamin C
Supplement Comparison

  • Calcium: 21st Century Melatonin 5 mg has 2.4× more
  • The image below shows:
    • Side-by-side charts with label nutrient amounts, per serving
    • Nutrient forms as listed on the label
    • 10 nutrients compared
Bar chart: per-serving label amounts and listed forms for 21st Century Melatonin 5 mg vs Metagenics Ultra Potent-C® 1000 Vitamin C.

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Frequently asked questions

Which active ingredients does 21st Century Melatonin 5 mg have?

  • Calcium appears as Calcium Carbonate
  • Melatonin

Which active ingredients does Metagenics Ultra Potent-C® 1000 Vitamin C have?

  • Vitamin C
  • Vitamin B3 (Niacin)
  • Calcium
  • Sodium
  • L-Lysine
  • Glutathione
  • Citrus Bioflavonoid Complex
  • L-Cysteine

Which categories do 21st Century Melatonin 5 mg and Metagenics Ultra Potent-C® 1000 Vitamin C belong to?

  • Sleep Formula
  • Single Vitamin

What health concerns do 21st Century Melatonin 5 mg and Metagenics Ultra Potent-C® 1000 Vitamin C address?

  • Sleep Quality
  • Antioxidant Support
  • General Health
  • Immune System Support

Which product has a higher amount of Calcium per serving?

  • 21st Century Melatonin 5 mg has the highest total amount of Calcium: 94 mg per serving

How do the serving sizes compare between the two supplements?

  • Serving size:
    • 21st Century Melatonin 5 mg: 1 tablet
    • Metagenics Ultra Potent-C® 1000 Vitamin C: 1 tablet
  • Calcium
    • This supplement has 94 mg
    • Recommended Dietary Allowance in men: 1000 mg
    • Recommended Dietary Allowance in women: 1000 mg
    • Tolerable Upper Intake Level: 2500 mg
  • Vitamin C
    • This supplement has 1000 mg
    • Recommended Dietary Allowance in men: 90 mg
    • Recommended Dietary Allowance in women: 75 mg
    • Tolerable Upper Intake Level: 2000 mg
  • Vitamin B3 (Niacin)
    • This supplement has 70 mg
    • Recommended Dietary Allowance in men: 16 mg
    • Recommended Dietary Allowance in women: 14 mg
    • Tolerable Upper Intake Level: 35 mg
  • Calcium
    • This supplement has 40 mg
    • Recommended Dietary Allowance in men: 1000 mg
    • Recommended Dietary Allowance in women: 1000 mg
    • Tolerable Upper Intake Level: 2500 mg
  • Sodium
    • This supplement has 10 mg
    • Adequate Intake in men: 1500 mg
    • Adequate Intake in women: 1500 mg
    • Tolerable Upper Intake Level: Not established

Last updated: February 19, 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