Jarrow Arginine-Citrulline Sustain
vs
Douglas Laboratories C-1000
Supplement Comparison

  • Vitamin C: Douglas Laboratories C-1000 has 100× more
  • The image below shows:
    • Side-by-side charts with label nutrient amounts, per serving
    • Nutrient forms as listed on the label
    • 6 nutrients compared
Bar chart: per-serving label amounts and listed forms for Jarrow Arginine-Citrulline Sustain vs Douglas Laboratories C-1000.

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Frequently asked questions

Which active ingredients does Jarrow Arginine-Citrulline Sustain have?

  • Vitamin C appears as Calcium Ascorbate
  • L-Arginine appears as L-Arginine Free Base
  • L-Citrulline appears as L-Citrulline Free Base

Which active ingredients does Douglas Laboratories C-1000 have?

  • Vitamin C appears as Ascorbic Acid

Which categories do Jarrow Arginine-Citrulline Sustain and Douglas Laboratories C-1000 belong to?

  • Amino Acid Formula
  • Single Vitamin

What health concerns do Jarrow Arginine-Citrulline Sustain and Douglas Laboratories C-1000 address?

  • Athletic Performance
  • Muscle Support
  • Heart & Cardiovascular Health
  • Antioxidant Support
  • Immune System Support

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

  • Douglas Laboratories C-1000 has the highest total amount of Vitamin C: 1000 mg per serving

How do the serving sizes compare between the two supplements?

  • Serving size:
    • Jarrow Arginine-Citrulline Sustain: 2 tablets
    • Douglas Laboratories C-1000: 1 capsule
  • Vitamin C
    • This supplement has 10 mg
    • Recommended Dietary Allowance in men: 90 mg
    • Recommended Dietary Allowance in women: 75 mg
    • Tolerable Upper Intake Level: 2000 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

Last updated: February 21, 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