21st Century B-Complex Plus Vitamin C
vs
Metagenics Sinuplex
Supplement Comparison

  • Vitamin C: 21st Century B-Complex Plus Vitamin C has 2.0× more
  • The image below shows:
    • Side-by-side charts with label nutrient amounts, per serving
    • Nutrient forms as listed on the label
    • 19 nutrients compared
Bar chart: per-serving label amounts and listed forms for 21st Century B-Complex Plus Vitamin C vs Metagenics Sinuplex.

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Frequently asked questions

Which active ingredients does 21st Century B-Complex Plus Vitamin C have?

  • Vitamin C appears as Ascorbic Acid
  • Vitamin B1 (Thiamin) appears as Thiamin Mononitrate
  • Vitamin B2 (Riboflavin) appears as Riboflavin
  • Vitamin B3 (Niacin) appears as Niacinamide
  • Vitamin B6 (Pyridoxine) appears as Pyridoxine HCl
  • Vitamin B5 (Pantothenic Acid) appears as D-Calcium Pantothenate
  • Calcium appears as Calcium Carbonate and Dicalcium Phosphate

Which active ingredients does Metagenics Sinuplex have?

  • Vitamin C appears as Ascorbic Acid
  • N-Acetyl-L-Cysteine (NAC)
  • Quercetin
  • Bromelain appears as Bromelain (from pineapple stem, 2,400 GDU/gram)
  • Stinging Nettle (Urtica dioica) Root appears as Stinging Nettle (Urtica dioica) Root 7:1 Extract

Which categories do 21st Century B-Complex Plus Vitamin C and Metagenics Sinuplex belong to?

  • B-Complex Formula
  • Herbal Extract

What health concerns do 21st Century B-Complex Plus Vitamin C and Metagenics Sinuplex address?

  • Antioxidant Support
  • Energy & Metabolism
  • General Health
  • Neurological Support
  • Respiratory Health

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

  • 21st Century B-Complex Plus Vitamin C has the highest total amount of Vitamin C: 300 mg per serving

How do the serving sizes compare between the two supplements?

  • Serving size:
    • 21st Century B-Complex Plus Vitamin C: 1 tablet
    • Metagenics Sinuplex: 1 tablet
  • Vitamin C
    • This supplement has 300 mg
    • Recommended Dietary Allowance in men: 90 mg
    • Recommended Dietary Allowance in women: 75 mg
    • Tolerable Upper Intake Level: 2000 mg
  • Vitamin B1 (Thiamin)
    • This supplement has 15 mg
    • Recommended Dietary Allowance in men: 1.2 mg
    • Recommended Dietary Allowance in women: 1.1 mg
    • Tolerable Upper Intake Level: Not established
  • Vitamin B2 (Riboflavin)
    • This supplement has 14.3 mg
    • Recommended Dietary Allowance in men: 1.3 mg
    • Recommended Dietary Allowance in women: 1.1 mg
    • Tolerable Upper Intake Level: Not established
  • Vitamin B3 (Niacin)
    • This supplement has 50 mg
    • Recommended Dietary Allowance in men: 16 mg
    • Recommended Dietary Allowance in women: 14 mg
    • Tolerable Upper Intake Level: 35 mg
  • Vitamin B6 (Pyridoxine)
    • This supplement has 5 mg
    • Recommended Dietary Allowance in men: 1.3 mg
    • Recommended Dietary Allowance in women: 1.3 mg
    • Tolerable Upper Intake Level: 100 mg
  • Vitamin B5 (Pantothenic Acid)
    • This supplement has 10 mg
    • Adequate Intake in men: 5 mg
    • Adequate Intake in women: 5 mg
    • Tolerable Upper Intake Level: Not established
  • Vitamin C
    • This supplement has 150 mg
    • Recommended Dietary Allowance in men: 90 mg
    • Recommended Dietary Allowance in women: 75 mg
    • Tolerable Upper Intake Level: 2000 mg

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).
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  • 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.
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  • Author: VIOscan Research Team