21st Century Calcium Citrate +D3 Maximum
vs
Metagenics MetaGlycemX™
Supplement Comparison

  • Vitamin D: 21st Century Calcium Citrate +D3 Maximum has 2.5× more
  • The image below shows:
    • Side-by-side charts with label nutrient amounts, per serving
    • Nutrient forms as listed on the label
    • 38 nutrients compared
Bar chart: per-serving label amounts and listed forms for 21st Century Calcium Citrate +D3 Maximum vs Metagenics MetaGlycemX™.

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Frequently asked questions

Which active ingredients does 21st Century Calcium Citrate +D3 Maximum have?

  • Vitamin D appears as Cholecalciferol (D3)
  • Calcium appears as Calcium Citrate

Which active ingredients does Metagenics MetaGlycemX™ have?

  • Vitamin C appears as Ascorbic Acid
  • Vitamin D appears as Cholecalciferol (D3)
  • Vitamin E appears as d-Alpha Tocopheryl Succinate
  • Vitamin B1 (Thiamin) appears as Thiamin Mononitrate
  • Vitamin B2 (Riboflavin)
  • Vitamin B3 (Niacin) appears as Niacinamide
  • Vitamin B6 (Pyridoxine) appears as Pyridoxine HCl
  • Vitamin B9 (Folate) appears as Calcium-L-5-methyltetrahydrofolate
  • Vitamin B12 (Cobalamin) appears as Methylcobalamin
  • Vitamin B7 (Biotin)
  • Vitamin B5 (Pantothenic Acid) appears as D-Calcium Pantothenate
  • Zinc appears as Zinc Citrate
  • Selenium appears as L-Selenomethionine
  • Copper appears as Copper Lysinate HCl
  • Manganese appears as Manganese Citrate
  • Chromium appears as Chromium Polynicotinate
  • L-Carnosine
  • Alpha Lipoic Acid
  • Green Tea appears as Decaffeinated Green Tea Extract (Camellia sinensis leaf, standardized to 60% catechins and 40% EGCG)
  • Taurine
  • Cinnamon Extract appears as Chinese Cinnamon (Cinnamomum cassia) Bark Powder

Which categories do 21st Century Calcium Citrate +D3 Maximum and Metagenics MetaGlycemX™ belong to?

  • Single Mineral
  • Metabolic Support Formula

What health concerns do 21st Century Calcium Citrate +D3 Maximum and Metagenics MetaGlycemX™ address?

  • Joint & Bone Health
  • Blood Sugar Support

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

  • 21st Century Calcium Citrate +D3 Maximum has the highest total amount of Vitamin D: 500 IU per serving

How do the serving sizes compare between the two supplements?

  • Serving size:
    • 21st Century Calcium Citrate +D3 Maximum: 2 tablets
    • Metagenics MetaGlycemX™: 2 tablets
  • Vitamin D
    • This supplement has 500 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 630 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 300 mg
    • Recommended Dietary Allowance in men: 90 mg
    • Recommended Dietary Allowance in women: 75 mg
    • Tolerable Upper Intake Level: 2000 mg
  • Vitamin D
    • This supplement has 200 IU
    • Recommended Dietary Allowance in men: 600 IU
    • Recommended Dietary Allowance in women: 600 IU
    • Tolerable Upper Intake Level: 4000 IU
  • Vitamin E
    • This supplement has 134 mg
    • Recommended Dietary Allowance in men: 15 mg
    • Recommended Dietary Allowance in women: 15 mg
    • Tolerable Upper Intake Level: 1000 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 9 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 90 mg
    • Recommended Dietary Allowance in men: 16 mg
    • Recommended Dietary Allowance in women: 14 mg
    • Tolerable Upper Intake Level: 35 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).
  • 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