NOW Foods Calcium & Magnesium
vs
Optimum Nutrition OPTI-MEN
Supplement Comparison

  • Vitamin D: same total amount on both labels
  • Magnesium: NOW Foods Calcium & Magnesium has 22× more
  • Zinc: NOW Foods Calcium & Magnesium has 13× more
  • The image below shows:
    • Side-by-side charts with label nutrient amounts, per serving
    • Nutrient forms as listed on the label
    • 43 nutrients compared
Bar chart: per-serving label amounts and listed forms for NOW Foods Calcium & Magnesium vs Optimum Nutrition OPTI-MEN.

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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 Optimum Nutrition OPTI-MEN have?

  • Vitamin A
  • Vitamin C
  • Vitamin D
  • Vitamin E
  • Vitamin K
  • Vitamin B1 (Thiamin)
  • Vitamin B2 (Riboflavin)
  • Vitamin B3 (Niacin)
  • Vitamin B6 (Pyridoxine)
  • Vitamin B9 (Folate)
  • Vitamin B12 (Cobalamin)
  • Vitamin B7 (Biotin)
  • Vitamin B5 (Pantothenic Acid)
  • Alpha-Carotene
  • PABA
  • Calcium
  • Iodine
  • Magnesium
  • Zinc
  • Selenium appears as L-Selenomethionine
  • Chromium appears as Chromium nicotinate glycinate chelate
  • Molybdenum appears as Molybdenum A.A. chelate
  • Boron appears as Boron citrate
  • Vanadium appears as Vanadium citrate
  • Lutein
  • Lycopene
  • Inositol
  • Alpha Lipoic Acid
  • Zeaxanthin
  • Amino Men Blend by Optimum Nutrition
  • Phyto Men Blend by Optimum Nutrition
  • Viri Men Blend by Optimum Nutrition
  • Enzyme Blend by Optimum Nutrition
  • Cryptoxanthin

Which categories do NOW Foods Calcium & Magnesium and Optimum Nutrition OPTI-MEN belong to?

  • Mineral Complex
  • Single Mineral
  • Multivitamin

What health concerns do NOW Foods Calcium & Magnesium and Optimum Nutrition OPTI-MEN address?

  • General Health
  • Heart & Cardiovascular Health
  • Joint & Bone Health
  • Men's Health

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

  • Both products list the same total amount of Vitamin D per serving

Which product has a higher amount of Magnesium per serving?

  • NOW Foods Calcium & Magnesium has the highest total amount of Magnesium: 333 mg per serving

Which product has a higher amount of Zinc per serving?

  • NOW Foods Calcium & Magnesium has the highest total amount of Zinc: 25 mg per serving

How do the serving sizes compare between the two supplements?

  • Serving size:
    • NOW Foods Calcium & Magnesium: 2 softgels
    • Optimum Nutrition OPTI-MEN: 3 tablets
  • 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 A
    • This supplement has 1500 mcg RAE
    • Recommended Dietary Allowance in men: 900 mcg RAE
    • Recommended Dietary Allowance in women: 700 mcg RAE
    • Tolerable Upper Intake Level: 3000 mcg RAE
  • Vitamin C
    • This supplement has 60 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 400 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 100 mg
    • Recommended Dietary Allowance in men: 15 mg
    • Recommended Dietary Allowance in women: 15 mg
    • Tolerable Upper Intake Level: 1000 mg
  • Vitamin K
    • This supplement has 75 mcg
    • Adequate Intake in men: 120 mcg
    • Adequate Intake in women: 90 mcg
    • Tolerable Upper Intake Level: Not established
  • Vitamin B1 (Thiamin)
    • This supplement has 1.5 mg
    • Recommended Dietary Allowance in men: 1.2 mg
    • Recommended Dietary Allowance in women: 1.1 mg
    • Tolerable Upper Intake Level: Not established

Last updated: February 2, 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