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C-500 Calcium Ascorbate-C

NOW
4.9
★ ★ ★ ★ ★
(15412 ratings)
Vitamin C 500 mg
Product Image
Score89
A high-value buffered vitamin C capsule with clear dosing and a large supply. Its support remains focused rather than broad.
How scoring works
Quantity:250 Capsule(s) • (250 servings)
Goals:
General Health
Immunity
Skin Health
Anti-Inflammatory Support

Score 89

A high-value buffered vitamin C capsule with clear dosing and a large supply. Its support remains focused rather than broad.
How scoring works

Also available as

1 option
100 servings C 500 mg • 100 Capsule(s) • 100 servings $5.00 ($0.05 per serving)
$14.50($0.05 per serving)
iHerb
$ 15.30
Daily Vita
$ 14.50
iHerb
$ 15.30
Vitacost
$ 16.63
Report prices

Analysis

The capsule delivers a practical vitamin C amount as calcium ascorbate, which may be gentler than plain ascorbic acid. Clear disclosure of both vitamin C and calcium makes the dose easy to evaluate.

The large bottle supports consistent long-term use and strong cost efficiency. A small citrus bioflavonoid addition is reasonable but too modest to drive the product's value.

Formulation depth is concentrated on vitamin C rather than comprehensive wellness, skin, or vision coverage. It best fits regular users who want a buffered capsule and prefer buying a larger supply.

Who is it for
  • Regular vitamin C users
  • People with sensitivity to unbuffered ascorbic acid
  • Adults who prefer a larger supply
Best for
  • Long-term buffered supplementation
  • Antioxidant support
  • Collagen and immune support

Pros

  • Fully buffered vitamin C form
  • Large supply with strong efficiency
  • Clear calcium and vitamin C disclosure

Cons

  • Minimal nutrient breadth
  • Bioflavonoid addition is small
  • Capsule format may not suit all users

Warnings

  • Include the calcium contribution when tracking total supplemental calcium
  • Buffered vitamin C may still cause digestive effects in sensitive users
  • People with a kidney-stone history should consider their total supplemental vitamin C intake

Nutrient quality

92 Highest impact

The amount is well below the adult tolerable upper limit. The token bioflavonoid amount adds little but does not dominate the formula.

Ingredient transparency

92 Highest impact

All listed active and mineral amounts are disclosed. The supplied data omit a full inactive-ingredient list.

Customer satisfaction

74 High impact

Feedback volume is substantial enough to make the aggregate rating more stable. No complaint text is supplied, so repetitive negative themes cannot be assessed.

Value for money

95 Highest impact

The large package delivers meaningful servings at a very low relative cost. The small bioflavonoid addition is the only low-impact extra.

Report analysis

Goals

General Health
General Health
Impact
Highest effect
A Goal FitA Strength of SupportC+ CoverageA Formula Quality
Vitamin C · 500 mg

Buffered calcium ascorbate supplies a strong Vitamin C amount for antioxidant, immune, and collagen support. The form is clearly disclosed and may be gentler than plain ascorbic acid for sensitive users.

A small calcium contribution and modest bioflavonoid addition broaden the formula only slightly. The design is still focused, transparent, and well suited to daily Vitamin C supplementation.

Study evidence
Vitamin C Supportive 56 studies
Immunity
Immunity
Impact
Highest effect
A Goal FitA Strength of SupportC CoverageA Formula Quality
Vitamin C · 500 mg

Buffered calcium ascorbate provides direct vitamin C support for immune cells, barrier integrity, and antioxidant control. The amount reaches a meaningful daily threshold and may be gentler than plain ascorbic acid.

Calcium yield is transparent, while the bioflavonoid addition is small. The focused formula offers strong vitamin C depth but little coverage beyond that pathway.

Study evidence
Vitamin C Supportive 53 studies
Skin Health
Skin Health
Impact
Highest effect
B+ Goal FitA- Strength of SupportC CoverageA Formula Quality
Vitamin C · 500 mg

The focused formula supports collagen synthesis and antioxidant protection in the skin. Calcium ascorbate provides a clearly disclosed buffered form that may be gentler on the stomach.

It does not provide collagen peptides, barrier lipids, or hydration-focused actives. The focused design is best suited to foundational collagen and antioxidant support.

Study evidence
Vitamin C Supportive 53 studies
Anti-Inflammatory Support
Cellular Defense
Anti-Inflammatory Support
Impact
High effect
C+ Goal FitA- Strength of SupportD+ CoverageA- Formula Quality
Vitamin C · 500 mg

Calcium ascorbate supplies antioxidant support that may help limit oxidative stress linked with inflammatory signaling. The disclosed 500 mg serving reaches a practical Vitamin C amount.

A fully buffered form and clear calcium disclosure improve comfort and label clarity. The formula still focuses on antioxidant protection rather than direct inflammatory-pathway modulation.

Study evidence
Vitamin C Supportive 50 studies
Vision Support
Macular and Blue Light Defense
Vision Support
Impact
Moderate effect
F Goal FitB Strength of SupportF CoverageB Formula Quality
Vitamin C · 500 mg

Calcium ascorbate provides a substantial vitamin C amount for general ocular antioxidant defense. It does not supply macular pigments, zinc, copper, or retinal lipids.

The buffered form and amount are clearly stated. Strong focus and disclosure cannot replace the missing vision-specific pathways.

Study evidence
Vitamin C Disputed 24 studies

Ingredients

IngredientAmount per serving
Vitamin C (Calcium Ascorbate)
 500 mg
Calcium (Calcium Ascorbate)
 55 mg
Citrus Bioflavonoid Complex
10 mg
Gluten Free Adults 18–50 Dairy Free
Report overview
Vitamin C (Calcium Ascorbate) · 500 mg OverallScore89
B+ Active Ingredient Quality & BioavailabilityA Dose, Safety & Label TransparencyA+ Value

Calcium ascorbate supplies a well-targeted dose in a stomach-friendly form. Separate calcium disclosure makes the buffered source easy to understand. The large bottle pairs strong formula quality with exceptional cost efficiency.

View ingredientView products
Loading alternative details
89 Performance

Ester-C Plus 1000 mg Vitamin C

Solgar
<p>The ingredient profile is a stronger fit for focused vitamin C support, supplying 1000 mg of vitamin C as Ester-C with calcium and citrus bioflavonoids. It provides at least as much vitamin C as the original while retaining a clearly disclosed active form.</p>
89 Performance

Buffered Gold C

California Gold Nutrition
<p>The ingredient profile is a stronger fit for focused vitamin C support, supplying 1000 mg of vitamin C as Sodium Ascorbate. It provides at least as much vitamin C as the original while retaining a clearly disclosed active form.</p>
88 Performance

C

Swanson
<p>The ingredient profile is a stronger fit for focused vitamin C support, supplying 1000 mg of vitamin C as Calcium Ascorbate with calcium and citrus bioflavonoids. It provides at least as much vitamin C as the original while retaining a clearly disclosed active form.</p>
89 Budget

Pure Buffered Calcium Ascorbate

NOW
<p>A lower cost per serving makes this a practical budget alternative, while it supplies 890 mg of vitamin C as Calcium Ascorbate with calcium. The vitamin C amount matches or exceeds the original's 500 mg serving.</p>
88 Budget

Sodium Ascorbate

NutriBiotic Immunity
<p>A lower cost per serving makes this a practical budget alternative, while it supplies 1100 mg of vitamin C as Sodium Ascorbate. The vitamin C amount matches or exceeds the original's 500 mg serving.</p>
87 Budget

100% Pure Vitamin C Powder

Swanson Premium Brand
<p>A lower cost per serving makes this a practical budget alternative, while it supplies 1000 mg of vitamin C as Ascorbic Acid. The vitamin C amount matches or exceeds the original's 500 mg serving.</p>
93 Value

Pure Buffered Magnesium Ascorbate

NOW
<p>Strong serving value is paired with 820 mg of vitamin C as Magnesium Ascorbate with magnesium. It matches or exceeds the original’s vitamin C amount and keeps the active formula clearly disclosed, balancing cost-effectiveness with a useful ingredient profile.</p>
93 Value

Sodium Ascorbate Capsules

NutriBiotic Immunity
<p>Strong serving value is paired with 850 mg of vitamin C as Sodium Ascorbate. It matches or exceeds the original’s vitamin C amount and keeps the active formula clearly disclosed, balancing cost-effectiveness with a useful ingredient profile.</p>
92 Value

Ester-C 500 mg With Citrus Bioflavoinds

American Health
<p>Strong serving value is paired with 1000 mg of vitamin C as Ester-C Calcium Ascorbate with calcium and citrus bioflavonoids. It matches or exceeds the original’s vitamin C amount and keeps the active formula clearly disclosed, balancing cost-effectiveness with a useful ingredient profile.</p>
Report alternatives

Sources

Published studies used for the product analysis and the top-ranked studies for each ingredient and goal.

  1. Relation between plasma ascorbic acid and mortality in men and women in EPIC-Norfolk prospective study: a prospective population study. European Prospective Investigation into Cancer and Nutrition.
    Khaw KT; Bingham S; Welch A; Luben R; Wareham N; Oakes S; Day N · Lancet (London, England) · 2001
    Cohort study19,496 participantsGeneral Health forVitamin C
  2. Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis.
    Bjelakovic G; Nikolova D; Gluud LL; Simonetti RG; Gluud C · JAMA · 2007
    Meta-analysis232,606 participants68 studies pooledGeneral Health forVitamin C
  3. Vitamin C intake and multiple health outcomes: an umbrella review of systematic reviews and meta-analyses.
    Xu K; Peng R; Zou Y; Jiang X; Sun Q; Song C · International journal of food sciences and nutrition · 2022
    Meta-analysis76 studies pooledGeneral Health forVitamin C
  4. Comparative Study on the Outcome of Periorbital Wrinkles Treated with Laser-Assisted Delivery of Vitamin C or Vitamin C Plus Growth Factors: A Randomized, Double-blind, Clinical Trial.
    Machado BHB; Frame J; Zhang J; Najlah M · Aesthetic plastic surgery · 2021
    Randomized trial149 participantsSkin Health forVitamin C
  5. Association between hemoglobin A1c, Vitamin C, and microbiome in diabetic foot ulcers and intact skin: A cross-sectional study.
    Tong KPS; Green SJ; Ortiz J; Wu SC · Health science reports · 2024
    Cross-sectional study42 participantsSkin Health forVitamin C
  6. What did we learn in 35 years of research on nutrition and supplements for age-related macular degeneration: a systematic review.
    Pameijer EM; Heus P; Damen JAA; Spijker R; Hooft L; Ringens PJ; Imhof SM; van Leeuwen R · Acta ophthalmologica · 2023
    Systematic review27 studies pooledVision Support forVitamin C
  7. Antioxidant vitamin and mineral supplements for preventing age-related macular degeneration.
    Evans JR; Lawrenson JG · The Cochrane database of systematic reviews · 2018
    Meta-analysis55,614 participants4 studies pooledVision Support forVitamin C
  8. Ascorbic acid metabolites are involved in intraocular pressure control in the general population.
    Hysi PG; Khawaja AP; Menni C; Tamraz B; Wareham N; Khaw KT; Foster PJ; Benet LZ; Spector TD; Hammond CJ · Redox biology · 2019
    Observational studyVision Support forVitamin C
  9. Efficacy of Vitamin C as Glucocorticoid Substitute for Reducing Pain and Inflammation After Total Hip Arthroplasty: A Randomized Controlled Trial.
    Jiang W; Xu H; Jiang X; Zhan Y; Ju Y; Xie J; Huang Z; Huang Q; Pei F · The Journal of bone and joint surgery. American volume · 2025
    Randomized trial107 participantsAnti-Inflammatory Support forVitamin C
  10. The Impact of Vitamin C on Analgesic, Anti-inflammatory, and Hemostatic Outcomes After Total Hip and Knee Arthroplasty: A Systematic Review and Meta-Analysis.
    Moftakhari Hajimirzaei S; Bagherzadeh Cham M; Dolikhani M; Tabatabaee SM; Ebrahimpour A · The archives of bone and joint surgery · 2026
    Meta-analysis1,162 participants10 studies pooledAnti-Inflammatory Support forVitamin C
  11. The impact of vitamin C supplementation on the perioperative outcomes after total hip and knee arthroplasty: a systematic review and meta-analysis.
    Liu X; Guo J; Li Y; Yang Y; Liu M; Gao Q; Yang Y; Wu X; Yue C · BMC musculoskeletal disorders · 2026
    Meta-analysis852 participants8 studies pooledAnti-Inflammatory Support forVitamin C
  12. Therapeutic Impact of Ascorbic Acid on Oral and Periodontal Tissues: A Systematic Literature Review.
    Ruzijevaite G; Acaite E; Jagelaviciene E · Medicina (Kaunas, Lithuania) · 2025
    Systematic review811 participants17 studies pooledAnti-Inflammatory Support forVitamin C
  13. Oral vitamin C administration reduces early recurrence rates after electrical cardioversion of persistent atrial fibrillation and attenuates associated inflammation.
    Korantzopoulos P; Kolettis TM; Kountouris E; Dimitroula V; Karanikis P; Pappa E; Siogas K; Goudevenos JA · International journal of cardiology · 2005
    Randomized trial44 participantsAnti-Inflammatory Support forVitamin C
  14. Dietary intake and blood concentrations of antioxidants and the risk of cardiovascular disease, total cancer, and all-cause mortality: a systematic review and dose-response meta-analysis of prospective studies.
    Aune D; Keum N; Giovannucci E; Fadnes LT; Boffetta P; Greenwood DC; Tonstad S; Vatten LJ; Riboli E; Norat T · The American journal of clinical nutrition · 2019
    Meta-analysis69 studies pooledGeneral Health forVitamin C
  15. Scientific Opinion on the substantiation of a health claim related to vitamin C and increasing non haem iron absorption pursuant to Article 14 of Regulation (EC) No 1924/2006.
    EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) · EFSA journal. European Food Safety Authority · 2026
    Guideline / consensusGeneral Health forVitamin C
  16. Vitamin C Depletion and All-Cause Mortality in Renal Transplant Recipients.
    Sotomayor CG; Eisenga MF; Gomes Neto AW; Ozyilmaz A; Gans ROB; Jong WHA; Zelle DM; Berger SP; Gaillard CAJM; Navis GJ; Bakker SJ · Nutrients · 2018
    Cohort study598 participantsGeneral Health forVitamin C
  17. Associations of Serum Biomarkers of Fruit and Vegetable Intake With the Risk of Cause-Specific Mortality and All-Cause Mortality: A National Prospective Cohort Study.
    Pu L; Zhang R; Wang X; Zhao T; Sun H; Han L · Frontiers in nutrition · 2022
    Cohort study12,530 participantsGeneral Health forVitamin C
  18. Vitamin C and contribution to the normal function of the immune system: evaluation of a health claim pursuant to Article 14 of Regulation (EC) No 1924/2006.
    EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) · EFSA journal. European Food Safety Authority · 2026
    Guideline / consensusImmunity forVitamin C
  19. Therapeutic effects of high-dose vitamin C supplementation in patients with COVID-19: a meta-analysis.
    Sun L; Zhao JH; Fan WY; Feng B; Liu WW; Chen RQ; Ban C; Dang AG; Wang M; Luo KT; Zhou GY; Yu FF; Ba Y · Nutrition reviews · 2024
    Meta-analysis2,334 participants14 studies pooledImmunity forVitamin C
  20. Effect of micronutrient supplements on influenza and other respiratory tract infections among adults: a systematic review and meta-analysis.
    Abioye AI; Bromage S; Fawzi W · BMJ global health · 2021
    Meta-analysisImmunity forVitamin C
  21. New evidence for antioxidant properties of vitamin C.
    Vojdani A; Bazargan M; Vojdani E; Wright J · Cancer detection and prevention · 2001
    Randomized trial20 participantsImmunity forVitamin C
  22. Enhanced Vitamin C Delivery: A Systematic Literature Review Assessing the Efficacy and Safety of Alternative Supplement Forms in Healthy Adults.
    Calder PC; Kreider RB; McKay DL · Nutrients · 2025
    Systematic review13 studies pooledImmunity forVitamin C
  23. Evaluation of the anti-wrinkle effect of an ascorbic acid-loaded dissolving microneedle patch via a double-blind, placebo-controlled clinical study.
    Lee C; Yang H; Kim S; Kim M; Kang H; Kim N; An S; Koh J; Jung H · International journal of cosmetic science · 2017
    Randomized trial23 participantsSkin Health forVitamin C
  24. Randomized trial of topical ascorbic acid in DMSO versus imiquimod for the treatment of basal cell carcinoma.
    Burke B; Bailie JE · Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie · 2022
    Randomized trial25 participantsSkin Health forVitamin C
  25. Vitamin C improves healing of foot ulcers: a randomised, double-blind, placebo-controlled trial.
    Gunton JE; Girgis CM; Lau T; Vicaretti M; Begg L; Flood V · The British journal of nutrition · 2022
    Randomized trial16 participantsSkin Health forVitamin C
  26. Dietary nutrient intakes and skin-aging appearance among middle-aged American women.
    Cosgrove MC; Franco OH; Granger SP; Murray PG; Mayes AE · The American journal of clinical nutrition · 2007
    Cross-sectional study4,025 participantsSkin Health forVitamin C
  27. Role of Oral Vitamin 'C' on Astigmatic Errors in Phacoemulsification.
    Mohan S; Sah K; Khattri M; Ahmad L; Sachan SK · Current eye research · 2021
    Randomized trial400 participantsVision Support forVitamin C
  28. Nutritional modulation of cataract.
    Weikel KA; Garber C; Baburins A; Taylor A · Nutrition reviews · 2014
    Narrative reviewVision Support forVitamin C
  29. Dietary n-3 Fatty Acid, α-Tocopherol, Zinc, vitamin D, vitamin C, and β-carotene are Associated with Age-Related Macular Degeneration in Japan.
    Aoki A; Inoue M; Nguyen E; Obata R; Kadonosono K; Shinkai S; Hashimoto H; Sasaki S; Yanagi Y · Scientific reports · 2017
    Case-control study530 participantsVision Support forVitamin C
  30. Adherence to a Mediterranean diet, lifestyle and age-related macular degeneration: the Coimbra Eye Study - report 3.
    Raimundo M; Mira F; Cachulo MDL; Barreto P; Ribeiro L; Farinha C; Laíns I; Nunes S; Alves D; Figueira J; Merle BM; Delcourt C; Santos L; Silva R · Acta ophthalmologica · 2019
    Case-control study883 participantsVision Support forVitamin C