Product Image

Ester-C 500 mg with Citrus Bioflavonoids

American Health
4.9
★ ★ ★ ★ ★
(17728 ratings)
Vitamin C 1000 mg
Flavonoid (mixture) 400 mg
Product Image
Score84
Strong buffered vitamin C with a substantial citrus complex, but only 45 servings per bottle. The proprietary blend also limits transparency.
How scoring works
Quantity:90 Tablet(s) • (45 servings)
Goals:
General Health
Immunity
Skin Health
Anti-Inflammatory Support
Vision Support

Score 84

Strong buffered vitamin C with a substantial citrus complex, but only 45 servings per bottle. The proprietary blend also limits transparency.
How scoring works

Also available as

7 options
240 servings Flavonoid (mixture) 400 mg, C 1000 mg • 60 Capsule(s) • 120 servings $9.16 ($0.07 per serving) 450 servings Flavonoid (mixture) 400 mg, C 1000 mg • 450 Tablet(s) • 225 servings $34.99 ($0.15 per serving) 225 servings C 1000 mg, Flavonoid (mixture) 400 mg • 225 Tablet(s) • 112 servings $18.89 ($0.16 per serving) 1000 mg • 180 Tablet(s) servings Flavonoid (mixture) 200 mg, C 1000 mg • 180 Tablet(s) • 180 servings $30.79 ($0.17 per serving) 1000 mg • 90 Tablet(s) servings Flavonoid (mixture) 200 mg, C 1000 mg • 90 Tablet(s) • 90 servings $17.00 ($0.18 per serving) 1000 mg • 120 Tablet(s) servings Flavonoid (mixture) 200 mg, C 1000 mg • 120 Tablet(s) • 120 servings $22.67 ($0.18 per serving) 240 servings Flavonoid (mixture) 400 mg, C 1000 mg • 240 Capsule(s) • 120 servings $29.39 ($0.24 per serving)
$9.58($0.21 per serving)
Vitacost
$ 10.55
Daily Vita
$ 10.54
iHerb
$ 9.58
Report prices

Analysis

A two-tablet serving provides 1000 mg of vitamin C as buffered calcium ascorbate. The form may be gentler than plain ascorbic acid while supplying ample support for normal immune function and collagen synthesis.

The 400 mg citrus bioflavonoid complex adds a meaningful second antioxidant component. Individual flavonoids are not listed by amount, so their relative contribution cannot be judged.

The bottle provides only 45 servings, making it less convenient than many otherwise similar Ester-C listings. Its focused formula is useful for vitamin C support but does not replace broader vision or general micronutrient products.

Who is it for
  • Adults wanting buffered high-dose vitamin C
  • People sensitive to acidic ascorbic acid
  • Users comfortable with two-tablet servings
Best for
  • Immune support
  • Collagen support
  • Focused antioxidant use

Pros

  • 1000 mg Ester-C
  • 400 mg citrus bioflavonoids
  • Buffered calcium ascorbate
  • Clear elemental calcium amount

Cons

  • Only 45 servings
  • Two tablets per serving
  • Bioflavonoid composition is not detailed

Warnings

  • The full-gram serving may cause loose stools or stomach discomfort
  • Stone-prone users should discuss regular high-dose vitamin C with a clinician
  • Calcium ascorbate adds 110 mg of calcium per serving

Nutrient quality

92 Highest impact

Buffered calcium ascorbate provides a well-regarded form at a meaningful amount. Compatible citrus bioflavonoids add support without making the formula filler-heavy.

.

Ingredient transparency

76 High impact

Active names and amounts are clearly stated, with no hidden proprietary dose. Complete intake directions and a full inactive-ingredient list are not included in the supplied data.

.

Customer satisfaction

73 High impact

Supplied satisfaction metrics indicate a strong result with a meaningful response pool. Detailed experience themes are absent, so recurring complaints and real-world purpose fit remain uncertain.

.

Value for money

97 Highest impact

Serving value appears favorable relative to the disclosed form and amount. The focused formula avoids low-value extras.

.
Report analysis

Goals

General Health
General Health
Impact
Highest effect
A- Goal FitA Strength of SupportB- CoverageA Formula Quality
Vitamin C · 1000 mg

A substantial dose of vitamin C provides direct antioxidant, immune, and collagen support, while the calcium ascorbate form may be gentler than standard ascorbic acid for some users. Citrus bioflavonoids complement the antioxidant focus without turning the formula into an overly broad blend.

The product offers useful depth for vitamin C but does not fill the wider nutrient gaps involved in comprehensive general health. The large vitamin C serving may cause diarrhea or stomach cramps and may be unsuitable for people prone to calcium oxalate kidney stones.

Study evidence
Vitamin C Supportive 56 studies
Immunity
Immunity
Impact
Highest effect
A- Goal FitA+ Strength of SupportC+ CoverageA Formula Quality
Vitamin C · 1000 mg

Buffered calcium ascorbate supplies a substantial vitamin C amount with good digestive tolerability. Citrus bioflavonoids add related antioxidant compounds without obscuring the main active.

The formula provides strong depth for antioxidant, collagen, and immune-related support but remains narrow. It does not cover the full range of foundational wellness needs.

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 · 1000 mg

A full vitamin C serving supports collagen synthesis and antioxidant defense. The buffered calcium ascorbate form may be easier on the stomach than plain ascorbic acid.

Citrus bioflavonoids add complementary antioxidant compounds. The formula has strong depth in one core nutrient but does not directly supply collagen, ceramides, or hydration support.

Study evidence
Vitamin C Supportive 53 studies
Anti-Inflammatory Support
Anti-Inflammatory Support
Impact
Highest effect
B- Goal FitA- Strength of SupportC+ CoverageA Formula Quality
Vitamin C · 1000 mg

Ester-C supplies a substantial vitamin C dose for antioxidant protection and regeneration of vitamin E. The 400 mg citrus bioflavonoid complex adds a second flavonoid-based antioxidant pathway.

The formula supports oxidative aspects of inflammation but does not directly address COX, LOX, omega-3 resolution, vitamin D signaling, or glutathione. A 1,000 mg vitamin C dose may increase urinary oxalate, making repeated use less suitable for people prone to calcium oxalate kidney stones.

Study evidence
Vitamin C Supportive 50 studies
Vision Support
Vision Support
Impact
High effect
D Goal FitB+ Strength of SupportD+ CoverageB+ Formula Quality
Vitamin C · 1000 mg

Vitamin C and citrus bioflavonoids provide antioxidant support that may help protect ocular tissues from oxidative stress. The substantial amounts support this single pathway but do not form a complete vision formula.

Lutein, zeaxanthin, omega-3 fats, vitamin E, zinc, and copper are all absent. The focused design is easy to assess, yet its benefits remain general antioxidant support rather than targeted macular or retinal nutrition.

Study evidence
Vitamin C Disputed 24 studies

Ingredients

IngredientAmount per serving
Vitamin C (Ester-C Calcium Ascorbate)
 1000 mg
Calcium (Ester-C Calcium Ascorbate)
 110 mg
Citrus Bioflavonoids Complex
400 mg
Gluten Free Adults 18–50 Vegan Dairy Free Sugar Free Vegetarian
Report overview
Vitamin C (Ester-C Calcium Ascorbate) · 1000 mg OverallScore90
A- Active Ingredient Quality & BioavailabilityA- Dose, Safety & Label TransparencyA+ Value

Patented, buffered Ester-C offers a higher-quality delivery form with strong stomach comfort. The 1000 mg serving fits the preferred dose range and the active amount is plainly stated. Cost efficiency is exceptional for a patented form.

View ingredientView products
Loading alternative details
89 Performance

C-500 Calcium Ascorbate-C

NOW
<p>The ingredient profile makes it a stronger quality-focused alternative for the same vitamin C goals. Buffered calcium ascorbate delivers a practical vitamin C amount with clear mineral disclosure and exceptional relative value. The small bioflavonoid addition is unlikely to contribute much but does not undermine the strong core formula.</p>
86 Performance

C

Swanson
<p>The ingredient profile makes it a stronger quality-focused alternative for the same vitamin C goals. Fully buffered calcium ascorbate provides a meaningful vitamin C serving with good stomach-comfort potential. The focused formula keeps the active nutrient clear and avoids decorative additions.</p>
87 Performance

Ester-C with Citrus Bioflavonoids

American Health
<p>The ingredient profile makes it a stronger quality-focused alternative for the same vitamin C goals. A buffered vitamin C form and a substantial citrus bioflavonoid amount create a simple, well-dosed antioxidant formula. Strong satisfaction signals and a long supply support value, though excipients and intake directions are not shown.</p>
89 Budget

Pure Buffered Calcium Ascorbate

NOW
<p>The lower serving cost makes it a more economical alternative while retaining the same vitamin C focus. the buffered mineral ascorbate form supplies a meaningful vitamin C amount with a digestive-comfort advantage over plain ascorbic acid. Clear active dosing and favorable serving value are strengths, though complete use directions and inactive ingredients are not supplied.</p>
87 Budget

100% Pure Vitamin C Powder

Swanson Premium Brand
<p>The lower serving cost makes it a more economical alternative while retaining the same vitamin C focus. The pure powder supplies a flexible, meaningful vitamin C serving with exceptional economy and no active padding. Plain ascorbic acid remains acidic, so sensitive users may prefer a buffered form.</p>
87 Budget

C 500 mg

Mason Natural
<p>The lower serving cost makes it a more economical alternative while retaining the same vitamin C focus. A simple moderate-dose tablet provides useful vitamin C at excellent relative value and with extensive aggregate feedback. Generic ascorbic acid and missing inactive-ingredient details are the main limitations.</p>
87 Value

Pure Buffered Magnesium Ascorbate

NOW
<p>The formula offers a more favorable balance of vitamin C quality and serving value than the original. Magnesium ascorbate provides a substantial fully buffered vitamin C serving with excellent relative value and clear mineral disclosure. Feedback volume is limited, and detailed use directions or non-active ingredients are not supplied.</p>
83 Value

C 500 mg

21st Century
<p>The formula offers a more favorable balance of vitamin C quality and serving value than the original. A large supply of straightforward vitamin C provides meaningful daily support with excellent value. Basic ascorbic acid and incomplete inactive-ingredient details keep the formula from feeling premium.</p>
84 Value

Ester-C 500 mg With Citrus Bioflavoinds

American Health
<p>The formula offers a more favorable balance of vitamin C quality and serving value than the original. Buffered Ester-C provides a substantial vitamin C serving with good stomach-comfort potential. Citrus bioflavonoids add compatible plant compounds without distracting from the core nutrient.</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. 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
  3. Serum vitamin C and spinal pain: a nationwide study.
    Dionne CE; Laurin D; Desrosiers T; Abdous B; Le Sage N; Frenette J; Mondor M; Pelletier S · Pain · 2017
    Cross-sectional study4,742 participantsGeneral Health forVitamin C
  4. 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
  5. Effect of Vitamin C Supplements on Respiratory Tract Infections: A Systematic Review and Meta-Analysis.
    Keya TA; Leela A; Fernandez K; Habib N; Rashid M · Current reviews in clinical and experimental pharmacology · 2022
    Meta-analysis10 studies pooledImmunity forVitamin C
  6. Vitamin C for the management of COVID-19: a systematic review and meta-analysis of randomized controlled trials.
    Abid H; Mushtaq I; Munir ABI; Shakil J; Vinjamuri S; Tadasare N; Kiran F; Muhammad Wali Mirza A; Fatima Khidri F; Shahid A; Ayyan M; Ehsan M; Cheema HA; Alsubari AMA; Sahra S; Siddiqi NI · Annals of medicine and surgery (2012) · 2026
    Meta-analysis9 studies pooledImmunity forVitamin C
  7. Split-Face Comparative Analysis Of Micro-Needling With Tranexamic Acid Vs Vitamin C Serum In Melasma.
    Raza MH; Iftikhar N; Anwar A; Mashhood AA; Tariq S; Bin Hamid MA · Journal of Ayub Medical College, Abbottabad : JAMC · 2022
    Non-randomized trial30 participantsSkin Health forVitamin C
  8. Vitamin C and postoperative outcomes following mandibular third molar extraction: a randomized split-mouth study.
    Demirel M; Aktas A; Kizil M; Yalcin N · Oral surgery, oral medicine, oral pathology and oral radiology · 2026
    Randomized trial56 participantsSkin Health forVitamin C
  9. 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
  10. 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
  11. 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
  12. 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
  13. 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
  14. 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
  15. 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
  16. 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
  17. 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
  18. 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
  19. 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
  20. 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
  21. 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
  22. 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
  23. 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
  24. 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
  25. 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
  26. 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
  27. 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
  28. 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
  29. 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
  30. 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
  31. 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
  32. Nutritional modulation of cataract.
    Weikel KA; Garber C; Baburins A; Taylor A · Nutrition reviews · 2014
    Narrative reviewVision Support forVitamin C
  33. 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
  34. 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