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Ultra-C 2000 mg Sustained Release

4.6
★ ★ ★ ★ ★
(570 ratings)
Vitamin C 2000 mg
Product Image
Score70
A sustained-release high-dose vitamin C tablet with rose hip. The amount is unnecessarily aggressive for many users and raises digestive and kidney-stone concerns.
How scoring works
Tablet
Quantity:90 Tablet(s) • (90 servings)
Goals:
Immunity
Anti-Inflammatory Support
General Health
Vision Support

Score 70

A sustained-release high-dose vitamin C tablet with rose hip. The amount is unnecessarily aggressive for many users and raises digestive and kidney-stone concerns.
How scoring works
$33.11($0.36 per serving)
iHerb
$ 33.11
iHerb
$ 33.11
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Analysis

The sustained-release tablet supplies vitamin C for antioxidant defenses, normal immune activity, and collagen formation. Rose hip adds a related botanical component, while gradual release may spread exposure.

The 2,000 mg serving is much larger than most people need for routine support and sits at the usual adult upper daily intake. Absorption is inefficient at this level, and digestive side effects become more likely.

The product may fit experienced users specifically seeking a very high amount under appropriate guidance. It is not a broad immune, skin, or eye formula, and a lower-dose product would be more practical for many daily users.

Who is it for
  • Experienced high-dose vitamin C users
  • Adults specifically wanting sustained release
  • People who can tolerate unbuffered ascorbic acid
Best for
  • Concentrated antioxidant intake
  • Sustained-release delivery
  • Focused vitamin C supplementation

Pros

  • Sustained-release format
  • Clearly disclosed vitamin C amount
  • Rose hip addition
  • Focused ingredient list

Cons

  • Very large daily amount
  • Unbuffered ascorbic acid
  • Narrow nutrient coverage
  • Diminishing absorption at the full serving

Warnings

  • The 2,000 mg serving may cause diarrhea, nausea, or abdominal cramping.
  • People prone to calcium oxalate kidney stones may find this high daily amount unsuitable.
  • The serving reaches the usual adult upper daily intake, so additional vitamin C from other supplements should be considered.

Nutrient quality

70 High impact

Sustained release and a focused active list provide a coherent vitamin C formula. The very high acidic amount substantially weakens dose balance and general-use suitability.

.

Ingredient transparency

81 Highest impact

Active ingredients and amounts are clear without a hidden blend. Missing directions and absent non-active ingredients leave the label incomplete.

.

Customer satisfaction

67 High impact

The aggregate satisfaction signal is good and supported by substantial volume. Missing review details prevent assessment of tolerance complaints or purpose fit.

.

Value for money

58 Moderate impact

A focused sustained-release formula provides some value. The excessive amount and middling serving economics make more moderate options more competitive.

.
Report analysis

Goals

Immunity
Immunity
Impact
Highest effect
A+ Goal FitA Strength of SupportB- CoverageA+ Formula Quality
Vitamin C · 2000 mg

A sustained-release 2,000 mg vitamin C dose strongly supports immune-cell function and antioxidant protection. Rose hip adds a relevant botanical source alongside the core vitamin.

The amount reaches the usual adult daily upper intake level and may cause diarrhea or stomach discomfort. People prone to calcium oxalate kidney stones may also find this high daily dose less suitable.

Study evidence
Vitamin C Supportive 53 studies
Anti-Inflammatory Support
Anti-Inflammatory Support
Impact
High effect
C Goal FitA- Strength of SupportC- CoverageA+ Formula Quality
Vitamin C · 2000 mg

Sustained-release vitamin C provides substantial antioxidant support, while rose hips add complementary plant compounds. The formula remains indirectly relevant to inflammation and does not target central inflammatory enzymes.

The 2,000 mg amount reaches the common adult upper daily intake and may cause diarrhea or abdominal cramping in sensitive users. Sustained release may improve exposure, but the formula still covers only one main antioxidant pathway.

Study evidence
Vitamin C Supportive 50 studies
General Health
General Health
Impact
High effect
B Goal FitB- Strength of SupportD CoverageA- Formula Quality
Vitamin C · 2000 mg

The sustained-release tablet supplies vitamin C with rose hips for concentrated antioxidant and collagen support. Vitamin C has strong established nutritional evidence, and the delivery format may spread intake over time.

The very large vitamin C amount exceeds what most people need for routine foundational support and adds little pathway breadth. It can cause stomach upset or diarrhea, and sustained high intake may be unsuitable for people prone to oxalate kidney stones.

Study evidence
Vitamin C Supportive 56 studies
Vision Support
Vision Support
Impact
High effect
D- Goal FitA Strength of SupportD- CoverageA- Formula Quality
Vitamin C · 2000 mg

Vitamin C supports antioxidant defenses in ocular tissues but does not provide the macular pigments or minerals used in comprehensive vision formulas. Rose hip adds little distinct support beyond the same antioxidant pathway.

The sustained-release vitamin C amount is substantial and clearly disclosed. Such narrow coverage makes it a weak standalone choice for broad retinal or macular support.

Study evidence
Vitamin C Disputed 24 studies
Skin Health
Skin Health
Impact
Moderate effect
C- Goal FitC+ Strength of SupportD CoverageB+ Formula Quality
Vitamin C · 2000 mg

Vitamin C provides a direct collagen-synthesis cofactor and antioxidant support. Sustained release may spread delivery across the day, while rose hips add related plant compounds.

The 2000 mg amount exceeds what is needed to satisfy normal vitamin C requirements and may increase digestive discomfort. No direct structural, hydration, or barrier ingredient broadens the formula.

Study evidence
Vitamin C Supportive 53 studies

Ingredients

IngredientAmount per serving
Vitamin C (Ascorbic Acid)
 2000 mg
Rose Hip (Rosa canina)
 200 mg
Gluten Free Adults 18–50 Vegetarian
Report overview
Vitamin C (Ascorbic Acid) · 2000 mg OverallScore69
C Active Ingredient Quality & BioavailabilityC+ Dose, Safety & Label TransparencyB+ Value

Sustained release improves delivery, but the 2,000 mg serving is higher than necessary for efficient absorption. The large single dose may increase digestive upset even though it is released gradually. Cost per gram is favorable, while the tablet's complete excipient profile remains unavailable.

View ingredientView products
Loading alternative details
86 Performance

Ester-C Plus 1000 mg Vitamin C

Solgar
Ingredient and delivery quality improve with 1,000 mg of buffered Ester-C with 108 mg of calcium and 200 mg of citrus bioflavonoids. Compared with the original 2000 mg ascorbic-acid formula, the substantial buffered dose and compatible bioflavonoids broaden support beyond plain ascorbic acid, although complete excipient details are not supplied.
86 Performance

C

Swanson
Ingredient and delivery quality improve with 1,000 mg of calcium ascorbate with 120 mg of calcium and 200 mg of citrus bioflavonoids. Compared with the original 2000 mg ascorbic-acid formula, the buffered form and meaningful bioflavonoid amount offer a broader formula than plain ascorbic acid, although complete excipient details are not supplied.
84 Performance

Ester-C 24 Hour Immune Support 1000 mg

NatureSmart
Ingredient and delivery quality improve with 1,000 mg of buffered Ester-C with 110 mg of calcium and 102 mg of citrus bioflavonoids. Compared with the original 2000 mg ascorbic-acid formula, the buffered form and bioflavonoids combine stomach-comfort potential with a focused vitamin C dose, although the supplied data do not include the complete inactive-ingredient panel.
89 Budget

Pure Buffered Calcium Ascorbate

NOW
A lower serving cost comes with 890 mg of vitamin C as buffered calcium ascorbate with 100 mg of calcium, compared with the original 2000 mg ascorbic-acid formula. the mineral-bound form may be gentler than plain ascorbic acid and keeps the active formula focused, although the full inactive-ingredient panel is not supplied.
88 Budget

Sodium Ascorbate

NutriBiotic Immunity
A lower serving cost comes with 1,100 mg of vitamin C as sodium ascorbate with 120 mg of sodium, compared with the original 2000 mg ascorbic-acid formula. the fully buffered powder provides a substantial, clearly disclosed amount, although careful measuring and sodium accounting remain important.
88 Budget

Buffered Gold C

California Gold Nutrition
A lower serving cost comes with 1,000 mg of vitamin C as sodium ascorbate with 130 mg of sodium, compared with the original 2000 mg ascorbic-acid formula. the simple buffered formula provides a full amount with no unrelated active ingredients, although the sodium contribution needs consideration on a restricted diet.
89 Value

C-500 Calcium Ascorbate-C

NOW
A stronger quality-to-cost balance comes from 500 mg of vitamin C as calcium ascorbate with 55 mg of calcium and 10 mg of citrus bioflavonoids. Compared with the original 2000 mg ascorbic-acid formula, the buffered form supports stomach comfort while retaining a practical daily amount, while the bioflavonoid addition is small.
84 Value

Ester-C 500 mg With Citrus Bioflavoinds

American Health
A stronger quality-to-cost balance comes from 1,000 mg of buffered Ester-C with a broad citrus bioflavonoid complex. Compared with the original 2000 mg ascorbic-acid formula, the formula adds several named citrus compounds while maintaining a substantial vitamin C amount, while the repeated complex entries make the exact internal amounts difficult to interpret.
88 Value

Sodium Ascorbate Capsules

NutriBiotic Immunity
A stronger quality-to-cost balance comes from 850 mg of vitamin C as sodium ascorbate with 100 mg of sodium. Compared with the original 2000 mg ascorbic-acid formula, the fully buffered form provides clear dosing and may be easier on the stomach than plain ascorbic acid, while the sodium contribution needs consideration on a restricted diet.
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. Supplemental Vitamins and Minerals for Cardiovascular Disease Prevention and Treatment: JACC Focus Seminar.
    Jenkins DJA; Spence JD; Giovannucci EL; Kim YI; Josse RG; Vieth R; Sahye-Pudaruth S; Paquette M; Patel D; Blanco Mejia S; Viguiliouk E; Nishi SK; Kavanagh M; Tsirakis T; Kendall CWC; Pichika SC; Sievenpiper JL · Journal of the American College of Cardiology · 2021
    Meta-analysisGeneral Health forVitamin C
  5. Vitamin C supplementation in kidney failure: effect on uraemic symptoms.
    Singer RF · Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association · 2011
    Randomized trial99 participantsGeneral Health forVitamin C
  6. 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
  7. 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
  8. 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
  9. 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
  10. Intake of vitamin C, vitamin E, selenium, zinc and polyunsaturated fatty acids and upper respiratory tract infection-a prospective cohort study.
    Raposo SE; Fondell E; Ström P; Bälter O; Bonn SE; Nyrén O; Plymoth A; Bälter K · European journal of clinical nutrition · 2018
    Cohort study1,533 participantsImmunity forVitamin C
  11. Vitamin C supplementation and salivary immune function following exercise-heat stress.
    Carrillo AE; Murphy RJ; Cheung SS · International journal of sports physiology and performance · 2009
    Randomized trial12 participantsImmunity forVitamin C
  12. Immunocompetence and oxidant defense during ascorbate depletion of healthy men.
    Jacob RA; Kelley DS; Pianalto FS; Swendseid ME; Henning SM; Zhang JZ; Ames BN; Fraga CG; Peters JH · The American journal of clinical nutrition · 1992
    Clinical trial8 participantsImmunity forVitamin C
  13. 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
  14. Double-blind, half-face study comparing topical vitamin C and vehicle for rejuvenation of photodamage.
    Fitzpatrick RE; Rostan EF · Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.] · 2002
    Non-randomized trial10 participantsSkin Health forVitamin C
  15. 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
  16. 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
  17. 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
  18. Comparison of the Efficacy of Intralesional Ascorbic Acid Mesotherapy and Intralesional Tranexamic Acid in Treating Melasma in the Skin of Colour Population.
    Aslam H; Muhammad A; Ullah A; Aziz N; Lakhiar JA; Ahmad B; Shahzadi A; Ahmad A; Chandni; Virdi G · Cureus · 2025
    Randomized trial110 participantsSkin Health forVitamin C
  19. Efficacy and Safety of tranexamic acid versus vitamin c after microneedling in treatment of melasma: Clinical and Dermoscopic study.
    El Attar Y; Doghaim N; El Far N; El Hedody S; Hawwam SA · Journal of cosmetic dermatology · 2022
    Randomized trial20 participantsSkin Health forVitamin C
  20. 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
  21. 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
  22. 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
  23. 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
  24. 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
  25. 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
  26. 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
  27. 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
  28. 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
  29. 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
  30. 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
  31. 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
  32. 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
  33. 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
  34. 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
  35. 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
  36. 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
  37. Nutritional modulation of cataract.
    Weikel KA; Garber C; Baburins A; Taylor A · Nutrition reviews · 2014
    Narrative reviewVision Support forVitamin C
  38. 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
  39. 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