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ProtoSorb C 500

Protocol For Life Balance
4.9
★ ★ ★ ★ ★
(129 ratings)
Vitamin C 500 mg
Rutin 25 mg
Acerola 25 mg
Flavonoid (mixture) 100 mg
Product Image
Score76
A stomach-friendly, well-dosed vitamin C option whose main strength is buffered delivery; the small botanical additions and support-blend labeling add less value.
How scoring works
Quantity:100 Capsule(s) • (100 servings)
Goals:
General Health
Immunity
Skin Health
Vision Support
Anti-Inflammatory Support

Score 76

A stomach-friendly, well-dosed vitamin C option whose main strength is buffered delivery; the small botanical additions and support-blend labeling add less value.
How scoring works
$28.00($0.28 per serving)
Pure Formulas
$ 28.00
iHerb
$ 28.00
iHerb
$ 28.00
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Analysis

Buffered vitamin C provides meaningful support for antioxidant protection, collagen production, and normal immune function. Calcium ascorbate with threonic acid should be easier on the stomach than standard ascorbic acid.

Citrus bioflavonoids, acerola, rose hips, and rutin reinforce the antioxidant theme. Their individual amounts are modest, so most of the practical value comes from the vitamin C rather than the broader blend.

The main vitamin and named supporting ingredients are disclosed, but the branded support-blend presentation makes the formula harder to read than necessary. It suits regular vitamin C use, especially for people who prioritize tolerability over a large botanical dose.

Who is it for
  • People who find acidic vitamin C uncomfortable
  • Adults seeking a focused antioxidant supplement
  • Users who prefer capsules with plant-based supporting compounds
Best for
  • Buffered vitamin C supplementation
  • Collagen and connective-tissue support
  • Everyday immune nutrition

Pros

  • Buffered calcium ascorbate form
  • Practical vitamin C amount
  • Named bioflavonoid and botanical support

Cons

  • Support-blend presentation reduces clarity
  • Acerola amount is small
  • Rutin is below a targeted-use amount

Warnings

  • Calcium from the ascorbate should be included when tracking supplemental calcium
  • Acerola and rutin are supporting ingredients rather than meaningful standalone doses
  • Check the serving against other vitamin C products to avoid unnecessary duplication

Nutrient quality

89 Highest impact

Buffered calcium ascorbate with threonic acid provides a well-regarded delivery form. Vitamin C is meaningfully dosed, while acerola, rose hips, and rutin are small supporting additions.

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Ingredient transparency

72 High impact

Most active amounts are clear, but the branded transport complex is not fully separated. The supplied data does not include a complete inactive ingredient list.

.

Customer satisfaction

66 High impact

The aggregate satisfaction measure is strong enough to support a favorable first impression. The limited volume and missing feedback themes leave repeat complaints and purpose fit uncertain.

.

Value for money

72 High impact

The price reasonably reflects buffered delivery and clear core dosing. Each serving provides solid value for a premium vitamin C form.

.
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Goals

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

A well-dosed buffered vitamin C form supports antioxidant protection, collagen production, and normal immune function. Bioflavonoids and related plant compounds add a plausible supporting role without replacing the main active.

The formula remains more focused than comprehensive, yet it gives meaningful depth to its intended pathway. The proprietary support blend is partly clarified by listed components, though its naming still adds some disclosure uncertainty.

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

Vitamin C directly supports immune cells, barrier defenses, and antioxidant control at a meaningful amount. Buffered calcium ascorbate and threonic acid provide a stomach-friendly delivery approach.

Bioflavonoids, acerola, rose hips, and rutin add related antioxidant support, but most are modest additions. The proprietary support blend reduces transparency even though named components are listed.

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

Buffered vitamin C supplies a substantial amount needed for normal collagen synthesis and antioxidant defense. The disclosed mineral ascorbate form may be gentler on the stomach than plain ascorbic acid.

The focused formula provides strong depth for one nutrient but does not supply collagen, ceramides, or direct hydration support. Supporting bioflavonoids add antioxidant context without making the product comprehensive.

Study evidence
Vitamin C Supportive 53 studies
Vision Support
Vision Support
Impact
High effect
B Goal FitA- Strength of SupportC- CoverageB- Formula Quality
Vitamin C · 500 mg

Vitamin C supplies a well-established ocular antioxidant and is part of clinically studied eye-nutrient combinations. Used alone, it cannot reproduce the broader protection of a complete AREDS2-style formula.

Buffered calcium ascorbate with threonic acid may improve digestive comfort, while the exact vitamin C and rutin amounts are disclosed. The focused antioxidant design does not provide macular pigments, omega-3 fats, or zinc for broader eye support.

Study evidence
Rutin Not classified 1 study
Vitamin C Disputed 24 studies
Anti-Inflammatory Support
Anti-Inflammatory Support
Impact
High effect
B Goal FitB Strength of SupportC+ CoverageB Formula Quality
Vitamin C · 500 mg

Buffered vitamin C provides meaningful antioxidant support, while rutin and citrus bioflavonoids add modest complementary activity. The vitamin C amount is well targeted for regular use.

Threonic-acid-enhanced calcium ascorbate offers a practical, stomach-friendly form. Several supporting ingredients are low-dose, and the large proprietary support blend limits confidence in their individual contributions.

Study evidence
Rutin Supportive 6 studies
Vitamin C Supportive 50 studies

Ingredients

IngredientAmount per serving
Vitamin C (Threonic Acid enhanced buffered Calcium Ascorbate)
 500 mg
Calcium (Calcium Ascorbate)
 60 mg
Transport C-PLUS(R)
650 mg
Citrus Bioflavonoid Complex
100 mg
Acerola powder
25 mg
Rose Hips powder
25 mg
Rutin powder (Sophora japonica)
 25 mg
Gluten Free Adults 18–50 Vegan Dairy Free Vegetarian
Report overview
Vitamin C (Threonic Acid enhanced buffered Calcium Ascorbate) · 500 mg OverallScore89
B+ Active Ingredient Quality & BioavailabilityA+ Dose, Safety & Label TransparencyB+ Value

Buffered mineral ascorbate supports digestive comfort and provides a practical delivery form. The 500 mg serving sits within the optimal range, and the listed formula avoids sugar-based fillers and artificial colors. Cost per effective amount is favorable for the form.

View ingredientView products
Rutin (Sophora japonica) · 25 mg OverallScore56
B- Active Ingredient Quality & BioavailabilityD- Dose, Safety & Label TransparencyD+ Value

Sophora japonica clearly identifies the rutin source, although the powder lacks purity or standardization details. The exact dose is disclosed outside the proprietary blend but remains too low for targeted capillary support. Its cost per active amount is average because most of the formula's value comes from buffered vitamin C and related ingredients.

View ingredientView products
Acerola · 25 mg OverallScore25
F Active Ingredient Quality & BioavailabilityF Dose, Safety & Label TransparencyD+ Value

The 25 mg acerola powder amount is too small for a focused acerola supplement and has no vitamin C standardization. Buffered calcium ascorbate supplies the main vitamin C, so the fruit powder functions mostly as a supporting ingredient. The disclosed amount is clear, but missing botanical details and low potency limit its fit for this collection.

View ingredientView products
Loading alternative details
86 Performance

C

Swanson
Fully buffered calcium ascorbate with citrus bioflavonoids provides a clear, well-dosed core with good stomach-comfort potential. The focused formula is easier to evaluate than the original’s a transport complex and small plant additions, although it offers less ingredient variety.
86 Performance

Ester-C Plus 1000 mg Vitamin C

Solgar
High-potency buffered vitamin C and a meaningful citrus bioflavonoid amount improve form quality and formula focus. It addresses the original’s small supporting amounts, but complete excipient and usage details remain unavailable.
87 Performance

Ester-C with Citrus Bioflavonoids

American Health
Buffered Ester-C and a substantial citrus bioflavonoid amount create a more coherent antioxidant formula. The long supply strengthens practicality compared with ProtoSorb C 500, while inactive ingredients and full directions are not shown.
80 Budget

Ultra C Formula

Swanson Premium Brand
A very low serving cost makes a practical ascorbic acid amount a more economical option than ProtoSorb C 500. It is less gentle than the original buffered form, and its tiny botanical additions add little.
84 Budget

Ester-C 500 mg With Citrus Bioflavoinds

American Health
Low serving cost combines buffered Ester-C with citrus bioflavonoids, offering stronger value than ProtoSorb C 500. Buffered delivery preserves the original’s stomach-comfort advantage while keeping the formula focused.
84 Budget

Ester-C 24 Hour Immune Support 1000 mg

NatureSmart
A low-cost serving provides substantial buffered Ester-C with a compatible citrus bioflavonoid complex. It offers clearer core value than the original’s small supporting amounts, though complete excipient details are not supplied.
82 Value

Buffered C-1000 Complex

NOW
A substantial buffered vitamin C amount and meaningful citrus bioflavonoids provide stronger ingredient depth at favorable serving value. Acerola and rutin remain secondary, and the high vitamin C amount may cause digestive upset in sensitive users.
83 Value

Ester-C plus 500 mg Vitamin C

Solgar
Buffered Ester-C offers a practical daily amount with small, clearly disclosed botanical and flavonoid additions at strong value. The vitamin C amount remains practical, and the active and supporting amounts are clearly disclosed.
79 Value

Buffered Vitamin C 500 mg

Bluebonnet
Buffered calcium ascorbate and a meaningful citrus bioflavonoid amount offer a balanced combination of comfort, disclosure, and value. Its vitamin C amount is comparable to the original’s practical serving, while rutin remains a minor addition.
Report alternatives

Sources

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

  1. 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
  2. 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
  3. 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
  4. 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
  5. 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
  6. 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
  7. 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
  8. The effects of rutin flavonoid supplement on glycemic status, lipid profile, atherogenic index of plasma, brain-derived neurotrophic factor (BDNF), some serum inflammatory, and oxidative stress factors in patients with type 2 diabetes mellitus: A double-blind, placebo-controlled trial.
    Bazyar H; Moradi L; Zaman F; Zare Javid A · Phytotherapy research : PTR · 2023
    Randomized trial50 participantsAnti-Inflammatory Support forRutin
  9. Rutin ameliorates inflammation and improves metabolic function: A comprehensive analysis of scientific literature.
    Muvhulawa N; Dludla PV; Ziqubu K; Mthembu SXH; Mthiyane F; Nkambule BB; Mazibuko-Mbeje SE · Pharmacological research · 2022
    Systematic reviewAnti-Inflammatory Support forRutin
  10. Rutin-loaded chitosan microspheres: Characterization and evaluation of the anti-inflammatory activity.
    Cosco D; Failla P; Costa N; Pullano S; Fiorillo A; Mollace V; Fresta M; Paolino D · Carbohydrate polymers · 2018
    OtherAnti-Inflammatory Support forRutin
  11. Oral enzyme combination therapy reduces systemic inflammation, urinary CTXII and pain in knee osteoarthritis: a proof-of-mechanism, randomised, crossover, double-blind, placebo-controlled trial.
    Henrotin Y; Pap T; Lieten S; Badot V; Dubuc JE; Urbin-Choffray D; von Eynatten M; Johansen OE; Rau S; Brabants K · RMD open · 2025
    Randomized trial45 participantsAnti-Inflammatory Support forRutin
  12. The Impact of the Combination of Proteolytic Enzyme and Rutin on the Post-operative Management of Inflammation: A Randomized, Controlled, Double-Blind, Comparative Clinical Trial
    Rathi PC, Rathi CL, Risbud SP, Ganu GP · Cureus · 2024
    Randomized trial65 participantsAnti-Inflammatory Support forRutin
  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. 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
  23. 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
  24. 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
  25. 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
  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. A randomized, double-masked study on the treatment of retinal vein occlusion with troxerutin
    Glacet-Bernard A, Coscas G, Chabanel A, Zourdani A, Lelong F, Samama MM · American Journal of Ophthalmology · 1994
    Randomized trial53 participantsVision Support forRutin
  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. 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
  33. Nutritional modulation of cataract.
    Weikel KA; Garber C; Baburins A; Taylor A · Nutrition reviews · 2014
    Narrative reviewVision Support forVitamin C
  34. 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
  35. 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