# High-dose intravenous vitamin C

Source: https://onco.cc/technologies/high-dose-vitamin-c/  
OnCo record `high-dose-vitamin-c` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Vitamin C tablets do not treat cancer: two randomised trials at the Mayo Clinic settled that in the 1980s. Intravenous doses reach blood levels high enough to generate hydrogen peroxide in tumours, and small trials alongside chemotherapy are under way, but no adequately sized trial has yet shown benefit.

## Summary

Linus Pauling's claim that 10 g of oral vitamin C prolonged survival was tested in two double-blind randomised trials at the Mayo Clinic (Moertel et al., NEJM 1985 and its 1979 predecessor) and found no benefit. Interest revived when pharmacokinetic work showed that intravenous ascorbate achieves plasma concentrations 100-fold higher than oral dosing, at which it acts as a pro-oxidant producing hydrogen peroxide in the extracellular space. Phase 1 and small phase 2 trials in pancreatic, ovarian, lung and brain tumours show that it is safe alongside chemotherapy and radiotherapy and may reduce some toxicities; a small randomised phase 2 in metastatic pancreatic cancer (Iowa, 2024) reported longer survival with intravenous ascorbate added to gemcitabine and nab-paclitaxel and needs confirmation in a larger trial. The NCI PDQ summary concludes that evidence of anticancer efficacy in humans is insufficient. High doses are contraindicated in G6PD deficiency and renal impairment and can interfere with glucose meters.

## Fields

- Kind: Technology
- Status: phase-2
- Last checked: 2026-09-10
- Tags: complementary; supportive-care; evidence:insufficient
- Principle: At millimolar concentrations ascorbate autoxidises to generate hydrogen peroxide, which is selectively toxic to cells with low catalase and high labile iron, features of some tumours.
- Strengths: Plausible pro-oxidant mechanism at intravenous doses; Good safety alongside chemotherapy in phase 1 and 2; Randomised phase 2 signal awaiting confirmation
- Limitations: Oral vitamin C definitively ineffective; No adequately powered randomised trial; Widely sold in private clinics ahead of evidence

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Intravenous_ascorbic_acid
- High-dose vitamin C versus placebo in advanced cancer with no prior chemotherapy, randomised double-blind trial (NEJM 1985): https://doi.org/10.1056/NEJM198501173120301
- NCI PDQ: High-dose vitamin C: https://www.cancer.gov/about-cancer/treatment/cam/hp/vitamin-c-pdq

## Connected records

- cancers: [Glioma & glioblastoma](https://onco.cc/cancers/glioblastoma/), [Ovarian cancer](https://onco.cc/cancers/ovarian/), [Pancreatic ductal adenocarcinoma](https://onco.cc/cancers/pancreatic/)
- fronts: [Supportive Care & Survivorship](https://onco.cc/fronts/supportive-care/)
- technologies: [Cytotoxic chemotherapy](https://onco.cc/technologies/cytotoxic-chemotherapy/), [Evidence-based integrative oncology](https://onco.cc/technologies/integrative-oncology/)
- companies: [Outperform Cancer](https://onco.cc/companies/outperform-cancer/)
- trials: [NCT + PD1 + Ketogenic Diet and/or Vitamin C for LARC](https://onco.cc/trials/nct07765667/), [Pilot Trial of Intravenous Vitamin C in Refractory Non-Hodgkin Lymphoma (NHL)](https://onco.cc/trials/nct00626444/), [Preoperative IMRT With Concurrent High-dose Vitamin C and mFOLFOX6 in Locally Advanced Rectal Cancer](https://onco.cc/trials/nct04801511/)
- bottlenecks: [Misinformation and unproven therapies](https://onco.cc/bottlenecks/b-misinformation/), [No incentive to repurpose cheap drugs](https://onco.cc/bottlenecks/b-generic-repurposing/)
- key papers: [High-dose vitamin C versus placebo in the treatment of patients with advanced cancer who have had no prior chemotherapy. A randomized double-blind comparison](https://onco.cc/key-papers/paper-moertel-n-engl-j-med/)
- institutions: [Holden Comprehensive Cancer Center, University of Iowa](https://onco.cc/institutions/iowa-holden/)
- roadmaps: [Diet, exercise and lifestyle roadmap: causes established → interventions that disappointed → exercise proven as treatment](https://onco.cc/roadmaps/nutrition-lifestyle-roadmap/)

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