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Vitamin C (incl. high-dose) & Glioblastoma

Checked 11 Nov 2026 · Glioblastoma

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Written based on 15 research studies on PubMed, searched on 11 Nov 2026.

The claim

Posts say high-dose vitamin C given through a drip can help people with glioblastoma, an aggressive brain tumour.

Where research stands

We found 35 published papers on vitamin C (incl. high-dose) and glioblastoma. They were published between 1969 and 2026. 3 of them are studies in people. At least 55 people took part. None of them compared people who got it with a group that did not. 5 were studies in animals, and 19 were only in cells in the lab. 1 paper is a review that sums up other studies. 2 new studies in people are running or will start soon, say the trial registers.

  • 3In people
  • 5In animals
  • 19Only in the lab

What the studies found

Trials in people

A small first test in people, mainly to check safety, added high-dose vitamin C to standard treatment. [1] 11 people could be evaluated, and the authors report no dose-limiting side effects. [1] A later trial with 55 people had no comparison group treated at the same time. [2] People in it lived a median of 19.6 months, against 14.6 months in older studies. [2] Neither trial compared people with a group that did not get vitamin C, so this does not show vitamin C caused the difference. [1][2]

Other studies in people

One report looked at iron-related markers in tumours of the 55 people and how long they lived. [3] Another study of 37 tumour samples linked more vitamin C in the tumour to longer survival. [4] Such a link does not show cause. [4]

Reviews

A 2021 review said high-dose vitamin C looks safe and may help in several cancers. [5] It said larger studies comparing with a group not getting it are needed. [5]

In animals

In mice, vitamin C with another treatment slowed human glioblastoma tumours more than either alone. [6] In rats, high doses of vitamin C slowed tumour growth and spread. [8] One study in guinea pigs suggested vitamin C may help the tumour progress instead. [9] Results in animals do not always hold in people.

In the lab

In cell studies, high-dose vitamin C killed glioblastoma cells, and added iron made this stronger. [10][11] Some types of glioblastoma cells were less affected than others. [13]

Verdict

Partly true

Two small trials in people had good results, but neither compared with a group not getting vitamin C. [1][2] Results in animals and cells are mixed but promising. [6][8][9][10][11] Nothing yet confirms it helps people, so the claim is partly true. [5]

Partly true means: people did well, but no fair test with a comparison group has shown it yet. Or only part of the claim holds. How we rate claims

What this means for you: A study in people is not proof that it helps you. Do not stop or change your medicines because of it. Ask your doctor before you start taking it.

Sources

  1. First-in-Human Phase I Clinical Trial of Pharmacologic Ascorbate Combined with Radiation and Temozolomide for Newly Diagnosed Glioblastoma.2019 · Clin Cancer Res · Study in people
  2. Magnetic Resonance Imaging of Iron Metabolism with T2* Mapping Predicts an Enhanced Clinical Response to Pharmacologic Ascorbate in Patients with GBM.2024 · Clin Cancer Res · Study in people
  3. Iron-based biomarkers for personalizing pharmacological ascorbate therapy in glioblastoma: insights from a phase 2 clinical trial.2024 · J Neurooncol · Other paper
  4. Increased Ascorbate Content of Glioblastoma Is Associated With a Suppressed Hypoxic Response and Improved Patient Survival.2022 · Front Oncol · Other paper
  5. Parenteral high‑dose ascorbate - A possible approach for the treatment of glioblastoma (Review).2021 · Int J Oncol · Review
  6. Combined effects of vitamin C and cold atmospheric plasma-conditioned media against glioblastoma via hydrogen peroxide.2023 · Free Radic Biol Med · In animals
  7. Selenium Modulates Cancer Cell Response to Pharmacologic Ascorbate.2022 · Cancer Res · In animals
  8. High doses of sodium ascorbate interfere with the expansion of glioblastoma multiforme cells in vitro and in vivo.2019 · Life Sci · In animals
  9. Glioblastoma Invasiveness and Collagen Secretion Are Enhanced by Vitamin C.2022 · Antioxid Redox Signal · In animals
  10. Analysis of High-Dose Ascorbate-Induced Cytotoxicity in Human Glioblastoma Cells and the Role of Dehydroascorbic Acid and Iron.2024 · Antioxidants (Basel) · In animals
  11. Targeting glioblastoma multiforme cells with pharmacological ascorbate: Disrupting DNA damage response and mTOR cascades via extracellular H2O2.2025 · Free Radic Biol Med · In the lab
  12. Pharmacological Ascorbate Restrains Epithelial-Mesenchymal Transition and Invasion in Glioblastoma Cells via Extracellular H2O2 Generation.2026 · Int J Mol Sci · In the lab
  13. Differential H2O2 Metabolism among Glioblastoma Subtypes Confers Variable Responses to Pharmacological Ascorbate Therapy Combined with Chemoradiation.2023 · Int J Mol Sci · Other paper
  14. Selenium supplementation protects cancer cells from the oxidative stress and cytotoxicity induced by the combination of ascorbate and menadione sodium bisulfite.2025 · Free Radic Biol Med · In the lab
  15. Combination of Ascorbic Acid and Menadione Induces Cytotoxic Autophagy in Human Glioblastoma Cells.2022 · Oxid Med Cell Longev · Other paper

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