High-dose intravenous vitamin C

That vitamin C at doses far above dietary levels is selectively toxic to cancer cells and can cure or substantially extend survival in advanced cancer.

Linus Pauling, a double Nobel laureate, championed this from the 1970s with Scottish surgeon Ewan Cameron. Two Mayo Clinic trials found no benefit and the mainstream moved on. Pauling's supporters objected that Mayo used oral vitamin C while Cameron used intravenous, which produces blood levels orders of magnitude higher. That objection was substantively correct and is why the question never fully closed.

Paraphrased summaries of publicly circulating reports, not verbatim quotes from identified individuals. Unverified by definition.

• “Had infusions twice a week through the worst of chemo. I cannot tell you if it touched the cancer but I got through treatment with far less nausea than I was warned about.”

  reported improvement, concurrent treatmentReported 2022

  Integrative-oncology patient forums; consistent with the adjunct trial findings

This is the claim on this list with the most legitimate scientific footing, and it still does not amount to a cure. Pharmacological ascorbate reaches concentrations orally impossible and generates hydrogen peroxide in extracellular fluid, which some tumour cells clear poorly. Phase I and II trials, notably at the University of Iowa, suggest it is reasonably safe alongside standard treatment and may reduce side effects. What has not been shown in any phase III trial is that it extends survival. It is being studied as an adjunct, not a replacement, and the researchers running those trials say so explicitly.