Researchers are studying high dose vitamin C as part of treatment for several cancers, including pancreatic cancer. These high doses of vitamin C (pharmacologic ascorbate) are not taken orally (by mouth), but in IVs (taken intravenously). It is always given alongside chemotherapy.
The intravenous vitamin C doses are 150 to 190 times larger than ordinary vitamin C tablets that are taken orally. This is because orally taken vitamin C cannot reach the blood levels needed to produce a pharmacologic effect.
Some of the results are amazing. For example, persons with pancreatic cancer it doubled survival compared to chemotherapy alone (from 8 months to 16 months) , and those receiving vitamin C used alongside standard chemotherapy had fewer side effects than when using chemotherapy alone. It is still unclear for which cancers the vitamin C treatment works and for which it doesn't.
The only problem is that pharma companies may not be interested because it can not be patented, and can't be developed as a new drug that they can make big profits off of. It's plain old vitamin C - but not as a nutritional supplement, but used as a medical drug (pharmacologic ascorbate).
Click on the link for the full story and dosing details. Excerpts from Medscape: Vitamin C’s Potential Use in Cancer Is Getting a Second Look
When Garry Buettner, PhD, who has been studying the chemistry and biochemistry of vitamin C for at least four decades, was diagnosed with myelodysplastic syndromes (MDS), he applied his research to his own life — reviewing the data and designing a protocol for his treatment.
The biochemist’s work has helped establish that at millimolar concentrations, intravenous delivery of vitamin C (ascorbate) can act as a prooxidant — generating hydrogen peroxide in a rodent tumor’s microenvironment. In fact, Buettner and his colleagues from the Free Radical and Radiation Biology Program at the University of Iowa in Iowa City, Iowa, recently published a scientific paper demonstrating that high-dose ascorbate increased the effectiveness of the chemotherapy agent azacytidine (Vidaza) in preclinical cell studies and in mice.
Buettner received his first chemotherapy treatment for MDS in early September 2023, shortly after he was diagnosed with cancer. He began taking infusions of high-dose ascorbate in February 2024, which have continued to be a part of each of his cancer treatment cycles since. He receives azacytidine as the standard of care in a repeating 28-day cycle (4 weeks). ...
“The big thing is that I am feeling good; my blood counts have been in or near the normal range. Can’t ask for more,” he continued.
The distinction between vitamin C as a nutritional supplement and pharmacologic ascorbate as a drug is key to understanding why this field has been so hard to communicate and so easy to dismiss. What researchers at the University of Iowa, the University of Kansas, and a few other institutions are studying bears almost no resemblance to the vitamin C tablets sold in drug stores. We are talking about doses 150-190 times higher, given intravenously, 2-3 times a week — sometimes for years.
To understand where things stand today, it helps to understand the confusion left by earlier efforts. In the 1970s, Linus Pauling championed oral vitamin C as a cancer treatment. However, Mayo Clinic randomized trials in the 1980s found no benefit and were published in The New England Journal of Medicine. For most of the oncology community, that was that.
The flaw in those early trials, researchers now understand, was the route of administration. Oral vitamin C cannot reach the blood levels needed to produce a pharmacologic effect. Mark Levine, MD, at the National Institutes of Health (NIH), recognized this and revived interest in high-dose intravenous ascorbate in the mid-2000s, connecting with Buettner and eventually with Joseph Cullen, MD, a surgeon at the University of Iowa. What followed was a decade-long effort to rebuild the rationale from cells to animals to patients.
One of the persistent misconceptions about high-dose vitamin C in oncology is that it acts as an antioxidant — and that giving an antioxidant alongside chemotherapy or radiation would blunt those treatments’ cancer-killing effects. For years, this concern kept medical oncologists at arm’s length.
The reality is more nuanced. When pharmacologic ascorbate is infused intravenously, plasma concentrations in the body can rise into the near 20 mM range, according to a randomized phase 2 study of patients with stage IV pancreatic cancer published in Redox Biology. This concentration is orders of magnitude higher than the roughly 0.06 mmol/L normally found in blood and cannot be achieved through oral intake. At these levels, vitamin C behaves very differently from its familiar antioxidant role.
Levine, Buettner, and colleagues co-authored a paper, published in Proceedings of the National Academy of Sciences, which found that pharmacologic ascorbate acts as a prooxidant, generating hydrogen peroxide in the extracellular fluid surrounding tumors. The authors of this and other papers think this is how pharmacologic ascorbate works when people take it.
What Human Trials Show
The most compelling human evidence of improved survival from pharmacologic ascorbate to date comes from research on pancreatic cancer.
The study of patients with pancreatic cancer mentioned earlier was conducted by researchers at Iowa. Cullen, who led the research, and his colleagues, added 75 g of pharmacologic ascorbate three times weekly to standard gemcitabine and nab-paclitaxel as first-line therapy in metastatic pancreatic cancer. The results were striking enough that the data safety monitoring board stopped enrollment early: patients receiving ascorbate showed roughly double the progression-free and overall survival (16 months vs 8 months) of those on chemotherapy alone.
“Double the survival — to me, that’s not heard of before,” said Qi Chen, PhD, at the University of Kansas Medical Center, Kansas City, Kansas, who trained directly under Levine at the NIH. “Even if you prolonged survival for 2 or 6 months in pancreatic cancer, that would be viewed as significant.”
Cullen noted an unexpected secondary finding: ascorbate patients tolerated chemotherapy substantially better.
In glioblastoma, Allen led a University of Iowa phase 2 trial of roughly 50-60 patients treated with pharmacologic ascorbate plus radiation and temozolomide. The study, published in Clinical Cancer Research in 2024, showed that about 20% had significantly improved overall survival vs the historical control group (19.6 months vs 14.6 months, respectively). Embedded within that trial was a notable biomarker finding: patients whose tumors had higher baseline levels of redox-active iron had substantially better progression-free and overall survival, suggesting tumor iron content may predict who benefits most. Allen’s group is currently conducting a phase 1 trial testing that theory. His team is also analyzing results of a phase 2 trial combining radiation, chemotherapy, and ascorbate for patients with non-small cell lung cancer. They hope to publish these findings this year.
"We currently do not have good predictors of whether cancers will be sensitive or resistant to pharmacologic ascorbate,” said Channing Paller, MD, oncologist at Johns Hopkins Medicine, Baltimore. She led a trial of docetaxel with or without ascorbate in heavily pretreated prostate cancer that showed no benefit — a result attributed in part to late-line patient selection and failure to verify adequate ascorbate blood levels were achieved.
So why hasn’t a rigorous phase 3 trial happened? One reason is that vitamin C cannot be patented, so no pharmaceutical company stands to profit from proving it works. A single dose of pharmacologic ascorbate costs roughly $150-$200 during the Iowa trials — compared with $15,000 or more per dose for many immunotherapies.
Cullen said he has a plan ready and five or six willing sites. What he lacks is funding. A Columbia University oncologist has expressed interest in co-leading a phase 3 pancreatic cancer trial, and the Medical College of Wisconsin, Milwaukee, has already participated in earlier ascorbate studies — suggesting that a multicenter infrastructure exists if resources can be secured.
Adverse events with pharmacologic ascorbate are substantially milder than those of most systemic cancer therapies.