University of Iowa study finds high vitamin C dosage extends life of some cancer patients

Medical researchers with the University of Iowa published a study last month which found that high doses of vitamin C, administered through an IV, increased the life span of individuals with terminal pancreatic cancer.

The results, published in the November issue of Redox Biology, came from a phase 2 trial that was conducted between 2018 and 2023 with 34 participants. The patients, each of whom had metastatic pancreatic cancer, received either standard chemotherapy or chemotherapy combined with infusions of high-dose vitamin C. On average, those who received the vitamin C infusions lived for 16 months after the trial started, while those who didn’t receive the infusions lived for an average of 8 months.

Those who received the vitamin C infusions also had fewer side effects and were able to tolerate more treatment, according to Dr. Joe Cullen, the senior author of the study.

Cullen, who is a University of Iowa professor of surgery and radiation oncology and a member of UI Health Care Holden Comprehensive Cancer Center, said the initial goal of the trial was to get patients to an average of 12 months of survival, so he was impressed with the result of 16 months.

“We've had ups and downs of course, but this is a culmination of a lot of people's hard work,” Cullen said. “It's really a positive thing for patients and for the University of Iowa.”

Cullen and other University of Iowa researchers have been studying the effect of vitamin C on cancer for decades.

“Vitamin C has kind of a long history. In the late ‘70s, Linus Pauling was touting it to cure everything and there were some initial studies that showed it might help in cancer,” Cullen said. “Then there were two randomized trials at the Mayo Clinic that showed no benefit of vitamin C, but they were given orally. It was an oral dose of vitamin C.”

About 25 years ago, UI researchers started to test the reaction that individual cancer cells had to high doses of vitamin C, and it worked well in removing cancer. The researchers found that when the vitamin is given through an IV, it appears in the blood stream in levels thousands of times higher than when it is given orally, and that increased level is what makes the difference.

“At high levels like this, (vitamin C) makes hydrogen peroxide, and the hydrogen peroxide basically kills the cancer cells. The normal cells tolerate the hydrogen peroxide, but the cancer cells don’t,” Cullen said.

Although this trial focused on prolonging life and easing pain during late-stage pancreatic cancer, Cullen said he believes vitamin C could be used earlier in treatment to help prevent cancer from reaching that terminal stage.

Cullen and his colleagues completed multiple phase 1 trials that also tested the use of vitamin C to treat advanced pancreatic cancer. Three patients from one of those early studies are still alive, and are cancer free, nine years after the study started.

Other UI research teams have been working to study the effect of IV-administered vitamin C on other forms of cancer. A study was published earlier this year showing an increase in survival of patients with glioblastoma, a deadly brain cancer, and a phase 2 trial testing the treatment on non-small cell lung cancer is currently underway.

All three trials were funded by a 2018 grant from the National Cancer Institute.

“It just shows the collaboration here at the University of Iowa and the team that we have, including medical oncologists, research nurses and basic scientists who really got together to make this work,” Cullen said.

The next step in the research, in order for vitamin C to be approved by regulatory agencies as a treatment option for cancer, would be to complete a phase 3 trial with a much larger set of participants. But that trial would require additional funding that the university doesn’t currently have, Cullen said.

“We’d love to do a phase 3 trial, but we just have to find a multimillionaire that’s going to fund it,” Cullen said. “Big drug companies that fund these trials, they have so much money to spend on these trials, but the problem is vitamin C is not going to make them much money, I don't think. So, that's kind of where we're stuck right now.”

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