Can IV Vitamin C Therapy Kill Cancer? | A Surprising Ally in the Fight Against Cancer

Cancer Cells with Low Catalase Levels Are Vulnerable to High-Dose IV Vitamin C Therapy

IV Vitamin C’s reputation as a cancer treatment has long been debated, often due to how it’s been administered. Researchers at the University of Iowa (UI) believe that oral intake of vitamin C—common in many past studies—results in low blood concentrations, limiting its effectiveness. In contrast, delivering vitamin C intravenously bypasses the digestive system, achieving blood levels 100 to 500 times higher than those from oral doses. This extremely high concentration appears to be key to vitamin C’s potential as a cancer-fighting agent.

Previous studies led by UI redox biology expert Dr. Garry Buettner demonstrated that at these high concentrations, vitamin C (ascorbate) selectively kills cancer cells without harming normal cells—in both lab settings and animal models. Building on this, UI Hospitals and Clinics are now conducting clinical trials for pancreatic and lung cancers, combining high-dose IV vitamin C with standard treatments like chemotherapy and radiation. Initial phase 1 trials showed the therapy is safe, well-tolerated, and may improve patient outcomes. Ongoing trials aim to assess whether it can extend survival.

In their latest study, published in Redox Biology, Buettner and his team investigated the mechanism behind vitamin C’s selective toxicity toward cancer cells. They found that when vitamin C breaks down, it produces hydrogen peroxide—a reactive oxygen species known to damage cells. While normal cells can efficiently clear hydrogen peroxide using an enzyme called catalase, cancer cells often lack this capability.

“Our findings show that cancer cells are significantly less efficient at removing hydrogen peroxide than healthy cells,” says Buettner. “This makes them much more susceptible to oxidative damage and cell death when exposed to high-dose vitamin C.”

The study highlights catalase as a key factor in this process. Tumor cells with low catalase activity were far more vulnerable to damage from hydrogen peroxide generated by high levels of vitamin C. In contrast, normal tissues, with higher catalase levels, remained largely unaffected.

This discovery could help identify which cancers are most likely to respond to high-dose vitamin C therapy. “Cancers with low catalase levels may be the most responsive,” Buettner explains, “while those with high catalase activity may be less affected.” Measuring catalase levels in tumors could guide future treatment strategies.