Daily Vitamin C Boosts Survival in Pre-Leukemia Trial

Why were these patients deficient in the first place?

More than half of participants had insufficient vitamin C levels at the start of the trial. Among those assigned to supplementation, blood concentrations returned to normal once the daily dose began.

That deficiency matters because these patients currently have few options. No approved treatment can stop CCUS from progressing to leukemia. Stem cell transplantation can treat MDS, but many patients can't undergo it because of age or other conditions. Doctors often have little to offer beyond monitoring.

"The standard approach for patients with pre-cancer blood disorders is to monitor their blood cell counts over time. This is, understandably, very frustrating — no one wants to hear that they have a condition that increases leukemia risk but there's nothing that can be done other than watch and wait," said Casey O'Connell, M.D., FACP, the Lawrence and Jane Kelly Chair in Hematology at USC and lead clinician at the USC trial site.

The EVITA trial, she said, took on that challenge by exploring whether vitamin C could address underlying factors driving leukemia development. The dose tested is comparable to what's available over the counter.

How might vitamin C work against leukemia?

The mechanism story centers on TET2, an enzyme that helps prevent cancerous growth by controlling whether specific genes are switched on or off. Vitamin C supports that enzyme's activity, helping maintain normal patterns of gene regulation — the system often called epigenetics.

Mutations in TET2 appear frequently in leukemia and related blood disorders. When the enzyme stops working normally, abnormal cells gain room to multiply and potentially turn cancerous. Experiments in cancer models have shown vitamin C can interfere with those cancer-associated cellular changes and slow leukemia progression, with the strongest effects appearing when supplementation begins before cancer is established.

"Our approach reflects a growing emphasis on cancer interception — intervening before cancer becomes established. We are working to build on the trial findings by exploring how exactly vitamin C interacts with pre-cancerous cells, including the idea that it may help restore normal epigenetic function in blood cells at risk of becoming leukemia," said Peter A. Jones, Ph.D., D.Sc. (hon), a distinguished professor at Van Andel Institute and co-leader of the Dream Team.

How solid are these results?

Cautious is the operative word. Scientists have probed vitamin C's possible role in cancer for more than seven decades, and much of that evidence was inconsistent. Only in the past decade have better research tools revealed the vitamin's involvement in controlling gene activity and guiding normal cell development.

Before EVITA, the Dream Team ran a pilot study in 2016 confirming that oral supplementation could meaningfully raise vitamin C in the blood. Encouraged, they launched EVITA in 2017.

"This early work was critical because it offered a foundation from which to develop the present trial," said Stine Ulrik Mikkelsen, M.D., Ph.D., the study's first author.

The international effort was led by Kirsten Grønbæk, M.D., Ph.D., a hematologist and professor at the University of Copenhagen. "These exciting preliminary findings lay the groundwork for a larger clinical trial to explore vitamin C as a possible way to improve patient outcomes," Grønbæk said. "It is too early to make definitive recommendations based on our results, but we are hopeful that a more expansive study will provide further insights."

Researchers are still mining the EVITA data to understand why the supplement group showed better survival. Until a phase 3 trial confirms the effect, no one should treat this as a recommendation to self-medicate.

The takeaway: a cheap, common vitamin showed a survival signal in a rigorous small trial — promising, but unproven until a larger study says so.