Vitamin C and Pre-Cancerous Blood Disorders: What a New Phase 2 Trial Found

Vitamin C is one of the most familiar nutrients there is. It supports immune function, helps wounds heal and protects cells from molecular damage. It also turns out that many people with pre-cancerous blood disorders and blood cancers have chronically low levels of it, which raises an obvious question: could restoring those levels improve outcomes?

A new phase 2 clinical trial, called EVITA, offers an early and carefully qualified answer. The results were published on September 21, 2026 in CANCER, the American Cancer Society journal, by a team led by the Van Andel Institute-Stand Up To Cancer Epigenetics Dream Team.

Who was studied, and how

The trial enrolled 109 people with clonal cytopenia of undetermined significance (CCUS) or myelodysplastic syndrome (MDS). Both are blood disorders that can progress into acute myeloid leukemia (AML), a cancer that is hard to treat. The risk of CCUS and similar conditions rises with age. There are no approved therapies that prevent CCUS from progressing to leukemia, and while MDS can be treated with a stem cell transplant, many older adults have other health conditions that rule it out. At the time of the trial, none of the participants were receiving cancer treatment.

Participants were randomly assigned to take either 1,000 mg of oral vitamin C daily for a year or a placebo identical in look, taste and smell. The trial was double-blind, so neither participants nor trial staff knew who was in which group until the end. That design is considered the gold standard because it limits bias. Trial sites were in Denmark (Copenhagen University Hospital-Rigshospitalet, Copenhagen University Hospital-Herlev and Aalborg University Hospital) and the United States (Keck Hospital of the University of Southern California).

Two details make this trial unusual. It is the first double-blind, randomized, placebo-controlled trial of oral vitamin C in pre-leukemia conditions and lower-risk myeloid cancers. And earlier trials generally gave vitamin C intravenously and focused on solid tumors, whereas EVITA used an oral dose comparable to many over-the-counter supplements.

What the researchers found

·         Vitamin C levels normalized. More than half of participants were vitamin C-deficient at the start. In the vitamin C group, blood levels returned to normal after supplementation began.

·         Fewer adverse events. People taking vitamin C had fewer adverse events during the trial and follow-up period.

·         Inflammatory signals shifted. Vitamin C changed the levels of cytokines, which are inflammatory signaling molecules, in directions associated with better outcomes. This suggests it may help regulate inflammatory pathways linked to the growth and progression of pre-cancerous blood cells.

·         No difference in clone growth. The two groups did not differ significantly in the growth rate of abnormal blood cells, a common measure of progression toward leukemia.

·         A survival signal, with a caveat. In an exploratory analysis, people who took vitamin C were significantly more likely to be alive after roughly three years of follow-up than those who received the placebo.

Why vitamin C? The TET2 connection

Scientists have explored vitamin C in cancer for more than 70 years, but inconclusive results and differences in study methods left its role unclear. Over the past decade, advances in technology revealed that vitamin C is an essential partner of TET2, an enzyme that helps suppress cancer cell growth by regulating whether certain genes are switched on or off. Mutations in TET2 are a common feature of leukemia and related disorders.

Later studies in cancer models found that vitamin C appeared to prevent cancer-related cellular changes and slow leukemia progression, with the greatest benefit when supplementation started before the disease was established. That timing is central to the idea of cancer interception: intervening before a cancer takes hold. A 2016 pilot study showed that oral supplementation could raise vitamin C levels in the blood, and the EVITA trial began in 2017.

How to read these results

The survival finding is the headline, but it came from an exploratory analysis in a trial of 109 people. Exploratory analyses are generally used to generate hypotheses rather than to confirm them, and the researchers themselves say a larger phase 3 trial is needed. The measure of abnormal cell growth, the more standard marker of progression, showed no significant difference between groups. The lead investigator, Dr. Kirsten Grønbæk, said it is too early to make definitive recommendations based on the results.

In practical terms, these results are a reason to run a bigger trial, not a reason for anyone with CCUS or MDS to start high-dose supplements on their own. Anyone with one of these diagnoses should discuss vitamin C with their hematologist.

What comes next

Additional analysis of the trial data is ongoing, focused on the biological mechanisms that might explain the survival difference. The team is also studying how 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.

This post is a summary based on the Van Andel Institute press release. For full methods, statistics and limitations, see the original paper.

Sources

·         Press release: Phase 2 trial suggests vitamin C may benefit people with pre-cancer blood disorders (Van Andel Institute, September 21, 2026)

·         Original paper: EVITA phase 2 trial, CANCER (DOI: 10.1002/cncr.70549)

Source: Vitamin C and Pre-Cancerous Blood Disorders: What a New Phase 2 Trial Found