Daily vitamin C was tied to fewer deaths in a trial of people with precancerous blood disorders

Of 35 people who died during follow-up in a randomized trial of daily vitamin C, 24 had been taking placebo and 11 had been taking the vitamin. The 109 participants all had a blood disorder that can turn into leukemia, either clonal cytopenia of undetermined significance or lower-risk myelodysplastic syndrome, and none was on cancer treatment while the trial ran.

The survival gap was an exploratory finding rather than the trial’s goal. On the question the trial was built to answer, vitamin C did not separate from placebo at all, and the investigators say the result is not yet strong enough to support new treatment recommendations.

EVITA: 1,000 milligrams a day for a year

EVITA is a phase 2, randomized, double-blind, placebo-controlled trial run at Denmark’s Copenhagen University Hospital Rigshospitalet, Herlev and Aalborg hospitals and at Keck Hospital of USC. According to HCPLive’s report on the trial, 55 participants received 1,000 mg of oral vitamin C daily for 12 months and 54 received a matching placebo. The VAI-Stand Up To Cancer Epigenetics Dream Team led the work, and the results appear in the journal Cancer, 2026, volume 132, issue 19.

Kirsten Grønbæk, M.D., Ph.D., of Rigshospitalet led the international trial, and Peter A. Jones, Ph.D., D.Sc., of the Van Andel Institute is co-senior author. The pairing traces to a 2016 pilot that checked whether an oral supplement could raise blood vitamin C levels; the phase 2 trial began in 2017. More than half the participants were vitamin C deficient at the start, and levels normalized in the vitamin C group, a baseline that complicates any reading of what the supplement did for people who were not deficient.

The rationale runs through an enzyme called TET2, which vitamin C helps activate. TET2 mutations are common in leukemia and its precursor conditions, and laboratory work had suggested vitamin C does the most good when given before a disease is fully established, according to the Van Andel Institute’s announcement. The same release calls EVITA the first double-blind, randomized, placebo-controlled trial of oral vitamin C in pre-leukemia or lower-risk myeloid malignancies, since earlier trials used intravenous dosing and focused on solid tumors.

The deaths: 24 versus 11, and where the number comes from

At a median follow-up of 33.6 months in the intention-to-treat population, 35 participants had died: 24 in the placebo group and 11 in the vitamin C group. That split, reported in the trial summary distributed with the paper, is why vitamin C recipients were described as significantly more likely to be alive after roughly three years.

The authors label the analysis exploratory and say a larger phase 3 trial is needed to confirm it. Grønbæk said that although it is too soon to make recommendations based on the results, the team hopes a larger study will give more definitive answers. Jones said the trial gives a strong rationale to keep exploring if and how vitamin C might benefit people.

The primary endpoint and the vitamin C secondary findings

The trial’s primary outcome was the growth rate of the abnormal, precancerous or cancerous blood cells, a common measure of progression toward leukemia. The two groups looked alike on it. Vitamin C did not slow that growth, which means the survival difference cannot be explained by the one mechanism the study was designed to test.

Secondary findings were mixed in the direction one would hope for, with a cost. Vitamin C recipients showed shifts in inflammatory signaling molecules in patterns linked to better outcomes, and they had fewer cases of anemia, pneumonia, acute aseptic arthritis and internal bleeding. Gastrointestinal problems were more frequent in the vitamin C group, which fits the effect described by the NIH Office of Dietary Supplements: high doses can cause diarrhea, nausea and abdominal cramps through the osmotic effect of unabsorbed vitamin C.

Clonal cytopenia, myelodysplastic syndrome and the phase 3 gap

The population is narrow. The published summary describes people with precancerous conditions or low-risk blood cancers, and coverage of the trial names the two diagnoses; the trial was not reported separately for the clonal cytopenia and myelodysplastic subgroups. No approved therapy currently prevents clonal cytopenia from progressing to leukemia, and stem cell transplantation, which can treat myelodysplastic syndrome, is out of reach for many older patients.

The 1,000 mg dose is more than ten times the 90 mg daily allowance the NIH lists for adult men, and below the 2,000 mg tolerable upper intake level, which applies to food and supplements combined. The trial gives no basis for self-dosing, because the dose was set by protocol, the participants were monitored in clinics, and the investigators themselves say the data cannot yet support treatment recommendations. Any person with an abnormal blood count would be dosing against a diagnosis that this trial did not test in anyone without it.

What a phase 3 trial would have to show is the one thing this one could not: that the 11-versus-24 gap in deaths holds up when survival is the prespecified endpoint.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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