Vitamin C is an essential nutrient best known for supporting immune function and acting as an antioxidant, but it also helps regulate important cellular processes. Scientists are increasingly studying how its effects on enzymes, inflammation, and gene activity could influence disease. Credit: Shutterstock

A phase 2 trial linked vitamin C supplements to better survival in people with certain blood disorders, a finding that requires further study in a larger phase 3 trial.

Vitamin C supplements were linked to better survival in a clinical trial involving people with precancerous blood conditions or low-risk blood cancers.

The finding offers a reason to investigate the vitamin further, although it came from an exploratory analysis. The growth rate of precancerous or cancerous cells, the trial’s main measure, was similar among participants taking vitamin C and those receiving a placebo.

Fewer deaths among vitamin C recipients

The phase 2 EVITA trial enrolled 109 patients in Denmark and the United States. Researchers randomly assigned 55 participants to take 1,000 milligrams of oral vitamin C daily and 54 to receive a placebo for 12 months. The study was double-blind, meaning neither the participants nor the researchers knew who was receiving which treatment. Results were published in CANCER, a peer-reviewed journal of the American Cancer Society.

After a median follow-up of 33.6 months, nearly three years, researchers had recorded 35 deaths. Of those, 24 occurred in the placebo group and 11 in the vitamin C group. The analysis counted participants according to their original treatment assignments, an approach called intention-to-treat analysis. The apparent survival benefit needs confirmation in a larger phase 3 clinical trial.

“We are encouraged by our findings and what they ultimately could mean for people with these early-stage blood disorders. Although it is too soon to make recommendations based on our results, we are hopeful that a larger study will give us more definitive answers,” said co-senior author Kirsten Grønbæk, MD, PhD, of Rigshospitalet, Copenhagen University Hospital in Denmark.

Vitamin C boosts gene-regulating enzymes

The reason for testing vitamin C lies in its effect on TET enzymes, proteins inside cells that help control which genes are switched on or off. Reduced TET function is a common driver of certain blood cancers. Vitamin C boosts these enzymes’ activity, prompting researchers to investigate whether supplements could help patients with blood conditions that can become cancerous or with low-risk blood cancers.

Although the supplements did not change the trial’s main measure of cell growth, participants taking vitamin C showed changes in inflammatory signaling that were consistent with better outcomes. Several health problems were also less frequent in this group, including anemia, pneumonia, internal bleeding, and acute aseptic arthritis, a sudden inflammation of the joints that is not caused by infection. Gastrointestinal problems, however, occurred more often among participants taking vitamin C.

The trial was led by the Van Andel Institute–Stand Up To Cancer (VAI–SU2C) Epigenetics Dream Team, of which Grønbæk is a longtime member. Co-senior author Peter A. Jones, PhD, DSc (hon), of Van Andel Institute in Grand Rapids, Michigan, co-leads the team.

“The EVITA trial gives us a strong rationale to continue exploring if and how vitamin C might benefit people with certain pre-cancer or early-stage blood cancers. More work is needed, but we are cautiously optimistic that these findings could inform future strategies to intercept leukemia development,” Jones said.

Reference: “Oral vitamin C supplementation in patients with clonal cytopenia of undetermined significance or lower-risk myeloid malignancies: Results from EVITA, a phase 2 randomized, placebo-controlled trial” by Stine Ulrik Mikkelsen, Ali Al-Mousawi, Amalie Bach Puglisi, Anders Pommer Vallentin, Astrid Østergaard Mortensen, Zachary Madaj, Toshinori Hinoue, Heidi Naomi Ottesen, Jakob Schmidt Jespersen, Linn Gillberg, Morten Tulstrup, Niels Richard Hansen, Jakob Werner Hansen, Mette Klarskov Andersen, Stacey Lyn Thomas, Christine Isaguirre, Ryan Sheldon, Marie Adams, Ryan Burgos, Stephen Baylin, Bo Kok Mortensen, Casey Lee O’Connell, Marianne Tang Severinsen, Peter William Laird, Jens Lykkesfeldt, Peter Jones and Kirsten Grønbæk, 21 September 2026, Cancer.
DOI: 10.1002/cncr.70549

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