A small clinical trial has raised the possibility that vitamin C supplementation could help some patients with precancerous blood disorders live longer, although researchers have not established that it prevents leukaemia or slows the growth of abnormal blood cells.
The study, conducted by an international team at four hospitals in Denmark and the United States, found that participants who received vitamin C were more likely to be alive after about three years of follow-up than those given a placebo. However, the survival finding came from an exploratory analysis and requires confirmation in larger studies.
According to a report by Newsweek, the trial, led by Professor Grønbæk, investigated the effects of oral vitamin C in patients with clonal cytopenia of undetermined significance and lower-risk myeloid malignancies — conditions in which abnormal blood cells may be present and the risk of developing more serious disease varies.
Despite the encouraging survival signal, the trial did not achieve its primary objective of significantly reducing the expansion of abnormal blood cell populations, known as clones.
Dr Lucy Hooper, a general practitioner and co-founder of Coyne Medical who was not involved in the study, said the findings were interesting but should not be interpreted as proof that vitamin C is an effective treatment for preventing blood cancer.
Although 109 patients were recruited, only 44 completed the full 12 months of vitamin C treatment, she noted, highlighting the need for caution when interpreting the results.
The research is part of growing scientific interest in whether certain interventions can be used to delay or prevent cancer in people whose blood conditions put them at increased risk.
One possible explanation being investigated involves TET2, an enzyme that helps control gene activity and supports normal blood cell development. Mutations affecting the enzyme are frequently found in leukaemia and related blood disorders.
Vitamin C supports TET2 activity, prompting researchers to investigate whether restoring adequate levels of the vitamin could help normalise gene regulation in blood cells. Previous research has suggested that vitamin C deficiency can impair the activity of TET enzymes, while restoring the vitamin may improve their function.
However, the EVITA trial did not prove that this biological process accounted for the difference in survival between the two groups.
The researchers said larger trials are needed to determine whether vitamin C can reliably improve outcomes for patients with these conditions. Preparations for a phase 3 trial are underway, with a possible launch in early 2027.
Further subgroup findings are also expected to be presented at the American Society of Hematology Annual Meeting in December 2026.
If future studies confirm the potential benefit, correcting vitamin C deficiency could become a useful addition to care for some patients at risk of developing blood cancer. For now, however, the evidence is not strong enough to recommend vitamin C as a proven way to prevent leukaemia or improve survival.
Hooper also cautioned against assuming that vitamin C supplements would benefit all cancer patients. She pointed to concerns raised in some studies about antioxidant supplements used during chemotherapy, including research suggesting possible adverse outcomes in certain groups.
The findings were published in the American Cancer Society journal Cancer in 2026 under the title, “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.”
The study therefore offers a lead for further investigation, rather than evidence that vitamin C can prevent blood cancer or replace established medical care.
Source: Newsweek; study published in Cancer. DOI: 10.1002/cncr.70549. https://pubmed.ncbi.nlm.nih.gov/42764731/
