What is the relationship between vitamin B12 and cancer?
In a report published by the research news website ScienceAlert, writer Fiona McDonald revealed that the relationship between vitamin B12 and cancer is more complex than previously thought. Recent studies indicate that abnormally high levels of this vitamin in the blood, not just low levels, are associated in several cases with tumors of the lung, breast, esophagus, and colon.
Vitamin B12, scientifically known as cobalamin, is an essential nutrient that no living organism can do without. It plays a crucial role in DNA synthesis, maintains the myelin sheath that protects nerves, contributes to the maturation of red blood cells, and aids in the metabolism of fats and amino acids. Because this vitamin is naturally available only in animal-based foods, those following strict vegan diets are most susceptible to deficiency.
The initial scientific assumption was that vitamin deficiency impairs the body’s ability to repair DNA, potentially paving the way for genetic mutations and cancerous tumors. However, a series of subsequent studies revealed a completely opposite pattern: elevated, rather than low, levels of the vitamin were observed in the blood of patients with lung cancer, followed by breast and colon cancer, across large-scale datasets with consistently replicated results.
Research shows that blood vitamin levels do not necessarily reflect dietary intake but are influenced by factors related to how the body stores, transports, and utilizes the vitamin. Key factors include:
* The liver stores large reserves of the vitamin; tumors—particularly those in the liver itself or highly metastatic cancers—can disrupt its storage, transport, and excretion mechanisms.
* Some tumors increase the production of blood-borne vitamin-binding proteins, raising their concentration in laboratory tests.
* Elevated vitamin levels in blood tests may be a symptom accompanying the disease rather than a cause of its development.
In this context, researchers at the University of Texas Medical Branch conducted a study involving data from 37,106 colon cancer patients, drawn from a global health database covering 108 healthcare systems. Blood tests for vitamin B12 were taken for each patient around the time of diagnosis. The results, published earlier this year in the journal Cancer Research Communications, revealed a striking pattern in survival rates.
Patients with vitamin levels exceeding 1,000 picograms per liter had an average survival rate of approximately five years, compared to nearly 11 years for those with normal levels, while those with low levels fared slightly better. Even after adjusting for factors such as age, treatment, and overall health status, it was found that the risk of death for patients with high vitamin levels was twice that of those with low levels and 65 percent higher than those with normal levels.
Furthermore, the research team observed significantly higher activity in a gene known as MTR after examining hundreds of tumors directly. This gene is responsible for producing an enzyme that requires vitamin B12 to synthesize a fundamental component of DNA. Tumors with higher activity in this gene were associated with the poorest survival rates, suggesting that aggressive tumors may be more efficient at exploiting and storing the vitamin to fuel their rapid division, rather than the reverse.
These findings align with a 2024 study of patients undergoing immunotherapy for cancer, which observed the same pattern of elevated vitamin levels associated with poorer outcomes, alongside similar research on oral cancer patients. However, a scientific review published the same year described the significance of elevated vitamin levels in already diagnosed patients as “still ambiguous,” cautioning that it is possible the disease itself is causing the elevated readings rather than the other way around.
On the other hand, the other side of the equation remains unresolved. A study conducted in Vietnam on 3,758 cancer patients and 2,995 healthy individuals identified a U-shaped relationship, where both unusually low and high dietary vitamin intake were associated with an increased risk of cancer compared to moderate levels. This remains an observational study relying on self-reported dietary questionnaires, meaning it can indicate an association but cannot prove a direct causal relationship.
The researchers concluded that elevated blood vitamin B12 levels may be a symptom of underlying physiological disturbances rather than a direct cause of cancer, while the explanation for the link between low levels and increased risk remains unclear. ScienceAlert emphasizes that the relationship between the vitamin and cancer is far from settled, as scientists continue to unravel the threads of this nutritional puzzle.
