A blood test comes back showing high vitamin B12, and most people read it as a non-event, maybe even a sign the supplements are working. Deficiency is the thing doctors flag, the cause of anemia, numb hands, and foggy memory.
A reading at the top of the range almost never gets a second look. A new analysis of more than 37,000 colon cancer patients worldwide suggests it should, because a high B12 number near diagnosis carried a quiet warning about how long people lived.
High vitamin B12, decoded
Your body uses B12 to build red blood cells, insulate nerves, and copy DNA each time a cell divides. The liver stockpiles years’ worth, releasing the vitamin into the blood as needed.
Researchers had long suspected the high end of the scale hides something. One French study found that people whose blood B12 stayed above 1,000 nanograms per liter faced sharply higher odds of developing a solid tumor.
Nobody knew whether high levels said anything once colon cancer is already diagnosed. The disease ranks among the deadliest cancers on Earth, so even a rough warning sign would count.
Records search worldwide
Bruce Chang-Gu, an M.D.-Ph.D. student at the University of Texas Medical Branch (UTMB) in Galveston, took up that question with pharmacologist Kamil Khanipov.
Their tool was a network of anonymized records from 108 healthcare systems worldwide.
The team pulled every adult diagnosed with colon cancer who also had a B12 blood test within a year of diagnosis. The search returned 37,106 patients, the largest group ever assembled for this question.
Each patient landed in one of three buckets. Low meant under 300 picograms per milliliter, normal ran from 300 to 1,000, and high meant anything above that line. Roughly two-thirds tested normal.
Five years versus eleven
Patients with high B12 lived a median of just under five years after diagnosis. Those with normal levels made it nearly 11 years, and the low group slightly longer than that.
A gap that wide could reflect sicker patients simply getting tested more, so the team matched people on demographics, treatments, and health history. High-B12 patients still died at up to nearly double the rate of the others.
Then came the twist. Low B12, the deficiency doctors actually screen for, made no difference to survival. The danger sign sat at the top of the range, something no one had shown before in a colon cancer study of this size.
Where the cancer travels
High B12 also tracked with metastasis, cancer breaking away to seed new tumors elsewhere. More than half of high-B12 patients with staging records had stage 4 disease at diagnosis, against roughly a third of those with normal levels.
The pattern held after diagnosis too. Within a year, 42% of the high group developed new spread, compared with 32% of matched patients, and liver tumors showed the sharpest jump, 23% versus 15 percent.
Signs of liver strain showed up far more often in the high group. The liver pulls double duty here: it stockpiles the body’s B12, and it is the single most common place colon cancer spreads to.
A liver overrun by tumors might be leaking its stored vitamin into the blood. The records can only hint at that, not prove it.
Clues inside the tumors
Numbers from a chart cannot show what a tumor is doing with the vitamin. So the team turned to genetics, comparing gene activity in 283 colon tumors against more than 300 healthy colon samples.
Tumor tissue was making far more of one enzyme than healthy tissue did. The standout was methionine synthase, a cellular worker that cannot run without B12 and helps copy DNA before a cell divides.
Patients whose tumors made the most of it lived a median of about five and a half years. Most with lower levels were still alive when the study’s tracking ended.
That fits a separate paper showing cancer cells stop multiplying when scientists disable this enzyme under realistic nutrient conditions.
Hungry tumors may be pulling the vitamin into their own growth machinery rather than just leaking it.
The supplement question
None of this proves B12 causes cancer to spread. The work is observational, built from records rather than experiments, so it cannot untangle which direction the relationship runs, at least not yet.
Still, the old assumption that extra B12 simply washes out of the body looks shakier. Patients who took B12 and folic acid supplements in the year before diagnosis fared modestly worse, a link that deserves a closer look.
Earlier population research reached a similar place, tying the highest blood B12 levels to higher death rates in the general population.
For now, an unexplained high reading looks like a signal worth chasing, not a number to shrug off.
A cheap warning light
The core finding stands regardless of mechanism. Across tens of thousands of patients on several continents, a routine blood test near diagnosis separated people who lived about five years from people who lived about 11.
That makes the vitamin a candidate biomarker, a measurable signal doctors use to judge how a disease will likely behave. A cheap one, too. A high result could prompt earlier scans of the liver and lungs, catching spread while it is treatable.
The enzyme finding opens a second door. Some chemotherapy drugs already attack one half of the chemical chain tumors use to copy DNA. Nothing on the market yet hits the half that runs on B12, giving researchers a fresh target.
The study is published in the journal Cancer Research Communications.
—–
Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates.
Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.
—–