Ahmed Elbediwy & Nadine Wehida, Kingston University/ The Conversation
We’ve all heard the recommendation: eat your fruit and greens, get your nutritional vitamins, and keep wholesome. For probably the most half, that steering holds up.
However some vitamins have a extra sophisticated story, and vitamin B12 is a captivating instance.
Also referred to as cobalamin, B12 is important for all times. It helps the physique produce pink blood cells, retains the nervous system functioning, and performs a central position in how cells copy and restore DNA.
B12 is discovered naturally in animal merchandise akin to meat, fish, eggs, milk, and cheese. Some cereals and breads are additionally fortified with it, serving to individuals who don’t eat meat get sufficient. Most individuals following a different food regimen get the really useful quantity, however vegans, individuals with sure intestine situations, and older adults who soak up vitamins much less effectively may need supplements.
With out sufficient B12, things can go wrong, typically severely, particularly if the deficiency just isn’t recognised and handled. But in recent times, researchers have been asking whether or not excessive ranges of B12 consumption or excessive ranges of B12 within the blood could possibly be linked to most cancers.
Staying balanced
The physique is consistently making new cells. Each time a cell divides, it wants to repeat its DNA precisely. Vitamin B12 is important to that course of. When ranges are too low, DNA might be copied incorrectly, resulting in mutations that, over a few years, could improve the danger of sure cancers, notably colon most cancers. For this reason B12 deficiency is taken severely.
A 2025 case-control research from Vietnam discovered what researchers described as a U-shaped relationship between B12 consumption and most cancers danger, with each decrease and better intakes related to elevated danger. As a result of this type of research can present an affiliation however can’t show trigger and impact, the takeaway just isn’t that B12 is harmful. It’s that steadiness that issues.
It might sound logical that if B12 helps wholesome cells thrive, taking further doses ought to supply further safety in opposition to most cancers. However analysis doesn’t absolutely help this. Vitamin B12 helps cell progress typically, not solely the expansion of wholesome cells.
One concern is that, if pre-cancerous cells are already current, very excessive availability of growth-supporting vitamins akin to B12 might, in idea, help their progress too. However this stays tough to show in people.
Total, research of high-dose B vitamin dietary supplements taken over lengthy durations haven’t proven clear protective effects in opposition to most cancers incidence or most cancers deaths. One evaluation did report a lowered danger of melanoma, however this was a cancer-specific discovering relatively than proof that high-dose B nutritional vitamins stop most cancers typically.
Some observational analysis has additionally urged a slight increase in lung most cancers danger linked to long-term, high-dose B6 and B12 supplementation, notably amongst males and people who smoke, though this type of research can’t show that the dietary supplements prompted the cancers.
Medical doctors have observed that many most cancers sufferers present unusually high levels of B12 of their blood. This raises an essential query: does elevated B12 contribute to most cancers, or can most cancers itself trigger B12 ranges to rise?
Analysis in 2022 concluded that prime B12 in most cancers sufferers is commonly an “epiphenomenon”. In different phrases, the vitamin seems alongside the illness however doesn’t essentially set off it. Additional analysis from 2024 reached a similar conclusion.
This impact is believed to contain two foremost mechanisms. First, tumours can have an effect on the liver, which shops massive quantities of B12. When the liver is broken or underneath pressure, it could launch extra B12 into the bloodstream. Second, some tumours could improve proteins that bind to B12 within the blood. This could push blood check readings greater with out essentially that means the physique’s cells are receiving or utilizing extra B12.
Helpful indication
Researchers are additionally recognising that elevated B12 might not be a explanation for most cancers, but it surely could possibly be a helpful marker of whether or not most cancers is current or progressing. A big 2026 research discovered that colon most cancers sufferers with very excessive B12 ranges survived a median of round five years, in contrast with almost eleven years for these with regular ranges.
Related patterns have been present in oral cancer and in patients receiving immunotherapy, the place elevated B12 has been related to poorer outcomes. Because of this unexplained, persistent excessive B12, particularly when it’s not brought on by dietary supplements, shouldn’t be ignored. It could level to liver illness, blood issues, or an underlying most cancers that has not but been detected.
For most individuals, this isn’t one thing to fret about. B12 from a standard food regimen containing meat, fish, eggs, dairy, or fortified meals just isn’t often the difficulty: it is rather tough to devour an excessive amount of B12 from meals alone. Deficiency stays a extra frequent and better-established downside than extra.
The priority is extended high-dose supplementation with out medical recommendation, or a blood check exhibiting persistently excessive B12 when somebody just isn’t taking dietary supplements.
The broader message is straightforward: extra just isn’t at all times higher. Most cancers can’t be prevented by loading up on any single vitamin. Lengthy-term habits matter extra: consuming a balanced food regimen, exercising often, avoiding smoking, defending your pores and skin, and attending routine well being screenings.
So what about vitamin B12? Get sufficient by means of meals or supplementation in case you want it, particularly if you’re vegan, older, or have a situation that impacts absorption.
However depart the megadoses on the shelf except a health care provider advises them. With B12, as with many vitamins, the purpose just isn’t as a lot as attainable. It’s the correct quantity.
Ahmed Elbediwy, Senior Lecturer in Most cancers Biology & Scientific Biochemistry, Kingston University and Nadine Wehida, Senior Lecturer in Genetics and Molecular Biology, Kingston University
This text is republished from The Conversation underneath a Artistic Commons license. Learn the original article.
