Emerging evidence from 2015-2025 studies establishes three critical takeaways about vitamin B12 and cancer risk. First, B12 deficiency unequivocally increases cancer risk through impaired DNA repair and methylation mechanisms—individuals with severe deficiency face double the colorectal cancer risk. Second, extremely high supplement doses appear equally problematic, with relative cancer risk rising 1.7-fold at levels exceeding 800 pmol/L.
Third, food-derived B12 appears safer than synthetic supplementation, suggesting biological differences in how the body processes naturally occurring versus supplemental forms. For clinicians, this research reinforces the importance of maintaining patients within optimal B12 ranges—typically 220-600 pmol/L—rather than aggressively supplementing asymptomatic individuals to supraphysiological levels.
Patients with documented deficiency should pursue correction through appropriate means, while those with adequate levels should avoid unnecessary high-dose supplements. Read the full article on GMJ Newsroom.
Was this article helpful?
