New research emerging from multiple studies between 2015-2025 reveals a complex relationship between vitamin B12 levels and cancer risk that defies the traditional ‘more is better’ nutritional paradigm. While severe B12 deficiency clearly increases cancer risk through impaired DNA synthesis and methylation, extremely high doses from supplements appear to pose their own health concerns.
According to meta-analyses, individuals with B12 levels above 800 pmol/L show a 1.7-fold increase in relative cancer risk, with some studies documenting a 300-400 percent elevation in lung cancer rates among long-term high-dose supplement users. The data suggests cancer risk follows a U-shaped curve, with optimal protection occurring within the normal physiological range rather than at the extremes.
These findings challenge current supplementation practices and suggest a more nuanced approach to B12 management is warranted. Read the full article on GMJ Newsroom.
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