High doses of vitamin B12 are safe and without side effects
6.0Moderate
evidence
evidence
The Claim
It is commonly believed that because vitamin B12 is water-soluble, taking high doses has no adverse effects and is completely safe.
Origin
This myth likely arises from the understanding that excess water-soluble vitamins are excreted in urine, coupled with the low toxicity profile of B12.
What Science Says
Although B12 is indeed water-soluble and generally safe, studies indicate that high doses over extended periods may have side effects, such as acne or rosacea in some individuals. Long-term effects of excessive intake are still under investigation, but current evidence suggests that moderation is prudent.
Verdict
Misleading
Sources
- PMID:41010960 Proton Pump Inhibitors (PPIs)-An Evidence-Based Review of Indications, Efficacy, Harms, and Deprescribing.
- PMID:40935571 Effect of methylcobalamin on capecitabine induced hand-foot syndrome in patients with HER2 negative early breast cancer: multicentre, double blind, randomised, placebo controlled, phase 3 trial.
- PMID:30636701 Ultra-high-dose methylcobalamin in amyotrophic lateral sclerosis: a long-term phase II/III randomised controlled study.