The Study
The origin of vitamin B12 levels and risk of all-cause, cardiovascular and cancer specific mortality: A systematic review and dose-response meta-analysis.
This study found that people with higher levels of vitamin B12 in their blood tended to die more often, but it doesn’t prove that the vitamin caused the deaths — maybe people who were already sick had higher levels. It’s like noticing that people who carry umbrellas are more likely to get wet — but umbrellas don’t cause rain.
Analysis score
Maximum 100 for a systematic review with meta-analysis.
Where the score came from
This study looked at lots of people and found that if your B12 blood level is too low or too high, you might be more likely to die from any cause or heart disease.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 548 / 100
Quality score
The highest quality evidence. Systematic reviews and meta-analyses that pool randomized controlled trials, giving the most reliable summary of experimental evidence.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — even moderately high B12 levels (like 400–600 pmol/L) were linked to noticeably higher death risk, suggesting B12 levels may be a warning sign.
- 2B12 below 190 pg/mL or above 948 pg/mL = higher death risk.
- 3Every 100 pmol/L increase in B12 = 4-6% higher death risk.
- 4Above 600 pmol/L = 50% higher death risk.
- 5Between 400–600 pmol/L = 34% higher death risk.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Archives of gerontology and geriatrics
Year
2023
Authors
Kefeng Liu, Zhirong Yang, Xiaojing Lu, Bang Zheng, Shanshan Wu, Jian Kang, Shusen Sun, Jie Zhao
Related Content
Claims (6)
If your blood has too little or too much vitamin B12, you might be at higher risk of dying from any cause or from heart disease — the safest range is in the middle, between 190 and 948 pg/mL.
People with very high levels of vitamin B12 in their blood—above 600 pmol/L—might be 50% more likely to die from any cause compared to those with lower levels, which could mean there’s a dangerous upper limit to how much B12 is safe.
People with higher levels of vitamin B12 in their blood seem to have a higher chance of dying from heart problems, but this link isn’t as clear as the link between high vitamin B12 and dying from any cause.
People with higher levels of vitamin B12 in their blood tend to have a slightly higher chance of dying from any cause — especially older adults — so high B12 might just be a sign that something else is wrong in the body.
People with vitamin B12 levels between 400 and 600 units in their blood are 34% more likely to die from any cause than people with lower levels—even though those levels are still considered normal by doctors.
Right now, scientists haven’t found a clear link between how much vitamin B12 is in your blood and whether you’re more or less likely to die from cancer.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.