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Vitamin B12 Supplementation: Is More Always Better?
Manuela Yepes-Calderón1, Caecilia S E Doorenbos1, Mariken E Stegmann2
1Division of Nephrology, Department of Internal Medicine, University of Groningen, University Medical Center Groningen, 9713 GZ Groningen, The Netherlands.
Nutrients
|May 27, 2026
Summary
Vitamin B12 supplementation without proven deficiency shows no consistent benefits for general well-being. Evidence does not support widespread use, with potential risks and inconsistent findings in most populations.
Area of Science:
- Nutritional Science
- Clinical Medicine
- Public Health
Background:
- Vitamin B12 supplementation is popular despite a lack of proven deficiency.
- Perceptions of underdiagnosis, well-being enhancement, and safety drive its use.
Purpose of the Study:
- To evaluate the evidence supporting claims of vitamin B12 supplementation benefits in non-deficient individuals.
- To examine current health authority guidance on vitamin B12 testing and supplementation.
Main Methods:
- Review of major health authority guidelines regarding vitamin B12 deficiency testing.
- Analysis of epidemiological data on vitamin B12 deficiency prevalence using biochemical criteria (serum B12 < 148 pmol/L).
- Synthesis of findings from supplementation studies with varying regimens and durations.
Main Results:
- Routine testing is advised against for asymptomatic individuals without risk factors.
- Vitamin B12 deficiency is uncommon (~2%) in high-income countries but frequent (up to 69%) in resource-limited settings.
- Supplementation shows no consistent benefits for fatigue, mood, cognition, or cardiovascular health in non-deficient populations.
Conclusions:
- Current evidence does not support widespread vitamin B12 supplementation for general well-being in the absence of deficiency.
- Benefits are limited to specific subgroups, such as those with hyperhomocysteinemia.
- While generally safe, rare adverse effects and potential associations with malignancy warrant further investigation, though causality is not established.
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