PlainPill

Vitamin B12

People mainly take Vitamin B12 for energy, mood, focus. Based on 277 first-hand reports and 376 meta-analyses & systematic reviews in the medical literature. Ranked #127 of 1,974 overall.

49
User score
Mostly positive
26% positive3% mixed8% negative64% unclear

Of reports that state an outcome, 70% are positive.

Clinical research
AStrong research base
376
meta-analyses
572
RCTs
21,907
papers

What Vitamin B12 does, according to users

Of the people who reported each effect, the share who said it got better.

What the research says

Systematic reviews and meta-analyses from PubMed, with their published conclusions.

AStrong research base

3+ meta-analyses or systematic reviews and 10+ randomized controlled trials in humans. The grade measures how much human research exists — read the conclusions below for what it found.

Nutr Bull · 2024 · Meta-analysis / systematic review
A systematic review and meta-analysis of functional vitamin B12 status among adult vegans

Conclusion: Subgroup analyses indicated that the use of vitamin B12 supplements among vegans contributes to significant improvements in all biomarker concentrations compared to their unsupplemented counterparts. Our findings underscore the need for improved strategies to redress poor vitamin B12 status with appropriate B12 supplementation use among those adhering to vegetarian and vegan diets.

PubMed 39373282 ↗
Arch Gynecol Obstet · 2024 · Meta-analysis / systematic review
A systematic review on the impact of nutrition and possible supplementation on the deficiency of vitamin complexes, iron, omega-3-fatty acids, and lycopene in relation to increased morbidity in women after menopause

Conclusion: In conclusion, maintaining optimum serum levels of nutrients and vitamins, either through a balanced and healthy diet consuming fresh fruits, vegetables, and fats or by taking appropriate supplementation, is essential in maintaining optimal health-related quality of life and reducing the risk for women during the menopausal transition and after menopause. Nevertheless, more recent studies need to be assessed to formulate adequate recommendations to achieve positive clinical outcomes.

PubMed 38935105 ↗
Ir J Med Sci · 2024 · Meta-analysis / systematic review
Efficacy of different routes of vitamin B12 supplementation for the treatment of patients with vitamin B12 deficiency: A systematic review and network meta-analysis

Conclusion: All IM, oral, and SL routes of administration of vitamin B12 can effectively increase the level of vitamin B12 without significant differences between them, as thought previously. However, the IM route was the top-ranked statistically but without clinical significance. We found no significant difference among studied administrated routes in all other CBC parameters and homocysteine levels.

PubMed 38231320 ↗

Dosage people report

As stated by users — not a recommendation. Follow the label or your doctor.

1 mlas reported
sublingualas reported
1000 mcgas reported
regularlyas reported
500 mcgas reported
dailyas reported

Reported side effects

How often each side effect came up across all reports.

acne ×5anxiety ×3jitteriness ×2part of ×1insomnia ×1pins and ×1brain fog ×1depression ×1

What users say

Verbatim quotes, shortened only — each links to the original discussion.

Other options for energy

User data from public discussions; research from PubMed. Information only, not medical advice — talk to a doctor before starting, stopping or combining anything. Data updated October 2, 2026. How we rate