Does vitamin B12 give you more energy?

Updated 3 Nov 2026

Short answer

Only when tiredness comes from a deficiency. Tiredness without a clear cause is a common sign of a low B12 level, and treatment works in most people with a deficiency.^[1] In people who have enough B12, supplements do not appear to improve endurance or sports performance.^[2] A 2021 review found only one trial on unexplained tiredness, too few to analyze.^[3] See the goal energy.

Sources (3)

Vitamin B12 deficiency in over 16s: diagnosis and management (NG239). National Institute for Health and Care Excellence (NICE), 2024. www.nice.org.uk
Vitamin B12: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements. ods.od.nih.gov
Effects of Vitamin B12 Supplementation on Cognitive Function, Depressive Symptoms, and Fatigue: A Systematic Review, Meta-Analysis, and Meta-Regression. Markun S, Gravestock I, Jäger L, Rosemann T, Pichierri G, Burgstaller JM Nutrients, 2021. PMID 33809274

More about vitamin b12

What is vitamin B12?Who is likely to be low in vitamin B12?What is vitamin B12 used for?Which foods contain vitamin B12?Is vitamin B12 safe?How long does vitamin B12 take to work?

For education; not medical advice. Talk to a doctor before you start, stop or change a supplement.