vitamin
Vitamin B12
The active, methylated form of vitamin B12. Critical for nerve function, red blood cell formation, DNA synthesis, and energy metabolism. Deficiency is common in vegetarians and older adults.
What it’s good for
Vitamin B12 for Low Mood
Mixed7 studies · 3 supporting · 3 against
7 safety notes
Your body needs B12 to make the mood chemicals serotonin and dopamine.
Dose: 1000–2000 mcg
Vitamin B12 for Poor Memory
Mixed5 studies · 1 supporting · 4 against
6 safety notes
Low B12 lets a compound build up that is toxic to nerves and linked with memory loss.
Dose: 1000–2000 mcg
Vitamin B12 for Headaches/Migraines
Mixed3 studies · 1 supporting · 1 against
6 safety notes
Lowers a compound linked with more frequent migraines and with blood vessel irritation.
Dose: 1000 mcg
Vitamin B12 for Eye Strain
Evidence2 studies · 1 supporting · 0 against
6 safety notes
Supports the nerves that run your eyes, including the muscle that does the focusing.
Dose: 1000 mcg
Vitamin B12 for Chronic Fatigue
Not verified6 studies · 4 supporting · 2 against
7 safety notes
Why it gets suggested: B12 is needed for the reactions that turn food into energy inside your cells.
Dose: 1000–5000 mcg
Tested as: hydroxocobalamin
Why we could not verify it: A proper search found trials of this compound, but not in the form named here — hydroxocobalamin. Evidence for one form is not evidence for another.
Vitamin B12 for Brain Fog
Not verified3 studies · 1 supporting · 2 against
6 safety notes
Why it gets suggested: B12 keeps nerves insulated and helps make the brain’s messengers, so low levels cloud thinking.
Dose: 1000–2000 mcg
Why we could not verify it: No randomized controlled trial or qualifying systematic review of methylcobalamin specifically for brain fog was found. Searches across PubMed, CrossRef, and general literature returned: (1) a 3-patient case series of benfotiamine + methylcobalamin for Long COVID brain fog (DOI 10.18103/mra.v14i2.6627) — not a trial and a combination product; (2) a large observational TREATME survey of ME/CFS and Long COVID patients where over 47% of patients reported subjective improvement with B12 interventions — no controls and form unspecified; (3) the Vijayakumar 2017 RCT (10.1016/j.conctc.2017.10.006) which tested MMSE cognitive domains but was designed for 'cognitive dysfunction' in post-menopausal wo