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
Evidence5 studies · 2 supporting · 2 against
7 safety notes
B12 is required for SAMe regeneration through methionine synthase. Deficiency causes elevated homocysteine and impaired methylation, reducing synthesis of serotonin, dopamine, and norepinephrine, all key mood-regulating neurotransmitters.
Dose: 1000–2000 mcg
Vitamin B12 for Chronic Fatigue
Evidence3 studies · 1 supporting · 1 against
7 safety notes
B12 is a cofactor for methylmalonyl-CoA mutase and methionine synthase, essential for mitochondrial energy metabolism and the citric acid cycle. Deficiency impairs fatty acid oxidation and myelin maintenance, causing profound fatigue.
Dose: 1000–5000 mcg
Vitamin B12 for Eye Strain
Not yet verified1 study · 0 supporting · 0 against
6 safety notes
Methylcobalamin supports optic nerve myelin sheath integrity and corneal nerve health. It modulates homocysteine levels that can damage retinal vasculature and may improve accommodative function of the ciliary muscle, reducing focusing fatigue.
Dose: 1000 mcg
Vitamin B12 for Poor Memory
Not yet verified1 study · 0 supporting · 0 against
6 safety notes
Vitamin B12 deficiency causes elevated homocysteine which is neurotoxic and associated with hippocampal atrophy. Adequate B12 supports myelin integrity and SAMe-dependent methylation necessary for memory consolidation.
Dose: 1000–2000 mcg
Vitamin B12 for Headaches/Migraines
Not yet verified1 study · 0 supporting · 0 against
6 safety notes
Elevated homocysteine is associated with increased migraine frequency. B12, along with folate and B6, lowers homocysteine through the methionine synthase pathway, reducing vascular inflammation and endothelial dysfunction.
Dose: 1000 mcg
Vitamin B12 for Brain Fog
No Benefit1 study · 0 supporting · 0 against
6 safety notes
How it was tested: 2021 meta-analysis of 16 RCTs (n=6,276) found no evidence B12 improves cognition
B12 is essential for myelin sheath maintenance and synthesis of S-adenosylmethionine (SAMe), a key methyl donor for neurotransmitter production. Deficiency causes demyelination and impaired neural signaling manifesting as brain fog.
Dose: 1000–2000 mcg