vitamin · for low mood
Vitamin B12
Your body needs B12 to make the mood chemicals serotonin and dopamine.
Say that in clinical terms
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.
How strong is the research?
Mixed evidence
A pooled analysis of 16 trials in 6,276 people found no improvement in thinking or mood.
Studied in a narrower group
7 papers read, 3 supporting, 3 against.
Who was studied: Mixed populations from observational studies. The mood benefit shows mainly where B12 was low.
How much to take
daily (sublingual preferred)
1000–2000 mcg
Works synergistically with folate. Test levels if on metformin, PPIs, or following a vegetarian diet.
Before you take it
- No NIH ODS or IOM Tolerable Upper Intake Level (UL) has been established for vitamin B12 in any form; the IOM found no adverse effects attributable to excess intake from food or supplements in any population studied and set no UL.
- Metformin significantly reduces B12 absorption by impairing calcium-dependent membrane action in the terminal ileum; patients on long-term metformin are at elevated risk of B12 deficiency and should have serum B12 monitored periodically.
- Proton pump inhibitors (PPIs) and H2-receptor antagonists reduce gastric acid secretion needed to release protein-bound dietary B12, thereby reducing absorption from food; this effect is substantially less pronounced for free supplemental B12 forms.
- High-dose folic acid supplementation can mask the hematological signs of B12 deficiency (megaloblastic anemia), potentially allowing neurological damage from covert B12 deficiency to progress undetected.
- Rare anaphylactic reactions have been reported with parenteral (injectable) B12 preparations; no equivalent hypersensitivity risk has been established for oral or sublingual supplemental forms.
- Individuals with Leber's hereditary optic neuropathy should avoid high-dose cyanocobalamin; methylcobalamin is the preferred supplemental form when B12 supplementation is clinically indicated in this population.
- Patients attributing low mood or depression to B12 deficiency and self-supplementing without medical evaluation may delay diagnosis and treatment of clinical depression, bipolar disorder, or other conditions requiring distinct interventions.
When to take it
Best taken: morning