Vitamin
Vitamin B12
Also known as: Methylcobalamin
An essential vitamin that supports nerve health, energy production, and cognitive function.
KÖGN Health grades Vitamin B12 as A+ (Strong evidence) and rates it 4.6 out of 5.
Last reviewed · June 2026
Primary effects
- Increased energy
- Improved cognition
- Reduced fatigue
How it works
Supports myelin formation and red blood cell production, enhancing brain energy and function.
Overview
Vitamin B12 is essential for neurological health and energy metabolism. Its active form, methylcobalamin, is directly involved in nerve function and brain energy production. Deficiency can lead to significant cognitive and neurological impairment, making it one of the most important vitamins for brain health. Supplementation is particularly important for individuals with low dietary intake, such as vegans.
The evidence
Vitamin B12 is essential for nerve function and, with folate and B6, for keeping homocysteine in check. The clearest cognitive evidence is corrective: deficiency (common in older adults, vegans and long-term metformin or acid-suppressant users) causes memory problems and worse that B12 can reverse. In people who are already replete, supplementing does not reliably sharpen cognition. The VITACOG trial showed B-vitamin benefit mainly in those with raised homocysteine.
How to dose it
The daily requirement is small (~2.4 µg), but supplements and the cognition trials use far more — commonly 500–1,000 µg/day — because absorption is limited and the aim is to correct low status.
When to take it
Chronic. Benefits track the correction of a deficiency over weeks to months, not a same-day lift.
Safety & side effects
Very safe; it is water-soluble and excess is excreted. No established toxic upper limit.
Who should avoid it
Generally safe for all. If you have a confirmed deficiency, the cause should be investigated rather than only supplemented. Some inherited eye conditions (Leber's optic neuropathy) are an exception — seek medical advice.
References
Related ingredients
Graded entries that target the same cognitive goals.
Categories
Draft — the dose, safety and evidence notes on this entry were prepared from the published literature and are pending editorial and clinical review.
Educational information, not medical advice. The evidence grade is KÖGN’s editorial assessment of published research, not a health claim. Speak to a qualified clinician before changing what you take.