Condition
Vitamin B12 Deficiency
Vitamin B12 deficiency happens when the body lacks enough of the vitamin it uses to keep nerves working, build DNA, and form red blood cells. The evidence is strongest for vitamin B12 itself and for folate, which works alongside it in the body. Even so, trials looking at cognition found no clear difference, and that evidence is very limited, though iron and B-complex vitamins have moderate support.
- Supplements studied
- 1
- Graded outcomes
- 1
- Trials
- 1
- People studied
- 3,012
Evidence by supplement
- Strong
- Moderate
- Limited
- Very limited
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Cognition No effect | NoneNo effect | 2,912 people | ||||
| Depression Symptoms | Improves (the measure goes down) | 2 studies | 2,912 people | |||
Studies that measured depression symptoms | ||||||
| Fatigue Symptoms | Improves (the measure goes down) | 1 study | 2,912 people | |||
Studies that measured fatigue symptoms | ||||||
| Homocysteine | Improves (the measure goes down) | 1 study | 100 people | |||
Key findings
- Cognition
The Vitamin B12 Deficiency Treatment protocol
1 primary supplement · 4 supporting supplements
- Vitamin B12 (Methylcobalamin or Cyanocobalamin)1,000–2,000 mcg daily oral for mild deficiency; injections for severe or malabsorption
Studies cited
5 studies from PubMed
- Folate and vitamin B12 supplementation in patients with schizophrenia and low serum folate level: A 24-week randomized, double-blind, placebo-controlled study.
- Effects of vitamin B12 supplementation on cognition, depression, and fatigue in patients with lacunar stroke
- A vitamin B-12 supplement of 500 μg/d for eight weeks does not normalize urinary methylmalonic acid or other biomarkers of vitamin B-12 status in elderly people with moderately poor vitamin B-12 status
- Effects of Vitamin B12 Supplementation on Cognitive Function, Depressive Symptoms, and Fatigue: A Systematic Review, Meta-Analysis, and Meta-Regression.
- Systematic review and meta-analysis of randomized placebo-controlled trials of folate and vitamin B12 for depression.