Vitamin B12 (Cobalamin)

Supplementation is essential for vegans and highly beneficial for older adults with declining absorption. Methylcobalamin and adenosylcobalamin are the active forms.

A rough internal score reflecting quantity, quality, and consistency of human evidence. Not a clinical recommendation.

Deficiency causes megaloblastic anemia, neuropathy, and cognitive impairment. Prevalence increases with age due to reduced intrinsic factor. Sublingual or injectable forms bypass absorption issues. Well-studied for homocysteine reduction with folate.

• Essential for red blood cell formation
• Required for nervous system myelination
• Supports DNA synthesis and methylation
• Reduces homocysteine with folate

RDA is 2.4 mcg. Supplemental doses of 500–2000 mcg for deficiency correction. Sublingual or injectable for malabsorption.

• Essentially non-toxic
• Acne-like eruptions (rare, high-dose)

Very safe. Cyanocobalamin contains trace cyanide but is clinically insignificant at normal doses. Check for B12 deficiency before high-dose folate.

Serum B12 is a poor marker of tissue status. Methylmalonic acid and homocysteine are better functional markers.

• Energy60
• Mood45
• Memory40