Essential

Vitamin B12

The highest-priority supplement for people eating fully plant-based because unfortified plant foods are not reliable B12 sources.

Form

Cyanocobalamin or methylcobalamin

Dose

50-100 mcg daily or 1,000-2,000 mcg twice weekly for maintenance

When to take

Any time of day, with or without food; morning or early afternoon if high doses feel stimulating.

Last reviewed

2026-06-17

Toxicity and cautions

No established upper limit and low toxicity risk, though rare acne-like reactions are reported.

Quality checks

Choose clear dosage labels and plant-based capsules or chewables. Blood work may include serum B12, methylmalonic acid, and homocysteine.

Popular brands

Deva
Solgar
Nature Made
NOW Foods
Jarrow Formulas

Related guide: read the full nutrition guide.

General information only

GreenFit provides general nutrition information only. It is not medical advice. For medical conditions, pregnancy, children, elderly people, eating disorders, kidney disease, diabetes, or medication-related concerns, consult a qualified doctor or registered dietitian.