Vitamin B12 deficiency is common — especially in vegans, vegetarians, older adults, and those taking metformin. Symptoms include fatigue, nerve damage, and cognitive impairment. We compare methylcobalamin vs cyanocobalamin and rank the best supplements.
Why We Reviewed Roundup
Methylcobalamin is the active, bioidentical form that the brain and nervous system use directly. Cyanocobalamin is synthetic and requires conversion, which some people with specific gene variants cannot do efficiently.
✅ Pros
- Essential for nerve function and energy
- Methylcobalamin: active form, no conversion needed
- Very safe — water soluble
- Critical for vegans and vegetarians
❌ Cons
- Cyanocobalamin contains cyanide (tiny amount — safe for most but not ideal)
- Sublinguals and lozenges work better than pills for absorption
Key Ingredients
- Methylcobalamin (preferred form)
- Adenosylcobalamin (another active form)
- Cyanocobalamin (cheap, widely used, fine for most)
Who Is This For?
Vegans, vegetarians, older adults (decreased intrinsic factor production), metformin users, and those with MTHFR gene variants.
Check Current Price on Roundup
Find our recommended B12 supplements via the affiliate links above.
View Best Price →Price & Value
B12 is very affordable: $10–$20 for 3–6 month supply.
Our Verdict
Choose methylcobalamin at 1000mcg sublingual for maximum absorption. Top picks: Jarrow Methyl B-12, Garden of Life B12, NOW Foods Methyl B12. We give it a N/A/5 and recommend it for vegans, vegetarians, older adults (decreased intrinsic factor production), metformin users, and those with mthfr gene variants.