Methylcobalamin vs. Adenosylcobalamin
Among 4,648 on-market vitamin b12 (cobalamin) products with an identifiable primary form, 99.4% use Methylcobalamin (4,621 products) and 0.6% use Adenosylcobalamin (27).
| Methylcobalamin | Adenosylcobalamin | |
|---|---|---|
| Quality tier | Tier 1 | Tier 1 |
| Vitamin B12 (Cobalamin) by weight | — | — |
| Share of market | 99.4% | 0.6% |
| On-market products | 4,621 | 27 |
| Median declared dose | 100 mcg middle half: 20–500 | 1,000 mcg middle half: 500–3,000 |
| Most common brands | Cellucor, Life Extension, Metagenics | Country Life, Seeking Health, Source Naturals Athletic Series |
Doses are declared per serving in mcg. “By weight” is the share of the ingredient that is the nutrient itself (e.g. elemental magnesium in a magnesium salt).
Why Methylcobalamin is tier 1
One of the two naturally active intracellular coenzyme forms, but per the same 2015 review there is no strong evidence it is clinically superior to cyanocobalamin for correcting deficiency. A commonly repeated "3x greater tissue retention" marketing claim (attributed to a 2015 journal study) could NOT be traced to any real paper -- treat as unverifiable/likely fabricated, not fact.
Source: Obeid R et al. 2015, PMID 25820384
Why Adenosylcobalamin is tier 1
The other naturally occurring coenzyme form, same rationale as methylcobalamin -- a genuine coenzyme form but not shown superior to cyanocobalamin for standard deficiency correction. "Dibencozide" is simply a synonym/brand name for this same molecule.
Source: Obeid R et al. 2015, PMID 25820384