Adenosylcobalamin, like methylcobalamin, is a metabolically active form of vitamin B12¹. Generally, vitamin B12 supplements, including adenosylcobalamin and methylcobalamin, are considered to have similar absorption rates. However, certain factors might affect an individual's response to different forms of vitamin B12:

1. Absorption Variability: Although absorption rates of vitamin B12 supplements are generally consistent across forms, personal physiological differences can impact effectiveness. For instance, at high doses (like the 2,000–3,000 mcg you mentioned), the absorption rate drops significantly, roughly to about 1.3% for doses around 1,000 mcg².

2. Metabolic Pathway Differences: Methylcobalamin and adenosylcobalamin play different roles in the body's metabolic processes. Methylcobalamin is crucial for DNA synthesis and central nervous system function, while adenosylcobalamin plays a key role in energy production and the metabolism of fatty acids and amino acids¹. The effectiveness might depend on which metabolic pathways are more relevant or deficient in your individual case.

3. Folate Interaction: Adding folate could potentially interfere with your vitamin B12 utilization, as both are involved in homocysteine metabolism. Rapid changes in levels or doses can alter your body's balance and uptake capabilities¹.

If adenosylcobalamin seems ineffective for you, it might be beneficial to consider whether specific metabolic needs or absorption issues are influencing this, and consult with a healthcare provider for tailored advice.

Footnotes

1. Office of Dietary Supplements - Vitamin B12. ↩ ↩² ↩³

2. Office of Dietary Supplements - Vitamin B12. ↩