Why do B12 pills contain 1000µg, since we need 2.4µg/day ?

I read that you absorb 10µg of a 500µg pill.

Do you absorb 1µg of a 50µg pill?

Do you absorb 10µg of a 10µg pill?


1 Answer 1


I think the numbers vary due to differences in absorption per individual. Different people may have different absorption rates.

Although we need very little B12 (sometimes we can go for many years without needing a B12 supplement) we still take (larger) amounts that are proven to work - to be on the safe side.

Current recommendations by Nutrition facts is that average adult should take around 2000µg/weekly or 50µg/daily of B12 in a form of cyanocobalamin.


Personally, I'm taking around 2500µg pill once a week and every time I tested my B12 levels they are on the higher side but still within recommended norms.

I believe that the recommendations are based on research and scientific evidence (that are usually listed as links on nutritionfacts website).

This may not be the ultimate truth as we're still receiving a new data.

  • 1
    i thank you for your response, i still don't understand why b12 pills contains 1000μg instead of 2.4μg. Also, I don't understand why nutritionfacts.org recommend B12 doses that higher than wikipedia Reference Daily Intake. Did I miss something ?
    – J. Doe
    Commented Aug 2, 2022 at 12:34
  • 1
    Sorry, I should have been clear on that topic as it was your actual question and elaborate a bit more on it. The numbers are coming from controlled trials where supplements were tested in individuals (sort of a trial/error). So in practice, these trials that tested b12 supplements came up with some results that are showing us which dose and form works the best. Body absorption and stability of the pill/supplement are playing the biggest role. I don't think we really know why higher doses are giving better results or why absorption varies. Note: I'm not a subject matter expert/nutritionist Commented Aug 2, 2022 at 13:20

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.