in addition the issue has become complicated because many people can no longer absorb B12 any more and/or utilize it well.
Same with D... due to genetic mutations cause by the pollution, including genetically modified organism horizontal and lateral gene transfer pollution, in our environments.
People with MS tend to be lower in B12 than D, but both are often found to be deficient. Diabetes same thing...
it is interesting if you get into exploring D and B12 that their deficiencies seem to go hand in hand and seem to be involved intimately together and implicated as a factor in many diseases like diabetes as well.