Recent research is stressing the importance of vitamin B12 to brain health. For a long time, we have considered a blood level of less than 200-250 to be borderline, and less than 150 to be deficient.
Recent studies, however, have shown that even with B12 levels in the “low normal” range, there is excess brain atrophy. Vitamin B12 plays an important role in the maintenance of fatty acids that promote healthy neurons and their supportive myelin sheaths.
A UK study, (http://www.vitasearchcom/CP/experts/AVoldiatzoglouAT10-12-08.pdf), of 107 healthy older volunteers, free of cognitive impairment, had their brains scanned repeatedly over a five-year period, as well as yearly physical exams and memory tests. They found excess brain shrinkage, (which has been correlated with cognitive loss), in those who had B12 levels in the lower end of the “normal” range.
While this doesn’t prove cause and effect, it suggests that our acceptable levels of B12 may need to be revised. The authors suggest that we use 300 as our lower limit of normal, and also follow other blood tests, (MMA and homocysteine levels), that are more sensitive to early B12 deficiency states.
B12 is plentiful in meat, fish, dairy products and fortified cereals. Older people with decreased absorption may need supplements, as may some vegans. Certain medications, such as seizure drugs and anti-acid pills, can interfere with B12 absorption as well.