I did a little research the other day on vitamin B12 for my Advanced Nutrition class at UConn, and I wrote this little blurb for our online discussion. I thought it was incredibly interesting and something everyone should hear, so I cleaned it up a little and put it on the blog. Because everyone reads my blog. Everyone. You ain't cool.
And yes, that means I have a higher standard for my blog posts than I do for my school assignments. I don't know whether that's a good thing or a bad thing. But it's definitely a thing.
A little background on B12. It's the one essential vitamin that's only present in animal foods, meaning vegans are shit out of luck (except for maybe supplementing with algae... maybe). It's present in just about every animal food out there, and especially high in organ meats like liver. The problem with B12, especially as we age, is that there are a lot of things that have to go right for B12 to be absorbed correctly. We need enough stomach acid, adequate pancreatic function, proper digestion and absorption in the small intestine... overall there's a lot of room for error, especially in older adults. Even if we're eating enough B12, that doesn't necessarily mean we're absorbing it.
Okay enough of that, here it is...
Why is this important? Because B12 is involved in the nervous system and for myelin sheath formation, one of the most common deficiency symptoms is neurological impairment. This could manifest in several ways, including problems with cognition, decreased mobility, or impaired memory. In the elderly, how do we know whether a decline in cognitive function is due to simple aging or due to a subclinical B12 deficiency? We don't. Especially if we're A) not testing for serum B12, and B) our deficiency level is set too low.
Interestingly, Japan has increased their cutoff for B12 deficiency to a serum level of 550 pg/ml (confirmed by Wikipedia)... very much higher than our cutoff of 100 pg/ml. Anyone below that level receives treatment. The Japanese also have lower rates of Alzheimer's disease and other dementia compared to us here in the States. It's just an association, but there may be a connection there between higher serum B12 in the Japanese and a lack of cognitive decline.
Based on this information, it would seem prudent to keep an eye on B12 status, especially in the elderly. According to the lecture notes, about 15% of the elderly are B12 deficient; the figures in the study cited above place that number at up to 40%. But we don't know how many reside at the low-normal level (a level that would be considered deficient in Japan). B12 supplementation seems to provide far more potential benefit than risk, so I see no reason why we don't give it a shot in those who are subclinically deficient, especially if we can prevent more serious symptoms if levels were to continue to drop.