RE: B12 suppliments
Posted Monday, January 7, 2013 at 10:44 AM
We do tend to store B12 for quite some time, so when first embarking upon a vegan diet, there is no need to be overly concerned. However, I do think that it is important to not only hang onto these stores, but to keep B12 circulating in the body as well.
The amount we need per day is so small, 2.4 micrograms. As you have noticed, most supplements have far more than this, and that's okay, because there is no "upper limit" as determined by health experts.
Because we tend to absorb less as we age, those same experts recommend supplementing with more than 2.4 mcg per day to ensure that enough gets through the gut wall (for anyone, regardless of dietary choices). How much gets through is individualized. I would suggest taking any amount you mentioned two to three times per week and consider supplemented foods (plant milks, grains, yeast, etc.) as bonus. The next time you do a regular blood test at your doctor's office, you can ask her/him to check your B12 status (stores and circulating) to make sure everything is good. If the numbers are too low, take the supplements more often. If they are excessive, you could consider scaling back on the micrograms if for no other reason than to save money, although I know of no reason for concern. If you have been supplementing regularly and the numbers are REALLY low, you may be better off taking a sublingual B12 (bypassing the gut all together).
As for methyl- vs. cyano- cobalamin, there is no evidence that one is better or worse than the other, in terms of manifesting into a health problem. If one can afford to "upgrade" to the more expensive methyl, I would certainly understand as the cyano is related to the less than appealing cyanide molecule.
I hope that helps! Let me know if you have any further questions.
Susan Levin, MS, RD
PCRM Director of Nutrition Education