Cyanocobalamin in People 65+
A study was just released out of the UK that measured the response of various markers of cyanocobalamin supplements in adults 65 years and older (1).
The study was a double-blinded, placebo-controlled study on 100 people with evidence of poor vitamin B-12 status. It used daily supplements in the amount of 10, 100, and 500 µg/day of cyanocobalamin for 8 weeks. The main marker of interest was urinary methylmalonic acid (uMMA) levels.
They found that 500 µg/day made a significant improvement in uMMA levels and most of that improvement was made in the first 2 weeks.
This result is in contrast to what the authors of the recent homocysteine meta-analysis said about cyanocobalamin taking 4 to 9 weeks to be converted to methylcobalamin. But, it should be noted, that the adenosylcobalamin co-enzyme form of vitamin B12 is required to reduce uMMA levels, not methylcobalamin. Methylcobalamin is required to reduce homocysteine levels and the 100 and 500 µg/day regimen also lowered homocysteine levels over the course of 8 weeks, though they did not say how long it took for the change to take place.
In a number of measurements, the ex-smokers improved more than the never-smokers. This is surprising because it would seem reasonable that, if there were any difference, ex-smokers would have more of a problem metabolizing cyanocobalamin than non-smokers.
Only 75-85% of the participants fully corrected their metabolic deficiency with 500 µg per day. It’s possible these people’s metabolic deficiency stemmed from a problem not related to vitamin B12.
The takeaway messages:
1. Even in people 65 years and older, cyanocobalamin worked in only two weeks time.
2. It might be a good idea to increase B12 recommendations for people 65 and older to 500 µg per day, rather than the 25 to 100 µg per day that I recommend for all adults.
3. Cyanocobalamin was effective even for ex-smokers. There were not enough current smokers in the study to determine the effectiveness for them.
1. Hill MH, Flatley JE, Barker ME, Garner CM, Manning NJ, Olpin SE, Moat SJ, Russell J, Powers HJ. A Vitamin B-12 Supplement of 500 μg/d for Eight Weeks Does Not Normalize Urinary Methylmalonic Acid or Other Biomarkers of Vitamin B-12 Status in Elderly People with Moderately Poor Vitamin B-12 Status. J Nutr. 2013 Feb;143(2):142-7. doi: 10.3945/jn.112.169193. Epub 2012 Dec 12. | link