5 Matching Annotations
  1. Nov 2020
    1. between themethionine synthase apoenzyme and oxidizedvitamin B12 may be broken. It is to be expected thatany Blt preparation administered during exposureto nitrous oxide would be rapidly oxidized tobivalent cobalt.

      That's what I assumed from other readings. Why, then, can I only find studies administering B12 near the time of the surgery? Those studies still found protective effects on homocysteine elevation, but that may be mostly due to the coadministered B9.

      This means B12 should be taken either well before NO, or sometime after. Given the short half life of NO, it should be fine to take B12 orally immediately after a final NO dose; the B12 will be absorbed shorty after the NO is eliminated.

    1. Fig 1

      Note that, though folate and B12 were given IV before and after surgery, it did not have an immediate effect. The NO induced rise in homocysteine was not blunted by the end of surgery. However, postoperative homocysteine was lowered to below baseline on all 3 measurement days. The NO induced rise in homocysteine lasted 2 days postoperatively.

      Unsurprisingly, this suggests a lag time between B vitamin administration and homocysteine drop. Thus, what I'd really like to see is a study administering B vitamins 1 day prior to NO use.

    1. This inhibition was completely reversible by addition to the culture medium of pteroylglutamate and 5-formyltetrahydropteroylglutamate and partly reversible by cyanocobalamin.

      This suggests those taking NO should supplement with both B9 and B12. It is likely that the effects on B9 are more acute, while B12 deficiency probably only becomes an issue with chronic abuse or in those with borderline B12 status to begin with.

  2. Aug 2020
    1. It appears therefore that the labeled vitamin was absorbed from the large intestine, perhaps by non-specific passive diffusion. Similarly, vitamin B12 synthesized in the large intestine by microbial flora could gain access to the tissues by such a mechanism. The possible role of intestinal vitamin B12 of microbial origin in rats, and perhaps in man, and factors affecting the utilization of this vitamin are discussed.

      This provides some reason to be agnostic as to whether vegans can obtain B12 naturally. Of course that shouldn't matter to any rational person (who'd just take a supplement). Note that I was searching for this info, and this is the first piece of evidence I found. Thus, I suspect there is more evidence since 1965. I'll try to tag updates with "nativeB12"

  3. Aug 2019