Vitamin B12 and Diet

We only need minute traces of Vitamin B12 in our diet, as little as 1µ gram per day, and provided we absorb this in our diet, all is well. If the stomach does not secrete hydrochloric acid properly, and the intestine thus not absorb the vitamin, then pernicious anæmia results. In cattle, sheep and other ruminants, microorganisms present in their rumen, can synthesise the vitamin, which is then used particularly for the methylmalonic acid to succinic acid isomerisation step, one of the isomerization steps catalysed by Vitamin B12. Humans do not have such microorganisms in their digestive system, so must absorb the vitamin from food.

Methanogens are a primitive type of bacteria, archeobacteria, capable of using methane at the end of their electron acceptor chain, they involve a nickel corrinoid (F430) and Vitamin B12 in the catalysis of the reaction :

4H2 + CO2 = CH4 + 2H2O

A cow produces about 40 litres of methane per day, and methane is a potent atmospheric 'greenhouse' gas!

If you are a beer drinker then you may be doing your heart a good deed!