Earlier quoted context omitted.
The rest of the sentence provides some important information: > It is synthesized by some bacteria in the gut flora in humans and other animals, but it has long been thought that humans cannot absorb this as it is made in the colon, downstream from the small intestine, where the absorption of most nutrients occurs.
ok, maybe not everything has been discovered about this, because how come my summer diet of only figs, tomatoes and some leafy greens doesn't cause any b12 deficiency symptoms? (as listed here https://www.nhs.uk/conditions/vitamin-b12-or-folate-deficien... ) but I'm not at all a vegan, it's just that currently there is an abundance of figs around, and why not use those calories. I may consume a fish later in the year…
> Our bodies store a greater amount of vitamin B12 than that of any other vitamin
> serious effects of vitamin B12 deficiency can take several years to emerge.