Legumes or sprouts are not an adequate source of B12 and neither are other plant sources.
Your assertion that Nori has B12 is downright wrong. B12 is only synthesized by microorganisms.
There are plenty of vegetarian options, but if you are vegan, you have to rely on fortified products and supplements. This has nothing do to with where you happen to live.
You can check recommendations from physicians, researchers and most importantly Vegan associations all across the globe to the see this is true.
“The Vegetarian Resource Group (VRG) suggests that vegans need to have reliable sources of vitamin B12 in their diets. (1) The Vegetarian Nutrition Dietetic Practice Group (VNDPG) of the Academy of Nutrition and Dietetics says that all vegetarians (including vegans) should include a reliable B12 source in their diets, such as fortified foods or supplements. (2) And The Vegan Society goes so far as to state, “What every vegan should know about B12: the only reliable sources of B12 are foods fortified with B12 and supplements.” (3)“
I have seen people get sick ignoring these issues in a vegan diet.
“According to vegan expert and co-author of Vegan for Life, Jack Norris, RD, there are no reliable sources of B12 in plants, contrary to many rumors about sources, such as tempeh, seaweeds, and organic produce. Plants have no B12 requirement, therefore they do not have any active mechanisms to make or store it. When you find B12 in plants, it is due to contamination, which is not a reliable source. Many seaweeds have B12 analogues, through their symbiotic relationship with cobalamin-producing bacteria, however the evidence is not clear that this form is active B12 in humans. And fermented foods, such as tempeh, are not fermented through B12-producing bacteria, thus they are not a source of B12. Rumors about bacteria on the surface of organic produce producing B12 have not been verified. “Chlorella may improve B12 status, but it’s by such a small amount that I wouldn’t rely on chlorella for B12,” adds Norris. Norris stresses that, unless a food obtained from multiple regions consistently improves B12 status, it should not be relied upon as a source of B12.“
A vegan diet can be a healthy and sensible choice for people living in a modern society with access to supplements and fortified foods as well as the care and knowledge to use them. Otherwise it is not an appropriate diet for humans, especially not outside of the modern Western organic supermarket and supplement infrastructure.
https://veganhealth.org/vitamin-b12/vitamin-b12-plant-foods/
I appreciate your input, but this level of categorical statement seems to fly in the face of historic and current diets which are vegan or vegan-like and have not relied on supplements, or at least not the type we are talking about here.
At any rate I'd review other dietitians/scientists as well; while it's been a long time since I read the literature on this (when a family member went vegan) your quote certainly wasn't consensus view at that time.
Absolutely agree if you were to eat such a restrictive diet, you have to pay attention to vitamin sources, or you can get sick. B12 particularly problematic because you don't need much at all and can go months/years in a deficit situation before showing any symptoms, which can make it hard to pin down.
(To be clear, when said family member did do this for a while, I suggested supplementing but the nutritional science types I was reading weren't nearly as categorical as your above quote)
I provided a source that systemically goes through available evidence (including anecdotal points about vegan cultures).
I think that is fair and it does not imply any value statements about a vegan diet.
None of this is discussion is intended to dissuade a persons' choice to eat vegan, but to ensure they have the tools to do it safely :)
