White button mushroom is the only natural source of absorbable B12. Seaweed, nori, and miso are best avoided as they contain inactive versions of B12 that hinder active B12 absorption. I am an O blood type and I really need B vitamins. I take whole food vitamin B Complex supplement. I also use certified organic nutritional yeast. The nutritional Yeast are all different. I recommend buying certified organic brands. There is about 24 mcg of vitamin B12 per tablespoon. It is also rich in vitamins B1, B2, B3, and B6. You could sprinkle nutritional yeast over popcorn, add to salads, or hummus, etc. Some people (especially children or O blood types) really need a raw egg yolk every so often to get the nutrition they need. If you have a humanely-raised, healthy chicken living in true sunshine, fresh air, pasture-raised bird that is not given hormones or antibiotics, it won’t harm the chicken, but the egg yolk, not the egg white is extremely helpful for many nutrients that are necessary for optimum health for many people. Avoid the egg white, it has enzyme inhibitors and is not good for health. I know that is not vegan, but it is more important to know this and be able to address than to be unhealthy or have a child with nutritional deficiencies.