From a colleague of mine, Jack Norris, RD, who is an expert on the B12 issue and I have quoted and referenced here many times.
https://veganhealth.org/vitamin-b12-veg ... ces/#yeastBrewer’s and Nutritional Yeasts
Brewer’s and nutritional yeasts do not contain B12 unless they are fortified with it. There is at least one vegan, B12-fortified yeast currently on the market: Red Star Vegetarian Support Formula. (Twinlab’s SuperRich Yeast Plus contains whey).
There are some drawbacks to relying solely on B12-fortified nutritional yeast:
Nutritional yeast often comes from bins in health food stores. If not careful, it would be easy for a store employee to order the wrong nutritional yeast out of the distributor catalogs which often list many yeasts. It would also be easy to accidentally put the wrong yeast into the Vegetarian Support Formula bin.
B12 is light sensitive. Nutritional yeast is likely to be exposed to the light because it is often stored in clear bins or plastic bags.
We know of one vegan who thought he was getting B12 from nutritional yeast yet developed B12 deficiency symptoms that resolved upon taking a B12 supplement.
If you are trying to use Red Star Vegetarian Support Formula for B12, make sure you are actually getting what you think. It is also best to keep it in the refrigerator or freezer, out of the light.
Red Star Vegetarian Support Formula nutritional yeast has many other nutrients and is a tasty food, but it’s safest not to rely on it for one’s sole source of B12.
Personally, I don't recommend it's use outside of that of a condiment used sparingly. The reason is, we need to focus our time, energy and attention on, and get the majority of our calories from, fruits, veggies, starchy vegetables, intact whole grains, and legumes. Everything else is at best a condiment and should be thought of as such.
In Health
Jeff