Q: I am a vegan and use nutritional yeast for the B12 content. I add the yeast to a potato recipe and was wondering if the heat destroys the B12.
A: While cooking does affect some nutrients, I would not worry about it in regard to B12 because B12 is heat stable.
However, I would not recommend nutritional yeast as a reliable source of vitamin B12. Nutritional yeasts do not contain B12 unless they are fortified with it and not all of them are fortified with B12. In addition, B12 is light sensitive and nutritional yeasts are often stored in bulk bins or plastic bags that are exposed to light.
If you are a vegan and want a reliable source of B12, I would recommend that you take a vitamin B12 supplement.
In Health Jeff