Found this picture on Wikipedia and it amuses me greatly. 🙃
Hmm, from what I read, it's usually just B12 which is added to nutritional yeast. And Wikipedia says:
As for safety, tolerable upper intake levels (known as ULs) are set for vitamins and minerals when evidence is sufficient. In the case of vitamin B12 there is no UL, as there is no human data for adverse effects from high doses.
[...]
The [European Food Safety Authority] also reviewed the safety question and reached the same conclusion as in the United States—that there was not sufficient evidence to set a UL for vitamin B12.
Also:
Vegan advocacy organizations, among others, recommend that every vegan consume B12 from either fortified foods or supplements.
My doctor told me the same. I actually had my blood checked a while ago and it was so low that I had to inject B12 with syringes. So, I would certainly recommend erring more towards potentially too much B12.
Us not having evidence for overdoses obviously does not mean that we know it to be entirely safe, but:
- our liver is generally quite good at throwing out garbage, and
- well, we do have crystal-clear evidence that too little B12 is bad for you.
So yeah, if you are talking about B12, I can recommend to reconsider. 🥴