The quick answer is that: No, nutritional yeast is not bad for you.
In fact, it’s quite healthy, and a great thing to eat if you’re a vegan.
Let’s quickly go over what’s in it.
Nutritional Yeast Macros and Nutrition
There’s basically 2 main things that make things “healthy” or “unhealthy”: ingredients that add things like sugar and trans fats, and vitamins and minerals.
Let’s start with the macro nutrition facts for nutritional yeast:
Tons of protein, a small bit of fat (no trans fats), some fiber, and no sugar.
It’s basically a dream come true for vegans.
There’s nothing unhealthy about it from the macros alone, so let’s look at what else is in nutritional yeast.
Nutritional Yeast Vitamins and Minerals
This type of yeast is fortified with all the B-Vitamins: thiamin, riboflavin, niacin, B6, folate, and B12.
If you’re not going to use a vitamin B12 supplement as a vegan, you should be eating nutritional yeast regularly.
There’s nothing in it that would hurt you unless you’re specifically allergic to it (which I’ve never heard of happening).
While it’s possible to eat too much nutritional yeast, you’d have to eat multiple cups per day, which seems very difficult.
Nutritional yeast is a healthy food in reasonable amounts. There’s nothing “bad” in it, and it’s a great source of protein and B-vitamins (good for the brain!).