I checked the label on my tub of Marigold Engevita nutritional flakes; nowhere did it say it has been fortified, but that may be down to different labelling regulations in the UK.

I eat the stuff as backup insurance on B vitamin rather than swallow yet more pills. Yes, I may be getting enough in my meats, but .. I like it in a salad with avocado, raw sauerkraut, broccoli sprouts and raw cyder vinegar.

Not the same as brewers yeast which I remember from the 70s. Brewers yeast tastes more every and yeasty; nutritional flakes are more nutty.

There's an explanation on livestrong.com, but the full page address won't copy paste