Nutritional Yeast

by Kate Payne • Photography by Jo Ann Santangelo

My relationship with nutritional yeast goes all the way back to the four years I spent meat-free in high school and college. Also peppered through this time was a six-month stint of chips-and-salsa veganism, where I perfected my devotion to the nutty, complex and cheese-like yeast flakes. And even though a return to dairy cheese ended my short-lived vegan streak and traveling in Italy derailed the vegetarianism, nutritional yeast has remained a pantry staple of mine.

Known affectionately as “nooch” by vegan and vegetarian cuisine champions, nutritional yeast, like all yeasts, is part of the fungus family—specifically, Saccharomyces cerevisiae. It’s grown in similar fashion as the packaged stuff in the baking aisle used for leavening breads, but the pasteurization and drying process deactivates nutritional yeast’s proofing powers.

Nutritional yeast and brewer’s yeast are related, but are not the same thing. (Brewer’s yeast is more bitter and tastes less cheese-like.)

Nutritional yeast contains a panel of B-complex vitamins via fermentation—niacin, riboflavin, thiamin and B-6—with the exception of B-12, which is usually added after the fermentation and pasteurizing. The deactivated yeast contains other health-promoting compounds, too, such as amino acids, folic acid, zinc and selenium, and is touted as a complete protein (like beans and rice in one!).

There is some debate over the MSG-like effects one might experience when eating certain brands of nutritional yeast. Try to stick with brands that use a low-temperature pasteurization process, which helps keep the high levels of glutamic acid—an amino acid protein that is naturally present in the yeast—from breaking apart and forming free glutamic acid. This free acid is something to avoid because of its excitotoxicity, which raises the levels of glutamate, a neurotransmitter, in our bodies and causes overstimulation of neurons that can lead to brain cell damage. 

High-heat processed nutritional yeasts or food additives that skate by on food labels without our notice—yeast extract, autolyzed yeast, ingredients that are “hydrolyzed,” to name a few—contain free glutamic acids as a result of the processing methods that break down proteins. So why are these excitotoxins in everything we eat? Well, they taste good and make other foods taste good. The beloved umami flavor is based on a savory foods’ glutamic acid content, which only transforms into a free acid when the foods are highly processed. All deactivated yeast contains some amount of free glutamic acid, because when the yeast cells are killed via pasteurization, the protein that makes up the cell walls degrades to a certain extent, breaking down into the amino acids that originally formed that protein.

There’s a balance in all of this, though, in the form of moderation, and not relying heavily on something that’s meant to be a minor addition to a meal. Still, I find myself wary of consuming nutritional yeast daily, and in volumes larger than one tablespoon. If the goal is to keep the amino acid protein intact, it’s probably best to avoid using nutritional yeast in recipes where it will be baked or heated beyond a boil at 212 degrees, which is the highest temperature it might reach during a low-temperature pasteurization process. For me, that means vegan baked cheese sauces relying on nutritional yeast are out, as well as baked goods where nutritional yeast is used as a cheese substitute. 

If consumers choose to completely avoid free glutamic acids, they’ll need to stay away from fermented foods, nourishing broths and anything pasteurized, according to the truthinlabeling.org campaign. Vegans and vegetarians who rely on nutritional yeast for a daily vegetarian source of vitamin B-12 might consider getting that in supplement or liquid form, because the nutritional yeasts that include B-12 in their RDA allowance are fortified with it after pasteurization. 

These classic snack recipes are favorites around our house, and a delicious way to incorporate nutritional yeast into our diet periodically.