Nutritional yeast shows up now and then in Moveable Feast ingredients lists; is this health-store item really needed in those recipes? No, but at 50 percent protein by weight, nutritional yeast adds that amino-acid-wielding, muscle-tissue-repairing boost backpackers need, especially in vegetarian recipes like the one for Kasha Burgers at then end of the article Against The Grain.
The food's consistency will be the same if you don't add the yeast, but the taste will lack nutritional yeast's cheesy flavor. And don't substitute baker's yeast—that's a whole other animal. Nutritional yeast also adds variety and protein punch when sprinkled on popcorn, rice, and bean dishes or mixed into sauces.