Nutritional yeast is a deactivated yeast, meaning, it doesn't grow or froth like baking yeast and it is completely different than brewer's yeast or baking yeast. It is a complete protein (having all essential amino acids), gluten free, and low in sodium and fat. Nutritional yeast is also the key ingredient in making dairy free cheese sauces. Some Nutritional Yeasts are fortified with Vitamin B12 - a vitamin not found in plants. Vitamin B12 deficiency causes tiredness, weakness, constipation, loss of appetite, weight loss, and anemia so it's important that we make sure we get it in our diet.