Nutritional Yeast - Nutrition

Nutrition

Because nutritional yeast is often used by vegans, who usually need to supplement their diets with vitamin B12, there has been confusion about the source of the B12 in nutritional yeast. Although yeast is closer to animals than plants in their genome and metabolism, they cannot produce B12, which is only naturally produced by bacteria. Some brands of nutritional yeast, though not all, are fortified with vitamin B12. When fortified, the vitamin B12 is produced separately (commonly cyanocobalamin) and then added to the yeast.

Although some species of bacteria that can produce B12 could potentially grow along with S. cerevisiae in the wild, commercially produced nutritional yeast is grown in controlled conditions that would normally not allow those bacteria to grow. Therefore, nutritional yeast should not be relied upon as a source of B12 unless it is fortified.

Nutritional values for nutritional yeast vary from one manufacturer to another. On average, 2 tablespoons provides 60 calories with 5 g of carbohydrates (of which 4 g is fiber). A serving also provides 9 g of protein and is a complete protein, providing all nine amino acids the human body cannot produce. It is also a source of selenium and potassium. While fortified and unfortified nutritional yeast both provide iron, the fortified yeast provides 20 percent of the recommended daily value, while unfortified yeast provides only 5 percent. Unfortified nutritional yeast provides from 35 to 100 percent of all of the B vitamins, except for B12. Fortified nutritional yeast adds 150 percent of vitamin B12 and 720 percent of riboflavin.