Dried Yeast

Commercial yeast makers grow cells in sweet liquid. For dried yeast, the cells are the intended product. Makers separate them from the growth liquid, inactivate them and dry them into an ingredient that stores and ships easily.^4,5,9

1. 01 // Source Yeast and sugars A yeast culture grows in a liquid medium commonly made with cane or beet molasses.
2. 02 // Process Cells multiplied Air is supplied during fermentation so the sugars produce more yeast cells.
3. 03 // Process Cells separated Centrifuges concentrate the yeast and remove most of the growth liquid.
4. 04 // Output Inactive dried yeast The separated cells are dried into a stable ingredient with no live yeast activity.

1. 01

   Adds nonanimal protein

   Whole yeast cells contain substantial protein. In a dog trial, dried yeast replaced some pork meal and wheat middlings while keeping the finished diets' protein content similar.¹

2. 02

   Recipe stays acceptable

   In a 20-dog two-bowl test, a recipe with 10% dried yeast was eaten about as well as its control and chosen first more often. The test did not isolate yeast as the reason.¹

3. 03

   Offers another protein supply

   Producers grow yeast on sugar feedstocks without raising animals. Dedicated growth and drying have costs; yeast recovered from other fermentations has generally been cheaper to produce for feed.^5,8

How much Controlled dog trials tested diets containing 10% and about 30% dried yeast; neither amount is a typical label guarantee.^1,2

1. Brands say

   Yeast replaces meat protein without a tradeoff

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   In one short trial, a diet with 10% dried yeast digested similarly to its control. In a separate 10-dog trial at about 30%, dry matter digestibility was 80.1% versus 86.3% for the poultry control. Performance depends on the recipe and amount.^1,2

2. Brands say

   Yeast makes kibble taste better to dogs

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   In an ADM-funded test, 11 of 20 dogs chose the 10% yeast recipe first on both days, against 5 for the control. Intake did not differ significantly, and the recipes also differed in pork meal and wheat middlings, so yeast's flavor was not isolated.¹

3. Brands say

   Dried yeast improves dogs' gut health

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   A 10-dog crossover trial found more fecal butyrate and a changed bacterial profile with a diet containing about 30% dried yeast. It measured stool markers over short periods, not whether dogs became healthier.²

4. Brands say

   Its beta-glucans boost dogs' immunity

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   A trial in 16 puppies found changes in immune markers after giving purified yeast beta-glucans, but no improvement in vaccine antibody response. Purified extracts differ from whole dried yeast in kibble, which has no demonstrated immune benefit.^3,9

5. Owners say

   Eating dried yeast causes yeast infections

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   Dried yeast is inactive Saccharomyces. Merck identifies Malassezia as a secondary skin infection in dogs with atopic disease. The 10% dried yeast feeding trial did not test skin disease, so an infection claim has no direct evidence.^1,4,7