Huge numbers of bacteria live in the human gut. We know those bacteria are important to our health, so we need to treat them well. We wanted to know whether it was possible to design new yogurts that can introduce special bacteria into the gut, to improve our well-being. We studied hundreds of types of bacteria isolated from cheese and yogurt and found that 24 of these bacterial species can performmost of the important bacterial functions that happen in the human gut. Therefore, there is exciting potential for designing new, gut-healthy yogurts.