Yakult's unique bacteria are scientifically proven to reach the gut alive and increase the bacteria in the gut. There are billions of unique L. casei Shirota bacteria in each little bottle of Yakult. Yakult was first introduced in Japan in 1935 by the scientist Dr Shirota, since then Yakult is available in 40 countries and millions of people around the world drink Yakult as part of their daily routine. Yakult is fat free and is available in a pack of seven, one for every day! Little Bottle. Big Difference.