Optibac Kids Probiotic Gummies Strawberry 30. Best Probiotics for Gut Health. Optibac Kids Gummies is a naturally delicious, vegan friendly bacteria gummy supplement.. Developed for children from 3 years onwards, each gummy contains 2 billion live cultures of Bacillus coagulans Unique IS-2, which has been scientifically researched in children, as well as calcium and vitamin D3.