Flights, change of time zones, unusual food... It's rather difficult to keep the stomach healthy. I use probiotics - Now-Foods-BerryDophilus-Kids
It provides 2 Billion CFU from a combination of 10 clinically validated probiotic bacterial strains designed to support gastrointestinal health and healthy immune system function.
Although it is for children, I enjoy it myself - they are very tasty, with berry flavor and it's no need to drink it with water. Just use 2 tablets instead of 1 for kids :)