If you are worried about contaminated food or water while traveling take pepto bismol capsules. This will coat the lining of your stomach and intestines making it harder for bacteria you ingest to cause an infection. Take one before each meal or at least 2 times a day. Note this will cause your stool to become dark colored and this is not an issue or sign of anything of concern.
You can also take a probiotic 1-2 times a day to help.