When I first started traveling around 20 years ago I had a very sensitive tummy just like most people who grew up in the west and always had their meals in very sterile environments. My first real trip of substance outside of my home country saw me get food poisoning in the first week and that put me out of commission and made me feel absolutely terrible for a few days. Thankfully it was just a few days because my entire trip was upended by it because I couldn't be more than a few steps from a toiler for basically 48 hours. Even after that I needed to be careful lest I end up yakking up my guts in the middle of the street in public.
Over the past 2 decades I almost never get an upset stomach and talking to other people including expats that live in areas that are known to contain food poisoning danger, this is something that just takes some time and you build up bacteria or something in your guts that make you immune to it. I have no idea if this is true but it does seem to be the case with almost everyone I have met over the years.
The street food scene is where you are going to find what I consider to be the most iconic food of travel anywhere you go in the world. This is also where the lack of running water and proper cleaning facilities are most likely to attack your stomach. Much of the time (according to a nurse friend of mine) the "food poisoning" isn't actually coming from the food anyway but rather, from the hands of the person who is handling the dishes as they do not wash their hands very frequently.
This is something to be concerned about if you are new to travel and I have seen many people get laid out with bad guts for days or longer because of something as innocent as a fried rice on the street. Mostly people tend to be on the lookout for poorly cooked shellfish or chicken and this is wise but according to my medical pal, almost all food poisoning isn't actually because the food is bad. In fact, she said that most food poisoning incidents just consist of someone handling raw food in one minute and then handling cutlery or cooked food immediately after. You take that food not knowing and accidentally eat something raw that you can't even taste. This bacteria ends up reeking havoc on your insides.
Been there, done that!
One thing i noticed as I started traveling most of the year and working on the go in various countries was that I stopped getting sick all of a sudden after a few years. I don't think this is because the food-handling situation changed nor the quality of food. I have always been someone that gravitates towards street food because it is the best place to experiment with local flavors without getting a huge bill at the end.
While I have no proof of this being the case, I think that I have actually built up an immunity to mild food poisoning over the years. A lot of my traveling friends and expats that live around the world say the same thing. This is likely why the populations in these countries continue to eat at street vendors because imagine if the locals were getting poisoned left and right? They would probably stop eating at these spots, right?
I would imagine that I have been "poisoned" just as much in the past 7 years or so as I was right at the start, but my body just knows how to fight it now. Again, I have no idea if this is a fact or not but I can't argue with my own experience. I haven't changed anything about how I travel and eat, I think my body has changed for me!