thinning of the blood is for the high altitude, not prevention of diarrhea. The subject is more about the high altitudes and not diarrhea, I just mentioned that I take and always have taken pepto bismol when I visit certain third would countries for a short period of time.
My doctor years ago told me to take pepto bismol for prevention, which was before there was internet. So when I started to travel again I googled it, to make sure there were some truth and almost everywhere I read it says it prevents 65% of the time.
This article says 65% prevention as what I see over and over and that pepto bismol removes harmful bacteria from the stomach.
Here's another article from aafp with a reference where the 65% study came from.
I can tell you I have been to places that more than half of the people I go with get really bad diarrhea, while I've never had an issue. Not coming to the conclusion that pepto bismol is the reason, but going on a trip once every few years I feel safer sticking to what has been working for me so far.
If you go to risk factors on this link it covers physically fit, age...etc
I exercise 5-6 days a week and I don't think I have a problem running or with my lungs at all, since I exercise/run often. My wife does have ashma, but after googling for awhile it appears if anything people with ashma do better with higher alltitudes, which I'm not sure completely why.
I was thinking about getting on this product before going to see if it might help prevent anything.